 This would have indicated the presence of septate lungs, ventilated by a hepatic-piston diaphragm, driven by the liver and a "Musculus diaphragmaticus", which in the fossil was visibly attached to the pubes.Such a system would be an argument against the idea that birds, whose lungs are ventilated by air-sacs, are coelurosaurian theropods, and an indication theropods were cold-blooded.John Ruben's conclusions have, however, been questioned by some scientists, such as Lawrence Witmer, who claimed the study to be flawed.