New study says dinosaurs were thriving until the asteroid hit

Turns out, dinosaurs weren’t already dying out when the asteroid hit Earth — they were doing just fine.

For a long time, many scientists believed that dinosaurs were already in decline before the massive asteroid crashed into Earth 66 million years ago. Fossils found from that time seemed to show fewer types of dinosaurs and a drop in their numbers. But a new study suggests that this idea might not be true at all.

Rethinking What We Thought We Knew

According to a report by Live Science, researchers now believe the drop in dinosaur fossils before the asteroid may be due to gaps in the fossil record — not an actual decline in dinosaur populations.

Scientists closely studied four major dinosaur families: Ankylosauridae (armored dinosaurs), Ceratopsidae (like Triceratops), Hadrosauridae (duck-billed dinosaurs), and Tyrannosauridae (like the T. rex). They looked at around 8,000 fossils from North America, dating back to two periods: the Campanian (about 83 to 72 million years ago) and the Maastrichtian (72 to 66 million years ago).

What they found was surprising: dinosaur diversity actually peaked about 76 million years ago. After that, it stayed relatively stable — until the asteroid hit and caused a sudden, catastrophic extinction.

Fossil Gaps, Not Dinosaur Gaps

One of the big problems? Fossils from the final period before the asteroid — the Maastrichtian — are harder to find. Rocks from that time are often covered by vegetation or hard to access. That means scientists may simply not have enough fossil evidence from that era, especially in North America, where half of all known dinosaur fossils have been discovered.

The Asteroid Changed Everything

The researchers found no major climate or environmental changes that would explain a natural decline in dinosaur populations. In fact, their models suggest these dinosaur families were still widespread and not at high risk of extinction — unless something extreme happened.

That “something” was the asteroid.

So instead of a slow fade, dinosaurs were likely wiped out in a sudden and dramatic event. As the researchers conclude, dinosaurs weren’t doomed before the asteroid — they were thriving.