Dinilysia was extinct genus of snake from the Late Cretaceous.
Physical appearance and biology
Measuring 10 feet long, the appearance and biology of Dinilysia was similar, if not identical, to modern pit vipers.
Behaviour and traits
Dinilysia was a specialist in hunting the mammals of its time. To do this, they used special sensory pits on their snouts as a way of detecting the heat signatures of other animals.
Two Tyrannosaurus chicks discover a Dinilysia while exploring the area around them. They play with it to the snake's annoyance, but they soon leave it when their mother has a standoff with an Ankylosaurus who was unknowingly intruding the T. rex family's territory.
Behind the Scenes
According to the Walking with Dinosaurs website, Dinilysia was the snake that briefly appeared in Death of a Dynasty.
The creature was live-acted by a modern day red-tailed boa. However, the episode in question was set in North America, and Dinilysia lived some 25 million years before Tyrannosaurus and lived in South America.