Re: [dinosaur] Eorhynchochelys, new toothless and shell-less stem turtle from Triassic of China

Nick Gardner is too modest to mention his blog, so here's his post on that paper.

In the extended abstract (the "paper", as opposed to the paper = "supplementary information" – as usual in Nature/Science/PNAS), the authors removed a lot of taxa from their original sample; evidently they did that to get a resolved tree, because their Extended Data Figure 7 shows the strict consensus tree that results from their complete taxon sample, and it's hardly resolved at all. But what happens if, instead of deleting taxa, you order the morphocline characters before running the analysis? Interesting things happen to amniote phylogeny, that's what. Very interesting things.

Gesendet: Mittwoch, 22. August 2018 um 19:14 Uhr
Von: "Ben Creisler" <bcreisler@gmail.com>
An: dinosaur-l@usc.edu
Betreff: [dinosaur] Eorhynchochelys, new toothless and shell-less stem turtle from Triassic of China

Eorhynchochelys sinensis gen. & sp. nov.

Chun Li, Nicholas C. Fraser, Olivier Rieppel & Xiao-Chun Wu (2018)

A Triassic stem turtle with an edentulous beak

Nature 560: 476–479

DOI: https://doi.org/10.1038/s41586-018-0419-1

https://www.nature.com/articles/s41586-018-0419-1

Free supplemental information

https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-018-0419-1/MediaObjects/41586_2018_419_MOESM1_ESM.pdf

The early evolution of turtles continues to be a contentious issue in vertebrate palaeontology. Recent reports have suggested that they are diapsids, but the position of turtles within Diapsida is controversial and the sequence of acquisition of turtle synapomorphies remains unclear. Here we describe a Triassic turtle from China that has a mixture of derived characters and plesiomorphic features. To our knowledge, it represents the earliest known stem turtle with an edentulous beak and a rigid puboischiadic plate. The discovery of this new form reveals a complex early history of turtles.