Question

Features of Therapsids that suggest this group was transitional to reptiles and mammals.

Answer 1

Therapsids has both characteristics that possessed by mammals and reptiles.

For example :
The skull.  Therapsids skull is the combination between the skulls of reptiles (that have many several bones) , and the skull of mammals

The teeth. All The teeth in a reptile usually has the same sizes. But the occipital condyle in many therapsids became double just like in mammals

hope this helps