New Material of Beelzebufo, a Hyperossified Frog (Amphibia: Anura) from the Late Cretaceous of Madagascar

Abstract

The extant anuran fauna of Madagascar is exceptionally rich and almost completely endemic. In recent years, many new species have been described and understanding of the history and relationships of this fauna has been greatly advanced by molecular studies, but very little is known of the fossil history of frogs on the island. Beelzebufo ampinga, the first named pre-Holocene frog from Madagascar, was described in 2008 on the basis of numerous disarticulated cranial and postcranial elements from the Upper Cretaceous (Maastrichtian) Maevarano Formation of Madagascar. These specimens documented the presence of a hyperossified taxon that differed strikingly from extant Malagasy frogs in its large size and heavy coarse cranial exostosis. Here we describe and analyse new, articulated, and more complete material of the skull, vertebral column, and hind limb, as well as additional isolated elements discovered since 2008. μCT scans allow a detailed understanding of both internal and external morphology and permit a more accurate reconstruction. The new material shows Beelzebufo to have been even more bizarre than originally interpreted, with large posterolateral skull flanges and sculptured vertebral spine tables. The apparent absence of a tympanic membrane, the strong cranial exostosis, and vertebral morphology suggest it may have burrowed during seasonally arid conditions, which have been interpreted for the Maevarano Formation from independent sedimentological and taphonomic evidence. New phylogenetic analyses, incorporating both morphological and molecular data, continue to place Beelzebufo with hyloid rather than ranoid frogs. Within Hyloidea, Beelzebufo still groups with the South American Ceratophryidae thus continuing to pose difficulties with both biogeographic interpretations and prior molecular divergence dates.

Evolution of hyperossification expands skull diversity in frogs

“…Hyperossification is common in anuran fossils (possibly because hyperossified elements are more likely to be preserved in the fossil record) and is present in putative archeobatrachians, mesobatrachians, and neobatrachians (58). Identifying the phylogenetic placement of these fossil taxa is challenging because the material is often fragmentary, and hyperossification seems to result in artificial groupings based on homoplastic features (44,59,60), despite the differences in shape identified across hyperossified species in our study. Our results corroborate these previous findings: Hyperossification likely has evolved multiple times across crown-group anurans, leading to increased rates of shape evolution.…”

“…Our framework will be useful in subsequent paleobiological studies of fossil frogs, especially when the 3D structure of the skull is recoverable. For example, Baurubatrachus pricei from the Late Cretaceous of Brazil (60), Beelzebufo ampinga from the Late Cretaceous of Madagascar (44), and Thaumastosaurus gezei from the Eocene of France (61) possess hyperossified, wide skulls with a posteriorly shifted jaw joint and bony articulation between the squamosal and maxilla, suggesting that these frogs specialized on eating relatively large, vertebrate prey.…”

Parks and Reserves in Madagascar: Managing Biodiversity for a Sustainable Future

“…Research in paleontology carried out in Madagascar revealed Cretaceous birds, amphibians, snakes, and mammals. The peculiar Beelzebufo from the Upper Cretaceous (100.5-66 Ma) of western Madagascar was a giant frog more closely related to extant frogs present in South America but absent from Madagascar [7]. The Mesozoic (251.902-66 Ma) snakes recovered in Madagascar belong to an extinct family [8], while the modern mammals currently occurring in Madagascar have no ancestors among the known paleontological records.…”

Frogs (Amphibia, Anura) from the Eocene and Oligocene of the Phosphorites du Quercy (France). An overview

“…Thaumastosaurus was therefore regarded as an anuran with South American affinities ('ceratophryines' being restricted to South America). Thereafter, such biogeographical affinities were supported by Roček and Lamaud (1995), Rage and Roček (2007), Evans et al (2008Evans et al ( , 2014 and Agnolin (2012). Roček and Lamaud (1995) provided the first detailed description of Thaumastosaurus bottii, based on various skull bones from La Bouffie, a late Eocene (MP 17) locality in the Phosphorites.…”