Vertebrate span across a diverse array of life on earth today. fish are the first to evolve and amphibians still live with strong ties to bodies of water which is evident in their life circle

Fossil evidence shows that vertebrates made the transition from water to land during the DEVONIAN period.

SALAMANDERS are amphibians that most closely resemble early tetrapods in body form with a long tail and 4 limbs of similar length.

A distinctive characteristic of mammals that is not observed in other vertebrates is ENDOTHERMY.

By the end of the CAMBRIAN period, all major animal lineages were present in the seas due to a great adaptive radiation of animals.

The vertebrate lung first appeared in AMPHIBIANS

Explanation:

Vertebrates started to transition from water to land later in the Devonian period. The vertebrates had to adjust to living on land such as withstanding gravity, breathing in air, adjusting senses to living on land than on water, and significant water loss due to the new environment. This was a big step in the realm of evolution because vertebrates were now able to thrive because they are no longer limited to the resources and space of water.

Salamaders are said to have not evolved much and have some characteristics that resemble early tetrapods. Regeneration of limbs is one of the salamanders unique capability which early tetrapods possessed.

Amphibians are ectotherms, which means they get their energy outside their body or their source of heat would be the heat from the environment. Amphibians and reptiles are ectotherms, and mammals are endotherms. Endotherms can generate heat internally.

The Cambrian period marks the Cambrian Explosion. According to fossil records modern organisms evolved rapidly and soon after split into different phyla due to adaptive radiation as a result of the extinction of dinosaurs.

The evolution of lungs is one of the most important changes in vertebrates which allowed early amphibians of water to move to land. It enabled them to breath air.

on island x the species needed to adapt because they were being subject to predators which didn't inhabit island y.  

i think the answer is composed of atoms