This paper came with much anticipation
following discussions several years ago with one of the authors (GHP) about mesosaurs (Fig. 2) and their relationship to pachypleurosaurs and thalattosaurs (Fig. 2) in the LRT. Unfortunately only 17 terminal taxa (many suprageneric) were employed by Laurin and Piñeiro 2017 (vs. the 1122 taxa in the large reptile tree, LRT).
pachypleurosaurs and thalattosaurs were not among the 17 taxa employed by Laurin and Piñeiro. That makes this study worthless with regard to mesosaur interrelations. Very unfortunate.
From the Laurin and Piñeiro methods:|
“We started from the matrix of Laurin and Reisz (1995), given that this was the matrix that we knew best, that we had confidence in the accuracy of the anatomical scoring, and that we were confident that we could apply the revised scores in a manner coherent with the original scoring.”
nested mesosaurs between Synapsida and Captorhinidae (Fig. 1). Neither suprageneric clade include basal members that in any way resemble mesosaurs.
A sampling of mesosaur sister taxa
as recovered by the LRT is shown here (Fig. 2). I challenge the authors to find better sister taxa among the Synapsida or the Captorhinidae.
A gradual accumulation of traits
is what we’re all looking for in a cladogram. If you don’t find that using your inclusion set, expand your inclusion set until you do.
Professors Laurin and Reisz
are at the top of the list of professional paleontologists, and have been at the top for decades. Unfortunately they’re holding on to an invalid hypothesis. There is no monophyletic clade ‘Parareptilia.’ Included members don’t look alike and simple expansion of the dataset splits them to other parts of the reptile family tree.
If you find yourself working with top workers
in the field and the results don’t make sense, you may be obligated to follow their lead. That seems to happen all too often. You’ll make more sensible discoveries if you keep a modicum of independence, or complete independence. And you’ll avoid the professional embarrassment of being criticized online instead of being hailed and complimented for ‘finally putting it all together’. This was an opportunity lost, no matter how much detail and data was provided.
This paper was edited by
Holly Woodward (Oklahoma State University) and reviewed by Michael S. Lee (South Australian Museum) and Juliana Sterli (Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Argentina). It’s almost unheard of to see editors and reviewers listed near the titles of papers, btw. More often they are thanked in the Acknowledgements section.
On the plus side
I’m happy to see Piñeiro included a mesosaur skull with every bone colored (Fig. 3). That’s the way to do it nowadays. And if you’re into mesosaurs, this paper does provide a great deal of data about mesosaurs.
Laurin M and Piñeiro GH 2017. A reassessment of the taxonomic position of mesosaurs, and a surprising phylogeny of early amniotes. Frontiers in Earth Science, 02 November 2017: 13 pp. https://doi.org/10.3389/feart.2017.00088
Piñeiro G, Ferigolo J, Ramos A and Laurin M 2012. Cranial morphology of the Early Permian mesosaurid *Mesosaurus tenuidens* and the evolution of the lower temporal fenestration reassessed. Comptes Rendus Palevol. 11(5):379-391.