Nyasasaurus
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Nyasasaurus Temporal range: Middle Triassic, 243 Ma |
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| Approximation of animal based on partial skeleton shown in black (first specimen, six vertebrae and a humerus) and blue (second specimen, three cervical vertebrae). | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauriformes |
| Genus: |
†Nyasasaurus Nesbitt et al., 2013 |
| Type species | |
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†Nyasasaurus parringtoni Nesbitt et al., 2013 |
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| Synonyms | |
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Nyasasaurus (meaning "Lake Nyasa lizard") is an extinct genus of dinosauriform reptile from the Middle Triassic Manda Beds of Tanzania that appears to be the earliest known dinosaur. The type species N. parringtoni was first described in 1956 in the doctoral dissertation of English paleontologist Alan J. Charig, but it was not formally described until 2013. Previously, the oldest record of dinosaurs was from Argentina and dated back to the late Carnian stage, about 231.4 million years ago (Ma). Nyasasaurus comes from a deposit that dates back to the Anisian, meaning that it predates other early dinosaurs by about 12 million years.
The type specimen, NHMUK R6856, is a partial skeleton belonging to an individual estimated to have been two to three metres in length. It consists of a right humerus, three partial presacral vertebrae and three sacral vertebrae (of the back, above the location of the hip bones). A second specimen, SAM-PK-K10654 consisting of three cervical vertebrae (neck vertebrae) and two posterior presacral vertebrae, is also known. It was attributed to the same species as NHMUK R6856 because the dorsal or back vertebrae of the two specimens are nearly identical. However, the vertebral features that link NHMUK R6856 and SAM-PK-K10654, including a connection between two bony projections called the hyposphene and hypantrum, are also found in other Triassic archosaurs. Because these characteristics are not unique to the two specimens (in other words, they are not autapomorphies), they do not by themselves provide sufficient evidence for grouping NHMUK R6856 and SAM-PK-K10654 under the same species. The authors of the 2013 description of Nysasaurus used a second line of evidence, the similar positions of the two specimens on evolutionary trees, to justify their placement in the same species.
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