Data from: A computational analysis of locomotor anatomy and body mass evolution in Allosauroidea (Dinosauria Theropoda)

We investigate whether musculoskeletal anatomy and three-dimensional (3-D)
body proportions were modified during the evolution of large (>6000
kg) body size in Allosauroidea (Dinosauria Theropoda). Three adaptations
for maintaining locomotor performance at large body size, related to
muscle leverage, mass, and body proportions, are tested and all are
unsupported in this analysis. Predictions from 3-D musculoskeletal models
of medium-sized (Allosaurus) and large-bodied (Acrocanthosaurus)
allosauroids suggest that muscle leverage scaled close to isometry, well
below the positive allometry required to compensate for declining muscle
cross-sectional area with increasing body size. Regression analyses on a
larger allosauroid data set finds slight positive allometry in the moment
arms of major hip extensors, but isometry is included within confidence
limits. Contrary to other recent studies of large-bodied theropod clades,
we found no compelling evidence for significant positive allometry in
muscle mass between exemplar medium- and large-bodied allosauroids.
Indeed, despite the uncertainty in quantitative soft tissue
reconstruction, we find strong evidence for negative allometry in the
caudofemoralis longus muscle, the single largest hip extensor in non-avian
theropods. Finally, we found significant inter-study variability in
center-of-mass predictions for allosauroids, but overall observe that
consistently proportioned soft tissue reconstructions produced similar
predictions across the group, providing no support for a caudal shift in
the center of mass in larger taxa that might otherwise reduce demands on
hip extensor muscles during stance. Our data set provides further
quantitative support to studies that argue for a significant decline in
locomotor performance with increasing body size in non-avian theropods.
However, although key pelvic limb synapomorphies of derived allosauroids
(e.g., dorsomedially inclined femoral head) evolved at intermediate body
sizes, they may nonetheless have improved mass support.