Schoch et al 2025 redescribed a redescribed specimen referred to Protorosaurus

Schoch et al 2025 reported,
“The late Permian (Lopingian) reptile Protorosaurus speneri has long been considered the earliest-diverging well-represented archosauromorph.

Not so. See below.

Although it is known from extensive skeletal material from the Kupferschiefer of the Werra Formation of Germany, its skull has remained incompletely known.”

Not so x2. See below.

“Extensive preparation and computed tomography scanning of a referred skull (Fig 4) have provided much additional information on the cranial structure, especially the basicranial and palatal regions.

This referred skull (Fig 4) was studied and reconstructed at least 2x before.

Phylogenetic analysis integrating the new anatomical data supports the hypothesis that Protorosaurus speneri is one of the earliest-diverging archosauromorphs to date.”

Not so. See below.

Question number 1: why avoid the holotype RCSH C specimen
(Fig 3) in preference for the slightly different and more articulated referred specimen NMK S 180 (Fig 4)? The LRT reconstructs and tests three putative Protorosaurus specimens along with the holotype. These two nest together. The other two referred specimens (Fig 2) do not nest with the holotype and referred specimens (Fig 1), so probably both unrelated taxa need a new generic name.

Phylogenetic backstory
Adding taxa in the LRT moves the taxon list of the Archosauromorpha (by definition) back to the Early Carboniferous (Viséan) following Silvanerpeton. Therefore, in the large reptile tree (LRT, 2338 taxa, subset Fig 1) protorosaurs are not among the earliest diverging archosauromorphs. A long list of other archosauromorphs precedes them.

So once again, textbooks are about a decade out-of-date solely due to taxon exclusion and holding on to tradition = avoiding testing discoveries. The LRT minimizes taxon exclusion by including 2300+taxa, including the less popular taxa and several specimens attributed to the same genus.

16 years ago Gottman-Queseda and Sander 2009
reported, “To date the only specimen bearing a nearly complete skull was the Spener (= holotype) specimen in London. However, because the skull is poorly and incompletely preserved and the specimen lacks preparation, a detailed reconstruction of the skull has not been possible.”

Not so poorly and incompletely preserved. The authors did not employ DGS methods. Contra the authors, the Spener specimen skull is completely preserved and a detailed reconstruction is presented here (Fig 3).

In 2022 Protorosaurus and the Protorosauria
remained traditional enigmas due to taxon exclusion. Wikipedia reports, “Protorosaurus is a genus of lizard-like early reptiles.”

That generic vague description means the Wikipedia authors did not know what Protorosaurus was, likely due to taxon exclusion. In the LRT, which tests over 2300 taxa, protorosaurs nest between terrestrial younginiiforms and archosauriforms (Fig 1) derived from diapsid archosauromorphs.

In 2022 I wondered – then answered
“how to tell the genus, Protorosaurus, apart from the genus, Prolacerta, the LRT indicates these taxa are currently shuffled together. So, at present, it just can’t be done. You can’t tell them apart phylogenetically because they don’t separate from one another phylogenetically. Since four tested specimens attributed to Protorosaurus speneri (Gottman-Queseda and Sandeer 2009) do not nest together, at least two need new generic names and one could use a new specific name based on morphological differences. The same may hold true for the several specimens currently attributed to Prolacerta.”

See figure 1 for the subset of the LRT that includes all four Protorosaurus specimens.

Compare the holotype skull of Protorosaurus
(Fig 3) with that of the referred specimen (Figs 4, 5).

The more interesting problem
is what separates archosauromorph protorosaurs from lepidosauromorph tanystropheids (including Macrocnemus, pterosaurs and Huehuecuetzpalli, Fig 5)?

It’s complicated. A suite of traits divides them in the LRT.

It’s worth noting,
protorosaurs and proterosuchids retain a longer finger 4 than 3, but their deep descendants do not.

Importantly, don’t omit taxa.
Otherwise you’ll end up like Peters 2000 who did not yet realize what he would learn by Peters 2007 by simply adding taxa and let the software recover a new hypothesis of interrelationships.

Don’t omit pertinent taxa.
The LRT can be your guide.

References
Evans SE and King MS 1993. A new specimen of Protorosaurus (Reptilia: Diapsida) from the Marl Slate (Late Permian) of Britain. Proceedings of the Yorkshire Geological Society 49, 229–234.
Gottmann-Quesada A and Sander PM 2009. A redescription of the early archosauromorph Protorosaurus speneri Meyer, 1832 and its phylogenetic relationships. Palaeontographica A 287, 123–220.
von Meyer 1830. Isis von Oken, p 518.
von Meyer 1832. Palaeologica pp. 109, 208.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Schoch RR, Sues H-D, Sobral G, Kurz C, Gottmann-Quesada and Spiekman SNF 2025. New data on the skull of Protorosaurus speneri (Reptilia: Archosauromorpha) and their phylogenetic significance. Journal of Systematic Palaeontology. 23 (1): 2496744. doi:10.1080/14772019.2025.2496744
Seeley K 1888. Research on the structure, organisation and classification of the fossil Reptilia 1. On the Protorosaurus speneri (von Meyer). Philosophical Transactions of the Royal Society, London B 178, 187–213.
Spener CM 1710. Disquisitio de crocodilo in lapide scissili expresso, aliisque Lithozois Miscellanea Berolinensia ad incrementum scientiarum ex scriptis Societati Regiae Scientiarum exhibitis 1:92-110.

wiki/Protorosaurus

The holotype of Protorosaurus enters the LRT

Source: https://pterosaurheresies.wordpress.com/2025/08/09/schoch-et-al-2025-redescribed-a-redescribed-specimen-referred-to-protorosaurus/