Rhynchosaur
Rhynchosaurs | |
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Mounted skeleton model of Hyperodapedon | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Clade: | Archosauromorpha |
Clade: | Crocopoda
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Order: | †Rhynchosauria Osborn 1903 |
Subgroups | |
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Rhynchosaurs are a group of extinct herbivorous Triassic archosauromorph reptiles, belonging to the order Rhynchosauria.[1] Members of the group are distinguished by their triangular skulls and elongated, beak like premaxillary bones. Rhynchosaurs first appeared in the Early Triassic, reaching their broadest abundance and a global distribution during the Carnian stage of the Late Triassic.
Description
Rhynchosaurs were herbivores, and at times abundant (in some fossil localities accounting for 40 to 60% of specimens found), with stocky bodies and a powerful beak. Early primitive forms, like
The teeth were unusual; those in the maxilla and palate were modified into broad tooth plates. The hind feet were equipped with massive claws, presumably for digging up roots and tubers by backwards scratching of the hind limbs. Similar to elephants they had a fixed number of teeth where those further back in the jaws replaced those who were worn out as the animal grew in size and the teeth was worn out because of a diet of very tough plants. In the end they probably starved to death.[3]
Like many animals of this time, they had a worldwide distribution, being found across
Classification
List of genera
List of rhynchosaur genera | |||||
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Genus | Species | Age | Location | Unit | Notes |
A. navajoi |
A stenaulorhynchine. | ||||
B. cooowuse |
A hyperodapedontine previously referred to Hyperodapedon. | ||||
B. mariantensis |
A stenaulorhynchine, previously known as the "Mariante Rhynchosaur". | ||||
B. sidensis |
late Anisian |
A basal hyperodapedontid. | |||
Elorhynchus | E. carrolli | late Ladinian? - earliest Carnian? | Argentina | Chañares Formation (Tarjadia Assemblage Zone) | A stenaulorhynchine. |
E. wolvaardti |
early Anisian |
Burgersdorp Formation (Cynognathus Assemblage Zone )
|
A basal (non-rhynchosaurid) rhynchosaur. | ||
F. spenceri |
late Anisian |
UK (England) |
A basal hyperodapedontid. | ||
H. browni |
Burgersdorp Formation (Cynognathus Assemblage Zone )
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A basal (non-rhynchosaurid) rhynchosaur. | |||
H. gordoni |
A hyperodapedontine, one of the most abundant and speciose rhynchosaur genera. Six valid species has been named, the most of any rhynchosaur. | ||||
H. huenei |
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H. huxleyi |
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H. mariensis |
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H. sanjuanensis |
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H. tikiensis |
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I. genovefae |
Makay Formation (Isalo II)
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A hyperodapedontine occasionally referred to Hyperodapedon. | |||
M. kuttyi |
A stenaulorhynchine. | ||||
L. brodiei |
UK (England) |
Bromsgrove Sandstone Formation
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A basal hyperodapedontid. | ||
M. browni |
Burgersdorp Formation (Cynognathus Assemblage Zone )
|
A basal (non-rhynchosaurid) rhynchosaur. | |||
N. colletti |
early Induan |
A basal (non-rhynchosaurid) rhynchosaur. The earliest known species of rhynchosaur, and the only known Early Triassic representative.[6] | |||
O. bairdi |
A hyperodapedontine previously referred to Hyperodapedon. | ||||
R. articeps |
UK (England) |
Tarporley Siltstone Formation
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A basal rhynchosaurid. | ||
S. stockleyi |
late Anisian |
A stenaulorhynchine. | |||
S. stockleyi |
Tunduru district |
A hyperodapedontine previously referred to Hyperodapedon. | |||
T. sulcognathus |
The latest surviving species, and the only rhynchosaur known with confidence to have survived into the Norian stage. |
Phylogeny
The Rhynchosauria included a single family, named Rhynchosauridae. All rhynchosaurs, apart from the four
Within Hyperodapedontidae, which is now a subgroup of Rhynchosauridae, two subfamilies have been named. Stenaulorhynchinae named by Kuhn (1933) is defined sensu Langer and Schultz (2000) to include all species more closely related to Stenaulorhynchus than to Hyperodapedon. Hyperodapedontinae named by Chatterjee (1969) was redefined by Langer et al. (2000) to include "all rhynchosaurs closer to Hyperodapedon than to "Rhynchosaurus" spenceri" (now Fodonyx).[9]
The
Rhynchosauria |
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References
- ISSN 2296-701X.
- .
- ^ Ancient herbivore's diet weakened teeth and lead to eventual starvation, suggests study
- ^ Justin A. Spielmann; Spencer G. Lucas & Adrian P. Hunt (2013). "The first Norian (Revueltian) rhynchosaur: Bull Canyon Formation, New Mexico, U.S.A." (PDF). New Mexico Museum of Natural History and Science Bulletin. 61: 562–566.
- hdl:10919/114487.
- ^ hdl:11449/167867.
- .
- S2CID 83566087.
- ^ S2CID 130644209.
- ^ Ezcurra MD. (2016) The phylogenetic relationships of basal archosauromorphs, with an emphasis on the systematics of proterosuchian archosauriforms. PeerJ, 4:e1778 [1]
Bibliography
- Benton, M. J.(2000), Vertebrate Paleontology, 2nd ed. Blackwell Science Ltd.
- Carroll, R. L. (1988), Vertebrate Paleontology and Evolution, W.H. Freeman & Co.
- Dilkes, D. W. 1998. The Early Triassic rhynchosaur Mesosuchus browni and the interrelationships of basal archosauromorph reptiles. Philosophical Transactions of the Royal Society of London: Biological Sciences, 353:501-541.
External links
Data related to Rhynchosauria at Wikispecies