The first genome wide phylogenetic analysis of two turtle species tackles the questions about the origin of the turtle’s unique anatomical features. Turtles have a unique exterior shell and skeletal layout that differs from that of their fellow tetrapods. Their carapace is a transformed vertebrae and ribs, their shoulder blades are ventral rather than dorsal, and their skulls lack temporal fenestra. These characteristics led to an analysis of their genome that found that turtles are closely related to Archosauria and that their morphological evolution was the cause of alterations in their signaling cascade. Investigations into their embryonic gene regulation led to the belief that they are morphologically similar to chickens, but have an hourglass-like divergence that shows where exactly (vertebrate phylotypic period) the structure of the shell begins to form.