Evolution What the Fossils Say and Why it Matters

FIGURE 12.2. The prosauropods were transitional forms between smaller primitive bipedal dinosaurs like
Eoraptor and the sauropods. (A) Family tree of the sauropods. (Drawing by Carl Buell) (B) Plateosaurus was
capable of both bipedal and quadrupedal locomotion and had a neck and tail intermediate in length between
smaller dinosaurs and the huge long-necked sauropods. (Photo courtesy R. Rothman)

(B)

Herrerasaurus

Plateosaurus

Massospondylus

Melanorosaurus

Cetiosaurus

Camarasaurus

Brachiosaurus

Titanosaurus

Diplodocus

Dicraeosaurus

225 195 136 65

(A) Triassic Jurassic Cretaceous