Protorosauria

Source: Wikipedia, the free encyclopedia.
Not to be confused with Protorosaurus.

Protorosaurs
Temporal range: Latest
Ma

Fossil specimen of
Teyler's Museum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauromorpha
Order: †Protorosauria
Huxley, 1871
Subtaxa

Protorosauria is an

paleontologist Thomas Henry Huxley in 1871 as an order, originally to solely contain Protorosaurus. Other names which were once considered equivalent to Protorosauria include Prolacertiformes and Prolacertilia.[1]

Protorosaurs are distinguished by their long necks formed by elongated

Crocopoda,[2] though some recent studies have recovered the group as monophyletic.[3] A number of members of Protosauria have been found to belong to a monophyletic group (though not including Protorosaurus) which was named Tanysauria in 2024.[4]

Classification

Protorosauria was considered to be a synonym of

Prolacertiformes for many years.[5]

Since 1998, many phylogenetic analyses have found Protorosauria, as used in its widest sense, to be a

phylogenetic analyses since 1998 have found a strongly supported clade that includes only the genus Prolacerta and the Archosauriformes.[7]

For this reason Prolacerta, Pamelaria, and several other related forms (collectively called

prolacertids
) have been removed from Protorosauria. Because the name Prolacertiformes is defined based on the genus Prolacerta, the name Protorosauria is used for the remaining group.

Only recently has Protorosauria been defined in a

Drepanosauridae (and relatives) and Tanystropheidae (and relatives). However, some analysis found Protorosaurus (and sometimes the closely related Czatkowiella) to be more advanced[12] or more basal[13]
than the node Drepanosauridae+Tanystropheidae, but always more basal than Prolacerta.

Some studies still use the term Prolacertiformes to include prolacertids and traditional protorosaurs, while restricting the term Protorosauria to the smallest clade that includes Protorosaurus, Macrocnemus, and Tanystropheus; thus Protorosauria is a true clade, while Prolacertiformes is an evolutionary grade of early archosauromorphs.[14]

Pritchard et al. (2015),[15] Nesbitt et al. (2015),[16] Ezcurra (2016)[17] and Spiekman et al., 2021[2] found that even this definition of Protorosauria, like Prolacertiformes, was an unnatural group of various non-Crocopodan archosauromorphs. These studies found that tanystropheids were archosauromorphs more closely related to crocopods than to Protorosaurus. Nevertheless, Ezcurra noted that archosauromorph systematics required further study, and that phylogenetic support for Protorosauria being a natural group was only barely weaker than the support for the group being unnatural.

Included groups

The Protorosauria includes the Permian genus

tanystropheids
, which have extremely long necks.

Another enigmatic group of Triassic reptiles, the

Drepanosauromorpha, have often been classified as belonging to the Protorosauria.[19]

derived group of archosaurs
.

While Senter (2004) reassigned the bizarre, arboreal drepanosaurids and Longisquama to a group of more primitive diapsids called Avicephala,[21] subsequent studies failed to find the same result, instead supporting the hypothesis that they were protorosaurs.

Cladogram

The following cladogram shows the position of Protorosauria among the Sauria sensu Sean P. Modesto and Hans-Dieter Sues (2004).[7]

Most recent studies have recovered Protorosauria as a whole as a paraphyletic, cladogram after Spiekman et al. 2021[2]

Diapsida

Although Protorosauria as a whole is often found to be a paraphyletic, a large group of former "protorosaurs" (excluding Protorosaurus) is frequently found to be monophyletic. This clade was given the name "Tanysauria" by Spiekman et al. in 2024.[4]

References

  1. ^
    ISBN 9780231135221
    .
  2. ^
    PMID 33986981
    .
  3. PMID 35984885
    .
  4. ^
    ISSN 1664-2384
    .
  5. ^ Benton, M.J.; Allen, J.L. (1997). "Boreopricea from the Lower Triassic of Russia, and the relationships of the prolacertiform reptiles" (PDF). Palaeontology. 40 (4): 931–953.
  6. doi:10.1127/pala/287/2009/123
    .
  7. ^
    doi:10.1111/j.1096-3642.2003.00102.x
    .
  8. PMC 1692244
    .
  9. doi:10.1139/e02-048
    .
  10. S2CID 86026836
    .
  11. ^ Renesto, Silvio; Spielmann, Justin A.; Lucas, Spencer G.; Tarditi Spagnoli, Giorgio (2010). "The taxonomy and paleobiology of the Late Triassic (Carnian-Norian: Adamanian-Apachean) drepanosaurs (Diapsida: Archosauromorpha: Drepanosauromorpha)". New Mexico Museum of Natural History and Science Bulletin. 46: 1–81.
  12. S2CID 38739295
    .
  13. ^ Borsuk−Białynicka, Magdalena; Evans, Susan E. (2009). "A long−necked archosauromorph from the Early Triassic of Poland" (PDF). Paleontologica Polonica. 65: 203–234.
  14. S2CID 86145645
    .
  15. S2CID 130089407
    .
  16. hdl:2246/6624. {{cite journal}}: Cite journal requires |journal= (help)CS1 maint: multiple names: authors list (link
    )
  17. PMID 27162705
    .
  18. ^ Borsuk–Białynicka, M.; Evans, S.E. (2009). "A long–necked archosauromorph from the Early Triassic of Poland" (PDF). Palaeontologia Polonica. 65: 203–234.
  19. doi:10.1080/02724634.1994.10011537
    .
  20. ^ Peters, D (2000). "A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis". Rivista Italiana di Paleontologia e Stratigrafia. 106 (3): 293–336.
  21. S2CID 83840423
    .
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