Question

Ancestor of mammal belongs to
A. Ornithischia
B. Therapsida
C. Silusidea
D. Chelonia
E. None of the above

Answer 1

Hint: Mammal-like reptiles belong to classical systematic non-mammalian lineages. These are a group of species, such as reptiles and birds, which are more closely related to mammals than to the members of the amniotic clade.

Complete answer: Mammals (Class Mammalia) evolved during the Mesozoic period from mammal-like reptiles more than 200 million years ago (mya). Therapsids are a genus of synapsids known to include mammals and their immediate evolutionary ancestry. The last recognized mammalian therapsids in the early Cretaceous period are extinct. All therapsids lineages other than mammals are extinct. Therapsida links to the ancestor of mammals, as there are numerous similarities found in both of them.
a) Ornithischia is the bird's ancestor. The word "Ornithischia" means ‘bird-hipped’. However, birds are more closely related to the Saurischian or 'lizard-hipped' dinosaurs than to the ornithischian dinosaurs.
c) The order which turtles belong to is Chelonia. Tortoises are the Chelonian or Testudines reptiles. They are distinguished by a special bone or cartilaginous shell made of their ribs, which acts as a shield. Colloquially, Testudines typically use the word "turtle" only for the purposes of fresh water and the sea.
Some of Therapsida's features are:
i. Vertical limbs that stretch out of the body.
ii. The Large Jaw and Heterodont teeth.
iii. The appearance of the body hair and fur.
iv. The body demonstrates the ability to monitor the temperature.
So, the correct answer is option B.

Note: Synapsids have separate teeth, such as canines, molars and incisors. Synapsids are one of the two major groups of amniotes that have evolved from basal amniotes. There is no human evidence of fossilized therapsid eggs, so artistic licenses have been used.