Question

Ancestral amphibians were tetrapods that evolved during
A) Carboniferous period
B) Cretaceous period
C) Jurassic period
D) Devonian period

Answer 1

Hint:The organisms that we observed today are not like this from the beginning, many organisms have undergone drastic evolutionary changes to become more modified and to survive. Tetrapods are the ancient organisms that are evolved to form modified amphibians.

Complete answer:
To answer this question, we should know about evolution in tetrapods. Tetrapods evolved from an organism that lived in water, this was not like the fish we are known today. The most closely related species with tetrapods is ray finned fish. They consist of a system of branching bony rays termed as lepidotrichia that elongate from the fin base. The other animals that evolve from the same evogram are; coelacanths, lungfishes, and some of the extinct animals. In tetrapods, the limbs are covered by skin and muscles like in coelacanths and have lepidotrichia at the end of the limbs. This ancient vertebrate has fins with lepidotrichia, gills, scales in the body, and aquatic organisms. They have an air filled sac called air bladder that connects to the back of the throat, used for breathing. The air bladder is also used for control of buoyancy during swimming and is termed as swim bladder. During evolution, they lost the control of buoyancy function of the air bladder and this is elaborated to form organs like lungs same as the terrestrial organisms.
So, when the evogram for coelacnaths and lungfishes are studied, it is observed that they lived between 390 and 360 million years ago that is during the Devonian period. During this evolutionary period, the fleshy-finned organisms’ moves to the land from the water and many parts of the skeletons also get changed into innovative and new that make them suitable to live in land. These evolved organisms are known to us as amphibians today.

Thus, the correct option is ‘D’ Devonian period.

Note:One of the changes that adapted by the tetrapods is connection between hindlimbs and the pelvis; this is called fused connection the sacrum. This characteristic is very helpful for the terrestrial organisms as it allows the use of hind limbs more efficiently for movement on land.