Study Says Whales Evolved From Raccoon-Sized, Deer-Like Animal

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Evolution is a funny thing, especially if it's part of your imagination that doesn't work, or if you're simply not good with imagery. Case in point: Whales evolved from a deer-like animal about the size of a raccoon according to a new report.

Digital Journal -- According to a new report in the journal Nature, whales did not evolve from the hippopotamus as previous believed.

Researchers have been actively searching for the whale's evolutionary missing link for the last 15 years, and it turns out it might be a raccoon-sized animal with the body of a small deer. Scientists say the closest known evolutionary cousin to the whale is a four-footed creature from India called Indohyus. Scientists say the animal likely hid in water if it was in danger.

"I think the most exciting moment came when my technician was preparing the skull and he by accident broke the ear off," Thewissen said in a recent podcast on Nature's website. "...He was ready to glue it back and he showed it to me and I realized that on the broken surface of this ear you could see that the inside of the bone was very thick, just like a whale and not like any other land mammal."

Scientists say the closest living animal that resembles Indohyus today is the chevrotain, or African mousedeer. The animal lives in the forest, but rushes to water to hide from predators (check out this video to see a chevrotain).

Researchers have speculated whale ancestors were land-walkers since the 19th century, but Hans Thewissen of Northeastern Ohio Universities Colleges of Medicine and Pharmacy put the missing links together using intermediate fossils to track the evolution from land to water.

"Although the first ten million years of whale evolution are documented by a remarkable series of fossil skeletons, the link to the ancestor of cetaceans has been missing," reads the abstract on Thewissen's article in Nature.

Thewissen and his team of researchers looked at the composition and structure of hundreds of Indohyus fossils (part of a larger group called Raoellids, which also lived around the same time as the first whales). Researchers noticed the skull and ear had striking similarities to cetaceans (a species that includes whales, porpoises and dolphins).

"The bones of Indohyus were actually extremely thick," said Thewissen's graduate student, Lisa Cooper, during Nature's podcast. "This is the kind of thing that we see in animals like hippopotamus that live almost entirely in the water. Although they can walk on land, their skeleton has changed that allows them to basically walk on the river bottom."

Indohyus's teeth were also chemically similar to other aquatic animals, suggesting it spent a great deal of time in the water.

According to evolutionary science, the long-standing belief has been whales were ancestors of land-walking carnivores who moved to water to eat fish. But Thewissen says this theory was wrong: "Clearly, this is not the case. Indohyus is a plant eater, and clearly is aquatic," he said in a statement.

Other experts in this field say Thewissen's findings are possible, but the analysis of ancestry is based on incomplete data. While some scientists are praising this work, others are skeptical that this fossil is supposedly closer than that of a hippo. Some say this theory is not conclusive because it only considers anatomical features, not molecular ones.

Evolutionary science is a slow process, and with Thewissen's findings, it's clear it might be a couple million more years until the science world reaches a consensus on how things have changed over time.