Question

What should be true of fossils of the earliest tetrapods?

a. They should be transitional forms with the fossils of chondricthyans that lived at the same time
b. They should feature the earliest indications of the appearance ofo jaws
c. They should show evidence of having produced shelled eggs
d. They should indicate limited adaptation to life on land

Answer 1

The earliest tetrapod fossils should show limited adaptation to land (option d), as exemplified by transitional specimens like Tiktaalik with features suited for water and early land life.

Step-by-step explanation:

The fossils of the earliest tetrapods should indicate limited adaptation to life on land. As the first tetrapods evolved from lobe-finned fish ancestors, they displayed features both suited to the water and initial adaptations for terrestrial life. Tiktaalik roseae is an example of such a transitional form, showing morphological characteristics that place it between sarcopterygian fishes having feet-like fins and early tetrapods with true limbs.

These ancestral tetrapods, like Ichthyostega and Acanthostega, possessed features such as four limbs and a mix of gills and lungs, but were not yet fully adapted for life on land. Their limb structure suggests limited terrestrial mobility, indicating a crucial stage in the evolutionary trajectory from aquatic to terrestrial life forms.