Dinosaur Family Tree-Saurischians

OK. The saurischian branch is a little more complicated. There are two main branches: theropods and sauropods. Theropods are mainly bipedal meat eaters, or omnivores (eat anything!). One member of this group is the famous Tyrannosaurus rex. Sauropods are mainly made up of quadrupedal plant eaters. A famous member of this group is apatosaurus (formerly brontosaurus). So, you have a head start this time on what some of these guys look like. T. rex (as it's sometimes called) made a well-known appearance in all three Jurassic Park movies, as did another theropod, spinosaurus. A relative of the apatosaurus (brachiosaurus) appeared in several Jurassic Park films, as well.

As we did last time with the ornithischians, we will take one group at a time. First, the theropods. When drawn a certain way, the theropod branch can look a little like a menorah. There's a main stem in the middle then the branching starts to go off in opposite directions from the middle.

Before branching out into the more complete areas, there a some early, small theropods that seem to continuously get shuffled around. Some of these are eoraptor, ceolophysis, herrerasaurus, and compsognathus. These were some of the precursors to all the rest of the theropods.

The first main branch coming of of theropods is allosaurs. Allosaurus is the main representative from this group. They are characterized by being quite large (some reaching close to 45 feet in length). They had large, but narrow heads usually with some type of bony head ornamentation. Small to medium size arms ending in three clawed hands. The legs were large and powerful ending in long three-toed feet. Their basic stance was somewhat like a large bird. Their backs were almost parallel to the ground with head held up by a thick powerful, yet flexible neck.

The rest of the groups kind of branch off fast and furiously, so we will give brief descriptions and name one dinosaur that represents each group. Most theropods in general have the same basic shape. Allosaurs seem to typify the group and consequently, many unknown theropods tend to get thrown in that group. At least until scientists find a home for them on the correct branch.


Next-Dinosaur Family Tree-Saurischians Part 2.