New fossil discoveries suggest that dinosaurs may have survived in ancient ecosystems before the mass extinction event, challenging prevailing theories about their demise.
The number of dinosaurs that existed before the asteroid impact is a topic of ongoing debate among scientists. While some researchers have suggested that dinosaur populations were declining in the years leading up to the massive extinction event, new evidence suggests that the availability of fossils from this period may be biased.
Dinosaurs roamed the Earth during the Mesozoic Era, which lasted from 252 million to 66 million years ago.
These prehistoric creatures were diverse and widespread, with over 1,000 known species.
Herbivorous dinosaurs like Stegosaurus and Triceratops dominated the landscapes, while carnivores like Tyrannosaurus Rex and Velociraptor hunted their prey.
Dinosaurs played a crucial role in shaping the Earth's ecosystems, and their fossils continue to captivate scientists and the public alike.
The Puzzle of Missing Fossils
According to Dr. Christopher Dean and his team at University College London, a dataset of over 8,000 fossils from four types of dinosaurs that lived between 84 million and 66 million years ago in North America reveals a surprising pattern. Many fossils were found in the earlier part of this period, but the number of discoveries drops significantly in the final 9 million years leading up to the Chicxulub impact.
This drop in fossil availability has led some scientists to believe that dinosaurs may have been doomed regardless of the asteroid’s impact. However, Dean and his team argue that the issue is not with the dinosaurs themselves, but rather with our ability to detect them.
‘The puzzle where half the pieces are missing,’ says Dean, ‘is that palaeontologists look for fossils in ancient layers of Earth’s crust that have since been exposed to the surface.’ This makes it difficult to estimate the number of dinosaurs in these areas, as we may be missing valuable information due to the limited availability of rocks.
Ecological Models and Stable Populations
Using ecological models, Dean’s team estimated that overall dinosaur numbers stayed stable before the asteroid impact. The researchers calculated that there were not fewer dinosaurs at this time, but rather our ability to detect them was influencing the patterns we see in the fossil records.
This finding adds to the growing body of research suggesting a bias in how many fossils palaeontologists can access from North America in the 9 million years leading up to the asteroid hit. However, it does not change the bigger picture that dinosaurs were likely in decline before the asteroid impact.
The Long-Term Decline of Dinosaur Diversity
Research by Manabu Sakamoto from Reading University in the UK suggests that during the 175 million-year period that dinosaurs roamed Earth, the rate at which new species of dinosaurs appeared was slowing down overall. This led to more dinosaur species going extinct than new ones evolving.
This long-term decline in dinosaur diversity still holds true, despite the new research suggesting a bias in the available fossils. Sakamoto’s work highlights the complex and multifaceted nature of extinction events and the need for continued research into this topic.
Conclusion
The discovery of fossils from the years leading up to the asteroid impact has provided valuable insights into the fate of dinosaurs. While our ability to detect these fossils may be biased, it does not change the fact that dinosaur populations were likely declining before the massive extinction event. Further research is needed to fully understand this complex topic and to shed light on the mysteries of the past.
- newscientist.com | Rethink of fossils hints dinosaurs still thrived before asteroid hit
