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Fossil oysters are commonly found in Rio Grande do Sul Coastal Plain (RSCP), where the main species are Ostrea cf. puelchana d'Orbigny, 1841 and Crassostrea praia Ihering, 1907. These fossils are transported towards the beach by storm events throughout the year, being available in the swash zone. The objective of this article is to reconstruct the Holocene palaeoenvironment by analysing these fossils. A total of 1898 valves, collected along Cassino and Hermenegildo beach, both in southernmost Brazil, were described. It was observed a prevalence of C. praia at Cassino beach (39.20%) and O. cf. puelchana at Hermenegildo beach (89.02%). Hermenegildo beach sample were statistically greater for C. praia height (p -value: 0.1736) and length (p -value: 0.4604) and for O. cf. puelchana height (p -value: 0.0602) and length (p -value: 0.07394). The predominance for northern and southern regions for each species indicates a palaeoenvironment setting that favoured these organisms, probably related to temperatures and salinity variation. The most common ichnogenera found in the oysters were Caulostrepsis and Entobia present in both sites, observed in over 40% of internal and external sides of the samples' shell. According to radiocarbon modelled age, the studied samples coexisted during the Mid-Holocene (8.290–8.130 cal. yr. BP), with the subsequent sea-level rise and fall the shells became bioavailable. The lack of samples with closed valves and high percentage of bioerosion in the inner side of the valve, indicates that the palaeoenvironment in both Cassino and Hermenegildo beaches gradually changed, not as result of an extreme event. [ABSTRACT FROM AUTHOR]

New bioerosion traces produced by insects in bones are reported from the Hyperodapedon Assemblage Zone of the Santa Maria Supersequence (Carnian, Brazil). The bones are assigned to a single rhynchosaur Hyperodapedon mariensis individual and among the traces, the ichnogenera Osteocallis (Osteocallis mandibulus, Osteocallis infestans, and Osteocallis isp.) and Amphifaoichnus (Amphifaoichnus isp.) are recognized, along with two morphotypes of indiscrete traces: clusters of grooves and borings. All the traces are assigned to the action of insects exploring the rhynchosaur carcass. Osteocallis and associated clusters of grooves are interpreted as feeding traces, but whether they represent necrophagic or osteophagic behavior is still uncertain. The lack of direct evidence for the ethological interpretation of Amphifaoichnus precludes its sole correlation with osteophagy, and other possibilities, such as the construction of temporary domiciles related to feeding or sediment moisture, are discussed. The traces analyzed here indicate that the insects explored a buried carcass, challenging the automatic association of Osteocallis and prolonged subaerial exposure of bones, placing insects as relevant taphonomic agents that affect the preservation of vertebrate carcasses. Additionally, the first appearance record of Amphifaoichnus is expanded back more than 140 Ma, indicating that complex behaviors employed by insects in bone exploration were already established in the early Late Triassic, shortly after the oldest records of invertebrate bioerosion in bones on continental settings. [ABSTRACT FROM AUTHOR]

The Eocene Nanjemoy Formation crops out on the Maryland and Virginia Coastal Plain, along the eastern coast of the United States. This formation is composed of sands, silts and clays and is divided into the Potapaco and Woodstock members. Remains of fishes, reptiles, birds, mammals, molluscs, fruits and seeds are common in the Potapaco Member, in addition to vertebrate coprolites. Here, we present an analysis of more than 2000 coprolites from the Fisher/Sullivan Site in Virginia. The chemical composition (phosphatic) and the type of inclusions (fish bones) indicate that only scats of carnivorous animals were preserved. The analysed specimens were grouped into six morphotypes: (1) the cylindrical morphotype is a cylinder with rounded ends; (2) the segmented morphotype is a cylinder segmented with rounded ends, and occasionally one end is concave; (3) the oval morphotype represents a bean‐shaped coprolite; (4) the scroll morphotype is cylindrical to conical in lateral view and has coils seen only at the ends; (5) the folded morphotype is a spiral that is concentrically folded; and (6) the sinuous morphotype is serpentine, with rounded ends. Coprophagy‐related scrape traces occur in different morphotypes and represent both invertebrate burrows and bite traces made by fishes. The mineralogical and chemical analyses indicate an early precipitation of phosphate and pyrite minerals, probably induced by the microbial community. All coprolites at the Fisher/Sullivan Site were produced by fishes: carcharhiniform sharks for the scroll morphotype and lamniform sharks, probably the genus Carcharias, for the folded morphotype; the oval, cylindrical and segmented morphotypes were likely produced by actinopterygian fishes. [ABSTRACT FROM AUTHOR]

Tetrapod tracks in eolianites are widespread in the fossil record since the late Paleozoic. Among these ichnofaunas, the ichnogenus Chelichnus is the most representative of the Permian tetrapod ichnological record of eolian deposits of Europe, North America and South America, where the Chelichnus Ichnofacies often occurs. In this contribution, we describe five sets of tracks (one of which is preserved in cross-section), representing the first occurrence of Dicynodontipus and Chelichnus in the “Pirambóia Formation” of southern Brazil. This unit represents a humid desert in southwestern Pangea and its lower and upper contacts lead us to consider its age as Lopingian–Induan. The five sets of tracks studied were compared with several ichnotaxa and body fossils with appendicular elements preserved, allowing us to attribute these tracks to dicynodonts and other indeterminate therapsids. Even though the “Pirambóia Formation” track record is sparse and sub-optimally preserved, it is an important key to better understand the occupation of arid environments by tetrapods across the Permo–Triassic boundary. [ABSTRACT FROM AUTHOR]