Pachagnathus
Pachagnathus Temporal range: Late Triassic, late Norian to
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Order: | †Pterosauria |
Family: | †Raeticodactylidae |
Genus: | †Pachagnathus Martínez et al., 2022 |
Species: | †P. benitoi
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Binomial name | |
†Pachagnathus benitoi Martínez et al., 2022
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Pachagnathus ("earth jaw") is an
Discovery and naming
The
PVSJ 1080 was described as a new genus and
Description
The only known part of Pachagnathus is a portion from the very front of the lower jaws, consisting of the mandibular symphysis (the fused portion at the tips of the lower jaw), although the jaw tip itself is missing. The symphysis is notably long, including at least five pairs of teeth and likely to have been even longer. This symphysis is very narrow and laterally compressed, so much so that the edges of the jaw tips are parallel to each other, with a preserved length of 61.5 mm but a maximum width of only 12.2 mm. An unusual feature of the symphysis is a ridge along the surface of the mandible running between the teeth. Uniquely in pterosaurs, it repeatedly alternates between a single midline ridge in the gaps along the toothrow and splitting into a pair in between pairs of teeth, leaving elliptical depressions between them. This ridge is likely created by the occlusal ridges along each tooth row being greatly emarginated and compressed into a single midline ridge. Such a combination of midline keel and a series of fossae is not known in any other pterosaur.[2]
The margins of the dentary slope inwards to form a sharp keel along the bottom, giving the jaw a sub-triangular cross-section roughly two times as deep as it is wide. The jaw is deepest at the level of the second preserved tooth, where the symphyseal ridge is drawn up into a high eminence, similar to Raeticodactylus and to a lesser extent the lower eminence of Eudimorphodon.[2]
The tooth sockets bulge prominently from the jaw and are separated by deep, bowl-shaped concavities in the jaw bone between the teeth so that the dental margin is highly
The teeth themselves are poorly preserved, but what is present indicate they were elliptical in cross-section, almost twice as long front-to-back as they are from side-to-side. Its
Classification
To determine the relationships of Pachagnathus to other pterosaurs, Martínez performed a
Pterosauria
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An additional analysis using the
Palaeobiology
Pachagnathus lived in a continental environment a long distance from the nearest coast, and was therefore almost certainly a terrestrial animal, compared to the various coastal Triassic pterosaurs found in the northern hemisphere. This corroborates hypotheses that significant parts of early pterosaur evolution may have taken place in terrestrial settings.[2]
The Quebrada del Barro Formation has also produced remains of the smaller and related pterosaur Yelaphomte, as well as a diverse range of vertebrate fossils including
See also
References
- ^ Müller R.T., Ezcurra M.D., Garcia M.S., Agnolín F.L., Stocker M.R., Novas F.E., Soares M.B., Kellner A.W.A. & Nesbitt S.J. (2023). ”New reptile shows dinosaurs and pterosaurs evolved among diverse precursors”. Nature 620(7974): p. 589–594. doi:10.1038/s41586-023-06359-z
- ^ ISSN 2056-2799.
- ^ S2CID 131662341.
- PMID 24768054.