Following is a transcript of the video. Narrator: A turtle's shell is as much a part of its body as our rib cage is of ours. In fact, it is their rib cage, and their spine, and their vertebrae, and ...
The fossil remains of some of the first animals with shells, ocean-dwelling creatures that measure a few centimeters in length and date to about 520 million years ago, provide a window on evolution at ...
Skeleton season may be just around the corner, but the skeleton age dawned with the early Cambrian Period, about 538 million to 506 million years ago. In this time span, most major animal groups ...