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Ancient skeletal remains shed new light on evolution

By Alan Silverleib, CNN
STORY HIGHLIGHTS
  • Unearthed remains are believed to be remains of an unknown species
  • Partial skeletons of adult female and young male hominid are nearly 2 million years old.
  • The species is thought to have been taller and stronger than older species
  • Team leader says discovery may help clarify a murky biological picture of that time
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(CNN) -- Scientists may have discovered a new branch on your family tree.

A team of researchers working in South Africa has unearthed what they believe are the remains of a previously unknown species predating modern humans. They recently discovered a couple of partial skeletons -- an adult female and a juvenile male -- that are nearly 2 million years old.

The two are believed to have been significantly taller and potentially stronger than "Lucy," the roughly 3 million year old skeleton discovered in Ethiopia in 1974.

Known as "Australopithecus sediba," the pair may provide a window into a previously little-defined period in human evolution.

"Australopithecus" means "southern ape," the researchers noted. "Sediba" refers to a "natural spring" or "fountain" in Sotho, a local language in South Africa.

The discovery of the remains was akin to stepping into a time machine, said Dr. Lee Berger from the University of the Witwatersrand in Johannesburg. It's providing a "really a special look into hominid evolution at that time," he told reporters.

Blog: Using satellites to find skeletons

Hominids are part of the biological family that includes humans, gorillas and chimpanzees.

The two skeletons, discovered in the remains of a collapsed cave, were not alone. At least two more partial skeletons have been discovered but not yet dug out, Berger said.

Berger and other researchers, including Dr. Paul Dirks from Australia's James Cook University, believe the pair may have fallen into the cave while searching for water. Their remains were washed into an underground pool and eventually entombed in rock in South Africa's Malapa cave complex.

The male is believed to have been between the ages of 10 and 13 when he died, the researchers concluded. The female was at least in her late 20s or early 30s.

Specifically, the two hominids lived between 1.78 and 1.95 million years ago, Berger's team concluded. They walked upright and shared several physical characteristics with the earliest known hominids.

Among other things, they had short fingers but extremely long forearms, Berger noted. Compared to other early specimens, their legs were long -- potentially signifying the start of an era marked by faster running and overall greater mobility.

Despite the fact that development of their feet was still in a "primitive" stage, he noted, "they could still climb trees [and] they were very competent walking ... on the ground."

Berger noted that they had "remarkably small" brains, but a more developmentally advanced pelvis and smaller teeth -- one of the hallmarks of modern man.

Could Australopithecus sediba be the so-called "missing link" that scientists have been looking for?

"I don't like the use of that term," Berger told reporters. It's a "Victorian-era" term that "implies some (specific) chain of evolution." But this is "undoubtedly a highly transitional species" with characteristics shared by later hominids, he noted.

The discovery promises to help clarify what has been, until now, a murky biological picture from 1.7 million and 2 million years ago, he said. It will "contribute enormously to our understanding of what was going on" at that critical juncture in the evolution of humans.

Researchers working with Berger and Dirk also discovered fossils in the cave from a saber-toothed cat, a brown hyena and a wild dog, among others.