| Unlike extant birds and mammals, most non-avian theropods had large muscular tails. Digital muscle reconstructions based on measurements of fossil specimens and dissections of modern reptiles show that the M. caudofemoralis of many non-avian theropods was exceptionally large. Because the M. caudofemoralis is the primary hindlimb retractor, large M. caudofemoralis masses give new evidence in favor of greater athleticism. The tails of theropods had a dynamic evolution and became specialized for a wide range of additional functions in various lineages. In Ceratosaurus the tail may have been adapted for swimming. In the South American abelisaurs, the angle of the caudal ribs was gradually adjusted to facilitate an even larger M. caudofemoralis that probably increased maximum running performance. In oviraptorosaurs, the tail supported a fan of feathers, and appears to have become modified for courtship displays. In dromaeosaurs, caudal rods may have allowed the tail to serve as an aerial rudder. |
