Nyasasaurus

Nyasasaurus ("Lake Nyasa lizard") is an extinct genus of Archosaur reptile from the Middle Triassic Manda Beds of Tanzania. It may be the earliest known dinosaur. The discovery was a handful of bones from two individuals, so its anatomy is only partly known. The bones were collected in the early 1930s, but have only recently been analysed.
Researchers said: ""Nyasasaurus" possesses a unique combination of dinosaur character states and an elevated growth rate similar to that of definitive early dinosaurs. It demonstrates that the initial dinosaur radiation occurred over a longer timescale than previously thought (possibly 15 million years earlier)".
The find was six vertebrae and a humerus from one specimen, and five vertebrae from another. The humerus has a muscle attachment which is characteristic of dinosaurs (a long 'deltopectoral crest'). Other features are consistent with its being a basal dinosaur.
Previously, the oldest record of dinosaurs was from Argentina and dated back to the Upper Triassic Carnian stage, about 231.4 million years ago (mya). "Nyasasaurus" comes from a deposit that dates back to the Middle Triassic Anisian stage, meaning that it predates other early dinosaurs by about 15 million years.