Vertebrate paleontology

From EvoWiki

Vertebrate paleontology seeks to discover the behavior, reproduction and appearance of extinct spined animals, through the study of their fossilized remains. It also tries to connect, on the evolutionary timeline, the animals of the past and their modern day relatives.

The fossil record clearly shows the evolutionary progression from early aquatic vertebrates to mammals. The earliest known fossil vertebrate was the jawless fish, Arandaspis discovered in rocks from the early Ordovician Period, of Australia, about 500 million years ago. The Devonian Period (395 to 345 mya) brought in the changes that eventually allowed lungfish-like crossopterygians to breathe air, then come ashore, thus becoming the first terrestrial vertebrates, the amphibians.

Amphibians developed forms of reproduction and locomotion and a metabolism better suited for life exclusively on land, becoming more reptilian. Full fledged reptiles appeared in the Carboniferous Period (345 to 280 mya).

The reptilian changes and adaptations to diet and geography are chronicled in the fossil record of the varying forms of therapsids. True mammals showed up in the Triassic Period (225 to 190 mya) around the same time as the dinosaurs, which also sprouted from the reptilian line.

Birds appeared in the Jurassic Period (190 to 136 mya) as some dinosaurs adapted to their ever-changing world.