How the turtle got its shell

Turtles are unique among reptiles in that they have a large shell, composed of a carapace on their back and a plastron on their belly. This shell largely develops from fused ribs and bones derived from the skin. Since turtles presumably evolved from a lizard-like ancestor to become the distinctively shelled creatures we know of today, we might …

Continue reading How the turtle got its shell

Did 189 gecko species migrate to Australia together?

Lizards have a widespread distribution, having conquered much of the earth, but certain groups of lizards are localized to a single continent. Here I illustrate an example from geckos. Carphodactylidae includes 28 species of geckos, all of which inhabit Australia. Species include the long-necked Northern leaf-tailed gecko (Orraya occultus) and the smooth knob-tailed gecko (Nephrurus laevissimus). Then there is …

Continue reading Did 189 gecko species migrate to Australia together?

Way back when snakes had legs

As I recently discussed, snakes are genetically nested within lizards. One of the major evolutionary implications of this fact is that snakes used to have legs. Just this week, researchers [1] heralded the discovery of a major fossil, helping to bridge the putative transition from legged-lizard ancestors to modern legless snakes. Tetrapodophis 125-113 million years ago …

Continue reading Way back when snakes had legs