Page "Turtle" Paragraph 37

However, it was later suggested the anapsid-like turtle skull may be due to reversion rather than to anapsid descent.

More recent morphological phylogenetic studies with this in mind placed turtles firmly within diapsids, slightly closer to Squamata than to Archosauria.

All molecular studies have strongly upheld the placement of turtles within diapsids ; some place turtles within Archosauria, or, more commonly, as a sister group to extant archosaurs, though an analysis conducted by Lyson et al.

( 2012 ) recovered turtles as the sister group of lepidosaurs instead.

Reanalysis of prior phylogenies suggests they classified turtles as anapsids both because they assumed this classification ( most of them studying what sort of anapsid turtles are ) and because they did not sample fossil and extant taxa broadly enough for constructing the cladogram.

Testudines were suggested to have diverged from other diapsids between 200 and 279 million years ago, though the debate is far from settled.

Even the traditional placement of turtles outside Diapsida cannot be ruled out at this point.

A combined analysis of morphological and molecular data conducted by Lee ( 2001 ) found turtles to be anapsids ( though a relationship with archosaurs couldn't be statistically rejected ).

Similarly, a morphological study conducted by Lyson et al.

( 2010 ) recovered them as anapsids most closely related to Eunotosaurus.

A molecular analysis of 248 nuclear genes from 16 vertebrate taxa suggest that turtles are a sister group to birds and crocodiles ( the Archosauria ).

The date of separation of turtles and birds and crocodiles was estimated to be.

The most recent common ancestor of living turtles, corresponding to the split between Pleurodira and Cryptodira, was estimated to have occurred around.

This last estimate may conflict with the fossil record depending on whether the genus Kayentachelys, whose fossils date to around, is the earliest known member of Cryptodira or lies outside the least inclusive clade containing Cryptodira and Pleurodira.