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Beaked Whale Fossil Shows When Humans Became Bipedal

Mar 17, 2015 03:54 PM EDT

Whales and humans seem like they have little in common, so it was surprising when a 17-million-year-old beaked whale fossil started helping researchers solve the puzzle of when humans first became bipedal.

According to experts, uplift associated with the Great Rift Valley of East Africa triggered environmental changes that directly impacted the course of human evolution. The landscape transformed from dense, elevated forest to flat, open grasslands, forcing our ancestors to abandon all fours and walk upright. But when exactly did this happen?

That's where the 22-foot beaked whale comes in. About 17 million years ago, the whale apparently took a wrong turn up an African river, as it was found 740 kilometers (460 miles) inland at an elevation of 620 meters (2,100 feet).

"The whale was stranded up river at a time when east Africa was at sea level and was covered with forest and jungle," researcher Louis L. Jacobs, a vertebrate paleontologist at Southern Methodist University, said in a statement. "As that part of the continent rose up, that caused the climate to become drier and drier. So over millions of years, forest gave way to grasslands. Primates evolved to adapt to grasslands and dry country. And that's when - in human evolution - the primates started to walk upright."

Beaked whales are some of the ocean's deepest divers, plunging to depths of 10,000 feet to feed. Researchers suggest that this particular whale (Ziphiidae) lived in the Indian Ocean, but mistakenly strayed into the ancient large Anza River and quickly became disoriented, unable to change its course.

"You don't usually find whales so far inland," Jacobs noted. "Many of the known beaked whale fossils are dredged by fishermen from the bottom of the sea."

Interestingly, the fossil was first discovered in Kenya in 1964, but until recently the fossilized beak and jaw bone had been lost in the archives of Harvard University for nearly 40 years after being misidentified as a turtle. Luckily, Jacobs - who knew of its existence but for years failed to locate the fossil - finally found the skull, for it's finally revealing its secrets.

The findings were published in the journal Proceedings of the National Academy of Sciences.
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