Data from: Convoluted nasal passages function as efficient heat exchangers in ankylosaurs (Dinosauria: Ornithischia: Thyreophora)

Convoluted nasal passages are an enigmatic hallmark of Ankylosauria.
Previous research suggested that these convoluted nasal passages
functioned as heat exchangers analogous to the respiratory turbinates of
mammals and birds. We tested this hypothesis by performing a computational
fluid dynamic analysis on the nasal passages of two ankylosaurs:
Panoplosaurus mirus and Euoplocephalus tutus. Our models predicted that
Panoplosaurus and Euoplocephalus would have required 833 and 1568 thermal
calories, respectively, to warm a single breath of air by 20°C. Heat
recovery during exhalation resulted in energy savings of 65% for
Panoplosaurus and 84% for Euoplocephalus. Our results fell well within the
range of values for heat and water savings observed in extant terrestrial
amniotes. We further tested alternate airway reconstructions that removed
nasal passage convolutions or reduced nasal vestibule length. Our results
revealed that the extensive elaboration observed in the nasal vestibules
of ankylosaurs was a viable alternative to respiratory turbinates with
regards to air conditioning. Of the two dinosaurs tested, Euoplocephalus
repeatedly exhibited a more efficient nasal passage than Panoplosaurus. We
suggest that the higher heat loads associated with the larger body mass of
Euoplocephalus necessitated these more efficient nasal passages. Our
findings further indicate that the evolution of complicated airways in
dinosaurs may have been driven by the thermal requirements of maintaining
cerebral thermal homeostasis.