| Named By: | Sterling J. Nesbitt, Paul M. Barrett, Sarah Werning, Christian A. Sidor & Alan J. Charig in 2013 |
| Time Period: | Middle Triassic, 243 Ma |
| Location: | Tanzania - Manda Formation |
| Size: | Up to about 3 meters long |
| Diet: | Uncertain |
| Fossil(s): | Partial post cranial skeleton including vertebrae, and right humerus |
| Classification: | | Chordata | Reptilia | Dinosauriformes | |
| Also known as: | | Thecodontosaurus alophos | |
Nyasasaurus (meaning "Lake Nyasa lizard") is an extinct genus of dinosauriform reptile from the Middle Triassic Manda Formation of Tanzania that appears to be the earliest known dinosaur. The type species Nyasasaurus parringtoni was first described in 1956 in the doctoral thesis 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. Nyasasaurus comes from a deposit that dates back to the Anisian stage, meaning that it predates other early dinosaurs by about 12 million years.