Amniote phylogeny emphasizing the crocodilians. The geographic ranges of the three crocodilians of interest are shown, along with approximate times of divergence of each group based upon the Timetree of Life . On the basis of the fossil record, the origins of dinosaurs and birds were Triassic and upper Jurassic, respectively , and birds from within dinosaurs [86, 87]. The phylogenetic position of turtles is unclear [2, 88, 89], however for simplicity we chose the consensus estimated position and divergence time presented in the Timetree of Life . The photos of the American alligator (Alligator mississippiensis), the saltwater crocodile (Crocodylus porosus) were kindly provided by Louis Guillette and the photo of the Indian gharial (Gavialis gangeticus) was provided by Alan Wolf. Mya; million years ago.