Synapsid

Synapsids Temporal range: Pennsylvanian–Holocene, 318[1]–0 mya PreꞒ Ꞓ O S D C P T J K Pg N
Examples of synapsids: Cotylorhynchus, Dimetrodon, Inostrancevia, Moschops, Castorocauda, Adelobasileus, Tachyglossus, and Panthera tigris
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Superclass:	Tetrapoda
Clade:	Reptiliomorpha
Clade:	Amniota
Clade:	Synapsida Osborn, 1903

Synapsids are one of the two major groups of vertebrates which evolved from basal amniotes.

'Synapsids' means 'fused arch', and refers to their skulls. The group includes mammals and earlier groups related to mammals. They were originally called "mammal-like reptiles", which is a bit confusing.

Synapsids are one of the two major groups of amniotes. Both groups evolved from early amniotes about 345 million years ago during the early or mid Carboniferous period. The other is the sauropsids, the group which includes reptiles and birds.^[2]

Synapsids include the Pelycosauria (Pennsylvanian to Permian), and the Therapsida (Lower Permian to present).

The pelycosaurs were dominant on land in the Permian, and many species became extinct at the Permian–Triassic extinction event.^[3] The therapsids were still dominant on land in the Lower Triassic, but by the Upper Triassic the dinosaurs had taken over.

1. ↑ Steen, Margaret C. (1934). "The amphibian fauna from the South Joggins. Nova Scotia". Journal of Zoology. 104 (3): 465–504. doi:10.1111/j.1096-3642.1934.tb01644.x.
2. ↑ Laurin, Michel; Reisz, Robert R. (2011). "Synapsida: Mammals and their extinct relatives" (Version 14 ed.). The Tree of Life Web Project. Archived from the original on 2012-12-07. Retrieved 2023-01-28.
3. ↑ A few relics survived into the Lower Triassic.