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 ...

Animals display an extraordinary array of structural adaptations that are intimately linked to their functional capacities. From the microscopic organisation of tissues and cells to the macroscopic ...

The field of paleobiology and the study of ecological diversity have some new data and it's proving to be quite different from what most theories of animal evolution have previously posited.