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Re: Dino-lung ventilation
Of course I agree with many of Troutman's comments, especially about the near
avian organization of the respiratory complex in dromaeosaurs. However, only
tridactyl theropods and sauropods probably had pulmonary air-sacs. All other
dinosaurs lacked the pneumatic vertebrae indicative of air-sacs. Although
most ornithischians had long abdominal ribs, they were not highly mobile.
Ornithopods actually lacked long posterior ribs, instead they had a
mammal-like lumbar region which suggests they also had a mammal-like
While on this subject, it is worth noting that in their Science article Ruben
et al. contend that all dinosaurs had septate lungs, rather than the alveolar
lungs found in mammals. Actually, this applies only to theropods. Because the
other major dinosaur groups left no descendents, it is not possible to
restore their lung anatomy via phylogenetic bracketing.