Tropeognathus

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Tropeognathus
Temporal range:
Ma
↓
Reconstructed skeleton, National Museum of Brazil
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Order: †Pterosauria
Suborder: †Pterodactyloidea
Family: †Anhangueridae
Subfamily: †Tropeognathinae
Genus: †Tropeognathus
Wellnhofer, 1987
Type species
†Tropeognathus mesembrinus
Wellnhofer, 1987
Synonyms

Tropeognathus (meaning "

azhdarchids.[1] The type and only species is Tropeognathus mesembrinus. Fossil remains of Tropeognathus have been recovered from the Romualdo Formation, which is a Lagerstätte located in the Santana Group of the Araripe Basin in northeastern Brazil.[2]

Discovery and naming

palatal (A2), and anterior
(A3) views

In the 1980s the German

Koine mesembrinos, "of the noontide", simplied as "southern", in reference to the provenance from the Southern hemisphere.[3]

The holotype, BSP 1987 I 46, was discovered in a layer of the Romualdo Formation within the Santana Group, dating to the latest Aptian and earliest Albian stages. Along with the holotype, several other pterosaur specimens were found in the fossil site, these specimens however, were referred to genera such as Anhanguera and Cearadactylus.[4][5] The uncovered holotype consists of a skull with lower jaws. A second specimen was referred by André Jacques Veldmeijer in 2002: SMNS 56994, which consists of a partial mandible.[6] In 2013, Brazilian paleontologist Alexander Kellner referred a third, larger, specimen: MN 6594-1, a skeleton with skull, with extensive elements of all body parts, except the tail and the lower hindlimbs.[7]

After Tropeognathus mesembrinus was named by Peter Wellnhofer in 1987, other researchers tended to consider it part of several other genera, leading to an enormous taxonomic confusion.

Reginald Walter Hooley in 1914.[14][15] This made Veldmeijer use the names Criorhynchus simus and Criorhynchus mesembrinus instead.[2] In 2013 however, Taissa Rodrigues and Alexander Kellner concluded Tropeognathus to be valid, and containing only T. mesembrinus, the type species.[7]

Back in 1987, Wellnhofer had named a second species called Tropeognathus robustus, based on specimen BSP 1987 I 47, which is a more robust lower jaw.[3] In 2013 however, T. robustus was considered as a species of Anhanguera, resulting in an Anhanguera robustus.[7]

Description

Size

Size comparison of Tropeognathus mesembrinus
Restoration of three flying individuals

Tropeognathus is known to have reached

Harry Govier Seeley back in 1870.[16][17]

Skull and crests

Restored fossil skull of Tropeognathus; note the prominent, keel-like snout-crests.
Skull comparison of different anhanguerians, notice Tropeognathus (E and F) with a well-developed "keeled" crest

The skull of Tropeognathus bore a distinctively convex, "keeled" crests on the lower end of its snout, with an opposing, smaller mass on the underside of the lower jaws. This structure was prominent, well-developed, and relatively large in Tropeognathus (especially in males); however, by comparison, these crests were somewhat weakly-formed as opposed to the thicker skull crests of other pterosaurs, such as Ornithocheirus.

anhanguerid Anhanguera possessed jaws that were tapered in width, but expanded into a broad, spoon-shaped rosette at the tip, which differed from Tropeognathus for having a narrower appearance.[18] The jaws can be distinguished from its relatives by a few differences in the crest: unlike its close relatives Coloborhynchus and Ornithocheirus, the crest on the upper jaw of Tropeognathus was more prominent and much larger, and therefore resulting in a broader skull.[1]

Vertebrae

The first five dorsal vertebrae of Tropeognathus are fused into a notarium, with five sacral vertebrae fused into a synsacrum, and the third and fourth sacral vertebrae are keeled within. The front blade of the ilium is strongly directed upwards, resulting in a narrow structure.[1]

Classification

Palate of Tropeognathus (B) compared to the palates of Ferrodraco (A) and Siroccopteryx (C), all of them are in occlusal view

In 1987, Wellnhofer assigned Tropeognathus to a

Tropeognathidae.[3] This concept was not adopted by other workers; several researchers place Tropeognathus mesembrinus in the Anhangueridae, along with Anhanguera, while other cladistic analyses place Tropeognathus within the Ornithocheiridae as a basal member, meaning that it was more closely related to Ornithocheirus than Anhanguera. This concept is mostly used by the European colleagues, who prefer to use the Ornithocheiridae as the most inclusive group rather than the Anhangueridae.[13] A topology made by Andres and Myers in 2013 placed Tropeognathus within the family Ornithocheiridae in a more basal position than Ornithocheirus, and the family itself is placed within the more inclusive clade Ornithocheirae.[19] However, many subsequent analyses made in 2019 and 2020 have recovered Tropeognathus within the family Anhangueridae,[20][21][22] with a specific one by Borja Holgado and Rodrigo Pêgas in 2020, placing Tropeognathus more specifically within the subfamily Tropeognathinae, sister taxon to Siroccopteryx.[23]

In popular culture

Hand puppet from Walking With Dinosaurs, Oxford Museum[24]

Tropeognathus mesembrinus was the subject of an entire episode of the award-winning BBC television program Walking with Dinosaurs (which used the first name of its cousin Ornithocheirus but was incorrectly named as a species of it, as Ornithocheirus mesembrinus).[14] In Walking with Dinosaurs: A Natural History, a companion book to the series, it was claimed that several large bone fragments from the Santana Group (known as Santana Formation in the book) of Brazil had indicated that O. mesembrinus may have had a wingspan reaching 12 meters (39 ft) and a weight of 100 kilograms (220 lb), making it one of the largest known pterosaurs.[25] However, the largest definite Ornithocheirus mesembrinus specimens described at the time measured 6 meters (20 ft), in terms of wingspan.[8] The specimens which the producers of the program used to justify such a large size estimate were described in 2012, and were under study by Dave Martill and David Unwin at the time of Walking With Dinosaurs' production. The final description of the remains found a maximum estimated wingspan of 8.70 meters (28.5 ft) for this large specimen.[1] Unwin stated that he did not believe the higher estimate used by the BBC was likely, and that the producers likely chose the highest possible estimate because it was more "spectacular."[26] Nevertheless, specimen MN 6594-V in 2013 was, at its degree of completeness, the largest known pterosaur individual.[1]

See also

References

  1. ^
    PMID 23538956
    .
  2. ^ a b c Veldmeijer, A.J. (2006). "Toothed pterosaurs from the Santana Formation (Cretaceous; Aptian-Albian) of northeastern Brazil. A reappraisal on the basis of newly described material Archived 2012-03-17 at the Wayback Machine." Tekst. – Proefschrift Universiteit Utrecht.
  3. ^ a b c d Peter Wellnhofer, 1987, "New crested pterosaurs from the Lower Cretaceous of Brazil", Mitteilungen der Bayerische Staatssammlung für Paläontologie und historische Geologie 27: 175–186; Muenchen
  4. PMID 28484676
    .
  5. ^ Leonardi, G. & Borgomanero, G. (1985). "Cearadactylus atrox nov. gen., nov. sp.: novo Pterosauria (Pterodactyloidea) da Chapada do Araripe, Ceara, Brasil." Resumos dos communicaçoes VIII Congresso bras. de Paleontologia e Stratigrafia, 27: 75–80.
  6. ^ Veldmeijer, A.J. (2002). "Pterosaurs from the Lower Cretaceous of Brazil in the Stuttgart collection". Stuttgarter Beiträge zur Naturkunde, Serie B (Geologie und Paläontologie). 327: 1–27.
  7. ^
    PMID 23794925
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  8. ^
    ISBN 0-7607-0154-7
    .
  9. S2CID 89420181
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  10. ^ Veldmeijer, A.J. (1998). "Pterosaurs from the Lower Cretaceous of Brazil in the Stuttgart Collection". Geoscience and Engineering. 327: 1–27.
  11. S2CID 128410270
    .
  12. ^ Unwin, D.M., 2001, "An overview of the pterosaur assemblage from the Cambridge Greensand (Cretaceous) of Eastern England", Mitteilungen aus dem Museum für Naturkunde in Berlin, Geowissenschaftliche Reihe 4: 189–221
  13. ^
    S2CID 86710955
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  14. ^
    ISBN 0-13-146308-X
    .
  15. ISSN 0374-5481
    .
  16. doi:10.1016/j.cretres.2011.09.003
  17. ^ Seeley, H.G. (1870). The Ornithosauria: an Elementary Study of the Bones of Pterodactyles. Cambridge, 130 pp.
  18. ^ Kellner, A.W.A. and Tomida, Y. (2000). "Description of a new species of Anhanguera (Pterodactyloidea) with comments on the pterosaur fauna from the Santana Formation (Aptian–Albian), northeastern Brazil." Tokyo, National Science Museum (National Science Museum Monographs, 17).
  19. ^
    S2CID 84617119
    .
  20. doi:10.1038/s41598-019-41280-4
  21. PMID 31784545
    .
  22. ^ Pêgas, R.V., Holgado, B., Leal, M.E.C., 2019. "Targaryendraco wiedenrothi gen. nov. (Pterodactyloidea, Pteranodontoidea, Lanceodontia) and recognition of a new cosmopolitan lineage of Cretaceous toothed pterodactyloids", Historical Biology, 1–15. doi:10.1080/08912963.2019.1690482
  23. ^
    doi:10.4202/app.00751.2020
    .
  24. ^ "Dinosaurs in the Museum" (PDF). Retrieved February 15, 2024.
  25. ^ Haines, T., 1999, "Walking with Dinosaurs": A Natural History, BBC Books, p. 158
  26. ^ Bredow, H.P. (April 18, 2000). "Re: WWD non-dino questions". Archived from the original on April 4, 2016. Retrieved January 20, 2011.
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