UCL Study Links 5 Theropod Groups' Tiny Arms to Massive Skulls
Updated
Updated · Futura · Jun 19
UCL Study Links 5 Theropod Groups' Tiny Arms to Massive Skulls
3 articles · Updated · Futura · Jun 19
Summary
Five giant theropod lineages—not just T. rex—independently evolved tiny arms alongside oversized skulls, according to a new University College London analysis.
Eighty-five theropod species were compared for arm length, skull size and body mass, revealing a clear pattern: as skulls became more robust and powerful, arms shortened.
Researchers say the shift reflects a hunting trade-off: bigger prey favored stronger jaws and heads, while forelimbs lost function and became less worth the energy cost.
Tyrannosaurids, abelisaurids, carcharodontosaurids, ceratosaurids and megalosaurids fit that pattern, while spinosaurs and megaraptorans followed a different route with longer arms and slimmer skulls.
The study argues convergent evolution repeatedly pushed apex predators toward the same body plan, though the reduced arms may still have had mechanical or behavioral uses.