Diopecephalus

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Diopecephalus
Temporal range: Tithonian
Pterodactylus kochi 2.jpg
Fossil in Augsburg Naturmuseum
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order:† Pterosauria
Suborder:† Pterodactyloidea
Clade:† Euctenochasmatia
Genus:† Diopecephalus
Seeley, 1871
Species
  • †D. kochi(type) (Wagner, 1837 (originally Ornithocephalus)

Diopecephalus is a genus of pterodactyloid pterosaur from the Lower Tithonian (Upper Jurassic) of the Lithographic Limestone, Bavaria, Germany. The type and only species is D. kochi, although the name has been applied to Pterodactylus longicollum , with longicollum erroneously listed as the type species. [1]

Contents

Juvenile type specimen Bsp as xix.png
Juvenile type specimen

Assigned species

Like many pterosaurs, it has had a confusing taxonomic history, being given names by various authorities which identify it with four other genera:

In 1871, British paleontogist Harry Govier Seeley in a footnote of a supplement to his pterosaur book The Ornithosauria, named a new genus Diopecephalus combining in it four already published taxa: "Another unnamed generic type is typified by Pterodactylus longicollum, P. rhamphastinus, and the two species included under the name P. kochi. In this genus the middle hole of the skull is entirely wanting. For it I suggest the name Diopecephalus". [2] The generic name Diocephalus was derived from Greek di, "two", ὀπή, opè, "hole" and kephalè, "head". It refers to Seeley's (mistaken) assumption that the antorbital fenestra was lacking in the snout side, leaving only the nostril and the eye socket. The "two species of P. kochi" according to Stephen Christopher Bennett refer to the holotype of P. kochi Wagner, 1837 (specimens SM 404 & BSP AS.XIX.3) and that of P. scolopaciceps (von Meyer, 1859): specimen BSP AS.V.29. [1]

In 2017, Steven U. Vidovic and David M. Martill resurrected the genus Diopecephalus for Pterodactylus kochi, [3] a taxon generally regarded as synonymous with Pterodactylus antiquus. [4] [5] Though historically considered distinct from antiquus, most modern analyses of kochi anatomy strongly suggest it represents a juvenile P. antiquus. Pterosaur expert Christopher Bennett noted that some allegedly diagnostic kochi anatomy actually reflected measurement errors of the kochi holotype, and that once corrected the two species cannot be adequately distinguished from one another. [5] Vidovic and Martill's suggestion that kochi is taxonomically distinct rely on a combination of characteristics rather than autapomorphies, including features such as the slope of the snout and the rounded shape of the back of the skull, the shape and distribution of teeth, and the length and depth of the cervical vertebrae. [3] Most of these features are typical for Pterodactylus or are known to vary with growth stage [1] [4] [5] and, as per Vidovic and Martill's previous work with another resurrected Pterodactylus-like genus, Aerodactylus , arguments discounting individual variation and preservational factors (e.g., specimen orientation, compression) from true taxonomic distinction were not provided. [6] Further work is likely needed to validate D. kochi as a genuine taxon, and not a synonym of P. antiquus.

A reevaluation of the relationship between Pterodactylus and Diopecephalus finds Diopecephalus not only distinct from Pterodactylus, but also not closely related, recovering it as a basal pterodactyloid. [7]

Classification

Below is a cladogram showing the results of a phylogenetic analysis presented by Andres, Clark & Xu, 2014. In the analysis, they identified Diopecephalus as Pterodactylus kochi, and sister taxon of Pterodactylus antiquus within the clade Euctenochasmatia. [8]

Archaeopterodactyloidea

A 2024 study finds it to be a basal pterodactyloid, while P. antiquus remains the most basal member of the Euctenochasmatia. [9]

References

  1. 1 2 3 Bennett, S. Christopher (2006). "Juvenile specimens of the pterosaur Germanodactylus cristatus, with a review of the genus" (PDF). Journal of Vertebrate Paleontology. 26 (4): 872–878. doi:10.1671/0272-4634(2006)26[872:jsotpg]2.0.co;2. S2CID   86460861.
  2. ↑ Seeley, H.G., 1871, "Additional evidence of the structure of the head in ornithosaurs from the Cambridge upper Greensand; being a supplement to "The Ornithosauria."" Annals and Magazine of Natural History, Series 4(7): 20–36
  3. 1 2 Vidovic, Steven U.; Martill, David M. (2017). "The taxonomy and phylogeny of Diopecephalus kochi (Wagner, 1837) and Germanodactylus rhamphastinus (Wagner, 1851)" (PDF). Geological Society, London, Special Publications. 455: 125–147. doi:10.1144/SP455.12. S2CID   219204038.
  4. 1 2 Jouve, Stephane (2004-09-10). "Description of the skull of a Ctenochasma (Pterosauria) from the latest Jurassic of eastern France, with a taxonomic revision of European Tithonian Pterodactyloidea". Journal of Vertebrate Paleontology. 24 (3): 542–554. doi:10.1671/0272-4634(2004)024[0542:dotsoa]2.0.co;2. ISSN   0272-4634. S2CID   86019483.
  5. 1 2 3 Bennett, S. Christopher (2012-12-09). "New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus". Paläontologische Zeitschrift. 87 (2): 269–289. doi:10.1007/s12542-012-0159-8. ISSN   0031-0220. S2CID   83722829.
  6. ↑ Bennett, S. Christopher (2018). "New smallest specimen of the pterosaur Pteranodon and ontogenetic niches in pterosaurs" . Journal of Paleontology. 92 (2): 254–271. doi:10.1017/jpa.2017.84. ISSN   0022-3360. S2CID   90893067.
  7. ↑ Smyth, Robert S. H.; and Unwin, David M. (2024-12-31). "Re-evaluation of Pterodactylus antiquus and Diopecephalus kochi: two troublesome taxonomic concepts". Journal of Systematic Palaeontology. 22 (1) 2421845. doi: 10.1080/14772019.2024.2421845 . ISSN   1477-2019.
  8. ↑ Andres, B.; Clark, J.; Xu, X. (2014). "The Earliest Pterodactyloid and the Origin of the Group". Current Biology. 24 (9): 1011–6. doi: 10.1016/j.cub.2014.03.030 . PMID   24768054.
  9. ↑ Robert S. H. Smyth & David Unwin, Re-evaluation of Pterodactylus antiquus and Diopecephalus kochi: two troublesome taxonomic concepts, https://doi.org/10.1080/14772019.2024.2421845

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