The ear bone fossil of an ancient toothed whale that lived 26 million years ago has revealed that its ability to echolocate is quite similar to the present day dolphins' sensory capabilities.
By leveraging revolutionary CT scanning technology, an international team of researchers were able to examine the insides of a fossilized ear bone that belonged to a xenorophid whale, one of the earliest ancestors of modern toothed whales that existed around 26 million years ago.
Examination of the ear revealed that the ancient whale had a 'cochlea' specialized for sensing high-frequency sound.
"When I first looked at the inner ear of the xenorophid, I was blown away by just how similar this incredibly old toothed whale was to a modern echolocating dolphin," said Travis Park, a PhD student at Museum Victoria and Monash University in Australia and lead author of the new study.
The fossil was particularly borrowed for investigation from the Smithsonian Institution's National Museum of Natural History.
Echolocation refers to a unique ability that certain marine mammals possess which enables them to produce high-frequency sound waves. By listening to the echoes that bounce back from the sound waves reflecting off objects (animate or inanimate), they are able to garner a better understanding of their surroundings in the deep blue seas.
This aids them in communicating with each other, navigating the waters, hunting for food and also helps them stay wary of dangerous predators around.
The odontocetes species that includes dolphins, toothed whales, beaked whales, killer whales, sperm whales and porpoises, encompass the ability to echolocate.
Dolphins are undoubtedly one of the most intelligent and social animals alive on earth today. The development of this extraordinary biosonar system played a pivotal role in the evolution of the odontocetes. It is this evolutionary advantage that presumably helped them diversify and spread bountifully across the oceans of the earth.
Non-marine mammals such as the blind bats are also super-sonic like the dolphins, and possess the ability to echolocate and sense their way around the deep, dark caves.
Precisely when this echolocation skill developed among these marine mammals has been a mystery for ages. The solution to this mystery has been addressed by the study, by asserting that the skill to echolocate dates back to millions of years ago and was present in ancient whales.
However with the groundbreaking finding, scientists now wonder: what were the ancestors of ancient whales like? Did they possess this skill, too?
"Our paper shows even the earliest known fossil odontocetes [toothed whales] have all the tools for echolocation seen in living dolphins. They must have evolved from something that didn't quite have all the tricks of the odontocete trade." said Dr Erich Fitzgerald, Museum Victoria's Senior Curator of Vertebrate Paleontology and co-author of the study.
"What were those animals like and how did they start down the path to sonic supersenses? The quest for odontocete origins continues." added Fitzgerald.
The finding of the research was published in the Royal Society's journal Biology Letters.
Photo: Ed Dunens | Flickr
