Castorocauda
SIZE: 500-800 grams, 43-50 centimetres long
ORIGIN: Inner Mongolia, Middle-Late Jurassic, around 166-157 million years ago
FACTS: Adapted for life in the water, this early mammal had paddle-like limbs, a flattened tail, and specialised teeth for eating fish. It’s one of the largest known Jurassic mammals, and although it somewhat resembles a modern beaver or platypus, it’s not closely related.
Kayentatherium
SIZE: Equivalent to a large cat or mid-sized dog
ORIGIN: Southwestern USA, Early Jurassic, around 200-183 million years ago
FACTS: One of the closest relatives of true mammals. They had at least some hair, walked upright, and had a high metabolism.
Volaticotherium
SIZE: 70 grams, 12-14 centimetres long
ORIGIN: Inner Mongolia, Middle-Late Jurassic, around 166-157 million years ago
FACTS: With its skin membrane (patagium) stretching between its body…