A new collection featuring research on the complex evolutionary cascade theory that made the unique gigantism of sauropod dinosaurs possible has now been published in PLOS ONE.

Sauropod dinosaurs were the largest terrestrial animals to roam the Earth, exceeding all other land-dwelling vertebrates in both mean and maximal body size. While convergently evolving many features seen in large terrestrial mammals, such as upright, columnar limbs and barrel-shaped trunks, sauropods evolved some unique features, such as the extremely long necks and diminutive heads they are famous for.

The unique gigantism of sauropod dinosaurs has long been recognized as an important problem in the evolution of vertebrates, raising questions as to why no other land-based lineage has ever reached this size, how these dinosaurs functioned as living animals, and how they were able to maintain stable populations over distinct geological periods.

Intrinsic neck curvature starts with the bones. In (A), cervical vertebrae C4 and C5 of Giraffatitan brancai specimen SI are shown articulated and undeflected, i.e., in osteologically neutral pose (ONP). Their vertebral axes, shown in red, naturally create a slight downward bend in ONP, contributing to the subtle ventral osteologically induced curvature (OIC) likely shared with other sauropod necks cranially (Figure 5). In (B) the giraffe Giraffa camelopardalis, cervical vertebrae C6 and C7 are shown also in ONP, revealing the naturally-ascending slope characteristic of giraffe necks at the base. Note the similarity in their opisthocoelous central articulations compared to the sauropod above. Vertebrae to scale; scale bar equals 10 cm. Giraffatitan photographs courtesy Christopher McGowan; giraffe photographs courtesy Brian Curtice. doi:10.1371/journal.pone.0078572.g001

This new Collection , Sauropod Gigantism: A Cross-Disciplinary Approach, discusses major efforts by evolutionary biologists and paleontologists to understand sauropods as living animals, and to explain their evolutionary success and uniquely gigantic body size.

The articles address these questions from a number of varied disciplinary viewpoints, including those of ecology, engineering, functional morphology, animal nutrition, and palaeontology. For instance, one section features articles from researchers that investigated sauropod mobility and posture, to better understand the reasons for their extremely long necks.

"You could explain gigantism just by looking at the trait of having many small offspring. But our model shows us there were probably several factors," says Dr. P. Martin Sander, a professor at the Steinmann Institute for Geology, Mineralogy and Palaeontology at the University of Bonn, Germany.