Mechanics drove selection of similar fins in early evolution of marine vertebrates
Similar traits not present in a last common ancestor are often the basis for constructing phylogenetic trees like the one seen above, but convergent evolution can foil the effort. Just published research in PLOS Biology on a group of like-finned, swimming vertebrates concludes that their refined propulsion mechanics likely evolved independently eight different times (convergent evolution). What a nice example how evolution by means of natural selection of favorable traits can be so powerful, and how new millennia scientists still learn by observed evidence the way Charles Darwin did. Note the time scale on the y-axis of the phylogentic tree that begins with the emergence of bilaterans during the Ediacaran more than 550 million years ago; Kimberella (shown in the lower image above) is the earliest undisputed bilateran fossil from this time.