Overview
- The peer-reviewed paper, published Wednesday in Proceedings of the Royal Society B, analyzed 82 theropod species to test links between arm length and head strength.
- The team reports forelimbs shortened in five separate lineages—tyrannosaurids, abelisaurids, carcharodontosaurids, megalosaurids, and ceratosaurids.
- Using a new skull-robustness index that blends bite force, skull shape, and bone connections, T. rex ranked highest, with Tyrannotitan second.
- Skull robustness correlated more strongly with reduced arms than either skull size or overall body size, with cases like Majungasaurus showing small bodies yet tiny forelimbs.
- Authors interpret the pattern as a shift to head-driven hunting against larger prey and note the evidence is correlational, with skull strengthening likely preceding arm shrinkage.