Imagine a world where furry mammals scuttle under the feet of gigantic dinosaurs, not yet destined to rule the Earth. It’s a ...

In several reptile lineages (except anapsids), openings developed in ... This condition originated in the reptilian ancestors of mammals and continues in mammals today. Diapsid condition is very clear ...

Mammal lineages are in red; diapsid reptiles, shown as archosaurs (birds, crocodilians and dinosaurs), are in blue; and lepidosaurs (snakes, lizards and relatives) are in green.