Early Triassic Prolacertoides is a squamate not a prolacertid

This small Early Triassic fossil from China
is represented by an anterior skull (IVPP V3233) lacking a mandible. Originally Yang 1973 allied Prolacertoides jimusarensis (Fig 1) with Prolacerta and kin among the prolacertids (aka protorosaurs). Ezcurra 2016 assumed a similar hypothesis of interrelationships because his taxon list was not adequately expanded.

Neither authors are correct in their assertions according to the large reptile tree (LRT, 2184 taxa) where more taxa are tested in order to minimize taxon exclusion issues like this one.

According to Wikipedia,
“VPP V3233 is a partially flattened and incomplete skull, with some bones being well preserved and others being badly damaged. The snout is tapering and lacks antorbital fenestrae. Unlike in Prolacerta and basal archosauriforms, there is extensive contact between the pterygoids. The pterygoids and palatines were seemingly toothless, although this observance may be due to poor preservation”.

All of this is interesting, but dodges the main problem: taxon exclusion. These authors are making comparisons to unrelated, superficially similar, cherry-picked taxa. The authors were not looking at lepidosaurs and squamates.

Lesson for today: FIRST: run your wide gamut analysis, no matter your assumptions. THEN: describe the specimen as it stands with tested related taxa. NEVER cherry-pick a taxon list. This is best done by building your own LRT. Yes, it can take years to build, but results will be worth the effort.

Because the LRT had to be split into four parts
for the software to work (maximum 1500 taxa), Prolacertoides was tested 4x. The theropod and fish subsets did not nest Prolacertoides with taxa sharing a long list of traits.

When tested with the lepidosauromorph portion of the LRT,
Early Triassic China Prolacertoides nested with little Tepexisaurus, a basal ?scincomorph from Early Cretaceous Mexico (Fig 2) and with even smaller Lanthanotus, a rare extant squamate from nearby Borneo, arising from Heloderma, the Gila monster. These taxa do share a long list of traits.

When tested with the archosauromorph portion of the LRT,
Early Triassic China Prolacertoides nested between Silesaurus and Lotosaurus, two larger herbivorous poposaurs from the Late Triassic of Poland and the Middle Triassic of China respectively. Despite the chronological and geographic proximity of Lotosaurus, these two archosauriform taxa do not share a long list of traits.

Noteworthy:
The archosauromorph prolacertilians (= protorosaurs) did not attract Prolacertoides. So Yang and Ezcurra were both far from the target due to cherry-picking their taxon lists.

References
Ezcurra MD 2016. The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms. PeerJ. 4: e1778.
Yang C 1973. The Discovery of Prolacertilia in Jimusar, Sinkiang. Vertebrata PalAsiatica 11(1):46–49.

wiki/Prolacertoides