An Enigmatic Small Neosuchian Crocodyliform from the Woodbine Formation of Texas

Abstract

New discoveries at the Arlington Archosaur Site (AAS), a Cenomanian (Late Cretaceous) locality in north‐central Texas, are filling gaps in our knowledge of mid‐Cretaceous Appalachian ecosystems, which remain poorly characterized. The AAS is notable because it preserves a diverse crocodyliform record. As seen in other sites that preserve four or more crocodyliform taxa, the species present at the AAS exhibit different snout shapes and body sizes, indicating that this high diversity of sympatric species was likely sustainable due to niche partitioning. Here we describe Scolomastax sahlsteini gen. et sp. nov., a new species of crocodyliform from the AAS, currently known from a partial right mandibular ramus. This species differs from other crocodyliforms in possessing features associated with durophagy or omnivory, including a shortened mandible, reduced tooth count, heterodonty, a dorsally expanded surangular, and enlarged attachments for jaw adductor muscles. Our phylogenetic analysis places this new taxon within Eusuchia as a member of Paralligatoridae and sister taxon to Paralligator gradilifrons. Scolomastax sahlsteini extends the record of paralligatorids into the Late Cretaceous of North America. This discovery represents the first appearance of this clade on the poorly known landmass of Appalachia, supporting a biogeographic connection between North America and Asia in the Early Cretaceous prior to completion of the Western Interior Seaway. However, relationships among other endemic crocodyliforms and tree instability within Paralligatoridae suggest further analysis is needed to resolve phylogenetic and biogeographic relationships (http://zoobank.org/urn:lsid:zoobank.org:pub:DC114471-6687-4BB5-8FAE-96F7278B1DAF). Anat Rec, 303:801–812, 2020. © 2019 Wiley Periodicals, Inc.

Paleocene resurrection of a crocodylomorph taxon: Biotic crises, climatic and sea level fluctuations

“…Elosuchus cherifiensis has been described as a pholidosaurid (e.g. Jouve et al, 2006;Jouve, 2009;Andrade et al, 2011;Fortier et al, 2011;Martin et al, 2013;Meunier et al, 2016;Young et al, 2016;Adams et al, 2017;Noto et al, 2019), or closely related to the clade formed by the pholidosaurids and dyrosaurids (Jouve, 2009;Wilberg, 2015;Ristevski et al, 2018;Wilberg et al, 2019).…”

Expanded Sampling Across Ontogeny in <I>Deltasuchus motherali</I> (Neosuchia, Crocodyliformes)

“…Appalachia, to the east, has remained something of a mystery, but recent discoveries are starting to reveal aspects of the diversity of this understudied landmass (e.g. Adams et al, 2017;Brownstein, 2018;Adrian et al, 2019;Noto et al, 2019). The Woodbine Group outcrops across north-central Texas and is situated within both this temporal and geographic gap.…”

“…The quality of preservation and the density of recovered fossil material are both unusually high, providing a window into the paleoecosystem of the Cenomanian coastline (e.g. Adams et al, 2017;Brownstein, 2018;Adrian et al, 2019;Noto et al, 2019).…”

“…As its name suggests, the site is particularly rich in archosaurian fossils, with at least four crocodyliform (Adams et al, 2017;Noto et al, 2019) and five dinosaur taxa (Main et al, 2014;Noto, 2016) known from the locality. Among these taxa, the most common species recovered from the AAS is the large neosuchian crocodyliform Deltasuchus motherali (Adams et al, 2017).…”

“…The Arlington Archosaur Site (AAS) is situated within the upper Woodbine (Lewisville) and consists of a 200 m long, 5 m thick hillside exposure, with 50 m representing the main fossil quarry (Figure 1B). This outcrop preserves a coastal environment that includes a mixture of marine, freshwater, and terrestrial influences (Noto et al, 2012;Adams et al, 2017;Noto et al, 2019). The outcrop is divided into four distinct facies, recording a transition from primarily terrestrial to primarily marine deposition (Main, 2013 Gradstein et al (2004).…”