Dolphins, porpoises and, in general, toothed whales, such as orcas, use a sensory system called echolocation that allows them to emit sound waves and interpret the echoes they generate when they bounce off objects in their environment, such as prey. In this way, they can determine the distance at which it is, its position, size and even recognize the surrounding terrain . To do this, they generate clicks at different frequencies that they manage to modulate and focus thanks to the melon, an organ that these animals have on their foreheads.
Now, Jonathan Geisler, professor of anatomy at the New York Institute of Technology, has found out that an ancestor of these animals already had this biosonar 28 million years ago. According to the journal Nature , Geisler, in collaboration with a team of experts from the University of Texas, Austin, and the College of Charleston, has reached this conclusion after examining the fossils of an extinct cetacean, little larger than a dolphin, known as Cotylocara macei . Scientists have compared their remains with those of other living and missing species and have found that an ancestor common to Cotylocara macei and other odontocetes developed a rudimentary form of echolocation between 35 and 32 million years ago. The fossil record shows that from that moment on there was a progressive increase in the size and complexity of the muscles and nasal air sacs that control the mechanism that generates sounds.
For Geisler, this occurred at a time when cetaceans were diversifying in terms of their feeding and relative brain size. ” Cotylocara had unique characteristics, such as a deep cavity at the top of the head, which could have served to reflect sounds, and a disc-shaped bony structure around the nasal openings that would enhance its natural sonar,” says Geisler. .
