@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

First fossil frog from Antarctica: implications for Eocene high latitude climate conditions

and Gondwanan cosmopolitanism of Australobatrachia

Ilium (NRM-PZ B282) of Calyptocephalella sp. from Seymour Island, Antarctica. Ilium in lateral (a), medial (b), ventral (c) and dorsal (d) views. Magnified region of the dorsal protuberance in lateral (e – dashed rectangle in orange color) and dorsal (f – dashed rectangle in yellow color) view. The dashed line in black on (a) indicates the probable outline of the posterior extension of the ventral acetabular expansion. The asterisk (*) on (a,c) indicates the shallow and broad depression of the ventral acetabular expansion. The double asterisk (**) indicates the notch caudally from the dorsal protuberance. The dashed red lines on (e,f) outline the intact bone surface. Abbreviations: ac, acetabulum; ar, acetabular rim; dae, dorsal acetabular expansion; is, iliac shaft; paf, preacetabular fossa; spf, supraacetabular fossa; vae, ventral acetabular expansion; vd, ventral depression.

Cenozoic ectothermic continental tetrapods (amphibians and reptiles) have not been documented previously from Antarctica, in contrast to all other continents. Here we report a fossil ilium and an ornamented skull bone that can be attributed to the Recent, South American, anuran family Calyptocephalellidae or helmeted frogs, representing the first modern amphibian found in Antarctica. The two bone fragments were recovered in Eocene, approximately 40 million years old, sediments on Seymour Island, Antarctic Peninsula. The record of hyperossified calyptocephalellid frogs outside South America supports Gondwanan cosmopolitanism of the anuran clade Australobatrachia. Our results demonstrate that Eocene freshwater ecosystems in Antarctica provided habitats favourable for ectothermic vertebrates (with mean annual precipitation ≥900 mm, coldest month mean temperature ≥3.75 °C, and warmest month mean temperature ≥13.79 °C), at a time when there were at least ephemeral ice sheets existing on the highlands within the interior of the continent.

3D models of some skeletal elements of Australobatrachia. (a,f) skull and (b–e,g–j) ilia of Calyptocephalella gayi (a–e); Telmatobufo venustus (f–h); Myobatrachus gouldii (i); Limnodynastes convexiusculus (j). Collection numbers of each specimen are listed in Table S1.

Citation: Mörs, T., Reguero, M. & Vasilyan, D. First fossil frog from Antarctica: implications for Eocene high latitude climate conditions and Gondwanan cosmopolitanism of Australobatrachia. Sci Rep 10, 5051 (2020). https://doi.org/10.1038/s41598-020-61973-5

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev