Podocnemididae


Podocnemididae is a family of pleurodire turtles native to Madagascar and northern South America. Podocnemidid turtles are commonly called "side-necked turtles" in direct reference to their inability to retract their heads backwards, but hide them sideways. In addition, their pelvis is fused to the shell which prevents any pelvic motion. Due to their pelvis being immobile they are unable to walk on land, which requires greater pelvis mobility. For this reason, Podocnemididae turtles are best suited for swimming and as a result live in aquatic environments. These turtles are all aquatic, inhabiting streams and other flowing water. Their shells are streamlined to aid in swimming.

Taxonomy and systematics

Podocnemididae has been merged into the closely related family Pelomedusidae as the subfamily Podocnemidinae. Some authors still maintain this classification, but here it is preferred to keep them distinct families in the superfamily Pelomedusoidea instead.
The family Podocnemididae contains only three living genera, two of them monotypic:
The family also contains a number of prehistoric genera, including Albertwoodemys, Bairdemys, Bauruemys, Brontochelys, Caninemys, Cordichelys, Dacquemys, Lapparentemys, Latentemys, Lemurchelys, Mogharemys, Neochelys, Papoulemys, Peiropemys, Pricemys, Shweboemys, Stereogenys, Turkanemys, Cambaremys, Carbonemys, Cerrejonemys, Kenyemys, Roxochelys and Stupendemys. Stupendemys lived around 5.5 million years ago in northern South America, and was the largest freshwater turtle and the largest pleurodire known to date.