A new species of Metoposaurus from the Late Triassic of Portugal and comments on the systematics and biogeography of metoposaurid temnospondyls

ABSTRACT

Metoposaurids are a group of temnospondyl amphibians that filled crocodile-like predatory niches in fluvial and lacustrine environments during the Late Triassic. Metoposaurids are common in the Upper Triassic sediments of North Africa, Europe, India, and North America, but many questions about their systematics and phylogeny remain unresolved. We here erect Metoposaurus algarvensis, sp. nov., the first Metoposaurus species from the Iberian Peninsula, based on several new specimens from a Late Triassic bonebed in Algarve, southern Portugal. We describe the cranial and pectoral anatomy of M. algarvensis and compare it with other metoposaurids (particularly other specimens of Metoposaurus from Germany and Poland). We provide a revised diagnosis and species-level taxonomy for the genus Metoposaurus, which is currently represented with certainty by three European species (M. diagnosticus, M. krasiejowensis, M. algarvensis). We also identify cranial characters that differentiate these three species, and may have phylogenetic significance. These include features of the braincase and mandible, which indicate that metoposaurid skulls are more variable than previously thought. The new Portuguese bonebed provides further evidence that metoposaurids congregated in fluvial and lacustrine settings across their geographic range and often succumbed to mass death events. We provide an updated paleogeographic map depicting all known metoposaurid occurrences, which shows that these temnospondyls were globally distributed in low latitudes during the Late Triassic and had a similar, but not identical, paleogeographic range as phytosaurs.

http://zoobank.org/urn:lsid:zoobank.org:pub:083C80C6-0AB6-49E1-A636-6A8BDBC06A47

ACKNOWLEDGMENTS

We thank the DFG (grant BU 2587/1-1), Jurassic Foundation, CNRS UMR 7207, Lamont-Doherty Earth Institute Climate Center (Columbia University), Chevron Student Initiative Fund (Columbia University), and American Museum of Natural History (M. Norell) for supporting this project. We thank T. Sulej (ZPAL) and R. Schoch (SMNS) for access to specimens in their care. During the course of this project, S.L.B. was funded by an NSF Graduate Research Fellowship and Doctoral Dissertation Improvement Grant (DEB-1110357). R.J.B. was supported during completion of this work by an Emmy Noether Programme Award from the DFG (BU 2587/3-1). We thank C. Hendrickx, A. Kasprak, F. Lopes, J. Marinheiro, E. Tschopp, and J. Whiteside for their assistance in the field; V. Duarte and N. Lopez for preparation; G. Niedźwiedzki, R. Schoch, and T. Sulej for discussions about metoposaurids; and M. Boulay (www.cossima-productions.com) for the 3D restoration of M. algarvensis. The reviewers R. Schoch and M. Ruta and the editor F. Witzmann provided very insightful comments that helped us improve the manuscript. We thank the local authorities of Câmara Municipal de Silves and Junta de Freguesia de Salir for accommodation and local support.

Handling editor: Florian Witzmann.