Taxon exclusion mars 2020 study of evolutionary innovation in reptiles

Simões et al. 2020 present
their vision of phenotypic diversity in reptiles (Fig. 1).

Unfortunately they do so
without knowing the last common ancestor of reptiles (Silvanerpeton) and the basal dichotomy of reptiles, both of which lead to a complete misunderstanding of the main branches in the phylogeny of reptiles. That lack of taxa led to a shuffling of the two major clades in the LRT, the new Archosauromorpha and the new Lepidosauromorpha.

For instance,
Simões et al. have no idea that ‘Diapsida’ is an invalid clade, unless restricted to only Archosauromorpha. Lepidosauriformes are the lepidosaur branch of the former ‘Diapsida’. Their figure 3 cladogram of the Lepidosauria omits Tritosauria and flips the order, nesting Iguania as a derived clade, rather than the basal clade it is in the LRT.

The large reptile tree (LRT) with 1746+ taxa remains the overlooked standard by which all smaller studies can be measured for no other reason that it includes more taxa. In the LRT phylogenetic miniaturization occurred at the genesis of many evolutionary novelties. This factor was overlooked in Simões et al. 2020 due to taxon exclusion.

Figure 1. Cladogram from Simoes et al. 2020 suffering from so much taxon exclusion that Archosauromorpha are shuffled within Lepidosauromorpha.

Figure 1. Cladogram from Simoes et al. 2020 suffering from so much taxon exclusion that Archosauromorpha are shuffled within Lepidosauromorpha.

The Simões et al. plan:
“Here, we explore megaevolutionary dynamics on phenotypic and molecular evolution during two fundamental periods of reptile evolution: (i) the origin and early diversification of the major lineages of diapsid reptiles (lizards, snakes, tuataras, turtles, archosaurs, marine reptiles, among others) during the Permian and Triassic periods, and (ii) the origin and evolution of lepidosaurs (lizards, snakes and tuataras) from the Jurassic to the present.”

Lacking pertinent taxa, Simões et al. mistakenly place turtles in diapsids and do not include pterosaurs, rhynchosaurs and tanystropheids in lepidosaurs.

Simões et al. conclude:
“Collectively, our findings suggest a considerably more complex scenario concerning the evolution of reptiles in deep time than previously thought.”

Without a proper phylogenetic context
anything this study presents is suspect or invalid from the get-go. Bring back your math, your charts, your statistics after you have a wide gamut, comprehensive cladogram with proper outgroup taxa, a working last common ancestor and valid branching thereafter, as in the LRT.

add more taxa. That will expand, clarify and validate your cladograms.

Simões TR, Vernygora O, Caldwell MW and Pierce SE 2020. Megaevolutionary dynamics and the timing of evolutionary innovation in reptiles. Nature 11:3322

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.