Dinosaur Family Tree-Saurischians Part 3

Now we turn to the gentler side of saurischians, the sauropods. Actually, the sauropodomorphs, technically. This group is further broken down into prosauropods and sauropods. Sauropodomorphs would lie at the same level as theropods.

Prosauropods, originally thought to be precursors to sauropods, are now considered to be a group on their own. This is what I mean when I say that these classifications change constantly. Even the one we are creating here is subject to change and may not exactly match another one you may find in a book or on the Internet.

Prosauropods were animals with long necks and tails, most were bipedal and quadrupedal and were characterized by having a large thumb claw on each hand. There arms were considerably shorter than their legs which made this varied way of walking possible. A common dinosaur of this group is Plateosaurus. I always thought Dino from the Flintstones was a Plateosaurus, but that has yet to be proven!

The sauropod group was made up of some of the largest, longest, and heaviest animals ever to walk the face of the earth. Their appearance is that of what most people think a dinosaur looks like. Apatosaurus (formerly brontosaurus) was a sauropod. They had very long heads and tails, walked on all fours and had huge, heavy bodies held up by large columnar legs. They had very small heads, though, and it is a wonder how they were able to get enough food through their small mouths to feed their sometimes enormous bodies.

Some sauropods. like Amargasaurus, had huge neck and back spines. And Another subgroup called titanosaurs (for good reason) included the biggest of the big. Argentinosaurus is considered to be the best candidate for the overall largest dinosaur ever. It is estimated to be about 115 feet long and weigh 80-100 tons. Sauroposeidon is considered the tallest holding its head over 55 feet off the ground. Sauroposeidon is part of the subgroup brachiosaur which had a more giraffe-like appearance having longer forelimbs than hind limbs and having a very pronounced slope from shoulders to tail.

Well, that wraps up a very basic look at the dinosaur clade, or family tree. I say basic because there are many, many subgroups and branches within the the major groups I've mentioned here, and these existing groups are constantly being rearranged. But, this should give you a basic idea of how all dinosaurs are grouped together and distinguished from one another.