(NaturalNews) The U.S. Navy is a very capable, well armed and highly technically advanced force, and that, of course, includes its sonar capabilities. But as developed as they are, sonar for seafaring mammals -- and whales in particular -- predate the Navy's by about 32 million years.
But so do the sonar capabilities of dolphins and other sea creatures, according to researchers who have recently revealed the fossilized skull of a 28-million-year-old marine mammal that also used sound to find its next meal or safely navigate muddied waters.
The animal, known as Cotylocara macei, is the earliest known cetacean that has skeletal evidence indicating some natural form of sonar, says the research team which reported its findings in the journal Nature.
As reported by The Christian Science Monitor:
After comparing the nearly complete skull with those of other fossil cetaceans, the team placed C. macei on the evolutionary tree just above the common ancestor to all toothed cetaceans. That branch of the whale family uses echolocation to find its food, unlike their cousins who feed by straining seawater through boney baleen plates. Right and humpback whales are modern examples of these strainers.
The study's findings establish "an important new piece of information on when echolocation originated, such that it originated almost immediately after the split between baleen whales and toothed whales," Frants Jensen, a researcher at the Woods Hole Oceanographic Institution in Woods Hole, Mass., who studies marine echolocation, said.
It's all in the clicks
For some time, researchers have shown an interest in the evolution of natural sonar, known as echolocation, in marine mammals because of the complexity involved in finding food or getting around in dark ocean waters.
Scientists know that sperm whales, which are the largest toothed whales on Earth, echolocate by emitting widely spaced sharp clicks; it sounds a lot like hitting two spoons together.
Some researchers say they have noticed that each whale appears to have its own unique rhythm, which allows it to distinguish its own sounds from those of other whales. Dolphins, by comparison, echolocate by emitting tightly-spaced clicks that sound a lot like a creaky door when it is opened.
Pitch and timing of a sea mammal's sonar is very often tailored to its surroundings, scientists say. Dolphins inhabiting harbor regions, for example, tend to use a frequency that "falls within a narrow window of relative silence amid the clutter of underwater noises in a harbor," CS Monitor reported.
New York Institute of Technology researcher Johnathan Geisler and two colleagues have discovered a new lane of early evolution among early toothed cetaceans with this capability with the newly described C. macei.
Interestingly, the skull was unearthed from a drainage ditch which forms one boundary of a housing development in College Park, S.C.
The developments were first constructed in the 1970s; as drainage ditches were built, "they hit this really rich, muddy sand that's produced a huge number of fossil cetaceans," Geisler said. "You never know what you'll find in your backyard."
'Modern' sonar developed around turn of 20th century
There have been many fossil discoveries there, but so far only a few of them have been formally described. The skull analyzed by Geisler and his team came from that collection, which is stored at the Mace Brown Natural History Museum at the College of Charleston.
Certain aspects of the skull got Geisler's attention.
"Cetaceans have very strange skulls, particularly the toothed whales, dolphins, and porpoises," he said.
Adds CS Monitor:
Many of the bones associated with the snouts, or rostrum, extend back to cover much of the skull -- a feature known as telescoping. It's a feature that becomes more pronounced as ancient lineages of toothed cetaceans evolved into today's animals.
The newly described skull shows a degree of telescoping usually seen in today's cetaceans, he continues. And it isn't seen in other members of the extinct family to which this species belongs.
"There were a lot of enigmas with this specimen," he says.
If the C. macei was able to use sonar, that means that the capability first evolved in toothed cetaceans between 32 and 35 million years ago, said the researchers.
Meanwhile, modern sonar was first developed as a submarine-detection device in 1906 by Lewis Nixon, as a way of detecting icebergs.