A small dinosaur that wasn't a baby T rex

A small dinosaur that scientists thought might be a baby T. rex was actually a full grown adult of a different species. Researchers studied its arm and tail bones and found fused growth rings that showed it was around twenty years old and done growing. They compared over two hundred fossils and found the small dinosaur had longer arms, bigger hands, and different skull features than T. rex. The findings mean two different tyrannosaur species lived together in North America just before the asteroid hit. The study came out in Nature on October 30, 2025.

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