For the research, biologists used 40 alligators, anaesthetised them with ketamine, and then played sounds to them through fitted earphones. This was to help to understand how dinosaurs could perceived the direction of sounds.
The reason for selecting alligators was because the crocodilians are extremely closely related to dinosaurs (closer by far than any living reptile as a matter of fact), although alligators (and crocodiles) they are not dinosaurs. Dating back to the era of dinosaurs, the body parts of these reptiles have not changed very much since the dinosaur era. Crocodilians have lived on earth for around 100 million years.
To help the researchers understand how American alligators (and potentially dinosaurs) determine where a sound is coming from special headphones were used. All animals perceive sound differently, and they unconsciously interpret small differences in time it takes for a sound to reach each ear (this is referred to as the interaural time difference).
Some animals respond to sounds better than others. Birds, for example, have very well-developed neural maps and can accurately chart the locations of sounds. Little research had been undertaken into alligators, and this led to a collaborative study between the University of Maryland and Technische Universität München, as The Independent reports.
The experimental findings indicated that alligators can create neural maps which are very similar to those previously observed in barn owls and chickens. These are different neural maps to those recorded in the equivalent structure in mammal brains.
The reason why there are similarities between alligators and birds (and potentially dinosaurs) is because of a common ancestor (birds evolved from dinosaurs). A genus called Archosaur emerged around 246 million years ago and at some stage divided into two lineages: one that resulted in alligators and one that led to dinosaurs, and eventually to birds.
The research has been published in the Journal of Neuroscience. The research paper is titled “Neural maps of interaural time difference in the American alligator: a stable feature in modern archosaurs.”
