The youngest occurrence of embolomeres (Tetrapoda: Anthracosauria) from the Sunjiagou Formation (Lopingian, Permian) of North China

Jianye Chen,Jun Liu

doi:10.5194/fr-23-205-2020

Abstract

Abstract. Embolomeri were semiaquatic predators prevalent in the Carboniferous, with only two species from the early Permian (Cisuralian). A new embolomere, Seroherpeton yangquanensis gen. et sp. nov. (Zoobank Registration number: urn:lsid:zoobank.org:act:790BEB94-C2CC-4EA4-BE96-2A1BC4AED748, registration: 23 November 2020), is named based on a partial right upper jaw and palate from the Sunjiagou Formation of Yangquan, Shanxi, China, and is late Wuchiapingian (late Permian) in age. It is the youngest embolomere known to date and the only embolomere reported from North China Block. Its phylogenetic position within Embolomeri is confirmed by the strongly developed descending flange on the quadrate ramus of the pterygoid. The new taxon is unique among embolomeres by features like a partial coverage of a denticle shagreens on the pterygoid; presence of a cylindrical shaft on the pterygoid, and two pairs of very large ectopterygoid tusks. Phylogenetic analysis shows Seroherpeton as being the sister group of a clade consisting of Proterogyrinus, Archeria, and Pholiderpeton. We hypothesize that the dispersal and decline of the embolomeres from Carboniferous to late Permian (Lopingian) is related to the climate changes, especially aridification, of the paleotropical regions.

Highlights

Embolomeri are a monophyletic group of large crocodilelike, semiaquatic predators, prevalent in the Carboniferous and early Permian (Cisuralian) (Panchen, 1970; Smithson, 2000; Carroll, 2009; Clack, 2012)
The holotype of Seroherpeton is a partial palate and upper jaw found from the late Permian (Lopingian) of North China
Its morphology is similar to tetrapodomorphs such as Eusthenopteron, especially with its large palatal tusks, the denticles on the palatal ramus of the pterygoid, and the oblique shaft on the pterygoid

Summary

Introduction

Embolomeri are a monophyletic group of large crocodilelike, semiaquatic predators, prevalent in the Carboniferous and early Permian (Cisuralian) (Panchen, 1970; Smithson, 2000; Carroll, 2009; Clack, 2012). The Pennsylvanian, especially the Bashkirian–Moscovian, was when the embolomeres were the most diversified, evidenced by the well-documented specimens of Anthracosaurus and Pholiderpeton (Eogyrinus) and the less well-known Calligenethlon, Leptophractus, Neopteroplax, Pteroplax, Carbonoherpeton, and Palaeoherpeton (Clack, 1987, 2012; Cope, 1873; Holmes and Carroll, 2010; Panchen, 1964, 1972, 1977). All these animals were distributed in the swamp forests in Euramerica, posi-. The new taxon expands the chronological and geographical ranges of embolomeres and bears important implications on the late Paleozoic paleogeography and climate (Abbreviations: YQZY, Yuanquan Land Resources)

Systematic paleontology

Discussion