Question

What are the synapomorphies of the following clades:

(1) Chordata

(2) Vertebrata

(3) Tetrapoda

(4) Amniota

(5) Diapsida

Answer 1

1. ln chordata the synmorphies are notochord, single dorsal hollow nerve cord, pharyngeal pouches/slits, endostyle, postanal tail.

2. In vertebrata the synmorphies are spinal coloumn or vertebral column and cranium is also a synmorphy.

3. In tetrapoda the synmorphies are strong ribs and presence of four limb.They have pair of bones i. e the ulna and radius and the tibia and fibula which is present in the epipodial segments of the forelimbs and hind limbs . Presence of digit in the end of each limb, an fenestra ovalis in the skull and skeletal features .

4. The synmorphies of amniotes are presence of a set of protective extra-embryonic membranes—the amnion, chorion, and allantois during the embryonic development .

5. Diapsida possess two holes (temporal fenestra) in each side of their skulls .