Question

The type of vertebrae in the sub order ophidia is
a. Acoelous
b. Procoelous
c. Heterocoelous
d. Amphicoelous

Answer 1

Hint: Ophidian is the sub order of the kingdom animalia. These are considered as the most common ancestor of pachyrhachis and serpentes(modern snakes). The skeleton of the snakes are typically small and fragile. Vertebrae can be of different types depending on their location in the body. A vertebra is composed of a body, or centrum. Vertebrae consists of various segments and arrangement of these vertebrae leads to different structures of the animals.

Complete answer:
Scientific classification of ophidian is kingdom animalia, phylum chordata, class reptilian, order squamata, clade toxicofera and clade ophidia. Lee and Caldwell describe ophidia as ancestor of serpentes that are modern snakes.

Acoelous vertebrae means lacking a true stomach and lacking a true body cavity. Edges of acoelous are flat. It is found in most of the mammals.

Procelous vertebrae having anterior surface concave at the anterior end of centrum and usually convex at the posterior end. In ophidia a ball-and-socket joint appears with the concavity in front, the ball or convexity behind. This kind of vertebra, called procelous. It is mostly found in reptiles. Snakes have procoelous vertebrae.

Heterocoelous vertebrae concave from one end and convex at the other end forming saddle shaped ends. These are found in free vertebrae of birds as they are most flexible of vertebral joints.

In amphicoelous vertebrae both the ends are concave also known as biconcave. It is found in most fish and amphibians.

Hence, the correct answer is option (B).

Note: Vertebrates represents majority of phylum chordata. Animals that have backbone are known as vertebrates. Backbone supports the body and protects the spinal cord. Some of the examples of serpent( modern snakes) are scolecophidia, anilis, loxocemus etc. fossilization is uncommon in snakes because of their small and fragile skeletons.