carry our demonstration of the credibility of a common ancestry of animals still further back. But we may point out here that it is not a theory, based merely upon one set of facts, but one singularly rich in confirmation. We can construct, on purely anatomical grounds, a theoretical pedigree. Now the independent study of embryology suggests exactly the same pedigree, and the entirely independent testimony of palaeontology is precisely in harmony with the already confirmed theory arrived at in this way.
Text Book of Biology, Part 1: Vertebrata · The Wunder Library — complete classics, free to read, with narration.