By José Carlos Cortés on @quetzalcuetzpalin-art
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Name: Nyasasaurus parringtoni
Name Meaning: Lake Nyasa Reptile
Described By: Nesbitt et al.
Classification: Avemetatarsalia, Ornithodira, Dinosauromorpha, Dinosauriformes, Dinosauria?
Nyasasaurus is one of the more fascinating fragmentary animals simply because of its fragmentary nature - and its age. Nyasasaurus is from the Manda Formation of Tanzania, living about 243 million years ago, in the Anisian age of the Middle Triassic. Now, this wouldn’t be very notable - Asilisaurus is also that age - except that it is uncertain what to classify Nyasasaurus as. It is is known from a humerus and vertebrae, and cannot be confidently classified as a Dinosaur, or a Dinosauriform like Asilisaurus. If it is a Dinosaur, it pushes back the origin of Dinosaurs long before they were first thought to evolve - if it is not a Dinosaur, it is simply another piece in the puzzle that is the origin of this clade of animals - being as close to a dinosaur as one can get without actually being a dinosaur (ie, the sister animal to the group).
By Jack Wood on @thewoodparable
If Nyasasaurus is a dinosaur, it would have predated all other known dinosaurs by about 10 to 15 million years. If it is a Dinosaur - and not just closely related to the ancestor of dinosaurs - then, when estimating the origin of dinosaurs, it is found that Dinosaurs were actually likely to have evolved in the Early Triassic, sometime between 252 and 247 million years ago, directly after the Permian Triassic extinction. This is much earlier than if Nyasasaurus is simply a sister taxon to Dinosaurs, where dinosaurs would have evolved in the Middle Triassic. It is even possible, if Nyasasaurus is a dinosaur, that Dinosaurs evolved in the Permian - right in the middle of the extinction, perhaps filling niches as they emptied rapidly.
By Scott Reid on @drawingwithdinosaurs
At the very least, Nyasasaurus as a Dinosaur indicates that Dinosauromorphs - and, perhaps, Avemetatarsalians as a whole - evolved in the chaos of that extinction, filling niches and diversifying rapidly before the Paleozoic was even over. Given that Nyasasaurus was most recently found to be a Dinosaur, then it seems like this hypothesis is worth thorough consideration - though, of course, more complete remains of Nyasasaurus could change it back to being sister to Dinosaurs.
https://en.wikipedia.org/wiki/Nyasasaurus
Lloyd, G. T., D. W. Bapst, M. Friedman, K. E. Davis. 2017. Probabilistic divergence time estimation without branch lengths: dating the origin of dinosaurs, avian flight and crown birds. Biology Letters 12: 20160609.
Barown, M. G., D. B. Norman, P. M. Barrett. 2017. A new hypothesis of dinosaur relationships and early dinosaur evolution. Nature 453: 501-506.
Shout out goes to @thea-wood!