Evolution of the Side-Necked Turtles: The Family Podocnemididae

The family Podocnemididae consists of 20 genera and 30 species considered here as valid and diagnosable by cranial characters. Three of these genera and eight species persist into the Recent fauna, barely reflecting the evolutionary diversity and distribution of the group. The family extends from the Late Cretaceous to the Recent and occurs in North and South America, Europe, Asia, and Africa. A phylogenetic analysis utilizes 31 podocnemidid taxa (30 named and one unnamed; a total of 37 taxa analyzed includes outgroups) in the Podocnemididae that are analyzed using PAUP. The resulting consensus of nine equally parsimonious cladograms is the basis for a new classification of the family. The family Podocnemididae is reconfirmed as monophyletic, using the unique possession of a cavum pterygoidei formed by the basisphenoid, pterygoid, prootic, and quadrate, underlain by the pterygoid and basisphenoid, among other characters. Much of our resolution agrees with that of França and Langer (2006), which can be modified and restated as follows: (Bauruemys (vilavilensis (Podocnemis (Peltocephalus, Erymnochelys))). The two clades proposed by Broin (1991) and Lapparent de Broin (2000b, 2001, 2003a, 2003b), designated by her as the “subfamily Podocnemidinae” and the “subfamily Erymnochelinae,” are inconsistent with our analysis. In our analysis the “Podocnemidinae” (sensu Broin, 1991) is paraphyletic, and the “Erymnochelinae” (sensu Broin, 1991) could be made monophyletic, with the important addition of Peltocephalus (placed in the “Podocnemidinae” by Broin). We add a number of new taxa to the basal Podocnemididae and to the broad-jawed subtribe Stereogenyina. Within the family Podocnemididae Cope, 1868, the sister taxon to all other podocnemidids and recognized as the subfamily Bauruemydinae, new, is Bauruemys elegans (Suárez, 1969a), known from associated skulls and shells. All other podocnemidids, the redefined subfamily Podocnemidinae Cope, 1868, are united by a slight to absent temporal emargination, a completely closed foramen jugulare posterius, and saddle-shaped cervical centra (modified as a separate state in Erymnochelys). A basal group of Cretaceous-Paleocene podocnemidids that are the sister group to all remaining podocnemidids, here termed the infrafamily Peiropemydodda, consisting of two taxa from the late Cretaceous of Brazil, Peiropemys mezzalirai, n. gen. et sp., and Pricemys caiera, n. gen. et sp., and Lapparentemys vilavilensis (Broin, 1971), n. gen.,