Extinct Creatures Fill Puzzling Gap In Fossil Record
Research reveals yunnanozoans as the oldest known vertebrates. New findings answer questions in fossil record. The puzzling gap in the fossil record that would explain the evolution of invertebrates into vertebrates has long puzzled scientists. Vertebrates share unique features, such as the backbone and skull, and include fish, amphibians, reptiles, birds, mammals, and humans. Invertebrates, on the other hand, are animals without backbones. The evolutionary process that led invertebrates to become vertebrates—and what those first vertebrates looked like—has been a mystery to scientists for centuries....