Ben Creisler
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Erythrosuchidae were large-bodied, quadrupedal, predatory archosauriforms that dominated the hypercarnivorous niche in the aftermath of the Permo-Triassic mass extinction. Garjainia, one of the oldest members of the clade, is known from the late Olenekian of European Russia. The holotype of Garjainia prima comprises a well-preserved skull, but highly incomplete postcranium. Recent taxonomic reappraisal demonstrates that material from a bone bed found close to the type locality, previously referred to as âVjushkovia triplicostata', is referable to G. prima. At least, seven individuals comprising cranial remains and virtually the entire postcranium are represented, and we describe this material in detail for the first time. An updated phylogenetic analysis confirms previous results that a monophyletic Garjainia is the sister taxon to a clade containing Erythrosuchus, Shansisuchus and Chalishevia. Muscle scars on many limb elements are clear, allowing reconstruction of the proximal locomotor musculature. We calculate the body mass of G. prima to have been 147â248 kg, similar to that of an adult male lion. Large body size in erythrosuchids may have been attained as part of a trend of increasing body size after the Permo-Triassic mass extinction and allowed erythrosuchids to become the dominant carnivores of the Early and Middle Triassic.
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Christopher T. Griffin, Michelle R. Stocker, Caitlin Colleary, Candice M. Stefanic, Emily J. Lessner, Mitchell Riegler, Kiersten Formoso, Krista Koeller & Sterling J. Nesbitt (2020)
Assessing ontogenetic maturity in extinct saurian reptiles.
Biological Reviews (advance online publication)
doi:
https://doi.org/10.1111/brv.12666https://onlinelibrary.wiley.com/doi/10.1111/brv.12666Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, lifeâhistory strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the leastâinclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260âmillionâyear history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and crossâstudy coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing methodâspecific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with wellârepresented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in wellâconstrained, empirically tested methods.
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The internal cast of a turtle shell, found near the town of Cabrejas del Pinar (Soria Province, Castile and Leon Autonomous Community, Spain), is presented here. It is the first fossil vertebrate recognized in the vicinity of that town. This specimen was found in a middle Cretaceous bed (Cenomanian), deposited in a coastal marine environment. It is recognized as attributable to a member of the crown group Pleurodira. No representative of this clade had so far been found in pre-Campanian strata in the Castile and Leon Autonomous Community. In fact, the pre-Campanian record of the crown Pleurodira is very limited in Laurasia. The hitherto known record of pre-Campanian turtles from Castile and Leon consisted of basal forms (members of the terrestrial clade Helochelydridae and of the freshwater Pleurosternidae) and of freshwater representatives of Eucryptodira, all of them found in layers older than that where the new turtle remain was found. The availability of characters in the analyzed specimen allows it to be recognized as compatible with the littoral bothremydid turtle Algorachelus.
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