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No, the first vertebrates evolved long before the Mesozoic. The first vertebrates, small jawless fish, evolved around 520 million years ago. Land animals had even evolved long before the Mesozoic Era.
The fact that jawless fish retain the notochord during development suggests that jawed vertebrates have evolved to develop without the notochord. This indicates that the notochord is an ancestral characteristic that has been lost or modified in the evolutionary lineage leading to jawed vertebrates.
jawless fishes
a) jawless fishes.
The first class of animals to have jaws were the gnathostomes, which include all jawed vertebrates such as fish, amphibians, reptiles, birds, and mammals. Jaws evolved from skeletal rods that supported the gills in the early jawless vertebrates.
A: jawless fish
No. The 1st vertebrates appeared in the fossil record about 525 million years ago during the Cambrian Period. This was in the Paleozoic Era.
Jawless fish first evolved during the Cambrian, about 530 million years ago.
All of the described animals are vertebrates.
jawless fish
No, not all vertebrates have jaws. In fact, one specific vertebrate that does not have a jaw is the jawless fish!
Lampreys and hagfishes are the only jawless vertebrates to survive today. They both have a round mouth and for this reason are often referred to as cyclostomes.