Question

Present day mammals have their predecessor in

• A. Therapsids
• B. Diapsids
• C. Synapsids
• D. Anapsids

Answer 1

The correct option is C Synapsids

Synapsida is one of the subclasses of class Reptilia which include mammals like reptiles. Reptiles first appeared in the Pennsylvanian period and there became an abundance of primitive reptiles in the Permian period. It was this time when the appearance of mammals like reptiles occurred. In the Triassic period, there was the transition of reptiles to mammals.

Synapsids had a single skull opening behind each eye which is called "temporal fenestra".

Synapsids were considered to be the lineage of Reptiles and they evolved mammal-like characters, therefore called mammals like reptiles. Therapsida is the order under the subclass Synapsida consisting of four-legged vertebrates having a hole in each eye socket. The first true reptiles were referred as Anapsids. Anapsida gave rise to a separate lineage called Synapsida that included mammals like reptiles which further evolved into mammals.

The second lineage formed from Anapsids were Diapsids which had two pairs of additional holes roughly behind their eye sockets, in their skull.

So, mammals are believed to be evolved from synapsids.

So, the correct answer is C.