I must criticize this study's Eurocentric bias. All the samples examined here come from one region in Europe, so it doesn't really reveal much about trends in dinosaur diversity in the rest of the late Cretaceous world. If you really wanted to challenge the idea that dinosaur diversity was declining prior to the asteroid impact, you should do a study that encompasses more of the world.Non-avian dinosaurs became extinct 65 million years ago, and now researchers have proven that this die-off didn't happen over a long period of time.
A detailed look at dinosaur bones, tracks and eggs located at 29 archaeological sites located in the Catalan Pyrenees reveals that there was a large diversity of dinosaur species living there just before the fatal K-T extinction event, which many scientists believe was caused by several large meteors hitting Earth.
Dinosaurs thrived outside of this part of Spain as well before 65 million years ago, such as in North America, but this particular research, published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology, focused on the Catalan region, a former dinosaur hotbed.
Sites at towns like Tremp and Aren are rich in dinosaur bones, while those in Vallcebre contain many dinosaur tracks. Excavations at the town of Coll de Nargó have also unearthed many fossilized dinosaur eggs. These date to the Maastrichtian, the last stage of the Cretaceous period. The researchers could even see incredible dino diversification in the upper layers of the Maastrichtian, just before non-avian dinosaurs disappeared off the face of the planet.
The research also shows for the first time that the sauropod Titanosaurus (an herbivorous quadruped that grew to enormous sizes), as well as the nodosaurid dinosaurs (armoured herbivores), preferred swampy habitats, while other dinosaurs such as the dromaeosaurids (relatively small-sized carnivores, closely related to birds) lived in practically all types of environments.
For the Autonomous University of Barcelona's Violeta Riera, who worked on the project, studying dinosaurs in Catalonia is a privilege, given that “the dinosaurs found here are the last specimens that lived on Earth."
“The Pyrenees," she affirms, “are the only place in Europe where quality research can be carried out on the period in which they became extinct." No other European mountain range offers such rich sites since “at that time, Europe was a large archipelago with not much land for dinosaurs."
I'm also surprised at the finding that titanosaurian sauropods in Europe were wetland-dwellers. As paleontologist Robert Bakker showed in his Dinosaur Heresies, sauropods are typically found in sediments deposited in seasonally dry, savanna-like environments. That makes some sense, for you'd think animals as heavy as sauropods would have a hard time moving across muck.
"
- PeZook
