A New Crown-Group Frog (Amphibia: Anura) from the Early Cretaceous of Northeastern Inner Mongolia, China

Abstract

Based on 12 well-preserved skeletons of postmetamorphic individuals, a new crown-group frog taxon is named and described from the Lower Cretaceous Guanghua (upper part of Longjiang) Formation (stratigraphic equivalent of the world-famed Yixian Formation) exposed in Dayangshu Basin, Hulunbuir, in the far northeast of Inner Mongolia, China. The new taxon, Genibatrachus baoshanensis, documents another Early Cretaceous anuran having reduction of the presacral vertebrae to eight in number, similar to several frog taxa of roughly the same age from Spain and Brazil. The new frog also displays several features that are ontogenetically and phylogenetically informative, including ontogenetic fusion of the palatine to the sphenethmoid, and ontogenetic fusion of ribs to the diapophyses of the posterior trunk vertebrae. In addition, the new discovery extends the geographic range of Early Cretaceous frogs of the Jehol Biota northward to near the 50th parallel north in East Asia.

Two pelobatid frogs from the late Miocene of Caucasus (Russia)

“…Nevertheless, the systematics of Pelobatidae and relationships within the group are still a matter of discussion (е.g., Gao and Chen, 2017). Pelobates has a rich fossil record consisting of isolated bones and articulated fossils of various ontogenetic series from tadpoles to adults, whereas Eopelobates rarely occurs (Estes, 1970;Špinar, 1972;Roček, 1981;Sanchiz, 1998;Roček and Rage, 2000;Wuttke, 2002, 2004;Rage and Roček, 2003;Roček, 2013;Roček et al, 2014, and others).…”

A new hynobiid-like salamander (Amphibia, Urodela) from Inner Mongolia, China, provides a rare case study of developmental features in an Early Cretaceous fossil urodele

“…The Guanghua Formation has been dated at 125 Ma ( Heilongjiang Institute of Geological Survey, 2005 ), and thus is stratigraphically equivalent to the Yixian Formation in western Liaoning Province, which has a geochronological range of 122–129 Ma by Ar 40 /Ar 39 dating ( Chang et al, 2009 ). Also from the Pigeon Hill locality, well-preserved frog fossils have been recently described and represent a rare fossil record from the far north of China ( Gao & Chen, in press ). Prior to this discovery, all Early Cretaceous salamander fossils known from China were found within a geographical range limited between 40th–45th parallel in North China from Jehol and nearby areas ( Fig.…”

Peer Review #1 of "Phylogeny of Paleozoic limbed vertebrates reassessed through revision and expansion of the largest published relevant data matrix (v0.2)"

“…However, there are no other crowngroup frogs in our matrix; if the mentioned analyses are correct, our Liaobatrachus OTU merely bears the wrong name and contains too much missing data. Further, Gao & Chen (2017) found little if any support in this part of the tree, while Chen et al (2016) did not perform any robustness analyses; both analyses contain less than twice as many characters as taxa and were focused on more highly nested crown-group frogs; the arrangement of Mesophryne, Yizhoubatrachus and Callobatrachus as an uninterrupted grade differs starkly from the positions found in earlier literature (summarized in Marjanović & Laurin, 2013b: fig. 3), which were widely dispersed through the salientian stem and the base of the crown; and both analyses peculiarly lack L. zhaoi Dong et al, 2013, which is preserved in three dimensions and therefore is the source of most of the scores of our Liaobatrachus OTU.…”

“…-Dong et al (2013) lumped what had been described as five monospecific genera (Liaobatrachus, Dalianbatrachus, Callobatrachus, Mesophryne, Yizhoubatrachus) as three species of Liaobatrachus and added a fourth. Chen et al (2016) and Gao & Chen (2017) preferred to consider Liaobatrachus and Dalianbatrachus nomina dubia and include the other three nominal genera as separate OTUs in their phylogenetic analyses; rather than finding them as a clade, they found them as a grade on the bombinanuran stem just within the anuran crown-group. However, there are no other crowngroup frogs in our matrix; if the mentioned analyses are correct, our Liaobatrachus OTU merely bears the wrong name and contains too much missing data.…”