An edentulous frog (Lissamphibia; Anura) from the Upper Cretaceous (Campanian) Dinosaur Park Formation of southeastern Alberta, Canada

Abstract

The frog Tyrrellbatrachus brinkmani, gen. et sp. nov., is described on the basis of seven incomplete maxillae from vertebrate microfossil localities in the Upper Cretaceous (Campanian) Dinosaur Park Formation, in the Dinosaur Provincial Park area, southeastern Alberta, Canada. The maxillae are distinctive in a unique suite of features related to size, shape, and proportions of the bone, texture of the labial surface, form of the surface for inferred contact with the squamosal, form of the lamina horizontalis and the processus pterygoideus, relative depth of the crista dentalis, and in being edentulous (i.e., lacking teeth). The higher level affinities of Tyrrellbatrachus are uncertain, although certain features exclude it from several known families; for example, the presence of a processus pterygoideus excludes it from Gobiatidae (Late Cretaceous, Asia), whereas the presence of a crista dentalis and of a relatively unreduced pars facialis exclude it from Pipidae (Cretaceous-Recent, Africa and South America). The lack of teeth in Tyrrellbatrachus is notable because although tooth loss is widespread among extant anurans and has arisen independently multiple times, it has rarely been documented among Mesozoic anurans. Comparisons with the only other edentulous anuran from the Mesozoic of the Northern Hemisphere, namely Theatonius (late Campanian -late Maastrichtian, western USA), reveal no compelling similarities to support a close relationship between the two genera. Those taxa represent an early (Campanian) instance of independent tooth loss in anurans and, potentially, the oldest record of tooth loss in nonpipid anurans.Résumé : La grenouille Tyrrellbatrachus brinkmani, gen. et sp. nov., est décrite sur la base de sept maxilles incomplètes issues de localités de microfossiles vertébrés dans la Formation de Dinosaur Park du Crétacé supérieur (Campanien), dans la région du Dinosaur Provincial Park du sud-est de l'Alberta (Canada). Les maxilles se distinguent par un ensemble unique de caractères associés à la taille, à la forme et aux proportions de l'os, à la texture de la surface labiale, à la forme de la surface en ce qui concerne le contact inféré avec l'os squamosal, à la forme de la lame horizontale et du processus ptérygoïde, à la profondeur relative de la crête dentaire et au fait qu'elles sont édentées. Les affinités de haut niveau de Tyrrellbatrachus sont incertaines, bien que certains caractères l'excluent de plusieurs familles connues. Par exemple, la présence d'un processus ptérygoïde l'exclut des gobiatidés (Crétacé tardif, Asie), alors que la présence d'une crête dentaire et d'une extrémité faciale relativement non réduite l'exclut des pipidés (Crétacé-Récent, Afrique et Amérique du Sud). L'absence de dents chez Tyrrellbatrachus est importante puisque, bien que la perte de dents soit répandue chez les anoures actuels et qu'elle soit apparue de manière indépendante à de multiples reprises, elle a rarement été documentée chez des anoures du Mésozoïque. Des comparaisons avec le seul autre anoure édenté ...

Rampant tooth loss across 200 million years of frog evolution

“…Several crown-group fossil frogs have been described that are edentulous, including Theatonius lancensis (Fox 1976), Tyrrellbatrachus brinkmani (Gardner 2014), Saltenia (Baez 1981), and Vulcanobatrachus (Trueb et al 2005) from the Late Cretaceous, and Chelomophrynus bayi from the Eocene (Henrici 1991). The majority of these taxa have been hypothesized to be members of the Pipoidea.…”

Introduction to the Special Issue commemorating the 30th anniversary of the Royal Tyrrell Museum of Palaeontology, with a summary of the museum’s early history and its research contributions

“…3C) recovered during the course of his work have documented the existence of new taxa and have yielded fresh insights into the osteology, biology, and distributions of previously known taxa (e.g., Wilson et al 1992;Fox 1996, 1998;Gardner 2000Gardner , 2015Sankey et al 2002;Neuman and Brinkman 2005;Newbrey et al 2009;Wilson et al 2013;Gardner and Brinkman 2015).…”

“…Other projects have relied on specimens housed in other institutional collections; those include specimens that RTMP crews helped find and collect as part of joint fieldwork in other jurisdictions (the SinoCanada Dinosaur Project was a particularly rich source for those kinds of specimens) or on specimens that the RTMP was not involved in collecting (often those projects are the result of RTMP researchers with particular expertise being invited to work with external colleagues on specific specimens). RTMP researchers have worked on material from all continents and have been involved in describing several hundred new species, including three new ones in this commemorative issue Gardner 2015;Wu and Brinkman 2015).…”