The evolution of executive functions in Archosauria: Visual working memory and motor inhibition across ectotherms and endotherms

Executive functions are a set of cognitive skills enabling goal‑directed behaviours. Both mammals and birds have highly proficient executive functions, despite diverging from each other around 360 million years ago. This cognitive convergence is due to both taxa being tachymetabolic endotherms. They can maintain a stable and elevated body temperature with a high metabolism. However, in order to sustain this physiology, they also require substantial amounts of food compared to ectotherms. Thus, mammals and birds evolved larger brains and higher neuron densities, leading to improved executive functions.
Archosauria is the taxon including crocodylians and birds, which are respectively ectotherms and endotherms. Moreover, they possess a nidopallium caudolaterale (NCL), a brain region functionally equivalent to the mammalian prefrontal cortex and mediating executive functions. However, the crocodylian NCL is more rudimentary than the avian NCL. Thus, modern archosaurs show a diversity of thermal physiology, neuron density, and brain anatomy, making them an ideal taxon to study the evolution of executive functions.
In this thesis, we examined the visual working memory and motor inhibitory control of American alligators, emus, domestic chickens, ring doves, and common ravens. We studied self‑control, interference control of visual working memory, memory retention, and the interaction between visual memory and motor inhibitory control. Overall, the results show that alligators can perform on par with emus and chickens when having to choose between two visual stimuli of different values in a self‑control test. However, they have a less robust visual working memory compared to birds. Even though they retain the presence of hidden food items, they are more susceptible to interference. Finally, in the context of a motor inhibitory control task, the use of memory instead of a visual stimulus improves their ability to override a motor impulse.