Question

What did Sir Richard Owin propose about the ancestry of all chordates, what information did he use to support his proposal, did the information come from fossils, the bones of living vertebrates or both?

Answer 1

Sir Richard Owen proposed archaetype to explain the ancestory of all chordates.In archaetype, he proposed that there exists a common structural plan for all the chordates as well as all the clases of vertebrates.

To support his proposal , Sir Owen use the term homology which is defined as the same organ in different animals under every variety of form and function. Or in simple terms same structure of organ to perform different functions in different organisms.  To take one example of homology: Structures as different as a bat's wing, a seal flipper, a cat's paw and a human hand nonetheless display a common plan of structure, with identical or very similar arrangements of bones and muscles.

Sir Richard came to the conclusion by examining both the fossils and the bones of vertebrate. Owen's most famous taxonomic act resulted from his examination of reptile-like fossil bones . Owen concluded that the bones  were not lizards, but represented "a distinct tribe or sub-order of Saurian Reptiles." He named this taxon the Dinosauria.