Strong jaws, not bigger bodies, drove giant theropods to shrink their forelimbs
A new study of 82 theropod species finds that giant predators didn’t shrink their arms because their bodies grew larger; instead, as jaws and skulls became more powerful, forelimbs became less necessary and were reduced in five independent lineages. The researchers linked arm length to skull robustness, showing a stronger correlation with powerful jaws than with body size. Skull development preceded arm reduction, meaning the bite-based hunting strategy replaced grasping by the arms. This convergent pattern across tyrannosaurids, abelisaurids, carcharodontosaurids, megalosaurids, and ceratosaurids suggests tiny arms were an evolutionary consequence of jaw power, not a byproduct of overall gigantism.
