synapsid vs dimetrodon

synapsid and dimetrodon both are nouns.

Word	Noun	Adjective	Verb	Adverb
synapsid	Yes	No	No	No
dimetrodon	Yes	No	No	No

As nouns, dimetrodon is a hyponym of synapsid; that is, dimetrodon is a word with a more specific, narrower meaning than synapsid:

synapsid: extinct reptile having a single pair of lateral temporal openings in the skull
dimetrodon: carnivorous dinosaur of the Permian in North America having a crest or dorsal sail

Other hyponyms of synapsid include protomammal, therapsid, ictodosaur, pelycosaur, edaphosaurus.

synapsid (noun)	dimetrodon (noun)
extinct reptile having a single pair of lateral temporal openings in the skull	carnivorous dinosaur of the Permian in North America having a crest or dorsal sail