This date is significantly earlier than researchers first estimated

Mar 14, 2014 16:11 GMT  ·  By

Several marine animals are capable of producing high-frequency vocalizations that enable them to communicate over large distances through water. This trait, generically called echolocation, is roughly similar to what we see in bats, with a few differences. Now, investigators say that this characteristic may have evolved a lot sooner in whale ancestors than originally thought. 

According to scientists with the College of Osteopathic Medicine at the New York Institute of Technology, it would appear that the ancient relatives of dolphins, porpoises and toothed whales had echolocation capabilities, including vocalizations and the ability to process their echoes, some 28 million years ago. This is roughly halfway between when dinosaurs disappeared and modern times.

In the new study, scientists led by associate professor Jonathan Geisler discovered a fossil of a new marine species near Charleston, South Carolina. The team says that the extinct creature, now called Cotylocara macei, is an antecessor of modern-day marine mammals, and the earliest known creature of the sea to feature this trait.

The group, including University of Texas in Austin expert Matthew Colbert and College of Charleston researcher James Carew, both coauthors of the study, published details of its discovery in the March 12 issue of the top scientific journal Nature, PhysOrg reports.

“The most important conclusion of our study involves the evolution of echolocation and the complex anatomy that underlies this behavior. This was occurring at the same time that whales were diversifying in terms of feeding behavior, body size, and relative brain size,” Geisler explains.

Unlike humans, who produce sounds through the voice box in the larynx, marine mammals use a constricted area located in the nasal passages, right below the blowhole, for the same purpose. This system is more complicated than what we can see in our own species, but this complexity accounts for the extended range of the sounds they make.

These constricted areas are surrounded by air and fat pockets, and by large muscles, all of which are intricately intertwined in a very small area of the animals' faces. Discovering species such as C. macei helps scientists reconstruct the step-by-step evolution of this intricate apparatus.

“Its dense bones and air sinuses would have helped this whale focus its vocalizations into a probing beam of sound, which likely helped it find food at night or in muddy water ocean waters. The anatomy of the skull is really unusual. I've not seen anything like this in any other whale, living or extinct,” Geisler says.

The research team also determined that the group of whales C. macei belonged to split off from the main branch of the family around 32 million years ago. While the first group eventually went extinct, the main branch continued to this day.