700 million years ago, a remarkable creature emerged for the first time. Though it may not have been much to look at by today’s standards, the animal had a front and a back, a top and a bottom. This ...

When people build cities and introduce invasive creatures, resident critter populations sometimes adapt Brian Handwerk | Science Correspondent Several species have evolved in response to human ...

Embryonic germ layers are the fundamental organizing principle in animal development. They provide the structural basis from which tissues and organs arise. During early embryogenesis, cells divide to ...

The fossils of ancient salamander-like creatures in Scotland are among the most well-preserved examples of early stem tetrapods -- some of the first animals to make the transition from water to land.