Question

During the evolution of tetrapods, most of the traits criticial to the transition to land first evolved prior to tetrapods exiting the water. Identify one shared, derived (synapomorphic) trait for each of clade Vertebrates, clade Gnathostomes and clade Osteichthyans (3 traits in total) that were later important to the evolution of terrestrial tetrapods. Describe how the evolution of these three traits helped tetrapods overcome the challenges of life on land. **PLEASE BE DESCRIPTIVE AND PROVIDE FULL SENTENCES**

Answer 1

The tetrapods evolution began in the late Devonian period where they had come from loved finned fish. It was certain that their legs were too weak to support their midsection in the earliest of tetrapods. It was also observed that the oxygen levels in those times were less which further led to the development of the lungs which they were still swimming and a swim bladder. Also the development of the circulatory system paving way for the heart in future was also seen.

Gnathostomes were the the jawed vertebrates . The jaws were an extension of the gills support arches . They possess paired appendages . The males have developed claspers and the female the basal body for mating . The ancestors seemed to have fins both pectoral and pelvic for better swimming. They seem to also have an internal ear. They moved from desh to saline waters and converted the ammonia to urea to help with the osmolarity for saline waters

Osteichthyans are bony fishes . They had a small underdeveloped lung to thrive in lowOxygen level waters. These have been modified to swim bladders for better boyancy.Tooth pattern was somewhat between sharks and bony fish suggesting carnivorous nature