Aardonyx
Aardonyx | |
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Reconstruction of the skull | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | †Sauropodomorpha |
Clade: | †Anchisauria |
Genus: | †Aardonyx Yates et al., 2010 |
Species: | †A. celestae
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Binomial name | |
†Aardonyx celestae Yates et al., 2010
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Aardonyx (
Based on the structure of the hind limbs and pelvic girdle of Aardonyx, the dinosaur normally moved bipedally but could drop to quadrupedal movement similar to
According to Matthew Bonnan, a co-author of the study, "We already knew that the earliest sauropods and near-sauropods would be bipeds. What Aardonyx shows us, however, is that walking quadrupedally and bearing weight on the inside of the foot is a trend that started very early in these dinosaurs, much earlier than previously hypothesized." Bonnan adds, "On a scientific level, it's really fulfilling to have a hypothesis on how you think dinosaurs got large, then to test that in the field and get back these kind of data — a new dinosaur — that really does start to fill in some of those anatomical gaps."
Description
The genus is known from disarticulated bones belonging to two immature individuals. The material consists of cranial elements,
Classification
Aardonyx is thought to be the
Cladogram showing the position of Aardonyx within Sauropodomorpha
after Yates et al., 2010:[1]
The following cladogram shows the position of Aardonyx within Massopoda, according to Oliver W. M. Rauhut and colleagues, 2020:[6]
Massopoda |
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Paleobiology
Feeding
Aardonyx shows a transition toward the bulk-browsing form of feeding characteristic of sauropods. The jaws of Aardonyx are narrow and V-shaped with a pointed symphysis, a plesiomorphic characteristic shared with other basal sauropodomorphs. In sauropods, the jaws are broad and U-shaped to allow for a wider bite. The absence of a lateral ridge at the caudal end of the
The presence of plesiomorphic V-shaped jaws along with the absence of fleshy cheeks is an unusual characteristic of Aardonyx. Previously, it was thought that broader jaws evolved before the reduction and loss in fleshy cheeks as an adaptation toward bulk-browsing in sauropods. The sauropod Chinshakiangosaurus possessed jaws that were U-shaped, while still retaining fleshy cheeks, the opposite of the condition seen in Aardonyx.[7] Because Chinshakiangosaurus is a more derived sauropodomorph, this suggests that a wide, cheekless gape may have evolved twice in Sauropodomorpha: once with Aardonyx and again with sauropods more advanced than Chinshakiangosaurus.[1]
Locomotion
Characteristics of the limbs of Aardonyx suggest that it was habitually bipedal. Evidence for bipedalism can be seen in the forelimbs; the structure of the radius and ulna limited the degree to which the
Another characteristic that suggests a slower gait in Aardonyx is the robustness of
References
- ^ PMID 19906674.
- ^ a b c Associated Press (November 11, 2009). Scientists: New dinosaur species found in South Africa NPR.
- Dixon, Robyn (2009-11-12). "New dinosaur species may be a missing link". Los Angeles Times. Johannesburg.
- Dixon, Robyn (2009-11-12). "Missing link African dinosaur discovery excites scientists". The Age. Johannesburg.
- PMID 19906674.
- S2CID 220294939.
- .
- ^ Carrano, M. T. (2005). The evolution of sauropod locomotion: morphological diversity of secondarily quadrupedal radiation. In Curry Rogers, K. A. and Wilson J. A. (eds.) The Sauropods: Evolution and Paleobiology, pp. 229–251. Berkeley, CA: University of California Press.
External links
Media related to Aardonyx at Wikimedia Commons
- Western Illinois University: Earth Claw
- Fleshed-out restoration of an Aardonyx celestae. Archived 2010-03-09 at the Wayback Machine by paleoartist Julius T. Csotonyi
- Matthew Bonnan's blog, Jurassic Journeys, where Aardonyx is discussed.
- Dracovenator, Adam Yates's blog site where Aardonyx is discussed.