synapsid
/sɪˈnæpsɪd/
noun
- A group of ancient reptiles that had a single opening in the skull behind each eye, and from which mammals eventually evolved.
- Fossils show that synapsids lived long before the dinosaurs.
- The synapsid is an ancestor of modern mammals.
- Scientists classify synapsids as a key group in the evolution of warm-blooded animals.
adjective
- Relating to the group of reptiles that includes the ancestors of mammals.
- The synapsid skull has a distinctive opening behind the eye.
- Many synapsid fossils have been found in South Africa.
- The synapsid lineage eventually gave rise to all mammals.