Join us in this fascinating episode with Dr. Araújo, a renowned paleontologist, as we delve into the mysteries of mammalian evolution and the crucial transition to endothermy. Endothermy, the ability of an organism to maintain its body temperature internally, is a feature that has played a significant role in the ecological dominance of mammals and birds. However, when and how this characteristic appeared during mammalian evolution has long been uncertain due to ambiguous fossil evidence.

Dr. Araújo presents his innovative approach to investigate this key evolutionary transition using the morphology of the semicircular ducts of the inner ear. These ducts, filled with endolymph, monitor head rotations and are vital for motor coordination, navigation, and spatial awareness. Changes in these structures could reflect the ectotherm-endotherm transition, as higher body temperatures would impact endolymph viscosity and semicircular duct biomechanics.

Dr. Araújo and his team developed the thermo-motility index, a proxy based on the bony canal morphology, to track morphofunctional changes across 56 extinct synapsid species. Their findings suggest an abrupt evolution of endothermy during the Late Triassic period in Mammaliamorpha, associated with a sharp increase in body temperature and an expansion of aerobic and anaerobic capacities.

This episode provides intriguing insights into the evolution of endothermy and the physiological characteristics that define mammals. Tune in for an enlightening discussion on the mysteries of our evolutionary past.

Keywords: Dr. Araújo, Mammalian Evolution, Endothermy, Semicircular Ducts, Inner Ear, Thermo-Motility Index, Late Triassic, Mammaliamorpha, Paleontology, Synapsid Species, Ectotherm-Endotherm Transition, Body Temperature, Aerobic Capacity, Anaerobic Capacity.

Araújo, R., David, R., Benoit, J. et al. Inner ear biomechanics reveals a Late Triassic origin for mammalian endothermy. Nature (2022). https://doi.org/10.1038/s41586-022-04963-z