Isn’t this just high tech phrenology? Shouldn’t they use DNA to trace these ancestral families?
Not phrenology, morphology. Morphology rooools. There’s no DNA in stuff this old *most of the time*. You’ve no doubt seen the T-Rex hemaglobin stories, FR has had a lot of duplicate topics for that matter. :’)
The way DNA is sometimes used to find common ancestry is to actually find very similar genes (those are three-basepair groups on a DNA strand, in this case a chromosome) in two different living samples, and try to estimate the length of time since the common source was identical and living.
Not really.
Long before DNA technologies were developed, animals were classified on the basis of anatomical features. DNA in such old specimens is sometimes non-existent, but the old methods of classification are still valid.