Did Dinosaurs Face Extinction Before the Asteroid? New Scientific Clues Revealed

It’s a big question in paleontology. Were dinosaurs thriving when an asteroid struck Earth 66 million years ago, or were they already declining? A recent study dives into this debate using North America’s fossil record.

Researchers focused on the 18 million years before the extinction event that ended the Cretaceous period. They found clues suggesting that dinosaurs were actually doing well right before the asteroid hit. The analysis, detailed in Current Biology, could reshape our understanding of the timeline of dinosaur existence.

Despite what the fossil evidence seems to show—over 8,000 fossils indicate a peak in dinosaur species 75 million years ago followed by a decline—paleontologist Chris Dean from University College London argues that interpretations of these records can be misleading. He explains that the fossil record is not a complete picture. Many fossils may be missing because they were never preserved or discovered. This has been recognized since the 1970s but is only recently being addressed with improved analysis techniques.

The researchers applied a method called occupancy modeling. This approach estimates the presence of species in an area and accounts for potential biases in our fossil records. Dean mentions that it’s the first time this method has been used on such a large scale for dinosaurs.

The study specifically looked at four dinosaur families: armored dinosaurs like Ankylosaurus, three-horned herbivores such as Triceratops, duck-billed dinosaurs, and carnivores like Tyrannosaurus rex. They created a grid of North America, identifying fossil locations and the frequency of fossil searches in those areas. They found that the actual diversity may have been greater than the fossil record suggested.

One key finding was that geological factors could explain perceived declines in diversity. The study proposed that a lack of exposed rock during that time may skew our understanding of dinosaur populations. Geological processes like tectonics and mountain building might have hidden their true diversity.

As coauthor Alfio Alessandro Chiarenza pointed out, dinosaurs may not have been doomed. If the asteroid had not struck, they could have continued to coexist with mammals and other species.

Experts like Darla Zelenitsky from the University of Calgary acknowledge the complexities this study highlights, noting that the rock record often makes it hard to assess true dinosaur diversity during the late Mesozoic. The more accessible rock there is, the better our chances are of discovering fossils, leading to a clearer picture.

However, not all scientists agree. Mike Benton from the University of Bristol finds the new research thorough but cautions that it doesn’t rule out the possibility that dinosaur diversity was indeed declining before the asteroid impact.

As our methods improve, the conversation about dinosaurs continues. Each new study helps clarify the picture of their existence and the events that led to their extinction.

For more information on paleontology and current research, you can explore Current Biology and learn more about ongoing debates in this fascinating field.

Source link