Marmorerpeton

Marmorerpeton is an extinct genus of prehistoric stem group-salamanders that lived in Britain during the Bathonian stage of the Middle Jurassic.[1] They are among the oldest known salamanders.[2] Two species were named when the genus was first described by Susan E. Evans et al. in 1988, M. freemani, and M. kermacki, from fragmentary remains found via screenwashing in the Forest Marble Formation of England.[1] Due to the size of their osteocytic lacunae suggesting a large genome size and some morphological characters, like the presence of calcified cartilage in the medulla of its humerus, it was assumed that Marmorerpeton was neotenic.[3][4] New more complete remains of a new species M. wakei were described in 2022 from the Kilmaluag Formation of the Isle of Skye, Scotland. These conclusively demonstrated that Marmorerpeton was neotenic, and was a member of the family Karauridae, with the other two members of the family, Karaurus and Kokartus being known from the Middle-Late Jurassic of Central Asia.[5] The teeth appear to have been weakly pedicellate.[1]

Cross section of a Marmorerpeton femur in normal transmitted (left) and polarized (right) light

Marmorerpeton Temporal range: Middle Jurassic,
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Family:	†Karauridae
Genus:	†Marmorerpeton Evans et al. 1988
Type species
†Marmorerpeton freemani Evans et al. 1988
Species
†M. freemani Evans et al. 1988 †M. kermacki Evans et al. 1988 †M. wakei Jones et. al. 2022