Lichtig and Lucas 2021
reexamine Chinlechelys, a Late Triassic hard shell turtle known from disarticulated bits and pieces. They report, “Chinlechelys tenertesta is a turtle from the Upper Triassic Bull Canyon Formation of the Chinle Group of eastern New Mexico, USA, which has largely been ignored in recent studies of the phylogenetic position of turtles (Testudinata) within the Tetrapoda. Here, we present the first comprehensive description of the morphology of Chinlechelys tenertesta.”
Always good to see more data.
“We challenge the identification of Permian Eunotosaurus africanus as a stem turtle and instead suggest that it is a caseid synapsid.”
In the large reptile tree (LRT, 1822+ taxa, subset Fig. 2) Eunotosaurus nests with Acleistorhinus and caseids, but these are all synapsid mimics derived from Milleretta within Lepidosauromorpha. The omission of dozens of taxa by Lichtig and Lucas is the reason for this issue.
“We do not consider Pappochelys rosinae to be a close relative of turtles. It more closely resembles the basal placodont sauropterygians, particularly Palatodonta bleekeri. Indeed, phylogenetic analysis based on correctly coded character states places Pappochelys rosinae in the Sauropterygia as the sister taxon of placodonts.“
That agrees with an earlier nesting in the LRT.
The morphology of Chinlechelys tenertesta supports the placement of Testudines outside of crown Sauria, as a taxon derived from pareiasaurs based on the morphology of the dorsal osteoderms and skull roof.”
That agrees with an earlier nesting in the LRT, but lacking pertinent taxa the Licthtig and Lucas 2021 cladogram overlooked the dual origin of turtles (Peters 2018, and video below), the basalmost softshell and hardshell turtles, the small horned transitional taxa without shells and the lepidosauromorph origin of caseids and eunotosaurs. A 2016 abstract by LIcthtig and Lucas first presented their new look at Chinlechelys. Here it is five years later, finally online. If you wonder why those paid
Commenting on this paper on the Dinosaur Mailing List,
paleontologist David Marjanovic wrote, “I have rather more to say about this paper (good, bad, and ugly…) than would fit here, but there’s one thing that qualifies as a failure of peer review: the astonishing lack of awareness of any molecular analyses of amniote phylogeny published after 2012 (apart from a study from 2013 that used the presence/absence of genes as characters).”
The fact is: molecular analyses too often deliver false positives in deep time studies. If you are a paleontologist, or if your last name is Marjanovic, please stay away from molecular analyses. They represent the entrance to taxonomic Hell and a colossal waste of time and published paragraphs. Stick with traits to recover and model actual evolutionary events.
References
Lichtig AJ and Lucas SG 2016. Chinlechelys: a reexamination of North America’s oldest (Triassic, Revultian, Norian) turtle and its impact on theories of turtle origins. Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.
Lichtig AJ and Lucas SG 2021. Chinlechelys from the Upper Triassic of New Mexico, USA, and the origin of turtles.
Palaeontologia Electronica 24(1):a13. doi: https://doi.org/10.26879/886
https://palaeo-electronica.org/content/2021/3316-triassic-turtle-chinlechelys
Free pdf:
https://palaeo-electronica.org/content/pdfs/886.pdf
Peters D 2018 https://www.researchgate.net/publication/328388481_The_dual_origin_of_turtles_from_pareiasaurs
The Pterosaur Heresies 