Sauropodomorpha

Template:Dinoseries

A contrast of two sauropods - a brachiosaurid Brachiosaurus on the left and diplodocid Diplodocus on the right. (WWD images' compilation)

The Sauropodomorpha dinosaurs are a branch of Saurischian, or lizard-hipped dinosaurs, and are close cousins to the carnivorous theropods; however, their own diet was herbivorous, like that of the ornitischia dinosaurs (ceratopsians and co.).

All of the Sauropodomorpha dinosaurs had long necks and tails, pillar-like legs and relatively small heads with jaws full of peg-like teeth. Also, although they were dinosaurs, which usually were cold-blooded, this branch of the dinosaurs had evolved gigantothermy - i.e. they achieved a body bulk big enough to sustain a sufficiently warm internal temperature, making them more hot-blooded instead. There were two groups of Sauropodomorpha dinosaurs, the Prosauropods and the Sauropods proper. Prosauropods like Massospondylus and Plateosaurus lived during the late Triassic and early Jurassic time periods; Sauropods - during the late Jurassic and Cretaceous.

Featured in the first episode of Walking with Dinosaurs, Plateosaurus was a typical prosauropod dinosaur: at 8-9 meters in length, it towered over other early dinosaurs, such as Coelophysis, who was featured fleeing at the end of that episode, when the herd of plateosaurs arrived at the start of the wet season. Such prosauropods caused the extinction of Placerias and other, more primitive reptilian plant-eaters, but as time went on, they got too small to compete with their sauropod cousins, while such ornitischians as Stegosaurus possessed a superior digestive system, and together the sauropods and the bird-hipped dinosaurs drove the prosauropods to extinction. (Another theory is that as the Jurassic climate became cooler and wetter, the prosauropods, which were pre-adapted to a more arid climate, were unable to cope, and died out.)

Diplodocus (a diplodocid) and Brachiosaurus (a brachiosaurid) were also featured in Walking with Dinosaurs, the second episode. They were considerably larger than their extinct prosauropod cousins (this episode took place in late Jurassic, almost a 100 million years after the previous one), and differed sharply from each other. The diplodocids (such as Diplodocus and its cousin Apatosaurus featured in a cameo in Allosaurus: Walking with Dinosaurs Special) were longer than taller, they fed on relatively low-growing vegetation, and were unable to raise their heads above their shoulder level. Their tails were especially long, thin and whip-like to counterbalance their equally long necks and small heads. In the second episode of Walking with Dinosaurs, the narration was centered around the lifecycle of the diplodocid Diplodocus, how it was hatched, lived and died during the late Jurassic. (It also had a cameo appearance in the closing credits of the last episode of Walking with Monsters, demonstrating a Mesozoic world ruled by dinosaurs).

That episode also featured (in a cameo) the brachiosaurid Brachiosaurus, contrasting it with Diplodocus along the way. Unlike the diplodocids, the brachiosaurids were built more like modern-day giraffes, with front legs and shoulders higher than hind legs and the rear end; and the long sauropod neck made the brachiosaurids even taller. Unlike the diplodocids and other big herbivores of late Jurassic, such as Stegosaurus, brachiosaurids fed on especially high-growing vegetation, as they demonstrated in "Time of the Titans".

By the time of the Cretaceous, however, both the diplodocids and the brachiosaurids had died out, unable to cope with the shrinking landmass and the competition from the new, more advanced ornithiscians (something that was hinted at in the fourth episode of Walking with Dinosaurs). The third group of Sauropods, the titanosaurids, however, flourished on the territory of modern-day Africa and North and South America. Argentinosaurus, featured in the first episode of Chased by Dinosaurs, was probably one of the biggest titanosaurids and one of the biggest dinosaurs to have ever lived. Titanosaurids were built more like diplodocids than brachiosaurids, but had relatively shorter muzzles than either of them. The episode "Land of the Giants" followed the migration of one such herd (earlier sauropods featured in Walking with Dinosaurs and Allosaurus were shown migrating from place to place as well), as well as their contribution to Cretaceous South American ecosystem.

Just like the other dinosaurs, the last Sauropodomorpha dinosaurs, the titanosaurids, died out during the K/T Extinction 65 MYA.