Reptile phylogeny and the interrelationships of turtles

Abstract

A comprehensive analysis of amniotr interrrlationships is presented in a11 attempt t o trst turtle intcrrclationsliips. 'The results rrftitc earlier hypotheses that turtles are related to parareptilrs, i.e. to procolophonids or pareiasaurs. Iristrad, turtles are shown to be the sistergroup of Sauropterygia, the two clades being nested within Sauria as sister-group of Lrpidosauriforrnes. This sccriario is also supportrd by several devc~opnicrital arid soft tissuc charactcrs which arc shown to I)r congrurnt with the current phylogeny. 'l'hc analysis strongly supports a moriophyletic Pararrptilia, sister-group of a monophylctic Eurcptilia. The I)iapsiida, howrvcr, is paraphyletic unless it includes turtles and sauropterygians. Additionally, the position of turtles within Diapsida ha5 major irnplications for the evolutionary history and/or significancc of many characters, i.r. tempor;il fiwrstration. 0

Sensory Evolution and Ecology of Early Turtles Revealed by Digital Endocranial Reconstructions

“…On the other hand, the minimum spanning trees (see Supplementary Material) show that even when inside the fossorial morphospace P. quenstedti is closest to Placodus, a marine lepidosauromorph, and Pseudopalatus, an aquatic archosauromorph. A phylogenetic proximity to Sauropterygia (the lepidosauromorph lineage that includes Placodus) has been proposed previously (deBraga and Rieppel, 1997) and is associated with the hypothesis that turtles originated in marine environments Joyce, 2015). The proximity of P. quenstedti and Placodus in our PC1/PC2 plot (Figure 6) may recall this hypothesis, but the poor sampling of sauropterygians together with the extensive overlap between all groups (phylogenetic and ecological) cause us to refrain from considering this a robust interpretation.…”

“…Unique morphological characters, including the anapsid cranial configuration, which lacks temporal fenestrations, and the presence of a bony shell formed by a dorsal carapace and a ventral plastron have long obfuscated the phylogenetic affinities of turtles (Rieppel, 2007;Lyson et al, 2010). While most molecular studies have recovered turtles nested within diapsid reptiles and often as a sister-group to Archosauria (birds and crocodiles) (Hedges and Poling, 1999;Wang et al, 2013;Field et al, 2014), most studies based on comparative anatomy have placed turtles outside of Diapsida (Gauthier et al, 1988;Lee, 1997;Werneburg and Sánchez-Villagra, 2009;Neenan et al, 2013;Scheyer et al, 2017) or alternatively inside Lepidosauromorpha (deBraga and Rieppel, 1997;Rieppel and Reisz, 1999;Li et al, 2008;Liu et al, 2011). The scant fossil record of stem-turtles (i.e., non-Testudines Testudinata) has further obscured the evolutionary origin of this group.…”

A thin-shelled reptile from the Late Triassic of North America and the origin of the turtle shell

“…The various highly contrasting phylogenetic hypotheses of turtle origins often directly favour one model over the other. In particular, testudinate affinities with armoured groups of reptiles (Gauthier 1994;Laurin & Reisz 1995;Lee 1996Lee , 1997a provide phylogenetic support for the composite evolution of the turtle shell, whereas an affiliation with non-armoured amniotes (deBraga & Rieppel 1997;Rieppel & Reisz 1999;Hill 2005) favours a de novo mode.…”

Recent Advances in the (Molecular) Phylogeny of Vertebrates

“…Recent paleontological analyses reveal that the traditional assignment of turtles to the anapsids may be only weakly supported (deBraga & Rieppel 1997, Rieppel & deBraga 1996, Rieppel & Reisz 1999. Alternatively, turtles have been suggested to be the closest living relatives of the Lepidosauria (tuatara and squamata, i.e., lizards and snakes) ( Figure 6B) (deBraga & Rieppel 1997, Rieppel & deBraga 1996, Rieppel & Reisz 1999, or the sistergroup of Archosauria (crocodiles and birds) ( Figure 6C) (Hennig 1983).…”