Question

Identify the incorrect pair regarding vertebrae:
A. Birds – Amphicoelous
B. Fishes – Procoelous
C. Urodela – Procoelous
D. Caecilians – Amphicoelous

• A. A, C
• B. A, D
• C. B, D
• D. B, C

Hint:

Birds → Heterocoelous; Urodela → Amphicoelous; Fishes → mostly Amphicoelous, some Procoelous.

Answer 1

The Correct Option is A

- A. Birds – Amphicoelous: Incorrect. Birds have heterocoelous vertebrae in the neck region, not amphicoelous. Amphicoelous vertebrae (concave on both sides) are more typical of fish.
- B. Fishes – Procoelous: Correct for some advanced fishes, but not all.
- C. Urodela – Procoelous: Incorrect. Urodela (salamanders) generally have amphicoelous vertebrae.
- D. Caecilians – Amphicoelous: Correct. Caecilians do have amphicoelous vertebrae.
Hence, A and C are incorrect pairs.

Answer 2

In vertebrates, the shape of the vertebral centra varies among different groups, and these shapes are categorized as amphicoelous, procoelous, opisthocoelous, etc.

Let's analyze each pair:

A. Birds – Amphicoelous: This is incorrect. Birds have heterocoelous vertebrae, which allow for the great flexibility required for flight and neck movement. Amphicoelous vertebrae, which are concave on both ends, are typical in some fishes and amphibians but not in birds.

B. Fishes – Procoelous: This is correct. Many fishes have procoelous vertebrae, where the vertebral centrum is concave in front and convex behind, aiding in flexibility and swimming movements.

C. Urodela (salamanders) – Procoelous: This is incorrect. Urodeles generally possess amphicoelous vertebrae, which are concave at both ends, providing some flexibility but less specialized than procoelous.

D. Caecilians – Amphicoelous: This is correct. Caecilians have amphicoelous vertebrae suitable for their burrowing lifestyle.

Hence, the incorrect pairs are A (Birds – Amphicoelous) and C (Urodela – Procoelous).

Understanding vertebral types helps in studying vertebrate evolution and locomotion adaptations.