Brownstein et al 2022 fail to find ‘the evolutionary origins of the prolonged extant squamate radiation’

From the Brownstein et al 2022 abstract
“Here, we describe three-dimensionally preserved partial skulls of two new crown lizards from the Late Jurassic of North America. Both species are placed at the base of the skink, girdled, and night lizard clade Pan-Scincoidea, which consistently occupies a position deep inside the squamate crown in both morphological and molecular phylogenies.”

Always good to see a new taxon, but do these move lizard origins?

No. The work suffers from taxon exclusion.

Is it good that the authors confessed to studying molecular phylogenies? No. It would have been better for them to confess to alchemy or astrology.

This study should reminds you of another recent one by Whiteside et al 2022, that suffered from the same issues.

Missing from the taxon list:
an Early Permian iguanid squamate, MNC TA 1045 (Fig 3), found alongside the holotype of basal diapsid Ascendonanus. It nests in the large reptile tree (LRT, 2173 taxa, Fig 2) within Iguania. The other coeval specimens do not.

Just so everyone is clear, in the LRT squamates appeared in the Early Permian = 298mya. That’s quite a bit sooner than Brownstein et al are excited about with their Late Triassic = 200mya, skink.

Unfortunately,
this study (Fig 1) suffered from taxon exclusion. The authors had no idea their late-surviving Early Cretaceous, outgroup taxon, Huehuecuetzpalli was most closely related to the excluded lepidosaur and Middle Triassic pterosaur ancestor, Macrocnemus.

Also due to taxon exclusion, the authors didn’t realize
that Eichstaettisaurus is basal to Serpentes in the LRT where Mosasauria is not related to Serpentes. Gekkos are snake sisters in the LRT, but not in Brownstein et al 2022. In the LRT and in Brownstein et al 2022 skinks are derived squamates, appearing after all other squamate clades.

Here the authors are “Pulling a Larry Martin” from a cherry-picked taxon list.

“We find strong evidence for close relationships between the two new species and Cretaceous taxa from Eurasia. Together, these results suggest that early crown squamates had a wide geographic distribution and experienced complicated morphological evolution even while the Rhynchocephalia, now solely represented by the tuatara, was the dominant clade of lepidosaurs.”

Taxon exclusion remains the number one problem in paleontology. The authors don’t realize that Late Triassic pterosaurs and their tanystropheid cousins are also lepidosaurs
This just one more case in point. Using terms like ‘dominant’ to describe any clade or taxon resembling a shy and retiring tuatara strains credulity. Pick your adjectives carefully. Not all discoveries are headline-grabbers.

You’ll notice no attention is paid to the Triassic skinks described by Brownstein et al 2022. That’s because they are scrappy fossils that do not warrant inclusion to the LRT.

References
Brownstein CD et al (4 co-authors) 2022. Evolutionary origins of the prolonged extant squamate radiation. Nature communications https://doi.org/10.1038/s41467-022-34217-5