Asilisaurus

Asilisaurus
Temporal range: Middle Triassic, 245 Ma
↓
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Dinosauriformes
Clade: †Silesauridae
Genus: †Asilisaurus
Nesbitt et al., 2010
Species: †A. kongwe
Binomial name
Asilisaurus kongwe
Nesbitt et al., 2010

Asilisaurus (/ɑːˌsiːliːˈsɔːrəs/ a-SEE-lee-SAWR-əs; from Swahili, asili ("ancestor" or "foundation"), and Greek, σαυρος (sauros, "lizard") is an extinct genus of silesaurid archosaur. It is one of the oldest known animals on the dinosaur/pterosaur side of the archosaurian tree (the Avemetatarsalia), dating to about 245 million years ago.[1]

Fossils were uncovered in Tanzania and date back to the Anisian stage of the Middle Triassic. It was described in 2010 by a team of researchers from the United States, Germany, and South Africa, in the journal Nature; the type species is A. kongwe. It is the first example of an avian-line radiation during the Anisian, with the diversification of archosaurs during this time previously only documented from crocodylian-line archosaurs. It was the first non-dinosaurian dinosauriform recovered from Africa.[2]

Asilisaurus measured from 1 to 3 metres (3 to 10 ft) long and 0.5 to 1 metre (2 to 3 ft) high at the hip, and weighed 10 to 30 kilograms (20 to 70 lb).[2]

In a recently published research conducted by paleontologists from Virginia Tech, Asilisaurus was thought to be ontogenetically of polymorphism, just like a big family with siblings and cousins but differing in height or body mass. Researchers suggested that the early dinosaurs were also the case because of their close affinities. Through examining the muscle scars of femora of enough Asilisaurus specimens as well as histological studies, they proposed that instead of considering variations as sexual differences, they are better interpreted as individual differences.[3]

References

  1. ↑ Nesbitt, S.J.; Sidor, C.A.; Irmis, R.B.; Angielczyk, K.D.; Smith, R.M.H.; Tsuji, L.A. (2010). "Ecologically distinct dinosaurian sister group shows early diversification of Ornithodira". Nature. 464 (7285): 95–98. doi:10.1038/nature08718. PMID 20203608.
  2. 1 2 "Oldest known dinosaur relative discovered". ScienceDaily. March 3, 2010. Retrieved March 3, 2010.
  3. ↑ Griffin, C. T.; Nesbitt, Sterling J. (2016-03-04). "The femoral ontogeny and long bone histology of the Middle Triassic (?late Anisian) dinosauriform Asilisaurus kongwe and implications for the growth of early dinosaurs". Journal of Vertebrate Paleontology. 0 (0): e1111224. doi:10.1080/02724634.2016.1111224. ISSN 0272-4634.
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