The oldest dinosaur?
Until this latest discovery, the oldest well-dated and unambiguous dinosaurs were known from the Late Triassic of Argentina, but the new specimen Nyasasaurus parringtoni pushes dinosaur origins back another 10-15 million years to the Middle Triassic. The find lends support to phylogenetic analyses that had predicted Dinosauria had Middle Triassic roots.
Although the Nyasasaurus material consisted of just a humerus and six vertebrae, a morphological study revealed several shared dinosaurian characters and Sarah's histological analysis of the bones showed that, like dinosaurs, Nyasasaurus bone grew at a rapid, sustained rate.
1Nesbitt, S.J., P.M. Barrett, S. Werning, C.A. Sidor, and A.J. Charig. 2012. The oldest dinosaur? A Middle Triassic dinosauriform from Tanzania. Biology Letters 9(1). doi: 10.1098/rsbl.2012.0949