Data from: Evolutionary changes in pubic orientation in dinosaurs are more strongly correlated with the ventilation system than with herbivory

Among dinosaurs, the pubis has convergently retroverted four times in
Maniraptora (Theropoda) and once in Ornithischia. Although a clear
correlation has not been demonstrated, it has been previously proposed
that two traits were related to pubic retroversion: the reduced importance
of cuirassal ventilation, and a herbivorous diet. Here, we analyse the
possible influence of these traits on pubis orientation. Cuirassal
ventilation was plesiomorphically present as an accessory ventilation
mechanism in Dinosauria and was powered by the M. ischiotruncus, which was
probably connected to a propubic pelvis. Cuirassal ventilation was reduced
in both Ornithischia and Maniraptora, some of which also evolved
herbivory. According to our results, cuirassal ventilation is more
strongly correlated with pubic orientation than herbivory. The
retroversion of the pubis during the evolution of birds resulted in major
changes in the musculature of the tail. These changes increased the
efficiency of the pubocaudalis muscles, which enhanced the birds’
capability for take‐off from the ground. The release of the evolutionary
constraint on pubic orientation through changes in the ventilatory system
can therefore be considered to be an important step in bird evolution.