sentence: Synapsids are one of the two major groups of amniotes.
sentences_before: This class includes mammals and earlier groups related to mammals.
sentences_after: The sister group, which gave rise to the reptiles, is the Sauropsida. Both groups evolved from early amniotes about 345 million years ago during the early or mid Carboniferous period.
concept_name: synapsid
headings: Synapsid