Synchrotron analysis of a ‘mummified’ salamander (Vertebrata: Caudata) from the Eocene of Quercy, France

Abstract

An incomplete 'mummy' from the Phosphorites du Quercy (presumed Eocene) was identified as a salamander during the 19 th century. The specimen has now been computed tomography (CT) scanned, and this revealed the incomplete skeleton (with perfectly preserved bones) and soft tissues (lung). The fossil represents a new, wellcharacterized taxon. Despite the absence of the skull, several features allow a phylogenetic analysis. The fossil belongs to pseudosaurian caudates; it is tentatively assigned to the Salamandridae, although affinities with Plethodontidae cannot be definitely ruled out.

Exceptional soft tissues preservation in a mummified frog-eating Eocene salamander

“…This plexus comprises three nerves that emerge from the spinal cord through the spinal foramina of the last trunk vertebra, the sacral vertebra and the first caudosacral vertebra. These spinal foramina are large ( Tissier et al, 2016 : figs. 5B and 6B–6C).…”

“…The study of the skeleton of Phosphotriton confirmed that this fossil is a urodele amphibian; more precisely, the phylogenetic analysis presented by Tissier et al (2016) suggested that it is a stem-salamandrid, although they did not definitely discard relationships with the Plethodontidae.…”

“…The only specimen of P. sigei (MNHN.F.QU17755) was investigated with the help of propagation phase contrast synchrotron X-ray microtomography, which gives a better contrast to differentiate tissues from the mineral matrix than traditional absorption based synchrotron X-ray microtomography. The method and parameters of acquisition are described in Tissier et al (2016) . A 3D model is given in Supplemental Information 1 in 3D PDF file format.…”

“…Unfortunately, these ‘mummies’ were collected in the 19th century and their precise provenance and geological age are unknown. However, it is suspected that they come from the late middle or late Eocene ( Laloy et al, 2013 ; Tissier et al, 2016 ).…”

“…Until recently, only the external morphology of the ‘mummies’ was known. However, recent tomographic studies showed that the skeleton is preserved within the ‘mummies’ of the frog Thaumastosaurus gezei ( Laloy et al, 2013 ) and of the salamander Phosphotriton sigei ) ( Tissier et al, 2016 ). The specimen of P. sigei includes a large part of the trunk (preserved posterior to the shoulder girdle), the anterior portion of the tail and the proximal portions of the hind limbs ( Fig.…”