Move deeper into the systematics of dinosaur groups by selecting one of the boxes containing a picture.
With the discovery of many new species since the 1840s,
the Dinosauria now contains two major groups of dinosaurs: the
or "bird-hipped" dinosaurs, and the
"lizard-hipped" dinosaurs. The division between the two groups was made by H.G. Seeley
in 1888. The etymology behind the two names ("bird-hipped" vs.
"lizard-hipped") is not very accurate,
since some saurischians had bird-like hips, and ornithischians' hips were
somewhat birdlike due to convergent evolution, not due to direct ancestry.
In fact, birds are saurischians!
Saurischia contains two main groups:
- Sauropodomorpha is the first group, and includes both
the "prosauropods" a probably paraphyletic (artificial) group of largely
herbivorous, dominantly quadrupedal dinosaurs such as Plateosaurus;
and the Sauropoda:
long-necked, long-tailed, enormous herbivorous dinosaurs like
Apatosaurus (formerly called Brontosaurus), Brachiosaurus, and Diplodocus.
is the second saurischian group, consisting of the carnivorous dinosaurs.
The Theropoda includes some extinct dinosaurs such as
Tyrannosaurus rex and
it also includes the living dinosaurs the
Ornithischia contains several groups of herbivorous dinosaurs,
including several basal groups, but primarily three large ones:
includes the various armored dinosaurs, like
Stegosaurus and Ankylosaurus.
consists mainly of the pachycephalosaurs (bone-heads) and the
ceratopsians (horned dinosaurs), like Triceratops.
Ornithopoda is the third Ornithischian group,
and includes not only small bipedal plant-eaters like
Heterodontosaurus, but also the often large
"duck-billed dinosaurs," like Maiasaura and Edmontosaurus.
- Weishampel, D.B., P. Dodson, and H. Osmolska (eds.). 1990. The
Dinosauria. University of California Press, Berkeley. 733 pp.