We think of giraffes as long-necked creatures, but compared to ancient sauropod dinosaurs (a family that includes the brachiosaurus and apatosaurus) even the longest-necked giraffe may as well be nicknamed "Stumpy". In a paper published online at arXiv site, two paleontologists analyzed the biology of sauropods in an attempt to figure out which features allowed the dinosaurs to grow necks six times longer than giraffes.
Turns out, there are some distinct differences — especially in the anatomical architecture of the vertebra closest to both animals' skulls — that really stand out. As this helpful slide shows, a sauropod with the vertebra of a giraffe would be in very bad shape, indeed.
This paper, by the authors' own account, began life "as a late-night discussion over a couple of beers", which means it's basically the paleontology equivalent of "Who would win in a fight: Darth Vader or Superman?" Which is awesome. Better yet, the paper is quite easy to read and the information is organized in a way that will probably make more sense to you than the typical scientific research paper. So dig in! It's worth it! Here's one short excerpt taken from a part discussing some of those differences in the cervical vertebra (the aforementioned vertebra closest to the skull):
Many groups of animals seem to be constrained as to the number of cervical vertebrae they can evolve. With the exceptions of sloths and sirenians, mammals are all limited to exactly seven cervicals; azdarchids are variously reported as having seven to nine cervical vertebrae, but never more; non-avian theropods do not seem to have exceeded the 13 or perhaps 14 cervicals of Neimongosaurus, with eleven or fewer being more typical.
By contrast, sauropods repeatedly increased the number of their cervical vertebrae, attaining as many as 19 in Mamenchisaurus hochuanensis. Modern swans have up to 25 cervical vertebrae, and as noted above the marine reptile Albertonectes had 76 cervical vertebrae. Multiplication of cervical vertebrae obviously contributes to neck elongation.
Via Bora Zivkovic