First scampering onto the scene around 230 million years ago, theropod dinosaurs were some of the biggest predators on the block — and also some of the smallest. From the ferocious 14,500-pound Tyrannosaurus to the feathery 2-pound Microraptor, these prehistoric beasts pushed size to the extremes.
For decades, paleontologists thought the theropods evolved into giants and pipsqueaks by adjusting the pace of their growth: Only by growing more quickly than their ancestors did they bulk up, and only by growing more slowly did they trim down. But in 2023, an analysis of bones from 42 separate species of theropod put that theory to the test. Published in Science in February, the results revealed that the theropods used an assortment of developmental mechanisms to size up and size down.
