Sauropod Dinosaurs

The sauropods ("lizard foot") were members of the saurischian, or "lizard hipped," group of dinosaurs. The thing I have always found amazing about the sauropod dinosaurs is how such huge animals, the largest terrestrial animals ever to walk the earth, managed to exist.

The sauropod dinosaurs were quadrupedal animals, meaning that they walked on all four legs. It was long believed that the sauropods developed from early herbivorous dinosaurs which appeared during the middle Triassic Period (230 to 195 million years ago), known as the InfraOrder Prosauropoda ("before the sauropods"), many of whom were bipedal or walking on two legs. It has been determined, however, that that the Prosauropoda and Sauropoda were actually cousins on the family tree of the subOrder Sauropodomorpha. The sauropods themselves appeared sometime in the late Triassic Period or early Jurassic Period (195 to 140 million years ago).

In the early years in the study of paleontology, scientists could not believe that such enormous animals could have possibly walked the earth. In my next article, "Sauropod Myths," I will be looking at some of the early hypotheses or myths that surrounded these interesting animals.

We now know that the sauropods were indeed terrestrial animals, and they had two very interesting adaptations to their bodies that helped them to support their huge weight. First, we see large cavities hollowed in the sauropod vertebrae (backbones). These cavities helped to decrease the weight of the bone, but they were formed in such a way as to not sacrifice the strength of the bones; we see this same adaptation to decrease weight in flying animals such as birds and pterosaurs as well. These cavities were seen even in the earliest of the sauropods, and became more pronounced in the later sauropods.

The second interesting development seen in the sauropod skeleton is an alteration to the pelvic girdle or hips of the sauropods. The sauropods were saurischian or "lizard hipped" dinosaurs. In the sauropod pelvis, the ilium (the top bone in the diagram) and the first four vertebrae (five in later sauropods) were firmly fused together. This formed a solid support for the heavy tail, which we now know the sauropods did not drag behind them.

The shape of their teeth indicate that they were herbivorous (plant eating). They would have had to have eaten huge amounts of plant material in order to provide enough calories to live on. An animal this size probably produced over one ton of dung per day! That's a lot of coprolites! Many paleontologists believe that the sauropods probably had some form of fermentation in their massive guts, similar to that of our modern ruminant animals. My own research has shown that all extant (still living) animals that rely on a herbivorous diet have some sort of fermentation occurring either in their stomachs or in their intestines, this is seen in reptiles, birds, and mammals.

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