Craniata

Chapter 34 Vertebrates Lecture Outline Overview: Half a Billion Years of Backbones Vertebrates are named for vertebrae, the series of bones that make up the vertebral column or backbone. There are about 52,000 species of vertebrates, far fewer than the 1 million insect species on Earth. Plant-eating dinosaurs, at 40,000 kg, were the heaviest animals to walk on land. The biggest animal that ever existed is the blue whale, at 100,000 kg. Humans and our closest relatives are vertebrates. This group includes other mammals, birds, lizards, snakes, turtles, amphibians, and the various classes of fishes. Concept 34.1 Chordates have a notochord and a dorsal, hollow nerve cord The vertebrates belong to one of the two major phyla in the Deuterostomia, the chordates.