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The Pennsylvanian–Permian Maroon Formation of northwest Colorado is an up to 4,600 m thick succession of mainly siliciclastic continental red-beds deposited in equatorial intermontane basins of the Ancestral Rocky Mountains. Sedimentary surfaces of fluvio-lacustrine to eolian siltstones and fine-grained sandstones from various stratigraphic levels within the Maroon Formation preserve cm-sized straight to gently curved sediment-filled acicular structures referred to five morphological groups: single, branched, stellate, rosette, and bunched. Depositional environment, shape, and size of the structures are most similar to ice crystal marks that result from freezing of water-saturated fine-grained substrate at the sediment-air interface. They differ from other syngenetically produced crystals and crystal pseudomorphs in sedimentary rocks mainly by crystal shape and environmental conditions. The potential ice crystal marks of the Maroon Formation are notable for the fidelity and morphological diversity of the crystal casts and could be a key for the understanding of similar but hitherto often only called enigmatic structures of the sedimentary rock record. The ice crystal mark occurrences in the Maroon Formation suggest that night frost affected lower elevation equatorial areas during the climax of the Late Paleozoic Ice Age and may stimulate research on evolutionary adaptations of early terrestrial biota to overcome significant air temperature fluctuations.

Documented evidence of root nodules in fossil plants is exceedingly rare, and thus the evolutionary history and paleobiology of these specialized structures hosting symbiotic microorganisms continue to be largely unresolved. Here we report adpression fossils of slender roots from the ~237-million-yr-old Madygen Formation in Kyrgyzstan, to which are laterally attached spheroidal protuberances up to 2.5 mm in diameter that we interpret as root nodules based on spatial arrangement and comparisons with other fossil and extant root nodules, along with several types of other plant structures exhibiting a superficially similar appearance (e.g., fertile organs, rhizome tubers). The producer of the roots and the biological nature and affinities of the microorganisms inhabiting the nodules remain unknown. The Madygen fossils are nevertheless significant because they represent the second-oldest record of root nodules worldwide, predated only by permineralized mycorrhizal root nodules from the Triassic of Antarctica.

Pareiasauromorpha is one of the most important tetrapod groups of the Permian. Skeletal evidence suggests a late Kungurian origin in North America, whereas the majority of occurrences come from the Guadalupian and Lopingian of South Africa and Russia. However, Pareiasauromorpha footprints include the ichnogenus Pachypes, which is unknown from strata older than late Guadalupian. A revision of several Pachypes-like footprints from the Cisuralian-Guadalupian of Europe and North America confirm the occurrence of this ichnogenus and of the ichnospecies Pachypes ollieri comb. nov. beginning in the Artinskian. This is the earliest known occurrence of Pachypes and it coincides with the Artinskian reptile radiation. Based on a synapomorphy-based track-trackmaker correlation, P. ollieri can be attributed to nycteroleter pareiasauromorphs such as Macroleter. Therefore, the earliest occurrences of pareiasauromorph footprints precede by at least 10 myr the earliest occurrence of this group in the skeletal record. Moreover, the palaeobiogeography of the group is extended to the Cisuralian and Guadalupian of western Europe.

Nonmarine biostratigraphic/biochronologic schemes have been created for all or parts of the late Carboniferous–Middle Triassic using palynomorphs, megafossil plants, conchostracans, blattoid insects, tetrapod footprints and tetrapod body fossils, and these provide varied temporal resolution. Cross correlation of the nonmarine biochronologies to the Standard Global Chronostratigraphic Scale has been achieved in some parts of the late Carboniferous–Middle Triassic in locations where nonmarine and marine strata are intercalated, the nonmarine strata produce biochronologically significant fossils and the marine strata yield fusulinids, conodonts and/or ammonoids. Other cross correlations have been aided by magnetostratigraphy, chemostratigraphy and a growing database of radioisotopic ages. A synthetic nonmarine biochronology for the late Carboniferous–Middle Triassic based on all available nonmarine index fossils, integrated with the Standard Global Chronostratigraphic Scale, is presented here. The focus is on the nonmarine biostratigraphy/biochronology of blattoid insects, conchostracans, branchiosaurid amphibians, tetrapod footprints and tetrapod body fossils within the biochronological framework of land-vertebrate faunachrons. Correlation to the Standard Global Chronostratigraphic Scale presented here is divided into seven time intervals: Pennsylvanian, Carboniferous–Permian boundary, Cisuralian, Guadalupian, Lopingian, Permian–Triassic boundary and Early to Middle Triassic. The insects, conchostracans and branchiosaurs provide robust nonmarine correlations in the Pennsylvanian–Cisuralian, and the footprints and tetrapod body fossils provide robust correlations of varied precision within the entire Pennsylvanian–Middle Triassic. Radioisotopic ages are currently the strongest basis for cross correlation of the nonmarine biostratigraphy/biochronology to the Standard Global Chronostratigraphic Scale, particularly for the Pennsylvanian–Cisuralian. Chemostratigraphy and magnetostratigraphy thus far provide only limited links of nomarine and marine chronologies. Improvements in the nonmarine-marine correlations of late Paleozoic–Triassic Pangea require better alpha taxonomy and stratigraphic precision for the nonmarine fossil record integrated with more reliable radioisotopic ages and more extensive chemostratigraphic and magnetostratigraphic datasets.

The origin of extant amphibians remains largely obscure, with only a few early Mesozoic stem taxa known, as opposed to a much better fossil record from the mid-Jurassic on. In recent time, anurans have been traced back to Early Triassic forms and caecilians have been traced back to the Late Jurassic Eocaecilia, both of which exemplify the stepwise acquisition of apomorphies. Yet the most ancient stem-salamanders, known from mid-Jurassic rocks, shed little light on the origin of the clade. The gap between salamanders and other lissamphibians, as well as Paleozoic tetrapods, remains considerable. Here we report a new specimen of Triassurus sixtelae, a hitherto enigmatic tetrapod from the Middle/Late Triassic of Kyrgyzstan, which we identify as the geologically oldest stem-group salamander. This sheds light not only on the early evolution of the salamander body plan, but also on the origin of the group as a whole. The new, second specimen is derived from the same beds as the holotype, the Madygen Formation of southwestern Kyrgyzstan. It reveals a range of salamander characters in this taxon, pushing back the rock record of urodeles by at least 60 to 74 Ma (Carnian–Bathonian). In addition, this stem-salamander shares plesiomorphic characters with temnospondyls, especially branchiosaurids and amphibamiforms.

The origin of Reptilia and the biostratigraphic and palaeobiogeographic distribution of its early representatives are still poorly understood. An independent source of information may come from the extensive Carboniferous footprint record of reptiles, which is arguably richer and more complete than the skeletal record. Nevertheless, previous studies often failed to provide useful information because they were based on poorly preserved material and/or characters non-exclusive of reptile tracks. In fact, a large part of the supposed early reptile tracks can be assigned to the anamniote ichnotaxon Hylopus hardingi. Here, we revise the ichnotaxon Hylopus hardingi based on anatomy-consistent material, attribute it to anamniote reptiliomorphs, and distinguish it from Notalacerta missouriensis, the earliest ichnotaxon that can be attributed to reptiles, and the somewhat younger Varanopus microdactylus (attributed to parareptiles, such as bolosaurians) and Dromopus lacertoides (attributed to araeoscelid reptiles and non-varanodontine varanopids). These attributions are based on correlating morphofunctional features of tracks and skeletons. Multivariate analysis of trackway parameters indicates that the late Bashkirian Notalacerta missouriensis and Hylopus hardingi differ markedly in their trackway patterns from Late Mississippian Hylopus hardingi and Late Pennsylvanian reptile tracks, which appear to share a derived amniote-like type of gait. While the first occurrence/appearance of reptile tracks in the tetrapod footprint record during the late Bashkirian corresponds to the first occurrence/appearance of reptiles in the skeletal record, footprints significantly enlarge the paleobiogeographic distribution of the group, suggesting an earlier radiation of reptiles during the Bashkirian throughout North America and possibly North Africa. Dromopus appeared in the Kasimovian together with the diapsid group Araeoscelidia, but footprints from Western-European occurrences enlarge the paleobiogeographic distribution of diapsids and varanopids. Varanopus and bolosaurian parareptiles appear in the Gzhelian of North America. Older parareptiles are, however, known from the late Moscovian. In all, the footprint record of early reptiles supplements the skeletal record, suggesting possible future lines of research.

The poor preservation and apparent monospecifity of Permian tetrapod footprints from eolian paleoenvironments have thus far hampered their reliable interpretation. This study clarifies how this is due to distinct and repeated ichnotaphonomic effects on trackway pattern and footprint morphology on originally inclined planes. Once these effects are excluded, the anatomy-consistent ichnotaxobases useful for ichnotaxonomy can be recognized. Several nomina dubia are identified, among these the ichnogenus Chelichnus, here considered a taphotaxon. The eolian ichnoassociations from the Lopingian of Scotland and Germany include six different ichnotaxa: cf. Capitosauroides isp. (?eutheriodont therapsid), Dicynodontipus geinitzi (cynodont therapsid), Dolomitipes isp. (dicynodont therapsid), Pachypes loxodactylus n. comb. (pareiasaurian parareptile), Procolophonichnium isp. (small parareptile) and Rhynchosauroides isp. (non-archosauriform neodiapsid). This is completely different from the interpretations of the last 20 years, which postulated that these paleoenvironments comprised monospecific associations of synapsid tracks. These ichnoassociations are instead moderately diverse, similar to low-latitude marginal marine to floodplain ichnoassociations and belong to the Lopingian Paradoxichnium footprint biochron. The Cornberg Formation of Germany, being constrained between the Illawarra reversal and the mid-Wuchiapingian Kupferschiefer at the Rotliegend/Zechstein transition, constitutes the earliest evidence of Lopingian tetrapod faunas at low paleolatitudes and the first evidence of low-paleolatitude faunal turnover related to the end-Guadalupian mass extinction from both the skeleton and the track record. This suggests a global extension of the dinocephalian extinction event, which occurred at high-mid (South Africa and Russia) and low (Western Europe) paleolatitudes of Pangea about 259–260 Ma and was probably triggered by the eruption of the Emeishan Large Igneous Province of SW China, which considerably changed global environmental conditions in both marine and continental settings.

A recent discovery from the Carboniferous–Permian transition of the southwest German Saar–Nahe Basin has revealed a medium-sized edaphosaurid skeleton. It is described as Remigiomontanus robustus gen. et sp. nov. Apart from a largely complete dorsal column, showing the typical hyper-elongated spines with lateral tuberculation, few other elements are preserved. Although lacking certain autapomorphies, the unique character combination of this new form strongly suggests an intermediate position between Ianthasaurus and Edaphosaurus. This study presents a revision of the complete European material of Edaphosauridae, counting the newly named genus Bohemiclavulus (type species Naosaurus mirabilis Fritsch, 1895), and a confirmation that Edaphosaurus credneri is an indeterminate juvenile of this most derived genus. Further fragments include a second young juvenile from the Dohlen Basin, east Germany, the lost spine set of Ramodondron from Boskovice Basin, Czech Republic, and a poorly preserved specimen from Autun, France, for which its hitherto parareptilian classification is debated. A renewed dataset is used to carry out a phylogenetic analysis. Exhaustive comparisons allow for a deeper understanding of back sail characters, which on the other hand hamper a phylogenetic resolution for both European and North American taxa. Previously reconstructed faunal provinces of edaphosaurid distribution are not evident from the present knowledge.

The morphology of fossil footprints is the basis of vertebrate footprint ichnology. However, the processes acting during and after trace fossil registration which are responsible for the final morphology have never been precisely defined, resulting in a dearth of nomenclature. Therefore, we discuss the concepts of ichnotaphonomy, ichnostratinomy, taphonomy, biostratinomy, registration and diagenesis and describe the processes acting on footprint morphology. In order to evaluate the morphological quality of tetrapod footprints, we introduce the concept of morphological preservation, which is related to the morphological quality of footprints (M-preservation, acronym MP), and distinguish it from physical preservation (P-preservation, acronym PP), which characterizes whether or not a track is eliminated by taphonomic and diagenetic processes. M-preservation includes all the morphological features produced during and after track registration prior to its study, and may be divided into substages (ichnostratinomic, registrational, taphonomic, stratinomic, diagenetic). Moreover, we propose an updated numerical preservation scale for M-preservation. It ranges from 0.0 (worst preservation) to 3.0 (best preservation); intermediate values may be used and specific features may be indicated by letters. In vertebrate footprint ichnotaxonomy, we regard the anatomy-consistent morphology and to a lesser extent the trackway pattern as the only acceptable ichnotaxobases. Only footprints showing a good morphological preservation (grade 2.0–3.0) are useful in ichnotaxonomy, whereas ichnotaxa based on poor morphological preservation (grade 0.0–1.5) are considered ichnotaphotaxa (nomina dubia) characterized by extramorphologies. We applied the preservation scale on examples from the Palaeozoic to the present time, including three ichnotaphotaxa and 18 anatomy-consistent ichnotaxa/morphotypes attributed to several vertebrate footprint producers. Results indicate the utility, feasibility and suitability of this method for the entire vertebrate footprint record in any lithofacies, strongly recommending its use in future ichnotaxonomic studies. Fil: Marchetti, Lorenzo. Urweltmuseum Geoskop; Alemania Fil: Belvedere, Matteo. Office de la Culture. Section d'Archéologie et Paléontologie; Suiza Fil: Voigt, Sebastian. Urweltmuseum Geoskop; Alemania Fil: Klein, Hendrik. Saurierwelt Paläontologisches Museum; Alemania Fil: Castanera, Diego. Institut Català de Paleontologia Miquel Crusafont.; España Fil: Díaz Martínez, Ignacio. Universidad Nacional de Río Negro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Marty, Daniel. Naturhistorisches Museum Basel; Suiza Fil: Xing, Lida. China University of Geosciences; China Fil: Feola, Silverio Francisco. Universidad Nacional del Sur; Argentina Fil: Melchor, Ricardo Nestor. Universidad Nacional de La Pampa; Argentina Fil: Farlow, James O.. Indiana University; Estados Unidos

The colonization of deserts by tetrapods occurred for the first time in the late Paleozoic. In spite of amniotes being the most abundant and diverse taxon in such environments, fossil tracks indicate that anamniotes also inhabited late Paleozoic deserts. In this paper, the presence of the tetrapod-footprint ichnotaxa Ichniotherium sphaerodactylum and cf. Ichniotherium is documented in the eolian Coconino Sandstone (early Permian), based on 16 trackways found at several localities in Arizona, USA. Because there is a strong association between Ichniotherium and different species of diadectomorphs, we also discuss some aspects of the ichnotaxonomy of this ichnogenus. Diadectomorpha is considered the sister taxon of Amniota and, as a consequence, the tracks described in this paper represent the oldest evidence of occupation of deserts by non-amniote tetrapods. The presence of Ichniotherium in this environmental context also sheds light on the paleobiology of Diadectomorpha and, as a result, the emergence of features typically related to Amniota. The ichnofauna of the Coconino Sandstone has been used as a model for the Chelichnus ichnofacies, which supposedly indicates a low-diversity desert fauna. On the other hand, the tracks described here demonstrate that diadectomorphs were also important faunal components of such deserts and suggests that the significance of this ichnofacies should be reconsidered.

The tetrapod footprint record of Permian eolian environments has long been underestimated because of overall poor preservation and its apparent monospecifity. The best known and most abundant Cisuralian record of tetrapod footprints is from the Coconino and De Chelly formations of Arizona, which, however, thus far encompassed only the ichnogenera Chelichnus and Dromopus. We revised the locomotion and taphonomy of these footprints and propose a new model, basing it on: 1) trackways changing direction, 2) trackways heading in different directions on the same surface, 3) trackways in situ, and 4) laboratory experiments with common wall lizards, Podarcis muralis. In all cases, the Chelichnus-like appearance of footprints is due to digit tip sliding on inclined depositional surfaces, masking the original footprint shape and orientation. Also, the trackway pattern and body position are largely influenced by the angle of inclination (dip) of the substrate being walked on. Based on an anatomy-consistent ichnotaxonomy, Chelichnus and Laoporus are here considered nomina dubia, and the footprints from the Coconino and De Chelly formations are revised and assigned to: parareptiles/captorhinomorph eureptiles (Erpetopus, Varanopus curvidactylus), bolosaurid parareptiles/ diapsid eureptiles (cf. Dromopus), varanopid synapsid (cf. Tambachichnium) and reptiliomorph amphibians (Amphisauropus, Ichniotherium sphaerodactylum). The ichnoassociation is dominated by parareptile/captorhinomorph tracks, similarly to all the late Cisuralian marginal marine, floodplain, alluvial fan and ephemeral lacustrine tetrapod ichnoassociations of North America, Europe and North Africa. A review of all the available data including the new results suggests a facies-crossing transition between an early-Cisuralian amphibian- and synapsid-dominated ichnofauna (Dromopus track biochron) and a late Cisuralian parareptile/captorhinomorph-dominated ichnofauna (Erpetopus track biochron) at low latitudes of Pangea.

Ichniotherium Pohlig, 1892 is a principal morphotype of Carboniferous-Permian tetrapod footprints referred to diadectomorphs. Though these tracks are relatively abundant in paleoequatorial regions ...

The Val Gardena Formation of the Dolomites region in northern Italy preserves the most significant assemblage of Late Permian tetrapod footprints in the world. More than 120 years of collecting resulted in about 900 publicly accessible specimens from the study area. This huge amount of data is comprehensively revised in the light of recent advances in the study of Late Palaeozoic – Early Mesozoic tetrapod ichnofossils. According to our analyses, the Val Gardena Sandstone Formation includes tracks that can be assigned to cf. Batrachichnus isp. (temnospondyl amphibian), Capitosauroides isp. (amphibian), Dicynodontipus isp. (cynodont therapsid), Dolomitipes accordii n. igen. n. comb. (dicynodont therapsid), cf. Dromopus isp. (neodiapsid), Pachypes dolomiticus (pareiasaurian parareptile), Paradoxichnium problematicum (archosauromorph neodiapsid), Procolophonichnium tirolensis n. comb. (procolophonoid parareptile), cf. Protochirotherium isp. (archosauriform neodiapsid) and Rhynchosauroides pallinii (ne...

Tetrapod footprints have long been known from Permian outcrops of the Cheguimi Sandstone in southern Tunisia, but never described in detail. The only recovered specimen preserves vertebrate tracks ...

The Late Carboniferous Souss Basin of south-central Morocco exhibits an approximately 1,800 m thick succession of fluvial and lacustrine deposits that have yielded diverse fossil remains of plants, insects, conchostracans, ostracods, jellyfish, fishes, and few tetrapod footprints. Recent exploration of ichnofossils of the Souss Basin led to the discovery of several trampled surfaces including tetrapod footprints assigned to the plexus Batrachichnus (Woodworth, 1900). Limnopus (Marsh, 1894), Dimetropus (Romer and Price, 1940), and Ichniotherium (Pohlig, 1892). These footprints can be referred to temnospondyl, basal synapsid (“pelycosaurian”), and diadectomorph trackmakers. The moderately diverse tetrapod footprint assemblage from the Souss Basin is important because it is the second-oldest record of tetrapod footprints from Africa and only the second record of the well-known ichnogenus Ichniotherium from outside of North America and Europe. Based on the variety of tetrapod tracks and previously col...

The Late Permian–Early Triassic sedimentary succession in the eastern Dead Sea Region of Jordan was surveyed for conchostracans (Crustacea: Branchiopoda). Whereas their occurrence in the Middle–Late Permian Umm Irna Formation could not be confirmed, the overlying Ma'in Formation contained a fauna comprising Rossolimnadiopsis Novozhilov and other, thus far, taxonomically undetermined conchostracans. Here, a new species, Rossolimnadiopsis hanskerpi nov. sp., is described and figured. It shows a very distinctive concavely curved dorsal margin and an elevated, outwardly curved semi-circular flange. Rossolimnadiopsis hanskerpi nov. sp. occurs in dark gray, laminated, lacustrine, siltstones of the Ma'in Formation (Nimra Member), which is considered to be of Early Triassic age. Based on literature data, Rossolimnadiopsis was previously recorded only from two localities in the Moscow syncline in Central Russia. In addition to Jordan, the genus has been identified in India and possibly in Germany. All these occurrences seem to be restricted to a narrow stratigraphic interval ranging from the Late Permian to the Early Triassic.

The south-central Moroccan Jebilet Massif comprises several occurrences of late Paleozoic continental red-beds. These deposits have been interpreted to be of Pennsylvanian-Permian age based on lithofacies. Any other reliable age constraint for these rocks was hitherto lacking. Recent fieldwork in late Paleozoic red-beds of the Koudiat El Hamra - Haiane Basin, near the center of the Jebilet Massif, yielded a remarkable association of continental trace fossils. The assemblage includes invertebrate traces (Helminthoidichnites tenuis, Scoyenia gracilis, Sphaerapus larvalis and cf. Spongeliomorpha isp.) as well as tetrapod footprints (cf. Batrachichnus isp, Dromopus lacertoides, Hyloidichnus bifurcatus and cf. Tambachichnium isp.). The tetrapod footprints suggest a late early Permian (Artinskian) to middle Permian (Capitanian) age of the fossil-bearing strata. The Koudiat El Hamra - Haiane fossil ichnofauna is similar to the one from the north-central Moroccan Tiddas Basin, leading to the possibility that both basins developed contemporaneously.

A taxonomic study has been carried out on the historical Gerola Valley locality (Pizzo del Diavolo formation, late Cisuralian), which represents one of the best tetrapod ichnosites of the whole Southern Alps (North Italy). With respect to previous studies, the ichnoassociation is now enlarged and lists the following taxa: Amphisauropus, Dromopus, Erpetopus, Hyloidichnus, Limnopus, Varanopus. The optimal preservation of the material, which in some cases shows even traces of the skin, allowed the recognition of a new morphotype of Varanopus. The invertebrate ichnoassociation is newly described and is representative of impoverished Scoyenia and Mermia ichnofacies. A detailed facies analysis of the uppermost arenitic–pelitic lithofacies of the Pizzo del Diavolo formation, which revealed the most abundant fossil content (Locality 1) and of two new localities (pelitic facies, Localities 2, 3) shows a transition from shallow lacustrine to floodplain and alluvial fan environments under a generally dry climate. Besides the taxonomic revision of vertebrate tracks, the final aims of our study are: i) the depositional, palaeoenvironmental and climatic reconstruction of this sector of the Orobic Basin through an integration of palaeontological data and facies analysis; and ii) the regional correlation of this key stratigraphic succession with other coeval ichnofaunas in Pangaea.

Ichniotherium tracks with a relatively short pedal digit V (digit length ratio V/IV < 0.6) form the majority of yet described Late Carboniferous to Early Permian diadectomorph tracks and can be related to a certain diadectid clade with corresponding phalangeal reduction that includes Diadectes and its close relatives. Here we document the variation of digit proportions and trackway parameters in 25 trackways (69 step cycles) from nine localities and seven further specimens with incomplete step cycles from the type locality of Ichniotherium cottae (Gottlob quarry) in order to find out whether this type of Ichniotherium tracks represents a homogeneous group or an assemblage of distinct morphotypes and includes variability indicative for evolutionary change in trackmaker locomotion. According to our results, the largest sample of tracks from three Lower Permian sites of the Thuringian Forest, commonly referred to Ichniotherium cottae, is not homogeneous but shows a clear distinction in pace length, pace angulation, apparent trunk length and toe proportions between tracks from Bromacker quarry and those from the stratigraphically older sites Birkheide and Gottlob quarry. Three Late Carboniferous trackways of Ichniotherium with relatively short pedal digit V from Haine's Farm, Ohio, and Alveley near Birmingham, United Kingdom, that have been referred to the ichnotaxa "Baropus hainesi", "Megabaropus hainesi" and "Ichniotherium willsi", respectively, share a marked outward rotation of foot imprints with respect to walking direction. Apart from this feature they are in many aspects similar to the Birkheide and Gottlob records of Ichniotherium cottae. With the possible exception of the Maroon Formation (Early Permian, Colorado) sample, Early Permian Ichniotherium trackways with a relatively short pedal digit V fall into the morphological spectrum of the three well defined 'Hainesi-Willsi', 'Birkheide-Gottlob' and 'Bromacker' morphotypes. With their more obtuse pace angulations and higher body-size-normalized pace and stride lengths the Bromacker type tracks imply higher walking speeds of their trackmakers compared to all other Ichniotherium tracks. More generally, a trend towards higher locomotion capability from the last common ancestor of all Ichniotherium producers to the last common ancestor of all "Ichniotherium with relatively short pedal digit V" and from the latter to the trackmakers of the mid-Early Permian Bromacker type can be deduced – with the reservation that overall sample size is relatively small, making this scenario a preliminary assessment. Whether the presumed advancements represent a more general pattern within diadectomorphs, remains open until the non-European Ichniotherium trackway record improves. Ichnotaxonomic implications are discussed.

Procolophonichnium is a globally distributed but rare tetrapod ichnogenus ranging from the ?Late Permian/Early Triassic through the Late Triassic. A Permian age of the holotype from the Karoo of South Africa, as has been proclaimed by some workers, is doubtful. Descriptions lack coordinates of the type locality but suggest instead a position in Lower Triassic strata. Procolophonichnium material from North and South Africa, central Europe, North and South America is re-evaluated. Furthermore, the new ichnospecies Procolophonichnium lockleyi from the Upper Triassic of the Germanic Basin is introduced, based on material with well-preserved trackways that show distinct morphological features, such as an extended “heel” behind digit V. Five ichnospecies are considered as valid: P. nopcsai (type ichnospecies), P. haarmuehlensis, P. nectouxi (new comb.) and P. polonicum as Procolophonichnium tracks from ?Upper Permian, Lower and Middle Triassic strata, and P. lockleyi ichnosp. nov. from the Upper Triassic. Track...

Paleozoic tetrapod footprints are a common and well-known phenomenon in almost all large European countries except for Spain. Here we report on hitherto unpublished vertebrate tracks from Permian red-beds of the south-central Pyrenees that with regard to their relative abundance, diversity and quality of preservation are suitable to fill this gap of knowledge. The described tracks come from two localities in muddy to fine-grained, sandy, alluvial plain deposits in the lower third of the Peranera Formation of the Erill-Castell Basin near Les Iglesies, northern Catalonia. The tracks can be assigned to five ichnogenera, i.e., Batrachichnus Woodworth, 1900, Limnopus Marsh, 1894, Varanopus Moodie, 1929, Hyloidichnus Gilmore, 1927, and Dromopus Marsh, 1894, that we interpret as footprints of temnospondyls, captorhinomorphs, and araeoscelids or similarly sized sauropsids with a lacertoid foot pattern. This ichnofossil assemblage is most similar to ichnofaunas from the Hermit Formation of the Grand Canyon, Arizona, the upper Abo and Robledo Mountains formations of New Mexico, and the main trace fossil site of the Tiddas Basin, Morocco, suggesting a late Early Permian (Artinskian) age for this stratigraphic level of the Peranera Formation. Considering the relative abundance and diversity of captorhinomorph footprints, the new Spanish tracefossil localities may cover the onset of the Early Permian radiation of non-diapsid eureptiles. The thick Late Paleozoic red-bed successions of the south-central Pyrenees have the potential to also bear footprints of otherwise unknown early therapsids, so systematic fossil prospecting of this area is strongly recommended.

The Sidi Kassem Basin is the only limnic basin of Westphalian age in Morocco. It is built up of 1,250 m of alluvio-fluvial to lacustrine deposits that have so far yielded plant fossils and invertebrate remains only. Recent exploration for fossil tetrapod footprints in floodplain-deposits of the basin revealed a moderately diverse vertebrate ichnofauna composed of tracks assigned to cf. Batrachichnus Woodworth, 1900; cf. Hylopus Dawson, 1882; Dimetropus Romer and Price, 1940; and Notalacerta Butts, 1891. The tracks can be referred to temnospondyl, anamniote reptiliomorph, non-therapsid synapsid (pelycosaur), and captorhinomorph trackmakers. The described ichnoassemblage is important in at least three aspects: (1) It suggests an Early to mid-Pennsylvanian age for the footprint-bearing strata of the study area. (2) It is the oldest association of tetrapod footprints from Africa. (3) It is the first evidence of the relatively rare ichnogenera cf. Hylopus and Notalacerta outside of North America and Europe. Ju...

A large, isolated temnospondyl interclavicle from Rockenhausen, Rhineland-Palatinate, is described that is derived from the Early Permian Meisenheim Formation of the Saar-Nahe Basin, south-western Germany. The element resembles closely the interclavicle of the North American genus Eryops in the following characters that justify its assignment to an eryopid temnospondyl: (1) The broad-ovate shape with a narrow, convex anterior margin and slightly convex or straight anterolateral margins, and the length-to-width ratio of approximately 0.7; (2) the ventral surface with a raised triangular field and the irregular dermal sculpture consisting of transversely oriented ridges, furrows and pits; (3) the anteroposteriorly shortened clavicular facets. The interclavicle from Rockenhausen represents the first unambiguous remain of an eryopid in the Saar-Nahe Basin. In contrast to dissorophoid and stereospondylomorph temnospondyls that constitute autochthonous faunal elements in the lakes of the Saar-Nahe Basin, eryopids seem to be allochthonous and might have been washed in from more distant habitats. Comparison of the morphologies and proportions of temnospondyl interclavicles suggests that the plesiomorphic state for temnospondyls is a proportionally small interclavicle equal in length and width or slightly longer than wide. Interclavicles that are broader than long are a derived character of zatracheids, certain dissorophoids (branchiosaurids) and Eryops and the specimen from the Saar-Nahe Basin, but evolved convergently in these groups. The much enlarged, elongate interclavicles appear to be a synapomorphy of stereospondylomorphs.

A complete skull and well-preserved postcranium of a dvinosaurian temnospondyl from the Carboniferous-Permian boundary of Germany is referred to a new genus and species, Trypanognathus remigiusbergensis. The skull closely resembles that of the early Permian dvinosaurian genus Trimerorhachis in outline and suture topology, but the occiput and the palate differ substantially. Derived states are the penetration of vomerine tusks through the splenial and symphyseal tusks through the premaxilla. Trypanognathus shares with dvinosauroids the lack of a squamosal embayment, an elongated basipterygoid process, a foreshortened palatine ramus exclusively reaching the ectopterygoid, the absence of pterygoid denticles, and enlarged palatal tusks. The body is elongate with well-ossified, but small limbs, the presacral count is ca. 28, and the pleurocentra are large and reached ventrally almost as far as the intercentrum. The new taxon nests within Dvinosauria above the trimerorhachid clade and Erpetosaurus, at the base of the broad-skulled dvinosauroids. Trypanognathus occurs in a tetrapod fauna that closely resembles early Permian assemblages of western North America, with which it shares sphenacodontid and edaphosaurid synapsids, as well as eryopid temnospondyls.

We describe an arthropod body impression associated with arthropod trackways of the ichnogenus Stiaria from the Lower Permian (upper Wolfcampian) Robledo Mountains Formation (Hueco Group) in the Prehistoric Trackways National Monument of southern New Mexico. The probable producer of these traces was a scorpion, and we name the likely scorpionid resting trace Alacranichnus braddyi, new ichnogenus and ichnospecies. There are no prior reports of scorpionid body impressions from terrestrial settings in the fossil record.

In 1858, Edward Hitchcock named Sphaerapus larvalis and S. magnus for burrows from the nonmarine Lower Jurassic Turners Falls Formation in Massachusetts. Walpia hermitensis White, 1929, from the Lower Permian Hermit Shale, Arizona, is also a little known ichnotaxon. Examination of the type material indicates that Sphaerapus is a senior subjective synonym of Walpia. Sphaerapus is also a nomen oblitum, but Walpia has not been sufficiently used to replace its senior synonym as a conserved name; thus, we use the senior synonym Sphaerapus as the valid name of this ichnogenus, which is monospecific (S. larvalis = S. magnus = W. hermitensis). Numerous specimens of Sphaerapus from the Lower Permian of New Mexico and Texas, and a new record from the Lower Jurassic of Massachusetts show that it is a horizontal endichnion or exichnion having an unpacked tunnel with a cylindrical to ellipsoidal cross section, in some specimens branching, and lined with flattened, lenticular, non-coprolitic sediment pellets that are i...

Abundant lycopsid remains from the Middle–Late Triassic Madygen Formation in southwestern Kyrgyzstan, Central Asia are described in detail, based on macromorphological and epidermal features. The lycopsid assemblage consists of the subarborescent morphotaxa Mesenteriophyllum kotschnevii , Ferganodendron sauktangensis and Pleuromeiopsis kryshtofovichii , and the herbaceous morphotaxon Lepacyclotes zeilleri that is described by the first time from Central Asia. In addition, two new species are introduced, Isoetites madygensis Moisan et Voigt sp. nov. and Isoetites sixteliae Moisan et Voigt sp. nov., which show a remarkable similarity to extant Isoetes species, i.e., a short corm and leaves with air channels, suggesting that this lineage goes back to the Early Mesozoic at least. The Madygen lycopsid flora consists of a mixture of subarborescent and herbaceous forms that has not been previously documented from the Ladinian–Carnian onward. The Madygen biota thrived at mid-northern latitudes in an intramontane basin, while most coeval occurrences represent tropical and subtropical biotas. The geographic position and climate are considered to be the main reasons for the unique flora and fauna found in the Madygen Formation, which shows a remarkably high abundance of lycopsids. The Madygen lycopsids show several characteristics indicating (semi-)aquatic habitats.

The Sidi Said Maachou area in the Moroccan western Meseta preserves a succession, up to 400 m thick, of hitherto poorly studied continental Triassic deposits. Recent detailed geological mapping proposes a lithostratigraphic subdivision of the predominantly red-coloured siliciclastic deposits into three formations. Laminated mudstones and fine-grained sandstones in the upper part of the Oued Oum Er Rbiaa Formation have the most interesting fossil content including plant impressions, rhizoliths, fish scales, and invertebrate and vertebrate traces. These biogenic remains are partially associated with tool marks, microbially induced sedimentary structures, oscillation ripples, desiccation cracks, and halite pseudomorphs, suggesting sedimentation in a playa-like, fluvio-lacustrine system under semiarid conditions. All tetrapod footprints from these beds are assigned to Brachychirotherium parvum and indistinguishable from other occurrences of the ichnogenus in Central Europe and North America. Supposed trackmakers are archosaurs of the crocodile stem-group (Crurotarsi) that were widely spread over Triassic Pangaea. Because Brachychirotherium is only known from Late Triassic (Carnian–Rhaetian) deposits, the same age is attributed to the footprint horizon of the Oued Oum Er Rbiaa Formation. This is the first record of Brachychirotherium on the African continent and the first record of Triassic tetrapod footprints in Morocco outside of the High Atlas.

Early Triassic chirotherian footprint assemblages from Poland, Germany, and Morocco are important for understanding archosaur evolution in the aftermath of the Permian-Triassic crisis. However, their ichnotaxonomy is confusing because various authors have interpreted their diversity differently. After an analysis and ichnotaxonomic re-assessment, the presence of the ichnogenera Brachychirotherium, Isochirotherium, and Chirotherium in these assemblages is not supported. Distant similarities with these ichnotaxa are functions of extra morphological variation and substrate-related factors. Instead, Early Triassic chirotherian footprints described under these names are assigned here to the ichnogenus Protochirotherium and to a more slender morphotype identified as Synaptichnium. In particular, Protochirotherium appears to be more widely distributed in central Pangea as a characteristic morphotype reflecting a distinct stage in archosaur evolution. Trackmakers were nonarchosaurian archosauriforms or, alternati...

The Early Permian Robledo Mountains Formation of the Hueco Group in the Robledo Mountains, south-central New Mexico, U.S.A., is a world-class ichnofossil Lagerstatte of supposed peritidal origin. Abundant and diverse invertebrate and vertebrate trace fossils occur in several thin horizons of siliciclastic red beds that are intercalated with thick successions of shallow marine limestone and shale. The depositional environment of the red beds has been discussed for decades but without any detailed sedimentary facies analysis. A recently completed systematic excavation shows that the majority of trace fossils is related to mud-draped surfaces within distal crevasse-splay siltstone to fine-grained sandstone. Interbedded mudstone with well-preserved macrofloral remains and a lungfish aestivation burrow represents a hitherto disregarded facies in overbank fines. Both environmental subzones were at least loosely covered with low-growing plants and experienced common periods of subaerial exposure. None of the physical and biological structures recorded in the measured section indicates tidal influence, but instead they support the reconstruction of a freshwater ecosystem dominated by arthropods and tetrapods. Given their proximity to carbonates of unambiguous subtidal origin, we propose that the trace-fossil-bearing red beds of the Robledo Mountains Formation formed in distal parts of an extensive coastal floodplain during alternating wet and dry conditions. If this interpretation is correct, it provides an impetus to continue ichnological and sedimentological field research in the study area, because the true tidal-flat ichnoguilds still await elucidation.

Diverse tetrapod track assemblages with Scoyenia invertebrate traces were discovered in the Triassic Timezgadiouine and Bigoudine formations of the Argana Basin (Western High Atlas, Morocco). The ichnofossils occur in alluvial plain sandstones and mudstones of the Irohalene Member (T5) and Tadart Ouadou Member (T6) considered Carnian-Norian in age by vertebrate remains and palynomorphs. Tetrapod footprints are assigned to Apatopus, Atreipus-Grallator, Eubrontes isp., Parachirotherium, cf. Parachirotherium postchirotherioides, Rhynchosauroides ispp., and Synaptichnium isp. They can be referred to lepidosauromorph/ archosauromorph, basal archosaur, and dinosauromorph trackmakers. Apatopus, represented by 11 tracks of a more than 4 m long trackway, is recorded for the first time outside of North America and Europe. The assemblage concurs with the proposed Late Triassic age of the track-bearing beds by the occurrence of Apatopus, Atreipus-Grallator, and Eubrontes. If this is accepted, the stratigraphic range ...

Bryophytes are found throughout the world in almost all terrestrial habitats. However, the fossil record of bryophytes is generally poor and fragmentary. In this contribution, we present the first unequivocal record of bryophytes from the Middle–Late Triassic Madygen Formation, in southwestern Kyrgyzstan, Central Asia. The bryophyte flora comprises two new species, the thalloid liverwort Ricciopsis ferganica and the leafy moss Muscites brickiae. In addition, a third form occurs, here described as Muscites sp. The dorsiventrally differentiated thallus of R. ferganica closely resembles that of the extant liverwort Riccia fluitans (Ricciaceae). The Central Asian finds represent the oldest known occurrence of the fossil genus Ricciopsis. The relative abundance of bryophytes in the Madygen fossil biota suggests that non-vascular plants played important role in special microhabitats within the Madygen palaeoecosystem and probably fostered the diversity of arthropods by providing favourable microhabitats for a range of aquatic and amphibiotic insects.

Associations between lycopsid and herbivorous arthropods are rare in the fossil record and equally sparse among the three surviving lineages of Lycopodiaceae, Selaginellaceae and Isoetaceae. However, from the Middle–Upper Triassic Madygen Formation of southwestern Kyrgyzstan, we describe the first association between an isoetalean host, Isoetites (a quillwort), and a pattern of elliptical egg insertion scars that altered the host's live plant tissues. This ovipositional damage, in some cases deployed in a stereotypical zigzag pattern, was most likely caused by small damselfly-like insects from the extinct suborder Archizygoptera of the order Odonatoptera (dragonflies). If this identification is correct, it indicates considerable behavioral stasis of dragonflies extending deep into the Mesozoic. Our detection of lycopsid ovipositional damage adds to the list of major plant hosts from the preangiospermous Mesozoic that were resources for host use by egg-laying dragonflies, particularly horsetails, ferns, and seed plants that included conifers, peltasperms, corystosperms, ginkgophytes, bennettitaleans and probably cycads.

The Permian Ikakern Formation of the Argana Basin yielded important tetrapod skeletal remains but is still poorly known for any other kind of fossils. Here we present a moderately diverse assemblage of invertebrate and vertebrate traces from red beds in the upper part of the formation (Tourbihine Member, T2) near Timezgadiouine. Recorded ichnotaxa include Spongeliomorpha carlsbergi ( Bromley and Asgaard, 1979 ), Striatichnium natalis Walter, 1982 , Amphisauropus Haubold, 1970 , Hyloidichnus Gilmore, 1927 , Erpetopus Moodie, 1929 , and Dromopus Marsh, 1894 . The traces occur in laminated muddy siltstone and fine-grained sandstone that we interpret as slack-water deposits in an episodically high energy fluvial setting. Including arthropod burrows, arthropod grazing traces and tetrapod footprints, the ichnofossil assemblage corresponds to the Scoyenia ichnofacies. The described trace fossils provide evidence for various invertebrates and vertebrates hitherto unknown from the body fossil record of the study area. By extending the stratigraphic and geographic range of some of the recorded ichnotaxa, our finds strongly emphasise the importance of the Argana Basin for the reconstruction and understanding of Late Palaeozoic terrestrial ecosystems.

Chroniosuchians are an enigmatic Permian to Triassic group of crocodile-like basal tetrapods. Their con- spicuous dorsal osteoderm systems include most of the group's yet documented postcranial morphological varia- bility but have hardly been considered in cladistic approaches. Aiming at the clarification of the internal rela- tionships of the Chroniosuchia, we have carried out a par- simony analysis including, among others, 23 morphological and osteohistological osteoderm characters and 12 chroni- osuchian taxa. According to the most parsimonious trees, taxa usually referred to Chroniosuchidae form a paraphy- letic succession with Madygenerpeton pustulatus and Chron- iosaurus dongusensis as the basalmost chroniosuchians and Uralerpeton tverdochlebovae as the sister group of Bystrowi- anidae (hypothesis A). However, the concurrent hypothesis of a basal split into monophyletic subtaxa Chroniosuchidae and Bystrowianidae (hypothesis B) is only slightly less par- simonious and supported by an alternative analysis which includes embolomeres as the only reptiliomorph outgroup. Searching for the better hypothesis, we compare the respective order of branching to the order of first occur- rences in the fossil record, demonstrating that hypothesis A provides a better stratigraphic fit than hypothesis B. Accordingly, the last common ancestor of the yet known chroniosuchians had a series of broad complexly interlock- ing 'chroniosuchid' osteoderms that served as a protection carapace apart from supporting the trunk during terrestrial locomotion. The later evolution of chroniosuchian carapaces was marked by a stepwise increase in flexibility and size reduction, which resulted in a loss of protective function and in a reduction in trunk support function. The flexibil- ity increase is paralleled by the evolution of the Crocodyl- omorpha whose extant members do not possess as extensively interlocking osteoderm systems as some of their Mesozoic relatives.

Elongated skin projections of the reptile Longisquama insignis from the Triassic of Kyrgyzstan are preserved as imprints on the only skeletal specimen and on seven additional pairs of fossil slabs and counter-slabs from the same locality and horizon. The integumentary structures became a matter of debate when they were assessed as “non-avian feathers” homologous to avian feathers. Conflicting interpretations of their morphology and relationship to other appendage types arose from the ambiguity of the fossil skin impressions. On the basis of comparative description of the individual morphology of all yet known Longisquama specimens we address aspects of taphonomy, development, and function and define to what extent Longisquama’s appendages share characteristics of avian vaned feathers. We explain the existing feather similarity by their development from a filamentous primordium and a complex sequence of individual processes, some of which are reminiscent of processes observed in feather development. Such an interpretation is in agreement with a set of homologous mechanisms of appendage morphogenesis in an archosauromorph clade including Longisquama and feather-bearing archosaurs but does not necessarily require that the appendages of Longisquama themselves are feathers or high-level feather homologues.

Tetrapod footprints from Late Palaeozoic deposits of Poland have been known for 150 years, but are poorly studied. Here we present the first comprehensive analysis of an extensive assemblage of fossil tracks from two artificial outcrops near Tlumaczow in the Polish part of the Intra-Sudetic Basin. Accompanied by conifer macrofloral remains and a few invertebrate traces, all footprints occur in reddish to greyish-brown, fluvio-lacustrine siltstones and sandstones of the Early Permian Slupiec Formation. Based on the study of nearly 120 slabs with tracks and trackways, we discern four distinct types of tetrapod footprints. These are assigned to the ichnotaxa Amphisauropus kablikae (Geinitz and Deichmuller, 1882), Ichniotherium cottae (Pohlig, 1885), Dimetropus leisnerianus (Geinitz, 1863), and Dromopus lacertoides (Geinitz, 1861) that can be referred to seymouriamorph, diadectomorph, “pelycosaurian”-grade synapsid and early sauropsid track makers. The Tlumaczow vertebrate track assemblage represents a typical early Early Permian (Asselian–Sakmarian) ichnofauna. Remarkable features are the dominance of footprints of terrestrially-adapted tetrapods and the relative abundance of diadectomorph tracks supporting interpretation of the fossil-bearing strata as part of an intermontane hinterland basin outside the range of semiaquatic anamniotes.

Habitat partitioning and site fidelity of spawning grounds are well-documented phenomena in extant selachians, but little is known about the reproductive strategies of their fossil relatives. Here we describe the selachian fauna of the Middle to Late Triassic Madygen Formation in southwestern Kyrgyzstan, Central Asia, based on several dozen tooth crowns and egg capsules. The material is assigned to three new taxa: Lonchidion ferganensis, sp. nov., and Palaeoxyris alterna, sp. nov., being teeth and egg capsules of hybodontid sharks, and Fayolia sharovi, sp. nov., being egg capsules of probable xenacanthids. Teeth of L. ferganensis, sp. nov., were almost exclusively found in pelecypod-rich shallow lacustrine mudstones and belong to juvenile individuals. Oxygen and strontium isotope data of tooth enameloid indicate freshwater conditions of the ambient water at the time of tooth mineralization. The egg capsules are common findings in near-shore lake deposits as well. Considering the mass co-occurrenc...

Although burrowing ability has been widespread in tetrapods for more than 300 million years, subsurface dwelling structures that indicate communal behavior are poorly evidenced from pre-Cenozoic strata. Here we present recently discovered tetrapod burrows from Middle Triassic red beds of the Argana Basin in central Morocco, whose complexity suggests an origin by gregarious animals. The well-preserved burrows occur in interbedded mudstones and sandstones interpreted as channel and overbank deposits of ephemeral, braided streams. All burrows originate from the top of thick-bedded sandstones and descend as moderately inclined (10°–30°), partially spiral tunnels to laterally extended, branched chambers in underlying mudstones. Tunnel segments are biconvex to planoconvex in cross section, up to 20 cm wide and 12 cm in maximum height and exhibit transverse scratch marks along the ceilings and sidewalls. Distinctive burrow characteristics include a laterally sinuous geometry (wavelength λ = 38–45 cm; amplitude A = 5–10 cm) of the tubelike passages and the presence of grouped alcoves in terminal chambers. We attribute the burrows to procolophonids or therapsids based on closely associated tetrapod tracks and the limited diameter of the excavations. Our findings represent the second oldest record of communal fossorial behavior by tetrapods and the oldest example from low-latitude areas. Beyond providing refuge from predators, these elaborate underground structures probably functioned as a buffer against diurnal or seasonal variations of air temperature and humidity in a semiarid habitat that was situated just north of the paleoequator.

Continental trace fossils of Early Permian age are well known in the western United States from Wolfcampian (~ Asselian to Artinskian) strata, but few examples are known from Leonardian (~ Kungurian) deposits. A substantial ichnofauna from strata of the lower part of the Clear Fork Formation at Lake Kemp, Baylor County, Texas, augments the meager North American record of Leonardian continental trace fossil assemblages. Ichnofossils at Lake Kemp occur in the informally-named Craddock dolomite member of the Clear Fork Formation, which is 12–15 m above the local base of the Clear Fork. The trace-bearing stratum is an up-to-0.3 m thick, laminated to flaser-bedded, dolomitic siltstone that also contains mud cracks, raindrop impressions, microbially induced mat structures, and some land-plant impressions. We interpret the Craddock dolomite member as the feather-edge of a marine transgressive carbonate deposit of an irregular coastline marked by shallow bays or estuaries on the eastern shelf of the Midland basin, and the trace-fossil-bearing stratum at Lake Kemp is an unchannelized flow deposit on a muddy coastal plain. The fossil site at Lake Kemp yields a low to moderately diverse fauna of invertebrate and vertebrate traces. A sparse invertebrate ichnofauna consists of arthropod feeding and locomotion traces assigned to Walpia cf. W. hermitensis White, 1929 and Diplichnites gouldi Gevers in Gevers et al., 1971. Tetrapod footprints are most common and assigned to Batrachichnus salamandroides (Geinitz, 1861), cf. Amphisauropus kablikae (Geinitz and Deichmuller, 1882), and Dromopus lacertoides (Geinitz, 1861), which represent small temnospondyl, seymouriamorph, and basal sauropsid trackmakers. Both the traces and sedimentary features of the fossil horizon indicate a freshwater setting at the time of track formation, and the trace assemblage represents the Scoyenia ichnofacies and the Batrachichnus ichnofacies in an overbank environment with sheet flooding and shallow ephemeral pools on an extensive coastal plain. The Lake Kemp tetrapod track assemblage is characteristic of the global Early Permian tetrapod ichnofauna found in red beds, which is dominated by a handful of ichnogenera that include Batrachichnus, Limnopus, Amphisauropus, Dromopus, Varanopus, Hyloidichnus, Ichniotherium and Dimetropus, which are the tracks of temnospondyls, seymouriamorphs, diadectomorphs, “pelycosaurs”, “captorhinomorphs”, and araeoscelids. The Lake Kemp tracks also further document the continuity of the ichnogenera Batrachichnus, Amphisauropus and Dromopus from Wolfcampian into Leonardian time and thus support the concept that Wolfcampian and Leonardian red-bed tetrapod footprints represent a single biostratigraphic assemblage.

Footprints of Early Mesozoic terrestrial tetrapods are inadequately known from NW Africa despite pervasive and well-exposed continental strata of corresponding age in that region. Here, we report on the first occurrence of a tetrapod ichnofauna from the middle part of the Triassic Timezgadiouine Formation in the Argana Basin, Central Morocco that is outstanding in terms of abundance, preservation, and diversity. Footprints of this assemblage are assigned to the ichnotaxa Chirotherium barthii, Isochirotherium coureli, Synaptichnium isp., Atreipus–Grallator, Rotodactylus isp., Rhynchosauroides isp., and Procolophonichnium isp., suggesting early archosaurian, dinosauromorph, lepidosauromorph and possible therapsid or procolophonoid trackmakers. Based on comparison with the abundant record of Early Mesozoic vertebrate ichnofossils from Europe and North America, the ichnofauna presented here indicates a Middle Triassic (Anisian–Ladinian) age for the track-bearing horizon in the Argana Basin. Its clearly Euramerican affinity sheds light on the migration and dispersal of early archosaur-dominated tetrapod faunas considering that several ichnotaxa of the assemblage are documented from Africa for the first time.

In terms of cumulative thickness and areal extent, the Khenifra Basin is one of the most important outcrops of Late Palaeozoic red-beds in central Morocco. Macro- and microfloral remains near the centre of the 1800 m-thick succession of interbedded conglomerates, sandstones, and mudstones are considered to be of middle to late Early Permian age. Here we give the first comprehensive analysis of the vertebrate ichnofossil record from the study area, based on 17 specimens of isolated footprints and incomplete step cycles collected at three localities that are lithostratigraphically equivalent to the plant-bearing horizons. The tetrapod ichnofauna comprises tracks of the plexus Batrachichnus Woodworth – Limnopus Marsh, Ichniotherium sphaerodactylum (Pabst), Dimetropus Romer and Price, and Dromopus Marsh which can be referred to temnospondyl, diadectomorph, synapsid (“pelycosaurian”) and early sauropsid trackmakers. This clearly Euramerican footprint assemblage, including the first occurrences of Ichniotherium and Dimetropus from outside Europe and North America, indicates a Late Carboniferous to Early Permian age of the fossiliferous strata. Judging from the relatively diverse ichnofauna and flora, the Khenifra Basin must have represented a well-established terrestrial ecosystem during that period. Its habitat could be specially important for the understanding of the phylogeny and dispersal of early tetrapods, inasmuch as we are able to report on an extremely rare type of diadectomorph footprint hitherto known only from the Early Permian of central Germany.

During the mid-1980s, structural geological field work in the up to 300 m thick red-bed sequence of the Permian Tiddas Basin, central Morocco, revealed the first occurrence of Palaeozoic tetrapod footprints in NW Africa. Preservational ambiguity of part of the few published trace fossils and resulting taxonomic inconsistency necessitate a long-needed reanalysis of the type locality. Based on 110 recently collected specimens the revised tetrapod ichnofauna of the study area comprises tracks of Batrachichnus Woodworth, 1900 — Limnopus Marsh, 1894, Amphisauropus Haubold, 1970, Dimetropus Romer and Price, 1940, Varanopus Moodie, 1929 — Hyloidichnus Gilmore, 1927, and Dromopus Marsh, 1894 which can be referred to small and medium-sized temnospondyl, seymouriamorph, basal synapsid (‘pelycosaur’), captorhinomorph, and araeoscelid trackmakers. This assemblage is interpreted to represent a late Early Permian (Artinskian–Kungurian) tetrapod ichnofauna. Due to the relative abundance of footprints assigned to semiaquatic tetrapods and sedimentological evidence for pronounced humid palaeoclimatic conditions we propose correlation of the track-bearing strata with the late Artinskian/early Kungurian wet phase. Regarding the quality, quantity, and peculiar diversity of its fossils, including the earliest record of seymouriamorph and advanced captorhinomorph tracks from the African continent, the Tiddas Basin could be of great importance for the reconstruction of late Early Permian terrestrial ecosystems in proximity to the interface of Euramerican and Gondwanan biotic provinces.

Plant fossils recently collected from the Middle–Late Triassic Madygen Formation in SW Kyrgyzstan, Central Asia are described in detail. Based on the combination of gross morphology and epidermal/cuticular anatomy, four different taxa are identified, assigned to the Cycadales, i.e. Pseudoctenis lanei and Bennettitales, Pterophyllum pinnatifidum, P. firmifolium and Otozamites sp. All taxa are new for the Madygen Formation. Remarkable is the first occurrence of Pseudoctenis and two Pterophyllum species in the Triassic of Central Asia. The fossils are generally well preserved, but without cuticles. Nevertheless, epidermal and cuticular features can be recognized because the cuticles left behind imprints in the very fine-grained matrix. Silicon casts, examined under a stereomicroscope and with SEM, revealed xeromorphic features that are traditionally considered as indicators of arid conditions. However, comparisons of the functionality of the xeromorphic features in living plants show that these features occur in xerophytic, as well as in hygrophytic and halophytic plants. Sedimentological data from Madygen show that the fossil flora grew in alluvial plains, delta plains, and shallow lacustrine environments. The xeromorphic features are consequently interpreted as functional adaptations to environmental influences involved in the self-cleaning of the leaf surface, regulation of excessive radiation and leaf temperature and as an effective mechanical defense against phytophagous insects.

Dermal ossifications are widespread in Permian and Triassic tetrapods, but only members of the Chroniosuchia possess a series of dorsal osteoderms with a complex plate-to-plate articulation mechanism in addition to a contact between each osteoderm and its associated vertebral spine. The stratigraphically youngest chroniosuchid, Madygenerpeton pustulatus, from the Triassic of Kyrgyzstan provides new insight on the function of the chroniosuchian osteoderm system. Osteoderms of M. pustulatus are broad, peaked-roof-shaped to arched, with enlarged posterodorsal and anteroventral articulation facets bearing unique sets of concentric rail-like ridges and furrows. Supplementing the multiple-overlap chroniosuchiantype articulation, the interlocking ridges and furrows confined the relative motion of two neighboring osteoderms to a rotation in slightly oblique and curved contact planes. Given the significant lateral narrowing of the dorsal ornamented non-overlap area, the horizontal component of the plate-t...

An assemblage of abundant and well-preserved tetrapod footprints has been discovered in the Tanamert Member (T3) of the Triassic Timezgadiouine Formation (Argana basin, western High Atlas, Morocco). It is the first fossil record from T3. Surfaces from different localities show a uniform tetrapod ichnofauna that consists of chirotherian and small lacertoid forms. The chirotherians are assigned to the plexus Protochirotherium—Synaptichnium, their trackmakers interpreted as basal archosaurs. The lacertoid imprints show close affinities with Rhynchosauroides and may reflect archosauromorphs or lepidosauromorphs. Protochirotherium—Synaptichnium assemblages are characteristic of the Early Triassic and were known previously only from units of this age in central Europe. Biostratigraphically, the European record implies a wide-spread pre-Anisian Protochirotherium—Synaptichnium dominated assemblage preceding the first appearance of Chirotherium barthii near the Olenekian-Anisian boundary. The stratigraphic positio...

Tetrapod footprints from the Permian Ikakern Formation of the Argana Basin have long been known but never studied in detail. Here we present the first comprehensive description of recently discovered tracks and trackways that come from near the uppermost layers of an up to 1800 m thick red-bed sequence. Assigned to Hyloidichnus Gilmore, 1927 and Pachypes Leonardi et al., 1975 , these ichnofossils suggest a Middle to Late Permian age of the track-bearing strata. Potential trackmakers are medium to large-sized moradisaurine captorhinids and pareiasaurs. This strongly parallels the bodyfossil record inasmuch as the only known skeletal remains of terrestrial tetrapods from the study area belong to both of these groups. Based on this twofold evidence, captorhinids and Pareiasauria have to be considered as abundant faunal elements of the ancient floodplain environment that is represented by the upper part of the Ikakern Formation. As one of only a few places in the world with closely associated body and ichnofossils of Late Palaeozoic age, the Argana Basin has a high potential for allowing the reconstruction of terrestrial ecosystems during the early stages of the break-up of central Pangaea and just before Mesozoic diapsid reptiles gained ascendancy. Further research on this stimulating topic will significantly contribute to the understanding of still poorly known Middle and Late Permian tetrapod ichnofaunas.

Ichnotaxonomic revision of two extended sequences of large tetrapod footprints from the Westphalian A Bochum Formation of western Germany suggests assignment of the specimens to the well-known Permo-Carboniferous ichnogenera Ichniotherium and Dimetropus. Trackway parameters and imprint morphology strongly support basal diadectomorphs and “pelycosaurian” -grade synapsid reptiles, respectively, as the most likely trackmakers. The ichnofossils thereby extend the first appearance of these two important groups of basal tetrapods by about 5–10 million years, to the early Late Carboniferous, which is in accordance with the minimum age for the evolutionary origin of the clades following widely accepted phylogenetic analyses. These trackways provide not only direct evidence bearing on activity and behaviour of large terrestrial tetrapods close to the origin of amniotes, but also serve as a valuable benchmark for the assessment of controversially interpreted vertebrate tracks from other localities of similar age.