How massive long-necked dinosaurs rose to rule the Jurassic herbivores
Volcanic activity may have altered plant life and ushered in rise of dinosaur giants
Long-necked sauropods, the largest animals ever to walk on Earth, may have thundered into dominance during the Jurassic Period thanks to a large burst of volcanic activity that began around 184 million years ago, a new study suggests. The resulting environmental crisis may have caused a shift in plant life that gave the tough-toothed, big-gutted herbivores a powerful advantage over other herbivores.
The find comes from the discovery of a new fossil of one of the earliest “true” sauropods in Argentinian Patagonia. Sediments bearing the newly described dinosaur, dubbed Bagualia alba, are precisely dated to 179 million years ago, paleontologist Diego Pol of the Paleontological Museum Egidio Feruglio in Trelew, Argentina, and colleagues report November 18 in Proceedings of the Royal Society B.
B. alba, the researchers found, had the telltale characteristics of true sauropods: large, column-like legs; massive size; long necks relative to the body; broad and strong jaws; and large, spoon-shaped teeth with thick enamel. Also known as eusauropods, this lineage came to dominate the Middle and Late Jurassic roughly 174 million to 145 million years ago (SN: 7/10/18), giving rise to awe-inspiring giants such as Argentinosaurus and Dreadnoughtus schrani (SN: 6/9/15).
During the Early Jurassic, between about 201 million and 174 million years ago, Pol says, plant-eating sauropods competed with many other herbivores, including sauropodomorphs — distant relatives such as Mussaurus patagonicus with less powerful jaws and shorter necks (SN: 5/20/19). What gave the eusauropod giants a leg up on their herbivorous competition has been unclear, in part because there are relatively few fossils dating to the transition between Early and Middle Jurassic.