Allen et al. 2018
(includes Professor MJ Benton as a co-author) recently produced an ‘archosauromorph’ supertree (Fig. 1, click to enlarge) that (according to the LRT) includes more than two dozen lepidosaurormorphs and one thalattosaur due to improper taxon inclusion brought about by massive taxon exclusion. You might remember Hone and Benton 2007, 2009 previously had troubles building their pterosaur origin supertree because they cherry-deleted pertinent taxa _that they said they were going to test_ in order to avoid confirming the four trees recovered in Peters 2000. Allen et al. repeat that mistake by deleting those taxa again, along with deleting other well-known and pertinent taxa in their latest illogical supertree fiasco (Fig. 1 frame 1).
the large reptile tree (LRT, 1305 taxa) is a single fully resolved cladogram that includes ancestral taxa going back to basal tetrapods. By doing so, the tree topology reveals that lepidosauromorphs split from archosauromorphs immediately following the invention of the amniote membrane. The interrelationships of all included taxa are recovered in the LRT with confidence because every candidate for sisterhood for every included enigma taxon are included in the LRT.
Unfortunately Allen et al. have a much smaller study with cherry-picked taxa
that misinform (= produce false positives) due to taxon exclusion. Allen et al. recovered 8 supertrees with no utility. They do not understand the basic Archosauromorpha / Lepidosauromorpha division within the Reptilia (= Amniota). Many of their other errors and misunderstandings appear as a result.
Odd sister taxa recovered in the Allen et al. 2018 tree include:
- Basalmost archosauromorph: Jesairosaurus, which is basal to the lepidosauriform drepanosaurs in the LRT
- Rhynchosaur and trilophosaur outgroup taxon: Pamelaria, a derived protorosaur in the LRT.
- The thalattosaur Vancleavea is still not being tested with other thalattosaurs, but in Allen et al. is derived from Yarasuchus.
- Lepidosauromorph, lepidosauriform, lepidosaur, tritosaur, fenestrasaur pterosaurs are still not being tested with other published fenestrasaurs (Cosesaurus, Sharovipteryx, etc.), but appear in the supertree derived from Vancleavea + Tarjadia + Doswellia and Proterochampsa + Cerritosaurus. This time Benton’s 1999 subject of study and former sister to pterosaurs, Scleromochlus, does not appear in the taxon list or the reference list (see what I mean about cherry-picking trees and papers?)
- Lagerpeton nests as a sister to pterosaurs. In the LRT Lagerpeton nests with Tropidosuchus.
- The basal bipedal crocodylomorphs, Lewisuchus and Saltopus nest with the poposaurs Silesaurus and Sacisaurus far apart from other bipedal or near bipedal crocs like Tarjadia, and on a distant branch, Litargosuchus, Hesperosuchus and Terrestrisuchus. Missing from the taxon list is a Tarjadia sister in the LRT: Erpetosuchus.
- Other basal bipedal crocs (Hesperosuchus) leading to higher crocs (Protosuchus) are derived from Postosuchus, with a juvenile Postosuchus (CM73372) at its base. Missing from this taxon list are Trialestes, Junggarsuchus and Pseudhesperosuchus, taxa close to the origin of Dinosauria.
- Ornithischia arises from the poposaur, Sacisaurus, outside of the Dinosauria (with Herrerasaurus and kin at its base).
- The basal theropod, Tawa, nests far from other theropods.
- Parasuchians are _still_ the sister clade to the pterosaur/poposaur/dinosaur clade and nest basal to Ornithosuchus and Rauisuchia + Ticinosuchus. In the LRT parasuchians arise from Elachistosuchus and Diandongosuchus taxa missing from Allen et al.
- Aetosaurs arise from the misplaced basalmost poposaur, Turfanosuchus, the misplaced basalmost croc, Gracilisuchus, and the misplaced fugusuchid, Revueltosaurus.
- Missing from the taxon list is Vjushkovia, the basalmost rauisuchid, and Decuriasuchus, which ties Vjushkovia to Turfanosuchus and the base of the Archosauria (crocs + dinos only in the LRT).
The Allen et al. study adds nothing but confusion to the Archosauromorpha.
It is indeed unfortunate that the next generation of paleontologists (Benton’s co-authors, including Allen) were apparently forced to keep their blinders on in order to succeed in an academic system that ignores, rather than tests pertinent published taxa.
When one creates a cladogram,
one has the responsibility to review each node to make sure all sister taxa look similar to one another at every node. If not, add taxa until they do.
In order for Allen et al. to understand
the separation of the new Lepidosauromorpha from the new Archosauromorpha, they need to include a long list of taxa going back to the Viséan Silvanerpeton and the Westphalian Gephyrostegus, where the two branches of the Reptilia split. They can do that easily by including the LRT in their next supertree analysis.
Allen BJ, Stubbs TL, Benton MJ and Puttick MN 2018. Archosauromorph extinction selectivity during the Triassic-Jurassic mass extinction. Palaeontology 2108: 1–14. doi: 10.1111/pala.12399
Benton MJ 1999. Scleromochlus taylori and the origin of the pterosaurs. Philosophical Transactions of the Royal Society London, Series B 354 1423-1446. Online pdf
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.