Paleo-air pressures and respiration of giant Odonatoptera from the Late Carboniferous to the Early Cretaceous

Adult Odonatoptera are among the most efficient flying predators. They have retained many physical characteristics over an immense period stretching from the Carboniferous to the present. Over this time they have greatly varied in size and mass, as shown in the fossil record and in particular by the length, shape, and structure of their wings. A fossil of Meganeurites gracilipes indicates that this large ‘griffenfly’ had a ‘hawker’ hunting behavior similar to certain extant species, with long periods of flight in which power, thermoregulation, and respiration would therefore tend to a ‘steady state’ equilibrium, allowing oxygen requirements and tracheole volumes to be projected and compared to extant ‘hawkers’. Comparing these values with standard pO2 models allows paleo-atmospheric density estimates to be derived. The results suggest that paleo-air pressure has varied from over two bars in the Late Carboniferous, Late Permian, and Middle to Late Jurassic, with lower values in the Early Triassic and Early Jurassic.