According to Ferreira et al. (2015), the family name derives from two Greek words: "podos" (foot) and "cnemis" (leg armor worn by Roman soldiers.) • Epifamily
Podocnemidinura: The family Podocnemididae has two sister families (Hamadachelys and Brasilemys); the relationship of these three families is sometimes recognized by grouping them as the epifamily Podocnemidinura. •
Podocnemidinae: An earlier classification, rejected by Gaffney, treated Podocnemididae as a subfamily (Podocnemidinae) within the closely related family
Pelomedusidae.) According to
Gaffney et al. (2011), the family Podocnemididae can be diagnosed from its
cranial traits including "the unique possession of a cavum pterygoidei formed by the basisphenoid,
pterygoid, prootic, and
quadrate [bones], underlain by the pterygoid and basisphenoid." •
Podocnemis – South American side-necked river turtles
Taxonomy Fossils show that podocnemidids were once found in Europe, Asia, North America, and Africa.
Stupendemys lived around 5.5 million years ago in northern South America, and was the largest freshwater turtle with a carapace length of , the largest of any known turtle and is the largest pleurodire known. While
Peltocephalus and
Erymnochelys have often been recovered as more closely related to each other than to
Podocnemis in morphological analyses,'' All extant podocnemidids inhabit freshwater environments, as did most fossil members, but the extinct tribe Stereogenyini are though to have inhabited marine environments, although they appear to have been restricted to shallow coastal habitats. This is comparable to the
Bothremydidae, another extinct group of side-necked turtles that are also known to have inhabited marine environments. Genera: •
Stem group taxa (Podocnemidoidae) • †
Brasilemys == References ==