Overview
- The paper, published in May 2026, analyzed 82 theropod species and found a consistent, strong correlation between reduced forelimb length and a new measure of skull robustness rather than overall body size.
- Authors built a composite skull‑robustness metric that combines bite‑force estimates, skull shape compactness, and the tightness of cranial bone connections to quantify head strength across species.
- Forelimb shortening evolved independently in at least five groups — tyrannosaurids, abelisaurids, carcharodontosaurids, megalosaurids and ceratosaurids — with examples including Tyrannosaurus rex, Tyrannotitan, Majungasaurus and Carnotaurus.
- The team cautions the analysis shows correlation not proven causation but reports evidence that skull strengthening likely preceded arm reduction and that different clades reached similar tiny‑arm outcomes by distinct developmental routes.
- The findings reshape how scientists think about predator ecology by framing a shift to powerful bites as an adaptive response to larger prey and point to follow‑up biomechanical and developmental studies to test the proposed causal sequence.