Two bogus reptile clades: Crocopoda and Eucrocopoda

It’s truly a sad day in paleontology
when Wikipedia pictures the clade Archosauromorpha with a member of the Lepidosauromorpha, Trilophosaurus (Fig. 1). Just look at those sprawling limbs! Unfortunately, they forgot to make the spine sinusoidal in the mount.

Crocopoda (= croc-feet)
was defined by Ezcurra 2016 as all archosauromorphs more closely related to allokotosaurs (specifically Azendhosaurus and Trilophosaurus), rhychosaurs (specifically Rhynchosaurus), or Archosauriformes (specifically Proterosuchus) than to Protorosaurus or tanystropheids, like Tanystropheus.

In the large reptile tree (LRT)
no archosauromorphs are closely related to the lepidsauromorphs, AzendhosaurusTrilophosaurus. rhynchosaurs and tanstropheids. So the Crocopoda ‘starts off on the wrong foot.’

Figure 1. The authors of the Archosauromorpha page on Wikipedia chose a lepidosauromorph, Trilophosoaurus, as their icon image.

Figure 1. The authors of the Archosauromorpha page on Wikipedia chose a lepidosauromorph, Trilophosoaurus, as their icon image.

Eucrocopoda (= true croc feet)
is likewise beset by yet another set of problems based on a lack of understanding of the various splits at the base of the Archosauriformes. Eucrocopoda badly imagines Euparkeria, pterosaurs, Doswellia, and phytosaurs all rather quickly derived from giant erythrosuchids like Garjainia.

Nobody appears to be checking their own work here,
sort of like trusting DNA to recover tree topologies that make sense (= recover a gradual accumulation of traits).

As usual, it’s all due to
taxon exclusion. (And its corollary, inappropriate taxon inclusion). Lacking a large reptile tree (LRT, 1205 taxa) the authors of that Wiki page and the authors of Ezcurra et al. 2017 are shuffling together and interspersing lepidosauromorphs with archosauromorphs (Fig. 2) completely unaware of their infractions and atrocities, unhindered by a lack of a gradual accumulation of derived traits at several nodes.

Figure 1. Eucrocopoda and non-eucrocopoda colorized from Ezcurra et al. 2017.

Figure 1. Eucrocopoda and non-eucrocopoda colorized from Ezcurra et al. 2017. This cladogram is missing several dozen cherry-picked  to several hundred random taxa that would help clarify relationships,

Shall I list the problems?
Or do you want to find them on your own? Click the links below to compare morphologies at ReptileEvolution.com.

  1. Euparkeria and Doswellia
  2. Doswellia and Vancleavea.
  3. Dimorphodon derived from a sister to Teleocrater.
  4. Lotosaurus and Arizonasaurus.
  5. Riojasuchus and Aetosauroides.
  6. Riojasuchus and Erpetosuchus.
  7. Splitting Protorosaurus from Prolacerta.

We looked at more problems
with Ezcurra 2016 a few years ago here.

References
Ezcurra MD 2016. The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriformsPeerJ 4:e1778https://doi.org/10.7717/peerj.1778

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