Among the most bizarre animals in the Triassic deserts were the mammal-like reptiles known as Cynodonts. These odd animals are often referred to as the missing link between reptiles and mammals. These Cynodonts, such as Thrinaxodon, often lived in burrows to escape the desert heat, and would usually hunt at night to avoid predators.

Basic info

Meaning of name: Thrinaxodon means "trident tooth".

Time of existence: Thrinaxodon lived in the early Triassic, 252.17 million to 247.2 million years ago.

Diet: Thrinaxodon was a carnivore, and ate small animals, which would most likely include insects and small reptiles. They would occassionally even hunt baby dinosaurs like Coelophysis.

Threats: Thrinaxodon was in danger from many animals in the Triassic, including early dinosaurs and crocodiles. They also were at risk of starvation when prey was scarce.

Size: Thrinaxodon was only 1 and a half feet long.

Attributes: Thrinaxodon mated for life, and raised their young in their burrows. Thrinaxodon also possibly had some hair on its body. As said, they lived in burrows, and only went out to hunt at night, when it was not only cooler, but also safer. They had prongs on their molars, which most likely allowed them to keep a hold on prey. Thrinaxodon also produced milk, which was very no other reptile did. This milk was used to feed the pups.

A Thrinaxodon exiting its burrow

Appearances in the Walking with... series

Episode 1-New Blood

A pair of Thrinaxodon are one of the three main focuses of the episode, though they are only referred to as "Cynodonts". The male is first seen by the river, most likely just having gotten a drink. He then begins to return to his burrow, where his mate is sleeping. However, she senses his return and at first is hostile, believing it to be a predator. Once she realizes its her mate, she nuzzles him. Their young are seen nursing, and the male comes to check on them. After this, he begins to clean up the burrow, throwing some debris out before taking a brief rest.

The Thrinaxodon pair nuzzling

Later we cut to the middle of the dry season, and the Cynodonts are sleeping in their burrow. However, a pair of hungry Coelophysis begin to investigate the entrance of the burrow, and the Cynodonts begin to growl and bark, though the dinosaurs can't hear them. The male soon darts to the entrance of the burrow and hisses, scaring the hunters away. He sticks close to the entrance, smelling the air and making sure the dinosaurs are truly gone. Later, when evening hits, the Thrinaxodon are ready to go hunting, and check up on their young, who are now beginning to move about the nest. The male peeks his head out to check if the coast is clear, and he runs out to find food. A curious pup ends up following him close to the entrance, but the Coelophysis has returned, and snatches it up. The male runs after her and has a brief showdown with the dinosaur, growling and barking, and drives the hunter away. However, instantly after he returns into the burrow, the Coelophysis return, and he growls at them. Later, we are shown that the Coelophysis are attempting to dig the Cynodonts out, and they are no longer able to scare them off. The pair makes a very difficult decision-they cannibalize their young to deny the dinosaurs their prey, and then abandon their burrow in the moonlight, their future uncertain. Later, as the rains still haven't arrived and are late, it is revealed that the Thrinaxodon survived their brush with death and made a new burrow. The male goes out to hunt, and manages to catch a baby Coelophysis. He then returns into the burrow. Once the rains finally arrive, we are shown that the female has laid a new clutch of eggs, and is now watching over them. Her mate comes over to check, and nuzzles her. Millions of years later, their descendants, the mammals, will evolve, but be forced to live in the shadows, in a world ruled by dinosaurs.