The exceptional preservation of organisms is potentially influenced by various factors that reflect either the environmental context or aspects of the organisms' biology. There has been no systematic investigation of the relative impact of such factors upon the fidelity of preservation of an exceptionally preserved taxon. In this study, we present an integrated approach to taphonomic analysis of exceptionally preserved taxa using primarily quantitative data to analyze the taphonomy of exceptionally preserved frogs (Rana (Pelophylax) pueyoi) from the lacustrine-hosted, upper Miocene, Libros Konservat-Lagerstätte (Teruel, northeastern Spain). The frogs occur within several different laminated mudstone facies and vary in their size, degree of completeness, degree of articulation, limb positions, and the extent, type, and fidelity of preserved soft tissues. For each specimen, we coded its physical and soft-tissue taphonomy using twelve indices, and identified its lithological context. Systematic statistical analysis reveals no correlation between specimen size, any taphonomic index, and lithological context: variations in the taphonomy of the frogs are independent of centimeter-scale variations in lithology and, by inference, short-term fluctuations in environmental conditions. The consistently high fidelity of skeletal preservation and the preservation of soft tissues, therefore, ultimately reflect the general nature of the sedimentary environment, i.e., burial within laminated organic-rich muds below anoxic, monimolimnetic waters of a deep, stratified meromictic lake. The statistical analysis did, however, identify significant correlations between various taphonomic indices. These indicate that the observed variation in the fidelity of frog preservation can be attributed, in large part, to a suite of factors related to the biology of the frogs; the most important of these is the original biochemistry of specific tissues, especially the skin, and the postmortem fate of the skin.

The Capitanian (middle Permian) extinction and recovery event is examined in carbonate platform settings from western Tethys (Hungary and Hydra, Greece). The age model for these sections is poorly resolved and we have constructed a δ¹³C chemostratigraphic correlation scheme, supported by conodont and foraminifer data, which attempts correlation with the well-dated events in China. This reveals the timing of events was similar in all Tethyan regions: extinction losses in the middle of the Capitanian produced late Capitanian assemblages in Hungary and Hydra with a distinctive late Permian character (for example, they lack large fusulinaceans). There is no evidence for an extinction event at the end of the Guadalupian (Capitanian) suggesting that previous claims for an end-Guadalupian mass extinction are based on poorly dated records of a mid-Capitanian event. Base level was stable through much of the middle–late Permian transition with the exception of a major regression within the Capitanian Stage. The subsequent transgression established widespread shallow-water carbonate deposition, such as the Episkopi Formation in Hydra and the Nagyvisnyó Limestone Formation in Hungary.

The application of principles derived from recent ecosystems to paleoecosystems is an important tool for testing the universality of these principles, as well as identifying deviations that require further investigation. Here, we estimate the predator and prey biomass in nine Italian Plio-Pleistocene mammalian paleocommunities and compare their relationships with recent ecosystems. The predator-prey biomass relationship is shown to be identical in extant and fossil communities for prey species less than 450 kg body mass (BM), thus indicating that biomass fluctuations from prey to predators were similar in Plio-Pleistocene and recent ecosystems for this BM range. However, if herbivores of 450 kg up to 1000 kg were also accepted as prey, the predator-prey biomass relationship differs significantly between Plio-Pleistocene paleoecosystems and recent ecosystems. Herbivores within this BM range occurred after the early Pleistocene, whereas both smaller (<450 kg) and larger (>1000 kg) herbivores were present in all ecosystems studied. The results of this study suggest that fossil herbivores of this particular BM range were ecologically different from similar-sized extant populations and did not constitute regular prey species for the predators present. Their emergence was not accompanied by a corresponding increase in biomass of predators. Thus, middle-Late Pleistocene ecosystems were potentially controlled from the bottom up rather than from the top down. The results reported herein show how successive estimates of body mass, density, and biomass can be used to reconstruct paleoecosystems.

The continental Pleistocene Alat Formation in Eritrea hosts one-million-year-old Homo erectus remains and includes lacustrine calcareous beds with exceptionally numerous and well-developed ichnofossils. They are referred to two different types with distinctive morphologies based on the shape of their casts on the bed soles. Ichnofossils of the first type, termed donuts, have a pronounced ring shape with an average diameter of ∼13 cm. Those of the second type have a rosette shape with a diameter of up to 35 cm and more than 20 short fingers arranged around a flat, circular area. We interpret the donut-shaped structures as casts imprinted by the conical pedal disk of an unknown organism on the soft floor sediment. A similar organism with a more complex pedal disk, characterized by protrusions, may have made the rosette-shaped ichnofossils. Both ichnofossils are interpreted as resting traces of soft-bodied animals anchored in a vertical position within the sediment. After their deaths, the traces were preserved as casts on the lake floor and subsequently filled by calcareous sand. The peculiar plug-shaped resting traces, the lacustrine habitat of the tracemakers, and the lack of similar traces in the literature suggest that these fossils represent two new ichnotaxa left by invertebrate organisms of unknown affinity.

Direct evidence of behavior in extinct tetrapods is rare. However, these traces can inform a variety of research questions touching on paleoecology, taphonomy, and functional morphology. Here we present fossil specimens from the Upper Cretaceous (Cenomanian) Woodbine Formation that exhibit tooth marks consistent with predation by a new taxon of large crocodyliform currently under study. Collected from the recently discovered Arlington Archosaur Site, the marked bones were largely found in a single peat horizon and in close association with the new crocodyliform. The feeding traces themselves consist of pits, scores, and punctures that occur on multiple turtle shell fragments and two dinosaur limb bones. The pattern of marks and the breakage on turtle carapaces and plastra suggest that they were crushed, whereas the marks on dinosaur bones indicate possible dismemberment. These interpretations and the association with a crocodyliform trace maker are based on observations of feeding behaviors and accompanying, diagnostic bite mark patterns made by extant crocodylians. The morphology of the new crocodyliform taxon and the distribution of bite marks indicates it was likely a generalist: an opportunistic predator that fed on a variety of prey, including turtles and dinosaurs. Given this evidence and the paleoenvironmental setting, the ecology of the large crocodyliform from the Woodbine Formation was likely most similar to that of fossil and living crocodylians inhabiting delta-plain environments. Not only were these crocodyliforms likely significant predators in the Woodbine paleoecosystem, they also played an important taphonomic role in the assembly of vertebrate remains from the surrounding community.

Arthrophycus is an iconic ichnogenus known from lower Paleozoic clastic strata worldwide, yet its origin remains controversial. A medial groove imparts a bilobed symmetry in some forms, implicating arthropods as the tracemaker. Other forms have regular annulae that evoke an annelid body plan. Transverse ridges in some bilobed forms of Arthrophycus, however, were deemed by some as too blunt to have been made by arthropods, and the annulation is unlikely to have anything but a superficial resemblance to “worms.” Recent work has converged on a nontrilobite, long-bodied arthropod as the likely Arthrophycus tracemaker. Given the breadth of morphological variation and range in size included in various ichnospecies of Arthrophycus, there are likely multiple tracemakers for this ichnogenus, and the tracemakers may belong to more than one phylum. Some ichnospecies of Arthrophycus may even represent the only physical record of an unknown or poorly fossilized group of organisms. Observations of the physiology and neoichnology of modern Arthrophycus tracemaker analogs support the conclusion that the maker of the Carboniferous ichnospecies Arthrophycus parallelus is neither an annelid nor a previously described arthropod but a yet unknown member of the Ecdysozoa.