Synapsids

Sinapsido

Synapsids are a group of animals that includes mammals and every animal more closely related to mammals. The synapsids diversified again to become the largest land and marine animals on Earth like mammals. The non-mammalian synapsids were described as mammal-like reptiles in classical systematics are now more correctly referred to as stem mammals or proto-mammals.


Although Synapsida includes modern mammals, the term is most often used when referring to non-mammalian, non-therapsid synapsids.

List of Synapsids

Unclassified


Dimacrodontidae


Diadectomorpha


Caseasaurs

The Caseasauria is one of the two major early synapsid clades, the other being Eupelycosauria. Caseasaurs are only known from the Late Carboniferous and Permian periods, and they are divided into two families: the small insectivorous or carnivorous Eothyrididae and the giant herbivorous Caseidae. These two groups share a variety of specialized traits related to snout and external naris morphology.


Varanopidae

The Varanopidae is an extinct family of amniotes that resembled monitor lizards and may have filled a similar niche, hence the name. Typically, they are considered synapsids that evolved from an Archaeothyris-like synapsid in the Late Carboniferous. However, some recent studies have recovered them being taxonomically closer to diapsid reptiles.


Haptodontiformes


Sphenacodontidae

The Sphenacodontia is a stem-based clade of derived synapsids. It was defined by Amson and Laurin (2011) as "the largest clade that includes Haptodus baylei, Haptodus garnettensis, and Sphenacodon ferox, but not Edaphosaurus pogonias". Basal Sphenacodontia are a transitional evolutionary lineage from early pelycosaurs to ancestral therapsids (which were the ancestors of more evolved forms and, eventually, mammals). Sphenacodontians could be considered proto-therapsids (despite the fact that therapsid progenitors diverged from other sphenacodontians around 30 million years ago and therapsids first appeared in the fossil record).


Palaeohatteriidae


Therapsida Unclassifed


Biarmosuchia


Dinocephalia


Anomodonts


Pylaecephalidae


Emydopoidea


Bidentalia Unclassifies


Cryptodontia


Kannemeyeriiformes


Gorgonopsians


Cynodonts (Cynodontia)


Therocephalians (Therocephalia)