The idea that dinosaurs were already declining well before the asteroid impact 66 million years ago seems established. However, a recent study published in
Science challenges this view, demonstrating that these giants were in full health until the very end.
In the San Juan Basin, New Mexico, rock layers preserve traces of dynamic ecosystems. Researchers analyzed fossils dating precisely to the Cretaceous-Paleogene boundary, thanks to advanced dating methods. This work indicates that local dinosaurs, like Alamosaurus, lived in diverse and active communities.
Moreover, ecological analyses show that dinosaur populations in North America exhibited marked regional differences. Rather than physical barriers, temperature variations shaped distinct 'bioprovinces'. Scientists like Daniel Peppe from Baylor University specify that these animals were not weakened, but thrived in diverse environments.
The asteroid impact abruptly ended this era of diversity. Unlike a gradual decline, the extinction was sudden, leaving an ecological void. In the following 300,000 years, mammals diversified rapidly, taking advantage of the vacant niches.
Furthermore, the temperature patterns that influenced dinosaur communities persisted after the catastrophe. This continuity guided the reconquest of life, with mammals developing characteristics adapted to their regions. Andrew Flynn from New Mexico State University notes that this post-extinction diversity differs from that observed after other similar events.
This research, conducted on protected public lands, shows how ecosystems respond to rapid planetary upheavals. It highlights how life can be both resilient and vulnerable in the face of extreme disturbances.