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Hadrosaurid social structure is still poorly understood. Evidence from bonebeds suggests that juvenile individuals of some hadrosaurid species lived apart from herds composed of older individuals, a phenomenon called age segregation. However, the timing at which juvenile individuals became segregated and later rejoined a multigenerational herd is unknown. Three monodominant bonebeds that preserve the remains of multiple individuals of the lambeosaurine hadrosaurid Hypacrosaurus stebingeri at different ontogenetic stages offer an opportunity to better understand the social structure of this species: the Devil's Coulee juvenile hadrosaur bonebed (JBB) from the Oldman Formation of Alberta (Canada) preserves a minimum of four similar-sized late juvenile individuals; the Blacktail Creek North (BCNB) bonebed from the Two Medicine Formation of Montana (USA) preserves a minimum of 23 early juvenile (previously referred to as "nestling") individuals; and the Lambeosite (LB) bonebed preserves four similar-sized late juvenile individuals and one adult individual. These bonebeds show uniform taphonomic signatures throughout their respective bone assemblages, characterized by little to no weathering and abrasion, uniform style of fracturing, and rare tooth marks on bones. All three bonebeds are interpreted as mass-mortality assemblages. Histological data indicate that the late juvenile individuals from the JBB were three years old at the time of death, similar to the slightly larger late juvenile individuals from the LB, whereas the early juveniles from the BCNB had not yet reached 1 year of age. A taphonomic comparison of the three bonebeds reveal that H. stebingeri individuals lived in age-segregated groups, likely cohorts, until into their fourth year of life when, after having reached sexual maturity, they rejoined a multigenerational herd. The smaller number of individuals preserved in bonebeds representing later ontogenetic stages could reflect a decrease in group size due to high juvenile mortality rate or to higher metabolic needs. • Two Hypacrosaurus stebingeri bonebeds preserve segregated groups of individuals. • Hadrosaurs were segregated according to their age until their fourth year of life. • The size of segregated groups appears to decrease with late ontogenetic stages. [ABSTRACT FROM AUTHOR]

Climate and environments have undergone significant changes throughout the Earth's history, which are reflected in the faunal record. In that sense, small mammals provide valuable palaeoecological insights due to their close relationship with their associated environments. Our research investigates the dynamics of small mammal communities in the Iberian Peninsula from the Late Pleistocene to the Holocene, comparing regional environmental variations as well as anthropogenic impacts. Our review of the small mammal assemblages from 26 archaeological sites across the Iberian Peninsula revealed a differential response of the small mammal communities between the northern and southern areas. The colder climatic conditions which characterized the Late Pleistocene favoured the presence of mid-European species (e.g., Alexandromys (Oecomicrotus) oeconomus, Chionomys (Chionomys) nivalis) in northern regions until the Mid Holocene, while other taxa today restricted to northern Iberia (e.g., Arvicola amphibius, Microtus gr. (Euarvicola) arvalis, Sorex araneus-coronatus) reached southern regions during the Last Glacial Maximum but disappeared at the beginning of the Holocene period. Palaeoenvironmental reconstructions indicate predominantly open landscapes and colder climates in the Late Pleistocene, with increased forest cover during the Early-Mid Holocene in northern areas. In contrast, the southern regions exhibited more stable environments compared to the northern ones. Our results underscore how the great environmental diversity and interactions between natural and anthropogenic factors affected the composition of Iberian small mammal communities during the last 20,000 years. Most specifically, during the Late Holocene, biogeographical patterns of the small mammals are mostly affected by anthropic activities, with changes in the distribution of some species (Microtus (Iberomys) cabrerae), and the entrance of new ones (synanthropic species). • Regionalization in the response of small mammals to climate change in the Iberian Peninsula. • Northern small mammal communities were more sensitive to climate changes. • Southern areas reveal minimal changes in small mammals since the Late Pleistocene. • Important landscape shift during the Late Holocene for the entire Iberian Peninsula. • Human activities, not climate, shaped small mammal communities since Mid Holocene. [ABSTRACT FROM AUTHOR]

Various predators are known to have ubiquitously contributed to the accumulation of fossil microvertebrate assemblages in Quaternary depositional settings. Deciphering the taxonomic identity of the predator responsible for each such assemblage through detailed taphonomic analysis has become a prerequisite for paleoecological research to gain insight into their prey and foraging habitat preferences. However, this flourishing field of research builds on the assumption that the pristine taxon-specific taphonomic signal of various predators could have become preserved in the fossil record, unbiased or only negligibly biased by a wide array of destructive post-depositional processes, which could introduce noise into the preservational system. Here we evaluate the likelihood that the predator taphonomic imprint could have been entirely obliterated by such post-depositional action within an especially large assemblage of the remains of micromammals (Rodentia, Eulipotyphla, and Chiroptera; N = 25,810) from Middle Paleolithic Layer C of Tabun Cave, Mount Carmel, Israel. The microfauna from this major stratigraphic unit (c. 2.5 m thick; uniquely yielding the fossils of both Homo sapiens and Neanderthals), with a mean chronometric age of c. 165 ka, has no contemporary analogues in the regional record, indicating exceptional paleoecological conditions for its timespan. We took advantage of the fact that Layer C (aka a major stratigraphic unit) was subdivided in more recent excavations into as many as 26 separate layers (aka beds), featuring relatively nuanced differences in sedimentary, diagenetic, and anthropogenic characteristics, to both independently assess the possibility that Layer C as a whole is isotaphonomic and evaluate the extent of taphonomic variation from bed to bed within it. While substantial variation and bias were revealed in a broad array of standard taphonomic indices of skeletal element fragmentation and differential representation, one index—the grading of digested molars according to the severity of digestion—proved robust against post-depositional distortions of the predatory signal. We discuss the implications of these findings for reliable taphonomic and paleoecological assessment in research with microvertebrate fossil remains. • Taphonomy of a large assemblage of Middle Paleolithic microvertebrates analyzed. • Variation in multiple taphonomic indices evaluated through one thick layer. • Most taphonomic indices demonstrated wide error ranges and low diagnostic value. • Molar digestion grading proved robust for identifying the accumulating predator. • Reliable and economic taphonomic assessment of microvertebrate remains discussed. [ABSTRACT FROM AUTHOR]

The aim of this work is to examine the rodent exploitation strategies employed by the human groups that occupied the Dry Puna of Argentina during the Early and Mid-Holocene. We analyze the characteristics of the archaeological bone assemblages and present stable isotope compositions of Chinchillidae remains recovered in two Puna sites dated between 10,600–5200 years BP. Since rodent population dynamics and diets are largely reliant on local resources given their reduced spatial range, these results provide new valuable information to explore local environmental conditions in the past and how these influenced the rodent exploitation strategies employed by the hunter-gatherers that inhabited this area during the Early-Mid Holocene transition. Thus, this work presents detailed zooarchaeological data as well as δ 13C VPDB and δ 15N AIR values measured on bone collagen extracted from Lagidium sp. and other chinchillid remains recovered at Hornillos 2 and Inca Cueva 4, two archaeological sites dating to this period. These results are compared with the δ 13C VPDB and δ 15N AIR values measured on modern plants collected in the vicinity of both sites to address rodent dietary change through time as well as human procurement strategies. Our results show certain continuities for the Early-Mid Holocene transition, underlining the importance of areas such as Inca Cueva and Hornillos for past human groups, given the consistent availability of key resources for subsistence. • Past rodent exploitation strategies are studied in the Dry Puna of Argentina. • Chinchillids were an important resource during the early and mid-Holocene. • Zooarchaeology and stable isotope analysis are combined to achieve new results. • Results show continuities between early and mid-Holocene human occupations. • The areas studied were used as refugia within a changing environment. [ABSTRACT FROM AUTHOR]

The impact of Late Pleistocene climatic oscillations, volcanism and the diverse terrain of the Armenian Highlands affected hominin population dynamics and movements through the region. To test different scenarios for the period 50–25 ka regarding expansion, adaptive response, intra-population interactions and extinction, we need local on-site paleoclimatic data found in association with hominin occupations. However, this approach has been hampered by the dearth and highly uneven spatiotemporal recovery of paleoclimatic data from prehistoric sites across the region. In this study, we analyze multiple assemblages of fossil micromammals from the Late Middle Paleolithic (LMP) Lusakert-1 rockshelter (two fossil-yielding strata; <55 ka) and Early Upper Paleolithic (EUP) Aghitu-3 Cave (four fossil-yielding strata; ∼39–24 ka) using geometric morphometric-aided taxonomy, to quantify the representation of different species among the abundant and diverse arvicoline genera (Microtus and Chionomys ; mean = 58% of assemblages). We combined this approach with quantitative species-level paleoclimatic reconstructions (Bioclimatic Model; 14 rodent taxa) to determine changes in habitat composition as well as temperature and precipitation shifts during the Late Middle–Early Upper Paleolithic. Taphonomic analysis was conducted to establish isotaphonomy among the assemblages. The analysis shows higher than present-day absolute temperatures for the series of occupations at both Lusakert-1 and Aghitu-3, making it unlikely that hominin activity at the sites coincided with extreme cold-climate phases. A multivariate comparison of the taxonomic abundances (genus level) across a wider sample of regional Middle Paleolithic (MP) and Upper Paleolithic (UP) cave sites (Hovk-1, Kudaro-1, Mezmaiskaya, Satsurblia and Dzudzuana) indicates the possibility of cold-period occupation at only two of the sites, Mezmaiskaya Layers 3 and 2 and Kudaro-1 Layer 3. We surmise that the manufacturers of LMP lithic industries in the Caucasus were well adapted to these challenging environments, thus undermining arguments that rapid climate change through the LMP/EUP period could alone have determined the course of population dynamics in this region. • Microfauna proxies enable direct site-to-site climate comparison. • Rodent taxonomy was improved through the Geometric morphometrics. • Interdisciplinary approach characterizes paleoecology in Lusakert-1 and Aghitu-3. • Higher temperatures observed in Lusakert-1 and Aghitu-3 than present-day. • Multivariate analysis suggests limited cold-period occupations in the region. [ABSTRACT FROM AUTHOR]

During the Early Jurassic, the shallow marine carbonate platforms of the western-Tethys margins were characterized by highly diverse benthos including larger foraminifera, sponges, bivalves, gastropods, brachiopods, echinoderms, and dasycladalean calcareous algae. In this paper, we document examples of such assemblages within the lower Pliensbachian part of the Rotzo Formation (upper Orbitopsella Zone) of the Southern Alps, Italy. This carbonate succession was deposited in a complex mosaic of marine and brackish habitats within a tropical lagoon of the Trento Platform area. Large terebratulide brachiopod shells form autochthonous accumulations comprising exceptionally well-preserved monospecific assemblages of Lychnothyris rotzoana. These brachiopod-bearing successions were analysed in terms of biotic components, microfacies analysis, shell biofabric (three-dimensional arrangement of skeletal elements), and taphonomic signatures to understand brachiopod response to changing conditions within a highly variable lagoonal palaeoecosystem. Findings show that terebratulide shell accumulations are dominated by adult specimens and juveniles are rare. The brachiopods thrived during low energy conditions that resulted in the accumulation of highly temporally-condensed shell beds. Stabilized by microbialite encrustations, the shells were not re-oriented during the subsequent rapid burial. The abrupt demise of these communities was possibly related to rapid environmental change, and causal factors are discussed. The medium-term response of brachiopods to the relatively instable ecosystem of the tropical lagoon shows that they were not able to adapt to continuous perturbations, and that continuing stress severely compromised the resilience of benthic taxa. • Large terebratulide brachiopods thrived in Pliensbachian lagoonal settings. • Autochthonous accumulations with abundant adults and rare juveniles. • Accumulations grew under low sedimentation rate and low hydrodynamic energy. • Stabilized by microbialites shells underwent to rapid burial and early lithification. • Unpredictable environmental changes brought about the demise of the community. [ABSTRACT FROM AUTHOR]

A rich insect fauna is found in the Cretaceous (Aptian) Nova Olinda Member of the Crato Formation in the Araripe Basin, northeastern Brazil. The Crato Formation was deposited close to the centre of the supercontinent Gondwana, prior to significant rifting. In this paper, we analyzed remains of 1135 insect specimens, representing 55 families, within two limestone facies of the Nova Olinda Member: pale yellow and dark gray limestones. We collected taphonomical data and assessed the paleoecological significance of insect faunas in terms of their distribution and interaction with the paleoenvironment. The insect fauna is dominanted by fully terrestrial taxa despite preservation in an aquatic paleoenvironment. Considering both facies, the distribution of insect families is similar throughout the Nova Olinda Member, which excludes possible overlapping of one entomofauna over another. The pale yellow limestones near the top of the section are richer in fossil insect content and show a higher incidence of aquatic and semiaquatic insects preserved in dorsoventral view compared to the dark gray limestones. This suggests that the Crato insects preserved in the pale yellow limestones experienced short transport distances or prolonged decay or both. In contrast, insects preserved in the dark gray limestones appear proportionally with higher degrees of disarticulation than those preserved in the pale yellow limestones, indicating that these insects underwent a higher degree of postmortem transport in the biostratinomic stage. Compared to descriptions of other Early Cretaceous assemblages, the taxonomic literature of Crato Paleoentomofauna shows distinct differences. The Yixian and Zaza formations are described as being dominated by beetles and wasps. The Crato Formation, however, is relatively richer in Paleoptera species. Both the sedimentary facies studied and the paleoentomological content reveal a complex ecosystem inserted in a depositional setting, similar to modern long-standing wetlands, and where periodically flooded zones were surrounded by dry lands with xeromorphic vegetation. • Crato insects preserved in the dark gray limestones appear proportionally with higher degrees of disarticulation. • The paleoentomological content reveals an ecosystem inserted in a setting similar to modern long-standing wetlands. • Compared to other Early Cretaceous assemblages, the Crato Paleoentomofauna is relatively richer in Paleoptera species. [ABSTRACT FROM AUTHOR]

Sampling bias and repeated resampling can lead to misinterpretation of the taphonomic history of a fossiliferous deposit. This is the case of the Schoenstatt Sanctuary site (Santa Cruz do Sul, Rio Grande do Sul, Brazil), the type-locality and richest vertebrate fossil occurrence of the early Carnian Santacruzodon Assemblage Zone (Santa Cruz Sequence, Santa Maria Supersequence, Paraná Basin). This site is characterized by the abundance of traversodontid non-mammalian cynodonts, especially Santacruzodon hopsoni and Menadon besairiei (plus Massetognathus ochagaviae). The abundance of cranial remains in a 2.5 m-thick massive mudstone led earlier workers to conclude that the accumulation was biogenically controlled (e.g., selective scavenging). Here we propose a new taphonomic interpretation, based on re-investigation of >2700 fossils, collected at the site over the past 27 years. Rhizoliths and early diagenetic features (e.g., micrite crusts) indicate the occurrence of several pedogenically modified levels within the outcrop. This occurrence of multiple calcic vertisols, added to the absolute dating already obtained for the Santa Cruz Sequence, may be related to the global Carnian Pluvial Event. Re -analysis of the historical fossil collections from this site provides the basis for a biostratigraphic division of Massetognathus (lower strata), Menadon (lower and middle strata) and Santacruzodon (upper strata), leading to a three-fold sub-zonation of the assemblage zone (AZ). The taphonomic mode of some Menadon skeletons suggest they were scattered by floodwaters, while burrowing and co-habitation behaviours are indicated for Santacruzodon. The revision led also to identification of at least 12 new non-cynodont morphotypes, including kannemeyeriiform dicynodont (already known for the AZ), archosauriform, rhynchosaurian and procolophoid taxa, increasing the faunal diversity of outcrop and Santacruzodon AZ. • Taphonomic revision of the Santacruzodon AZ type-locality. • Rhizoliths and diagenetic features indicate multiple depositional events. • Possible three-fold sub-zonation for this AZ. • Evidence for burrowing and gregarious behaviour in Santacruzodon. • First occurrences of rhynchosaurs and procolophonoids in Santacruzodon AZ. [ABSTRACT FROM AUTHOR]

Unmineralized tubular remains with variable morphology and preservability are common in Ediacaran and Cambrian rocks, providing important records of early animal evolution. Here we report a new occurrence of such fossils in the Soltanieh Mountains of northwestern Iran. A large, densely packed tube population is present in the lowermost part of low-energy, outer shelf mudrocks of the Fortunian Upper Shale Member (USM) of the Soltanieh Formation in the Jashn Sara section. Morphologically, these tubes are unbranched and straight to sinuously curved, with uniform diameters of 0.8–1.1 mm and lengths up to 34 mm. The fossils are preserved as orangish to cream-colored structures with low positive relief. X-ray diffraction and SEM-EDS reveal that Soltanieh tubes were largely infilled by variable mixes of pyrite framboids (and their oxidation products), silica, and clay minerals. In contrast, the sediment matrix is dominated by K-Al-silicate with lesser amounts of an Al-oxide/(oxy)hydroxide phase. The abundance of pyrite in the tubes indicates a prominent role for sulfate-reducing bacteria in the post-mortem decay of organic materials within the tubes, and abundant chert along the tube's inner margins further indicates the propensity of silica to precipitate on relatively recalcitrant organic structures. While the newly discovered population shares features in common with Sabellidites cambriensis , known from Terreneuvian strata in northern Europe and Avalonia, the Iranian fossils do not preserve the transverse annulations characteristic of Sabellidites walls. With this in mind, we leave our new population in open nomenclature. Nonetheless, the occurrence of abundant organic-walled tubes in the USM of the Soltanieh Formation adds to both the diversity of animal fossils found regionally in Terreneuvian rocks and the broader paleogeographic distribution of tubular metazoans in early Cambrian oceans. • Newly discovered tubular fossils from Fortunian mudrocks in Iran. • Preservation by early diagenetic pyrite and silica emplacement with later oxidation. • Key beds for stratigraphic integration of shelly, unmineralized, and trace fossils. • Faunal similarities among Gondwana, Baltica, and Avalonia in the earliest Cambrian. [ABSTRACT FROM AUTHOR]

Gorgonopsians were the dominant carnivores of the late Permian (Lopingian) and it is widely accepted that the clade became extinct at the Permian-Triassic boundary, almost 252 million years ago. However, South African collections house three historically-collected gorgonopsian specimens listed as Early Triassic in age, based on their discovery at localities producing the index fossil Lystrosaurus. Initial reports suggested that these specimens had been reworked from underlying Permian strata, but this possibility was never thoroughly addressed. The possible survival of gorgonopsians into the Triassic would significantly alter our understanding of the end-Permian mass extinction and post-extinction ecosystem dynamics. Here we use Synchrotron X-ray micro-computed microtomography to confirm the identifications and investigate the taphonomic histories of these three specimens. We also relocated the original localities to determine their stratigraphic position. We confirm that all three specimens are indeed gorgonopsians, belonging to the small-bodied genus Cyonosaurus , and that taphonomic assessments do not support reworking. Two of them can be confidently assigned to the latest Permian Lystrosaurus maccaigi-Moschorhinus Subzone of the Daptocephalus Assemblage Zone. In contrast, at the locality listed for the third specimen, NMQR 389, the lowermost outcropping strata belong to the upper Palingkloof Member of the Balfour Formation, which is Early Triassic in age. Despite the evident absence of Permian-aged rocks, other Permian fossils were reported from the same locality, thus casting doubts about the age of NMQR 389. Additionally, differences in preservation style between this skull and the newly collected material at the site cast doubt on its provenance. Although not supporting gorgonopsian survival into the Triassic, these new occurrences expand the range of the genus Cyonosaurus higher up in the extinction zone, increasing the complexity of the ecological turmoil that carnivores endured during "The Great Dying". [Display omitted] • Gorgonopsians became extinct at the Permian-Triassic boundary, but three skulls from South Africa were reportedly found in the Early Triassic. • The taphonomical analysis of all three specimens does not support reworking, unlike what was hypothesized by prior authors. • Study of the provenance localities indicate that two specimens are from late Permian strata. • The third Cyonosaurus specimen may have been mislabelled. [ABSTRACT FROM AUTHOR]

Vertebrate assemblages from the mid-Cretaceous (Albian-Cenomanian) Wayan Formation of Idaho and Vaughn Member of the Blackleaf Formation of Montana are dominated by the small burrowing dinosaur, Oryctodromeus cubicularis. Specimens can be assigned to three distinct taphofacies dependent on degrees of skeletal articulation and associated lithofacies. Taphofacies A comprises mostly to fully articulated specimens in bioturbated sandstones. Taphofacies B comprises partially articulated to associated collections of skeletal elements in pedogenic mudstones, siltstones, and fine-grained sandstones. Taphofacies C comprises isolated skeletal elements within the debris-flow deposit of the Robison Bonebed. Except for one associated nodosaur skeleton, Oryctodromeus is the only vertebrate represented by significant associations of skeletal elements or portions of articulated skeletal elements within the Wayan Formation/Vaughn Member units, and occurrences represent a paleocommunity dominated by a small cursorial and fossorial vertebrate. The co-occurrence of multiple individuals, representing presumed juvenile and adult growth stages, reinforce previous suggestions of parental care in this species. In addition, newly reported Oryctodromeus burrows compare in overall morphology and size with the burrow containing the holotype of Oryctodromeus. These data suggest the possibility that evidence for additional fossil taxa having had a communal and fossorial lifestyle may be discerned through further focused taphonomic investigations. [ABSTRACT FROM AUTHOR]

The Yanliao Biota contains numerous exceptionally preserved fossils of evolutionary importance. However, the palaeoenvironment of this biota has not been fully studied. Here we present the first taphonomic and palaeoecological analysis of fossil abundance data from two newly excavated sites in the Daohugou area. In our study we have investigated the taxonomic composition, specimen abundance and size distribution patterns of invertebrate palaeocommunities, and corresponding taphonomic features, such as completeness, articulation and fossil orientation. Our results show that abundant aquatic and terrestrial organisms from various ecological niches are preserved in very thinly planar-laminated mudstone. Aquatic organisms of the two excavations are represented by low-diversity but high-density assemblages containing four species: the clam shrimp Triglypta haifanggouensis , the mayfly nymphs Fuyous gregarious and Shantous lacustris , and the water boatman Daohugocorixa vulcanica. Triglypta haifanggouensis dominates the fauna with carapace lengths ranging from 1.34 mm to 5.62 mm. Size distributions of different bedding planes vary between normal, bimodal and polymodal, implying multiple causes of death: reproductive senescence, and mass mortality events related to active volcanism or to rapid environmental fluctuations within the lake. Generally calm depositional conditions were repeatedly interrupted by weak currents, indicated by preferred plan-view orientations of aquatic insects on four out of nine investigated bedding planes. Changes in the community composition of aquatic arthropods relate to varying lake depth through time, or to different dispersal strategies after community breakdown. Terrestrial insects are highly diverse but less abundant. As a result of rapid burial, 49.8% of which are almost complete and articulated. The flora surrounding the comparatively shallow lake was rich, picturing a thriving forest-like ecosystem with moisture relation in a warm-temperate climate. • Aquatic and terrestrial animals from various niches are preserved in same horizons. • Aquatic arthropods are characterized by low diversity and high to medium abundance. • Terrestrial insects are characterized by high diversity but low abundance. • Terrestrial insects are well-preserved and articulated as a result of rapid burial. • Mass mortality events triggered by volcano eruptions may have frequently occurred. [ABSTRACT FROM AUTHOR]

Island Southeast Asia (ISEA) is a key region for the study of human evolution. New fossil and archaeological evidence, from several islands, suggests an Early to Middle Pleistocene colonisation date by hominins. A taphonomic framework, however, such as that exists for Africa, is currently lacking, and taphonomical studies of ISEA vertebrate assemblages are very limited. In this paper, we apply multifocus and confocal microscopy to surface modifications on an Early to Middle Pleistocene avian assemblage from Mata Menge, in the So'a Basin of central Flores, Indonesia, with the aim of characterizing material and testing the relevance of 3D reconstructions to study the taphonomy of ISEA bone assemblages. Our observations document a number of bone surface modifications, including individual parallel grooves, overlapping spindle-like striations, elongated impacts, short composite grooves, and rows of pits. These features suggest that several taphonomic agents were at play during and after the accumulation of the Mata Menge small vertebrate assemblage. We find no unambiguous evidence for the exploitation of birds by the So'a Basin hominins, or for hominins being a significant accumulating agent of avian remains at Mata Menge. However, our work should be seen as preliminary, as direct comparative data on relevant biological agents are lacking. The markedly distinct faunal composition and climatic regimes of many Southeast Asian islands, and the potential use of different tools by hominins, warrants the development of a comprehensive taphonomical framework that is specifically relevant for ISEA. • A taphonomic framework for bone assemblages from Insular Southeast Asia is lacking. • We apply 3D microscopy to an avian bone assemblage from Mata Menge, Flores. • We document a number of intriguing bone surface modifications. • This suggests a role for several taphonomic agents during or after accumulation. • We find no unambiguous evidence for exploitation of birds by So'a Basin hominins. [ABSTRACT FROM AUTHOR]

Lower Jurassic larger bivalves, mostly represented by the monospecific lithiotid genera Lithiotis , Cochlearites and Lithioperna , formed large shell accumulations in the shallow-water carbonate Tethyan and Panthalassa margins. A quantitative analysis of lithiotid accumulations from the Trento Platform (northern Italy) was carried out in order to distinguish the distribution of autochthonous, parautochthonous and allochthonous lithiotids in the accumulation core and flanks. Various representative accumulations are characterized with respect to systematic content, shell cover, shell density, disarticulation, shell fragmentation and orientation of individual shells. Lithioperna shows a high shell cover within the accumulation core while that of Cochlearites is variable and Lithiotis is rare. All three lithiotids occur in high densities in the accumulation flanks. As expected, autochthonous individuals of all three genera are frequent in the accumulation cores where they are preserved in life position. In the flanks, most bivalves are parautochthonous except for Lithioperna which can grow in life position. All bivalves in allochthonous shell beds are highly fragmented and disarticulated. The studied traits are potentially useful as proxies for distinguishing core or flank facies when the accumulation does not crop out as a whole. Unlabelled Image • Following the end-Triassic extinction, Pliensbachian lithiotids formed shell accumulations. • Shell fabric and taphonomic attributes differ for the lithiotid monospecific genera in the accumulations. • Autochthonous individuals preserved in life position occur in the accumulation core. • Parautochthonous individuals dominated in the accumulation flanks. • Transported allochthonous shells occur on the bottom of the lithiotid accumulations. [ABSTRACT FROM AUTHOR]

Factors affecting cetacean preservation and distribution in ancient sedimentary successions are not well understood. Actualistic studies have focused on coastal and deep marine examples, and little is known about taphonomic processes occurring within shelf environments. In this paper, we integrate sedimentological, taphonomic and palaeontological data for the cetacean-bearing lower Miocene Gaiman Formation from Patagonia, Argentina, to analyse which factors affected the distribution and preservation of cetaceans in several localities of the Southwestern Atlantic. Facies analysis shows that the formation represents a transgressive-regressive stratigraphic cycle, with palaeoenvironments including coastal, storm-dominated shoreface, inner shelf embayment and open inner shelf. Cetacean remains show preservation styles varying from isolated elements to articulated specimens, with nearly all remains restricted to both embayment and open marine inner shelf settings. Two fossil cetacean assemblages are recognized: Assemblage A comprises small-sized odontocetes dominated by Platanistoidea, preserved mostly in inner shelf embayment deposits; and Assemblage B comprises large-sized odontocetes and mysticetes, dominated by Physeteroidea and Balaenopteroidea, preserved mostly in open inner shelf deposits. Cetacean preservation style is controlled by a combination of palaeoenvironmental conditions, such as energy and sedimentation rate, and by biological factors, such as cetacean body plan and its impact on carcass buoyancy. Ecological factors may also explain the stratigraphic distribution of cetaceans between coastal and oceanic assemblages. This novel integrative and multidisciplinary analyses improves our knowledge of cetacean taphonomy in shelf environments. • Four coastal and shelf marine facies are identified for the lower Miocene Gaiman Formation of Argentina. • Cetaceans are mostly recorded in inner shelf deposits. • Cetacean preservation style is controlled by environmental and biological factors. • Cetaceans distribution is mostly controlled by palaeoecological factors. [ABSTRACT FROM AUTHOR]

Since the 1980s an intense scientific debate has revolved around the hunting capacities of early hominin populations and the behavioral patterns of carnivores sharing the same ecosystem, and thus competing for the same resources. This debate, commonly known as the hunter-scavenger debate, fostered the emergence of a new research line into the Bone Surface Modifications (BSMs) produced by both taphonomic agents. Throughout the following 20 years, multiple studies concerning the action of carnivores have been developed, with a particular focus on the oldest archaeological sites in East Africa. Recent technological advances applied to taphonomy have provided new insight into carnivore BSMs. A newly developed part of this work relies on Geometric Morphometrics (GMM) studies aimed at discerning carnivore agency through the morphologic characterization of tooth scores and pits. GMM studies have produced promising results, however methodological limitations are still present. This paper presents the first combined application of Machine Learning (ML) algorithms and GMM to the analysis of carnivore tooth marks, generating classification rates of 100% between carnivore species in some cases. • A combination geometric morphometrics and machine learning for tooth mark analysis • This statistical approach can obtain up to 100% classification of carnivore agencies. • This presents significant statistical advances in bone surface modification analysis. • New statistical approach for morphological analysis [ABSTRACT FROM AUTHOR]

Abstract Massive coralla representing the tabulate coral Agetolites occur on a lime mudstone bed in the Upper Ordovician Xiazhen Formation of southeastern China. Other fossils include solitary rugose corals, bryozoans, trilobites, and mollusks. In addition, abundant spicules and spicule networks suggest that sponges were widespread. The occurrence of intact, unabraded fossils in micritic matrix and the absence of high-energy sedimentary structures indicate deposition in low-energy conditions. Thin section analysis of disoriented specimens demonstrates that geopetal indicators are consistent with stratigraphic "up" and differ from the growth axes of the corals, implying that geopetal infillings formed after disorientation. The growth axes of coralla were not redirected during life, suggesting that the corals were either dead at the time of disorientation or died as a result of disorientation. An examination of cyclomorphism indicates that the corals died at different times, rather than during a single event. A close association between sponges and corals is suggested by the presence of spicule networks in calices and intracorallum spaces of Agetolites. It is hypothesized that disorientation of corals was related to growth on biodegradable substrates. We suggest that many coral larvae settled on sponges that formed "sponge meadows". Disorientation of the resulting corals may have occurred when (1) a host sponge could no longer support the weight of a coral and collapsed, (2) increasing weight or imbalance of a coral caused it to fall off the sponge, or (3) a coral became detached when the sponge died and decomposed. If the coral was alive, sudden deposition in a disoriented position within muddy sediment resulted in its death. Disorientation of massive skeletons, such as colonial coralla, is most commonly attributed to water energy. This study suggests that ephemeral substrates may have been involved in some cases. Highlights • Massive skeletons of tabulate coral Agetolites were disoriented in lime mudstone bed. • The lime mudstone bed lacks any evidence of high-energy conditions. • Previously suggested causes of disorientation are inconsistent with present case. • "Sponge meadows" may have formed ephemeral substrates supporting these corals. [ABSTRACT FROM AUTHOR]

Abstract Bromalites (coprolites and possibly some cololites) from a turtle-dominated fossil assemblage from the Upper Triassic of Poland were studied. Bromalites collected at the Poręba site are grouped within four morphotypes (A, B, C, and D) attributable to sharks, medium-sized omnivorous or carnivorous tetrapods (likely turtles), sizable carnivorous archosaurs (likely theropods) and an indeterminate big herbivorous tetrapod (possibly dicynodonts or aetosaurs), respectively. Food residues, abundant eggs (possibly of parasites), and microorganisms were found within the materials. Several lines of evidence suggest that at least part of the type B specimens might have been produced by turtles, since (a) turtles are the prevailing tetrapods in the assemblage (over 4/5 of tetrapod bone remains), (b) coprolites are of adequate size, and (c) they appear to have been produced by a carnivore of a low metabolic rate, as seen in extant turtles. The content of the type B specimens would imply that the Late Triassic turtle Proterochersis porebensis was partly piscivorous, but possibly complemented its diet with a more diversified foodstuff, including plants. Semiaquatic habit of Proterochersis porebensis might also provide a taphonomic explanation of the relative abundance of turtle remains at the Poręba site, Poland. Shark bromalites and coprolite specimens attributable likely to theropod dinosaurs also contain abundant fish remains. Origin and classification of spiral and scroll bromalites left by fish are discussed in addition. Graphical abstract Unlabelled Image Highlights • Studied coprolites provide information on a turtle-dominated Late Triassic ecosystem. • Coprolites were produced by sharks, turtles, theropods, and a sizable herbivore. • Carnivores fed predominantly on fish in this fluvial environment. • The turtle Proterochersis porebensis was likely omnivorous and semiaquatic. • Life habits of early turtles were similar to those typical of extant taxa. [ABSTRACT FROM AUTHOR]

Abstract The action of predators, such as diurnal raptors, owls, mammals or humans, influence the nature of small vertebrate fossil assemblages but currently their taphonomic features are still poorly understood. In this study, we investigate the taphonomic signature of the snowy owl (Bubo scandiacus) based on an analysis of pellets collected at breeding sites located in Greenland and the Canadian Arctic. This taxon is widely distributed through the North Hemisphere and was an important predator in Pleistocene times. Taphonomic parameters suggest that, contrary to previous assumptions, B. scandiacus produces, on average, moderate digestion of incisors, molars and post-cranial elements, and should be classed as a Category 3 or Category 3/4 predator according to the terminology established by Andrews. Significant inter-site variability was observed for some of the damage considered (in particular, digestion on incisors), and a key finding is that variability and the associated statistical confidence intervals are crucial notions that should be taken into account when assessing taphonomical features, in order to reliably identify the potential predator(s) responsible for small vertebrate fossil accumulations. Highlights • Taphonomical features of Bubo scandiacus were investigated from three nest sites. • Inter-site and inter-study variabilities were observed on taphonomical features. • Snowy owl produces moderate digestion of incisors, molars and postcranial elements. • This predator must be classed as a Category 3 or Category 3/4. • Variability and associated statistical confidence intervals are crucial notions. [ABSTRACT FROM AUTHOR]

Abstract Spatial patterns in centennial-scale variations of the East Asian summer monsoon (EASM) during the Holocene are poorly constrained due to the lack of high-resolution records with detailed chronologies, especially in southern China. Here we present high-resolution (~35-yr) proxy records spanning the last 7500 years from a well-dated sediment core (YJ Core) from the northern inner shelf of the South China Sea. Al, Ti and Fe variations were employed as indicators of terrigenous influx and K/Al ratios were used as a tracer of chemical weathering to document variations in the intensity of the EASM. The results show a series of centennial-scale weak EASM events, which are generally synchronous with those inferred from other geologic archives from monsoonal regions in the eastern and southern China. Moreover, these events are synchronous with periods of weak solar activity, and the spectral analysis demonstrates that the EASM and solar activity share some general cyclicity patterns. We therefore suggest that solar activity is a fundamental driving force for the spatial synchronisation of the EASM on centennial timescales across the monsoon region. Highlights • Terrigenous influx in the northern SCS was strongly influenced by the East Asian summer monsoon. • Weak EASM events during the Holocene may be associated with variations in solar activity. • Solar activity triggered the spatial synchronisation of the EASM on centennial timescales across the monsoon region. [ABSTRACT FROM AUTHOR]

Abstract The Middle–Upper Jurassic Yanliao Lagerstätte contains numerous exceptionally preserved fossils of aquatic and land organisms, including insects, salamanders, dinosaurs, pterosaurs and mammaliaforms. Despite extensive study of the diversity and evolutionary implications of the biota, the palaeoenvironmental setting and taphonomy of the fossils remain poorly understood. We reconstruct both the palaeoenvironment of the Daohugou area (one of the most famous Yanliao fossil areas), and the biostratinomy of the fossils. We use high-resolution stratigraphic data from field investigation and excavations to document in detail the stratigraphic succession, lithofacies, facies associations, and biostratinomic features of the Lagerstätte. Our results show that frequent volcanic eruptions generated an extensive volcaniclastic apron and lake(s) in the studied area. The frequent alternation of thin lacustrine deposits and thick volcaniclastic apron deposits indicates either that the studied area was located in the marginal regions of a single lake, where the frequent influx of volcaniclastic apron material caused substantial fluctuations in lake area and thus the frequent lateral alternation of the two facies, or that many short-lived lakes developed on the volcaniclastic apron. Most terrestrial insects were preserved in the laminated, normally graded siltstone, claystone and tuff facies that form many thin intervals with deposits of graded sandstone, siltstone and tuff in between. Within each interval the terrestrial insects occur in many laminae associated with abundant aquatic organisms, but are particularly abundant in some laminae that directly underlie tuff of fallout origin. Most of these terrestrial insects are interpreted to have been killed in the area adjacent to the studied palaeolake(s) during volcanic eruptions. Their carcasses were transported by influxes of fresh volcaniclastic material, primarily meteoric runoff and possibly minor distal pyroclastic flow into the palaeolake(s), and were buried in palaeolake deposits prior to extended decay probably due to a combination of rapid vertical settling, ash fall and water turbulence. Highlights • Frequent volcanic eruptions generated extensive volcaniclastic apron and lake(s). • Mass mortality of land animals occurred during volcanic eruptions. • Terrestrial animal remains were transported into lake(s) and rapidly buried. • Yanliao ecosystem was frequently disturbed by active volcanism. [ABSTRACT FROM AUTHOR]

Abstract Taphofacies of Malvinokaffric macroinvertebrate-bearing rocks from the uppermost Pragian to lower Givetian in southwestern Gondwana are evaluated. During the Lower/Middle Devonian, the Paraná Basin (southern Brazil) was positioned at high latitudes in southwestern Gondwana (60° to 80°S). Integrated litho- and taphofacies interpretations in siliciclastic environments presented here provide paleoecological and paleoenvironmental insights. The six taphofacies recognized here showed changing depositional conditions in paleoenvironments ranging from shoreface to offshore shelf settings. They vary in recurrence and abundance, but all facies exhibit evidence of storm events. Winter storms are to be expected at latitudes 60° to 80° S under cool climate zone. Storm-related taphofacies recurrence during the latest Pragian to early Givetian points to two agents of sedimentation, direct wave erosion by winter storms and sedimentary processes related to combined flow during deposition (e.g. turbidity currents and oscillatory flow). Winter storms are considered more capable of affecting sediment transport than hurricanes, due to longer duration and larger coverage area in higher latitudes. Therefore, winter storms of high latitudes should generate more persistent currents in space and time. Finally, the taphofacies, lithofacies and high-latitude paleogeographic context of the Paraná Basin suggest the action of storm-influence in the genesis of all Lower/Middle Devonian Malvinokaffric assemblages here recognized. Highlights • Taphofacies analysis suggest storm-influence on Devonian Malvinokaffric assemblages. • Similar preservational process are observed in analogous environments from Devonian strata. • Different latitudinal and climatic settings are expressed in bio-taphofacies pattern. • The storm-related taphofacies recurrence studied herein result from winter storms. [ABSTRACT FROM AUTHOR]

Abstract A new fossiliferous level from the Las Chacritas Member (Bajocian-Callovian) of the Cañadón Asfalto Formation, which crops out in the Cañadón Asfalto Basin (Extraandean-Chubut) Argentina was analyzed. The study of this assemblage was made on the basis of paleoecological, sedimentological and taphonomic criteria. This polytypic assemblage is composed mainly of bivalves, spinicaudatans, gastropods, and ostracods, associated with plant remains (such as Brachyphyllum sp., Charophytes, conifers, seeds, and indeterminate remains). The tabular bed of oncolitic packstone facies corresponds to a shallow marginal lacustrine environment of intense organic productivity. Taphonomic and paleoecological features, such as closed articulated valves, random orientation, and size-frequency histograms indicate that the fauna is autochthonous. The short life cycle with a quick turnover of the population, suggests that the time averaging would only comprise a few years. In addition, the analysis of Energy dispersive X-ray spectrometry supports early diagenesis affecting the remains and favoring the dissolution of aragonite/calcite, as well as the silicification of shells. Therefore, this fossil assemblage can be classified as a sedimentological concentration, which could have been originated by seasonal cyclicity in an environment subject to water level fluctuations. Highlights • Continental invertebrate concentration from the Middle Jurassic of Patagonia • Polytypic benthic assemblage from lacustrine facies Cañadón Asfalto Formation • Early diagenesis in the vadose zone induced the silicification of the fossil remains. • Autochthonous concentration classified as a sedimentological origin [ABSTRACT FROM AUTHOR]

Abstract Much of our knowledge of early metazoan evolution is derived from unmineralized death mask or endorelief mold and cast fossils in Ediacaran clastic sedimentary rocks. This record is often regarded as a unique 'Ediacaran taphonomic window'; however, the prevalence of soft-bodied molds and casts in Paleozoic clastic rocks has been increasing, begging an extension, or modification, to our understanding of this preservational motif. Chief amongst such fossils are eldonids, a non-biomineralized group of stem deuterostomes. Because eldonids are also preserved as compressed or flattened fossils from deposits like the Burgess Shale, Chengjiang and Kaili, they offer a comparative case study for evaluating the taphonomic fidelity of mold/cast-style preservation during this interval. EDS and Raman microspectroscopic analysis of Ordovician and Devonian eldonid molds and casts, and comparison with Burgess Shale eldonids, suggests the mold/cast taphonomic style produces significantly lower fidelity of fossil preservation. We propose that eldonid mold/cast fossils are preserved by the adsorption of reduced iron ions onto tissues composed primarily of high molecular weight (HMW) biopolymers which require enzymatic degradation prior to decay. Nucleation and growth of aluminosilicates and/or sulfides around these adsorbed ions forms a fossilizable surface veneer, preserving a death mask mold. More labile tissues could not be fossilized in this mold and cast style. Ediacaran mold and cast fossils from South Australia, the White Sea region of Russia, Namibia, and Newfoundland exhibit preservational characteristics consistent with this new proposed model. Analysis of their preservational mode suggests that the first metazoans, which would have lacked HMW biopolymeric tissues, could not have been fossilized in this particular style. Thus, understanding the origin and earliest evolution of the Metazoa requires a focus on alternative modes of fossilization. Highlights • Eldonids from the Tafilalt Lagerstätte are preserved as molds and casts in sandstones. • These preserve only high molecular weight biopolymer tissues, by authigenic mineralization. • Ediacaran molds and casts are fossilized consistent with the Tafilalt taphonomic model. • Tafilalt-style fossils may not preserve entire organisms or complete communities. • The first animals to evolve on Earth could not have been fossilized in this Tafilalt style. [ABSTRACT FROM AUTHOR]

Abstract Patterns of origination and evolution of early complex life on this planet are interpreted largely from the fossils of the Precambrian soft-bodied Ediacara Biota. Excavation and reconstruction of beds of the Ediacara Member of the Rawnsley Quartzite at the National Heritage Ediacara fossil site Nilpena, in the Flinders Ranges of South Australia has exposed nearly 300 square meters of fossiliferous bedding planes. As a result, the taphonomy and sedimentology of the succession are well-constrained, rendering it possible to disentangle ecological from environmental and taphonomic signals. The fossil record that is preserved on these beds is a function of a number of factors including 1) sedimentary environment; 2) initial colonization; 3) nature of textured organic surfaces; 4) duration of time between episodes of disturbance; and 5) biostratinomic processes. The excavation and reconstruction of beds at Nilpena yield an exceptional and unique opportunity to examine not only the taxonomic composition of Ediacara communities but also their ecological character at various stages of development. Preserved ecological 'snapshots' of fossil assemblages range from immature communities of small-bodied individuals, associated with poorly developed organic mats to communities characterized by a high diversity of macrofaunal taxa, wide range of body sizes and the presence of dense textured organic surfaces. Highlights • 300 m2 of fossiliferous beds of the Ediacara Mbr are exposed at Nilpena, Australia. • We are able to disentangle ecological from taphonomic signals. • Most beds preserve ecological "snapshots." • Organic mats mediated Ediacara community ecology and taphonomy. • Beds preserved a diversity of marine benthic communities. [ABSTRACT FROM AUTHOR]

Abstract Archaeocyaths are an enigmatic group of calcifying sponges prevalent in early Cambrian (Terreneuvian to Series 2) successions around the world and preserved predominantly in reefal buildups, but also in adjacent reworked deposits. Here we report exceptionally preserved phosphatized archaeocyaths and small shelly fossils from phosphatized reef flank deposits at the top of the Salaagol Formation of southwestern Mongolia. Recent chemostratigraphic age models suggest that these archaeocyaths are among the earliest reported in the Terreneuvian Stage 2 (Tommotian). These fossils provide a window into the mechanisms of archaeocyath phosphatization, a generally rare mode of archaeocyath preservation. To assess the composition and nature of phosphatization, fossil assemblages were examined in insoluble residue and thin section. These archaeocyaths are preserved as phosphatic internal molds in residue, and both phosphatized and unphosphatized archaeocyaths are present in thin section. The occurrence of internal molds and complementary mineralogical data suggest that the decay of organic material within the archaeocyaths created the necessary redox conditions for apatite nucleation. We propose that, shortly after death, this assemblage was transported to a deeper water environment, and that the presence of organic matter in a low oxygen setting led to abundant phosphatization of archaeocyaths. Highlights • Archaeocyaths from the lower Cambrian of southwestern Mongolia were investigated. • Archaeocyaths and associated small shelly fossils (SSFs) are phosphatized. • The minerals in the assemblages suggest transportation to a low oxygen setting. • Analysis of these fossils links taphonomy to palaeoenvironment of preservation. [ABSTRACT FROM AUTHOR]

Abstract Compaction is one of the taphonomic processes responsible for fragmenting invertebrate shells, thereby removing them from the fossil record. Studies of drilling predation intensities in the fossil record depend on equal preservation of drilled and undrilled shells. However, predatory drill holes may weaken shells, and these shells may be preferentially destroyed during compaction, thus overprinting predation signals in the fossil record. Previous studies have experimentally compacted drilled and undrilled bivalve valves. Such experiments have not previously been performed with gastropod shells, which may respond differently to compaction. To test if drilled gastropod shells are preferentially removed by compaction, 227 undrilled and 28 drilled Olivella biplicata shells were subjected to compaction (70,602 N) within a sediment column. Multiple shells were tested together but were given ample space so as not to rest on one another, thereby avoiding forming point contacts. Many drilled and undrilled shells possessed aperture damage, removed apices, pinhole bores, and spionid worm bores, which in conjunction with shell size, were hypothesized to lower compactional shell strength. Shell strength was assessed by using the frequency of shell failure. Binomial logistic regression models were utilized to identify the variables controlling shell failure. Three models were created each using the whole O. biplicata sample. Each model used a unique and different definition of shell strength: any damage, breakage, and obliteration (<50% intact). Predatory drill holes were not found to predict shell failure significantly, regardless of shell failure definition. Instead, compaction tends to damage larger shells and obliterate shells with removed apices. Therefore, drilling predation intensities of fossil assemblages are not influenced by compaction. Highlights • Predatory drill holes do not weaken gastropod compactional shell strength. • Compaction does not alter drill hole frequencies in gastropod assemblages. • Larger shells damage more frequently than smaller shells. • Shells without apices are more frequently obliterated than shells with intact apices. [ABSTRACT FROM AUTHOR]

Abstract The taphonomy and palaeoecology of the early Miocene (Burdigalian) vertebrate assemblage of Ullujaya (East Pisco Basin, Peru) is here described. Vertebrate remains are concentrated in marine facies (Ct1a association) of the exposed Chilcatay Formation (dated 19–18 Ma) deposited within a 30–40 m deep, semi-enclosed, offshore environment. Coupled with ichnological observations, the size distribution of pyrite framboid relics reveals fluctuation of euxinic and oxic-dysoxic conditions at the seafloor. The assemblage is dominated by toothed cetaceans (kentriodontids, squalodelphinids, physeteroids, and the eurhinodelphinid-like Chilcacetus), together with a large dermochelyid turtle, some bony fish, and diverse elasmobranchs, mostly juveniles of Carcharhinus brachyurus and Cosmopolitodus hastalis. The vertebrate assemblage comprises a coastal community, dominated by mesopredators, representative of a warm-temperate, sheltered embayment connected with riverine and open-ocean environments. Vertebrate skeletons are typically disarticulated and incomplete, and some bone elements display shark bite marks. Microborings are observed at the bone surface. Bones exhibit a good degree of apatite mineralisation and bone cavities are locally filled by Ca-Mg carbonates. Our taphonomic observations suggest prolonged flotation of carcasses during which they were subject to biogenic and physical processes of partial destruction (including scavenging by sharks), before final deposition on a soft compact substrate. Preservation was favoured by the oxygen-deficient bottom conditions that inhibited the action of benthic macro-scavengers. Highlights • Early Miocene is an important but still poorly known phase in the evolutionary history of marine vertebrates. • We report on a conspicuous, newly discovered Burdigalian marine vertebrate assemblage from the southern coast of Peru. • Vertebrates, mostly cetaceans and sharks, inhabited a 30-40 m deep, warm-temperate, semi-protected embayment. • Their carcasses suffered prolonged flotation causing biogenic and physical processes of partial destruction. • Preservation of vertebrates was favoured by the oxygen-deficient bottom conditions at the seafloor. [ABSTRACT FROM AUTHOR]

Highlights • Fifteen ichnotaxa are present in biogenic substrates of Miocene Monte León Formation. • Gastropod and bivalve shells have different taphonomic signatures. • Concentrations include elements that underwent different taphonomic histories. [ABSTRACT FROM AUTHOR]

Abstract This study presents a taphonomic examination of the ca. 1.84 million year old (Ma) bovid fauna from FLK Level 22 (FLK Zinj), Bed I, Olduvai Gorge using a new GIS spatial analysis approach. The FLK Zinj site contains some of the best preserved evidence for meat eating by hominins and has been used extensively in reconstructions of early hominin behavior. However, despite numerous interpretations of site function, there is currently no consensus regarding how hominins acquired carcasses at FLK Zinj. Some interpretations argue that Early Stone Age hominins had early access to fleshed carcasses through hunting or active scavenging, while others argue hominins had late access to largely defleshed carcasses through passive scavenging. In this study, GIS was used to record bone preservation in the FLK Zinj assemblage as well as in several modern, experimentally-modified bone assemblages, which are used for comparison. The placement of hominin- and carnivore-produced modifications was documented on bones from these assemblages, and the GIS Spatial Analyst was used to identify patterning in tooth mark clusters as well as patterning in cut mark locations. This analysis suggests hominins had early access to fleshed carcasses at FLK Zinj, particularly of smaller prey, which they may have acquired through hunting. Damage patterns on larger carcasses are more difficult to interpret, but are consistent with early access through hunting or aggressive scavenging. A reanalysis of carnivore tooth mark frequencies on the FLK Zinj bovid fauna also supports an early access scenario. Highlights • Butchery marks and carnivore tooth marks on fossil prey provide information about past carnivore and hominin behavior. • This information is essential for answering questions about the origins of hominin meat eating. • Evidence for hominin meat eating is well preserved at FLK 22 (FLK Zinj), Bed I, Olduvai Gorge, Tanzania (c. 1.84 Ma). • Considerable disagreement exists among previous studies regarding whether hominins were hunting or scavenging at FLK Zinj. • GIS image analysis is used here to examine tooth mark distribution in the FLK Zinj assemblage and experimental assemblages. • Results suggest that hominins had early access to fleshed carcasses of smaller prey at FLK Zinj. [ABSTRACT FROM AUTHOR]

Originating in the late Hirnantian (latest Ordovician) and extending into the Rhuddanian (early Silurian), the global Rhuddanian Oceanic Anoxic Event (Rhuddanian-OAE), characterized by habitat-specific anoxic-euxinic seafloor conditions led to the deposition of widespread graptolitic black shales. However, the intricate relationship between habitat-specific seafloor redox conditions and graptolite diversity record of the Rhuddanian-OAE remains enigmatic. Here, we present a continuous sequence of seafloor redox records obtained from a core spanning from the upper Katian (Ordovician) to the middle Aeronian (Silurian) in the Changning region of SE Sichuan Province. This region represents the Inner Yangtze Sea within the upper Yangtze Platform of South China. Following the glaciation peak of the Hirnantian, our study unveils the evolution of bottom waters, transitioning from oxic to permanently euxinic, intermittently euxinic, anoxic, and suboxic–oxic transitional states. This evolution is supported by independent evidence, including trace metals (Mo, U, V) and C org /TP ratios, lithology, and TOC content. Local factors and global seawater drove redox changes of bottom water in Changning. In contrast to the increasing oxygenation in Changning and the northern hemisphere's suboxic bottom waters in Yukon, Canada, the bottom water of the southern hemisphere in the early Aeronian maintained a euxinic environment, potentially influencing the graptolite paleogeography of the early Aeronian. The graptolite diversity record was likely influenced by both paleoecological changes in the preferred habitat of deeper-water species combined with taphonomic processes that influenced their preservation potential. • High-resolution record of marine redox change, late Hirnantian-Aeronian, South China. • Climate, hydrography, marine productivity, sea level and tectonics controlled the local redox processes. • Global distribution of redox conditions may have influenced graptolite provincialism. • Graptolite biodiversity record was affected by paleoecological change and taphonomic processes. [ABSTRACT FROM AUTHOR]

Sclerobionts colonizing brachiopod shells derived from the oldest-known methane seep deposit (upper Silurian, Moroccan Meseta) are reported for the first time. Despite a large number of the brachiopod shells collected, all representing the atrypide species Septatrypa lantenoisi Termier, very few showed the presence of sclerobionts. The majority of the shells were taphonomically altered: worn, exfoliated and corroded. The sclerobionts are represented by cornulitid tentaculitoids and less common auloporid tabulate corals and epibiontic brachiopods. Although the observed assemblage certainly does not reflect the original taxonomic composition of the sclerobiont assemblage, it provides the first insight into the Palaeozoic encrusters inhabiting methane-seep ecosystems. As implied by the moderately 13C-depleted carbon isotope composition and simple, micrite-dominated paragenetic succession of the associated seep carbonates, the investigated community most likely represents a period of slow, diffuse fluid seepage, an interpretation consistent with the common perception of the seep-related brachiopods as non-chemosymbiotic, perhaps opportunistic seep-dwellers unable to colonize sites with more vigorous fluid flow. Likewise, the studied encrusters most likely were non-obligate inhabitants of the seep ecosystem, using the brachiopod shells as firm attachment sites and elevation above the seafloor. This colonization pattern would have probably improved their access to the prolific suspended organic particles and potentially limited their exposure to the highest environmental toxicity. As in the case of geologically much younger serpulid polychaetes, also the cornulitid tubeworms colonized the methane seeps relatively shortly after their first, Middle Ordovician appearance in the fossil record. • Sclerobionts from the oldest, Late Silurian methane seep ecosystem are reported for the first time. • Encrusting organisms colonized atrypide brachiopod shells. • The community inhabited an environment of slow, diffuse fluid seepage. • Encrusters are represented by cornulitids, auloporids and brachiopods. • Due to taphonomic alteration of the shells, the sclerobiont assemblage is certainly not complete. [ABSTRACT FROM AUTHOR]

Chondrodonta is a Cretaceous oyster-like bivalve with a predominantly calcitic, dorso-ventrally elongated and slightly inequivalve shell. In the Tethyan carbonate platforms this taxon occurs commonly in rudist-bearing limestone. Often preserved with still articulated valves, the opportunistic Chondrodonta had a cemented and gregarious life habit. In the Apulia Carbonate Platform (Gargano Promontory, southern Italy), Chondrodonta beds occur within lower Aptian lagoonal to platform–basin margin deposits. The studied Chondrodonta concentrations, which recorded the early evolutionary phase and spreading of this bivalve, are made up of specimens ascribed to Chondrodonta glabra Stanton. In the inner platform the meter-thick Chondrodonta accumulations were originated by autochthonous bouquet-like valve aggregates, frequently preserved in living position. These aggregates constitute superimposed carpets characterized by only a few generations which were affected by mass mortality and rapid burial processes. These mass mortalities were related to repeated environmental lethal fluctuations that occurred at the onset of the early Aptian OAE 1a. The quick fluctuations of the Chondrodonta populations are typical of unstable and unpredictable environments characterized by significant changes in trophic resources and hyperthermal and acidification peaks. The studied Chondrodonta specimens show different shell preservation according to their palaeobathymetric location. In the shallow-water inner platform specimens the internal aragonite shell layer was rapidly dissolved while in deeper-water margin ones it was preserved during the early diagenetic phases. This different preservation is interpreted as related to different aragonite saturation state of shallow seawater, and tentatively connected to the acidification peak that occurred at the onset of the early Aptian OAE 1a. [ABSTRACT FROM AUTHOR]

The size and frequency of gastropod drill holes in shells of their prey are common indicators of predator-prey ecology in the fossil record. Taphonomic processes occurring after predation, however, can influence the preservation of shells in a given fossil assemblage and can thus influence ecological inferences based on preserved shells. To determine if ocean acidification (OA) has the capacity to influence prey shell taphonomy in a gastropod drilling predation system, we tested for effects of elevated p CO 2 on dissolution rates, breakage force, and drill hole diameters in non-fragmented shells of two prey species of the cannibalistic naticid gastropod, Euspira heros . Drilled and non-drilled shells of Littorina littorea and E. heros were exposed to control (~300 μatm) and elevated (~800 and 4000 μatm) p CO 2 treatments for five weeks. Dry shell weight and drill hole diameter (outer and inner) were recorded for individual shells before and after exposure; the force required for shell breakage was recorded at the end of the exposure period. Shell mass loss in 800 and 4000 μatm, respectively, were ~1 and 7% for E. heros , and ~0 and 4% for L. littorea , compared to ~0% in the control for both species. Shell breakage force was unaffected by elevated p CO 2 , but was affected by species and drill hole presence, with E. heros shells requiring a force of ~220 and 269 Newtons in drilled and non-drilled shells, respectively, compared to ~294 and 415 Newtons in L. littorea . At 4000 μatm, outer drill hole diameter significantly increased by ~12% for E. heros , while inner drill hole diameter significantly increased by ~13% in E. heros and ~10% in L. littorea . Ultimately, this study provides the first documentation of molluscan shell taphonomy in the context of OA for a gastropod drilling predation system and sets the stage for future research. [ABSTRACT FROM AUTHOR]

The fossil record is essentially characterized by time-averaged assemblages as a consequence of the mixture of multiple generations of organisms into a single stratigraphic horizon. In order to investigate this issue a quantitative taphonomic analysis of fossil assemblages filling up Panopea burrows (ichnogenus Scalichnus ) and those preserved in sediment without this trace fossil on of a Pliocene deposit of SW Spain were carried out. A combination of processes can be inferred from the analysis of the fossils infilling Scalichnus burrows. Passive concentration of shells within trace fossils were is interpreted to have been produced during event processes (most likely storm events) and active burrowing of bivalve trace-makers probably represented the background conditions. These shell concentrations inside Scalichnus burrows constitute a potential sedimentological implement to understand the multi-storm events recorded on the taphonomic signature of the biofabric that otherwise may be unnoticed. The studied examples can be used as proxies for sequencing a series of amalgamated storm events inside bivalve burrows, assessing the magnitude and frequency of erosional events, and analysing the positive taphonomic effect of these equilibrium trace fossils. [ABSTRACT FROM AUTHOR]

The Abric Romaní site (Capellades, Barcelona, Spain) constitutes a key site for understanding the latest Neanderthal occupations in Western Europe. Here we present a comprehensive systematic and taphonomic analysis of a small-mammal assemblage from Level O of the Abric Romaní site, with the aim of reconstructing the paleoecological context in which the Neanderthals lived. The assemblage, which probably dates from a stadial episode between Interstadial 15 and Interstadial 14, contains fifteen small mammal species, including species uncommon for the northeast of Iberia, such as Sciurus vulgaris , Nyctalus lasiopterus and Pipistrellus pipistrellus . Taphonomic studies suggest a predatory origin for the assemblage, probably related to Strix aluco , and paleoecological inferences suggest lower temperatures (−3/−4 °C) and higher rainfall (+70/+170 mm) than at present and a landscape dominated by an open forest with watercourses. The new data improve our knowledge of trends associated with Marine Isotope Stage 3 that affected Neanderthal populations in the Iberian Peninsula, showing that the Neanderthals were well adapted to cooler and wetter conditions across Iberia. [ABSTRACT FROM AUTHOR]

Little is known of the human use of rainforest plant resources of prehistoric Sri Lanka due to the lack of preservation of organic material and the effects of various destructive taphonomic processes. Phytoliths recovered from a AMS radiocarbon and OSL dated sequence at Fahien Rock Shelter indicate interactions of anatomically modern humans with the lowland rainforests of south-western Sri Lanka from 44,952–47,854 cal. BP to 11,991–12,402 cal. BP. During this period, the Rock Shelter occupants extracted their livelihood from a number of wild plants including bananas, rice, breadfruits, durians, canarium and species of palm and bamboo. These taxa are associated with present-day disturbed lowland rainforests. Gathering and processing of plant resources by existing modern rainforest foragers cannot directly be compared with the subsistence activities of the Late Pleistocene Rock Shelter occupants. [ABSTRACT FROM AUTHOR]

Fossil plant assemblages play a critical role in paleoenvironment estimation, especially for the Cenozoic. However, the extent that the fossil assemblage reflects the source forest is difficult to estimate. The comparison between modern assemblages and their subfossil assemblages shows a significant difference, indicating that the transportation of plant organs can affect the accuracy of paleoenvironment analysis. In this study, we aim to detect leaf transport based on stomatal frequency (stomatal index and stomatal density) variation of 30 fossilized Fagus crenata leaves from the Sayama Formation (1.54–1.66 Ma). We distinguished the sun and shade morphotype of fossil leaves by using undulation index and calculated stomatal frequency variation of only sun fossil leaves. Considering the stomatal index variation of fossil Fagus crenata leaves, the paleo- p CO 2 variation in a warm period between 1.54 Ma and 1.66 Ma was estimated as ca. 35.0 to 39.6 pa. Based on this paleo- p CO 2 variation, altitudinal transportation range of the Early Pleistocene fossil Fagus crenata leaves was estimated at over 1000 m. We presume that leaves of Fagus crenata in the fossil assemblage possibly had come from a wide range of altitudes near the fossil site during the Early Pleistocene. This provides an example of altitudinal transportation of plants before their deposition, which suggests a consideration when reconstructing the palaeovegetation and palaeoclimate from fossil assemblages. [ABSTRACT FROM AUTHOR]

We report the occurrence of sponge borings in composite molds of heteropectinid shells from Early Permian marine siliciclastic deposits of the Paraná Basin of southern Brazil. Sponge borings are preserved mainly as chambers ( Entobia ) and channels ( Entobia and Clionolithes ). Three preservational variations of Entobia are present, morphologically equivalent to the alpha, beta, and gamma ontogenetic stages of clionid sponges. This equivalence suggests that the ontogenetic behavior in clionid sponges remains the same since Early Permian times and points to a conservative evolutionary trend for this group. The pattern of bioerosion and other taphonomic signatures indicate rapid shell burial due to frequent and energetic storm events that might have limited the time available for bioerosion activity. The new findings improve the Paleozoic record of Entobia and Clionolithes and indicate that sponge borings have potential to be preserved in ancient siliciclastic rocks. [ABSTRACT FROM AUTHOR]

The Carboniferous–Permian (C–P) transition records a shift in the composition and environmental setting of tropical flora and vertebrate assemblages across western and central Pangea. Here we report the discovery of a rare, multitaxic bonebed in the lower Halgaito Formation (Cutler Group) in Valley of the Gods and its vicinity (San Juan County), southeast Utah, USA. The assemblage, which comprises carcasses and disarticulated bones and teeth, preserves aquatic and semi-terrestrial elements including xenacanth chondrichthyans, actinopterygians, sagenodontid lungfish, and the temnospondyl amphibian Eryops , together with terrestrial taxa including the synapsids, Ophiacodon navajovicus , Edaphosaurus , and Sphenacodon , and a hitherto undescribed araeoscelidan reptile. Sedimentological, paleontological, and strontium isotopic evidence indicates the bonebed formed as a slackwater deposit at the confluence of a major freshwater stream channel and its tributary. The deposit probably formed through late stage flooding of a likely bottlenecked fluvial system, consistent with increasingly episodic or seasonal precipitation, concentrating carcasses of immature and mature shore-dwelling animals. Comparisons with vertebrate assemblages in the Cutler Group of New Mexico, USA suggest that the assemblage is correlative with the lower or middle assemblage of the El Cobre Canyon Formation (Cobrean and Coyotean Land Vertebrate Faunachrons; LVFs), and as such, is of latest Carboniferous age. Our findings strengthen the hypothesis that dryland-adapted vertebrate communities proliferated earlier in westernmost Pangea, well before earliest Permian time, compared to other tropical regions. [ABSTRACT FROM AUTHOR]

Exquisitely preserved Burgess Shale-type fossils from the Xiaoshiba Lagerstätte in the Cambrian (Series 2) Hongjingshao Formation of southern China provide remarkable perspective on early metazoans but have never been reported with plants. Here we first recognize a new assemblage of highly mineralized macroalgae from this biota. Based on morphological differences, there are three new genera and four new species identified: Doulia rara gen. et sp. nov., Eolaminaria simigladiola sp. nov., Singulariphyca ramosa gen. et sp. nov. and Rugophyca longa gen. et sp. nov. Relative to the other three species, S. ramosa is widely distributed among the beds, which may indicate a dominat species in this community. This new discovery fills part of the long gap in the detailed record of macroalgae between the Chengjiang Biota and the Kaili Biota, representing a localized macroalgal flourish at the end of Cambrian Stage 3. The assemblage that shows morphological characters similar to some macroalgae found in the Precambrian and primitive to those of the Cambrian Stage 5 lays the basis for revealing the evolutionary biology of early macroalgae and understanding the Precambrian-Cambrian transition questions. Taphonomic study of this fossiliferous bed indicates that some well-preserved macroalgae are preserved within their original habitats. Through analyzing the depositional environments of the known Cambrian macroalgae, we suggest that macroalgae tend to be preserved in relatively deep marine environments with less disturbance. [ABSTRACT FROM AUTHOR]

Bioturbation structures from Ponta das Bicudas in Santiago Island, Cape Verde Archipelagoare located in coarse-grained biocalcirudite sandwiched between basaltic lavas of the Upper Pleistocene Assomada Formation. Four ichnospecies have been identified: Rhizocorallium commune irregulare, Rhizocorallium jenense versum , nov ichnosubsp., Alaichnus kabuverdiensis nov. ichnogen. nov. ichnosp. and cf. Dactyloidites . From a taphonomic point of view, most trace fossil specimens are undergoing throughout intense erosion. Nevertheless, the observations made on their taphonomy and state of preservation allowed i) to reconstruct the original, complete structures of the trace fossils, ii) to evaluate the existence and magnitude of erosional and depositional episodes, and iii) to quantify the reach of erosion on the seafloor sediment. In this context, it was possible to quantify the thickness of sediment being eroded at the final erosional episode, which happened right before the second extrusion episode of volcanic pillow lava, which buried all the traces previously formed: the total interval of sediment eroded was estimated in ca. 1 m. From a palaeoenvironmental point of view, in a synthesis, the traces were produced in a soft to stiffground substrate composed of very coarse-grained biocalcirudite with common rhodolith debris, in a shallow setting (4 to10 m of depth) with moderate wave energy, nearby rocky basalt knobs where corals and red coralline algae crusts were growing. Organisms producing Rhizocorallium commune irregular settled in the seafloor during a first phase of sedimentation, which was followed by an erosional episode. Once sedimentation resumed, specimens of R. jenense versum nov. ichnosubsp. were produced and overlapped with the former ones. Later, a new erosional event erased most of the previous traces, being preserved only the basal imprint of the specimens. This was followed by a rapid sedimentation episode where Alaichnus kabuverdiensis nov. ichnogen. nov. ichnosp. recorded intense bioturbation activity of the bivalve Panopea . Subsequently, under low-energy sedimentation, a new episode of intense bioturbation of the seafloor occurred, resulting in the development of abundant cf. Dactyloidites . Finally, a strong erosional event – probably related to the onset of the second volcanic episode – cut all previous structures before being buried by the overlying, well preserved pillow lava. [ABSTRACT FROM AUTHOR]

The Upper Pleistocene (MIS5) site known as Cova del Rinoceront near Barcelona, Spain, contains a large assemblage of ungulate remains, among which the most dominant, in the uppermost Layer I, are those of the rare Mediterranean deer, Haploidoceros mediterraneus . In this paper, zooarchaeological and coprogenic analyses are used to evaluate the taphonomic and geological processes involved in determining the nature of the Layer I assemblage. The assemblage cannot have been generated by either hyenids or humans, nor does it constitute an accidental collection, as seen in other Pleistocene accummulations. Instead, the skeletal frequencies, coprogenic tracemarkers and the diagnostic biological damage on bones suggest it accumulated as a result of the feeding of a carnivore. The homogeneous pattern of carcass utilization and the predation of similar-sized ungulates suggest a canid as the main biological agent. [ABSTRACT FROM AUTHOR]

It is widely held that, within the Cretaceous fluvial and marine deposits of North America, ankylosaur remains are typically preserved upside-down; however, this anecdotal observation has yet to be substantiated. Likewise, none of the various hypotheses that purport to explain the frequent occurrence of overturned ankylosaurs has been tested either. This study is the first to apply quantitative and modeling approaches to address these shortcomings. We find strong statistical support for the dominance of upside-down occurrences, and favour a “bloat-and-float” model to account for them. According to this model, ankylosaur carcasses become reworked into fluvial or marine settings where they bloat and overturn prior to their final deposition. Differential floating behaviour between ankylosaurids and nodosaurids may have implications regarding the occurrence of the latter in marine depositional environments. This consideration of ankylosaur taphonomy might similarly help to explain the purported frequency of overturned glyptodonts, which share a similar bauplan with ankylosaurs. [ABSTRACT FROM AUTHOR]

The global trend towards a colder and more arid climate at the Eocene-Oligocene boundary triggered significant changes in the European flora. Here we study the latest Eocene (Priabonian) flora from lacustrine deposits at Sarral in the Ebro Basin, Catalonia, Spain, to evaluate vegetation changes near this boundary. Three main taphofacies are recognised: (1) assemblages composed of small, size-sorted leaves represented by Zizyphus , Fabaceae leaflets and Pinus needles, inferred to be wind transported from open woodlands located distal from the lake; (2) assemblages composed of whole unsorted leaves belonging to Salicaceae, Myricaceae ( Myrica arensi and Comptonia schrankii ), Lauraceae ( Daphnogene and Laurophyllum ) and helophytic plant stems, interpreted as remains of a riparian community; (3) assemblages comprising disarticulated organs of Tetraclinis , Cupressaceae and a few torn leaves of Myrica arensi and Salicaceae, interpreted as derived from riparian or open woodland vegetation upstream from the lake. The Priabonian Sarral flora is similar to the nearby early Oligocene flora of Cervera, making it difficult to distinguish the effects of the Eocene-Oligocene climatic crisis upon the vegetation. Sedimentological analysis indicates that the Sarral leaf bed represents deposition during a drier period of small-order climate cycles, whereas the Cervera flora represents vegetation during a wetter period of a similar cycle but under the cooler and more arid environmental conditions of the early Oligocene, thereby disguising large-scale Eocene-Oligocene climatic change. Understanding such short-term sedimentary and climatic cycles is crucial in order to correctly interpret the regional climatic signal based on leaf physiognomy. [ABSTRACT FROM AUTHOR]

Chitons are common marine invertebrates found worldwide that use aragonite to form their shell and are rare in the sedimentary and fossil records. Their rarity in the fossil record is interesting due to how abundant live chitons are. Previous work suggests that chitons resist dissolution, which appears inconsistent with their rarity in the sediment and fossil records and aragonite composition. This result warrants examination of other taphonomic processes on chiton skeletal material since other taphonomic processes may play a larger role in removal than previously thought. As many chitons are intertidal, mechanical abrasion of chiton valves is likely to occur; its extent is largely unknown and yet necessary to provide insight to the taphonomy of chiton material. Eight species of chitons were collected from the Otago Peninsula, South Island, New Zealand. A total of 129 valves were isolated, cleaned, weighed, and tumbled in a Lortone 3A rock tumbler for 96 h. The valves from each species lost an average of between 9 and 44% of their weight; damage varied among species. Leptochiton inquinatus (the sole lepidopleuran) lost the most material while the acanthochitonids ( Acanthochitona zelandica , and Notoplax violacea ) and the chitonids ( Chiton glaucus , Onithochiton neglectus , Sypharochiton pelliserpentis , and S. sinclairi ) were more resistant to abrasion. The dorsal layer of the valves (the tegmentum), which is penetrated by aesthete tissue and has a granular crystal microstructure, was the most damaged by abrasion in all species. The ventral layer (the articulamentum), which has a highly-organised crystal structure with fewer organic components than the tegmentum, showed the least signs of abrasion. Since abrasion reduces the tegmentum and changes the valve shape, it is likely that abraded chiton material is present but unrecognisable in the fossil record. The valves are estimated to last about seven years when in the intertidal zone when enduring abrasion alone, which is much less than the hundreds to thousands of years material is exposed. [ABSTRACT FROM AUTHOR]

A theropod tracksite was discovered in the Nemegt Formation (Maastrichtian) at Bügiin Tsav, Mongolia by the Korea-Mongolia International Dinosaur Project in 2009. A total of 67 tracks (14 trackways [one didactylous, 13 tridactylous] and 12 isolated tracks) belonging to four ichnomorphotypes were mapped on a single horizon. This indicates at least four different theropod trackmakers lived in the same area at the same time. This tracksite consists of laminated gray mudstone-yellowish brown siltstone couplets interbedded with eolian yellowish brown sandstone deposited on a distal floodplain. Abundant footprints with V-shaped profiles (cross-section) within in the vertical section indicate that dinosaurs repeatedly walked across in this area. Before the discovery of the tracks, the site was illegally excavated by fossil poachers, a widespread problem in the Gobi Desert. During excavation of the track horizon, a clenched, inclined Gallimimus foot skeleton was found in the mudstone, extended down 20 cm below the track-bearing sandstone layer. The occurrence of tracks closely associated with body fossils is unusual and taphonomically intriguing. It is possible that the foot skeleton represents an animal that died in its tracks. However, the depth of the foot in mud is probably too shallow for the animal to have been mired. Sedimentological and taphonomic evidence also suggests that the pes of Gallimimus may have passed straight through the track-bearing sandstone layer. The inclined right pes indicates that the body lay on its left side on the substrate. During decomposition in the mud, all digits were flexed but the distal phalanges were stuck and anchored in the stiff lower mud. Consequently, as more proximal phalanges were able to accommodate flexing, they were pulled away and dislocated from the anchored distal phalanges. Subsequent trampling by dinosaurs in the track-bearing sandstone would have further distorted the underlying foot. [ABSTRACT FROM AUTHOR]

The famous “Dragon's Tomb” Saurolophus bonebed at Altan Uul II preserves multiple complete skeletons with skin impressions, and is exceptional among Nemegt Formation dinosaur localities as the only mass accumulation of articulated individuals. Here, we present results from an on-going paleontological project focused on the Baruungoyot-Nemegt succession in order to document this unique locality. Sedimentological data allow us to confirm that the fossils and host sediments were deposited in the thalweg of a meandering paleochannel that experienced a variety of high and lower energy flow conditions. A variety of taphonomic data were collected from exposed fossils, including those displaced by poaching. Three-dimensional maps of the host sediments and fossils were generated, and 13 m 2 of exposed, in-situ bones were mapped. Previously undocumented portions of at least 13 additional Saurolophus individuals and a partial subadult Tarbosaurus skeleton were identified. The Dragon's Tomb is a monodominant bonebed with at least three size classes (juvenile, subadult, and large adult) of Saurolophus preserved. The bonebed has a minimum size of ~ 2000 m 2 , suggesting that over 100 Saurolophus carcasses may have contributed to the thanatocoenose. Although the data provide evidence for a catastrophic mass death of a social group of Saurolophus and provide the first evidence of gregariousness in this taxon, the cause of death cannot be determined. [ABSTRACT FROM AUTHOR]

This study tests the hypothesis that the early diagenesis of aragonite shells should differ fundamentally between marine and freshwater environments. This is predicted to be the case because aragonite is highly susceptible to dissolution in the TAZ (Taphonomically Active Zone) in low energy marine settings due to acidity caused largely by the oxidation of H2S generated by sulphate-reducing bacteria, but reduced sulphide activity in freshwater settings should result in less early dissolution of aragonite. To test this hypothesis a range of fresh-brackish-hypersaline and marine limestones were sampled from the Upper Jurassic (mid Oxfordian) Cabaços Formation of central western Portugal. In these freshwater and brackish deposits, molluscs are preserved mostly as sparite shell replacements indicating that the original aragonite was preserved through the TAZ and was later replaced during subsequent burial by calcite cement. In limestones deposited in more marine to hypersaline settings, molluscan remains mostly consist of the calcitic layers of bimineralic bivalves, as shell where the original was wholly calcitic, or as gastropod steinkerns. Exceptions occur and reflect other factors such as higher energy conditions during deposition whereby organic matter, as the drive for microbial decay processes, was removed. The implications for molluscan preservation including some hydrocarbon reservoirs are discussed. [ABSTRACT FROM AUTHOR]

Paleoenvironmental reconstructions based on micromammalian assemblages are a commonly used tool in paleoecology and zooarcheology. However, predator prey preferences may bias these assemblages to an unknown degree, thus leading to unreliable paleoenvironmental reconstructions. While attempts at taxonomically identifying micromammal predators through taphonomy has been conducted in the past, none has satisfactorily differentiated between owl taxa. Here we introduce the novel postcranial fracture index and revised versions of digestion indices for obtaining higher taxonomic resolution in taphonomic signatures. We taphonomically analyzed bone assemblages created by owls both in controlled feeding experiments and in the wild. We used blind experiment methodology involving multiple experimenters (each analyzing different bones) to test known and novel indices for reproducible taphonomic signatures within five species of owls ( Tyto alba , Asio otus , Athene noctua , Bubo bubo and Strix aluco ), Falco tinnunculus and Vulpes vulpes for comparison. We found that experimenter identity has a profound impact on the digestion indices. Nonetheless, the breakage indices and our novel fracture index found significant differences and subjective differences between owl species. Mandible breakage differentiated between Tyto alba and the other, more destructive owls. Postcranial breakage distinguished Strix aluco from the other owls. The postcranial fracture index differentiated between all species except between Athene noctua and Bubo bubo . We recommend a combination of taphonomic indices as a reliable tool for inferring owl species identity of micromammal assemblages. [ABSTRACT FROM AUTHOR]