A groundbreaking study led by Andrew Flynn, a geology professor at New Mexico State University, has provided new insights into the last surviving dinosaurs in New Mexico. Published in the October 23, 2023 issue of the journal Science, the research highlights the vibrant ecosystems that existed just before the catastrophic asteroid impact that contributed to the mass extinction of dinosaurs approximately 66 million years ago.
Flynn’s work, developed during his Ph.D. studies at Baylor University, involved collaboration with scientists from various institutions, including New Mexico Tech, the University of Edinburgh, and the Smithsonian Institution. The research focuses on the Naashoibito member of the De-Na-Zin Wilderness Area near Farmington, where the last non-avian dinosaurs thrived.
The study challenges the long-held belief that dinosaurs were in decline before the asteroid impact. According to co-author Dan Peppe, a professor of geosciences at Baylor University, the Naashoibito dinosaurs coexisted with the well-known Hell Creek species found in regions like Montana and the Dakotas. “These were vibrant, diverse communities,” Peppe stated, emphasizing that the New Mexico dinosaur fauna is distinct, dominated by the large sauropod known as Alamosaurus.
The Alamosaurus, one of the largest dinosaurs, is estimated to have measured the length of two semi-tractor trailer rigs and weighed between 30 to 80 tons. Its height ranged from 30 to 50 feet, making it comparable in size to a blue whale but significantly lighter.
Flynn noted, “What our new research shows is that dinosaurs are not on their way out going into the mass extinction. They’re doing great, they’re thriving.” This finding is crucial as it counters the narrative of a gradual decline in dinosaur diversity leading up to the extinction event.
Significant Findings on Biodiversity and Extinction
Another key aspect of the research reveals that the mammals that survived the extinction event retained distinct northern and southern bio provinces, differing from patterns observed in previous mass extinctions that tended to homogenize species. The research team utilized geological methods to date the dinosaur fossils accurately, leading to a significant conclusion that these fossils are from the final 380,000 years of the Cretaceous period.
Steve Brusatte, a professor of paleontology and evolution at the University of Edinburgh, remarked, “The extinction of the dinosaurs is the most famous instance of mass death in the history of Earth.” He pointed out that prior to this study, paleontologists had limited access to fossils unequivocally dated to the last few hundred thousand years before the asteroid impact. With these newly dated fossils, the research paints a clearer picture of the diversity that existed right before the mass extinction event.
Flynn expressed excitement over the findings, stating, “What we found is that these rocks were deposited in the last 380,000 years of the Cretaceous period. These were the very last dinosaurs alive in New Mexico before the asteroid impact.”
Future Research Directions
Looking ahead, Flynn plans to investigate fossil plants in the Naashoibito Member to further understand the ecological changes that occurred before and after the extinction. “I’m trained as a paleobotanist,” he explained, emphasizing the importance of discovering these fossils to compare the flora from before and after the extinction. Previous research in the area has provided insights into post-extinction flora, but understanding the pre-extinction landscape remains a critical gap.
While Flynn has yet to find these fossilized plants, he remains optimistic, stating that their absence does not mean they are not present in the area. “It just means we haven’t found them yet,” he concluded.
This research not only enriches the understanding of dinosaur ecosystems in the late Cretaceous period but also provides a fresh perspective on the dynamics of extinction events, underscoring the resilience of these ancient creatures leading up to one of Earth’s most significant ecological shifts.
