How did vertebrates evolve?
Answers
each complex thing is made of simple things
This also applies with Vertebrates , they evolved from higher non chordates. Like first coelom was introduced in phylum Annelida. Arthropods first shows the jointed appendages.phylum arthropods have well developed ganglion which forms nerve cord , phylum Echinodermata shows the exoskeleton first which are similar to the vertebrates. These similarities shows that the vertibrat are evolved from invertibrates.
The earliest vertebrates were jawless fish, similar to living hagfish. They lived between 500 and 600 million years ago. They had a cranium but no vertebral column. The first fish with a complete vertebral column evolved about 450 million years ago. These fish also had jaws and may have been similar to living sharks. Up to this point, all early vertebrates had an endoskeleton made of cartilage rather than bone. About 400 million years ago, the first bony fish appeared.
Amphibians, reptiles, mammals, and birds evolved after fish.
- The first amphibians evolved from a lobe-finned fish ancestor about 365 million years ago. They were the first vertebrates to live on land, but they had to return to water to reproduce.
-The first reptiles evolved from an amphibian ancestor at least 300 million years ago. They laid amniotic eggs and had internal fertilization. They were the first vertebrates that no longer had to return to water to reproduce.
-Mammals and birds both evolved from reptile-like ancestors. The first mammals appeared about 200 million years ago and the earliest birds about 150 million years ago.