Thursday, April 5, 2012

Odd fossil Foot Contemporaneous with Australopithecus

If nature has taught us anything, it is that a widely distributed creature will speciate vigorously to take advantage of different niches.  The expectation now is that we will find many separate traces of many species of primate including quite a few upright walkers.

At the same time, the extraordinary success of humanity caused the elimination of obviously competing species in the human ecological niche.  Those relying on niches not easily occupied by humanity, also learned to practice great caution.  That is why the smart ones are rarely seen.

We are also misled by our own fecundity and ability to harness agriculture.  Take that away and there would be a pretty slim human population quite happy to hunt each other for dinner.  Thus other competing creatures still surviving will tend to be scarce and also hiding from us.  The Sasquatch or Bigfoot is actually our best such example (10,000 eye witnesses and counting).

We also keep forgetting just how rare it is for a fossil to be produced anywhere.  On top of that most natural traps often depend on the victim's stupidity.  Thus the La Brea tar-pits were a poor prospect for trapping any primate but great for a carnivore trying to scavenge a stuck herbivore.

Discovery of foot fossil confirms two human ancestor species co-existed

by Staff Writers

Cleveland OH (SPX) Apr 02, 2012

The partial foot is the first evidence for the presence of at least two pre-human species with different modes of locomotion contemporaneously living in eastern Africa around 3.4 million years ago. 

A team of scientists has announced the discovery of a 3.4 million-year-old partial foot from the Woranso-Mille area of the Afar region of Ethiopia. The fossil foot did not belong to a member of "Lucy's" species, Australopithecusafarensis, the famous early human ancestor.

Research on this new specimen indicates that more than one species of early human ancestor existed between 3 and 4 million years ago with different methods of locomotion. The analysis will be published in the March 29, 2012 issue of the journal Nature.

The partial foot was found in February 2009 in an area locally known as Burtele.

"The Burtele partial foot clearly shows that at 3.4 million years ago, Lucy's species, which walked upright on two legs, was not the only hominin species living in this region of Ethiopia," said lead author and project leader Dr. Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History.

"Her species co-existed with close relatives who were more adept at climbing trees, like 'Ardi's' species, Ardipithecus ramidus, which lived 4.4 million years ago."

The partial foot is the first evidence for the presence of at least two pre-human species with different modes of locomotion contemporaneously living in eastern Africa around 3.4 million years ago. While the big toe of the foot in Lucy's species was aligned with the other four toes for human-like bipedal walking, the Burtele foot has an opposable big toe like the earlier Ardi.

"This discovery was quite shocking," said co-author and project co-leader Dr. Bruce Latimer of Case Western Reserve University.

"These fossil elements represent bones we've never seen before. While the grasping big toe could move from side to side, there was no expansion on top of the joint that would allow for expanded range of movement required for pushing off the ground for upright walking. This individual would have likely had a somewhat awkward gait when on the ground."

The new partial foot specimen has not yet been assigned to a species due to the lack of associated skull or dental elements.

The fossils were found below a sandstone layer. Using the argon-argon radioactive dating method, their age was determined to be younger than 3.46 million years, said co-author Dr. Beverly Saylor of Case Western Reserve University.

"Nearby fossils of fish, crocodiles and turtles, and physical and chemical characteristics of sediments show the environment was a mosaic of river and delta channels adjacent to an open woodland of trees and bushes," said Saylor. "This fits with the fossil, which strongly indicates a hominin adapted to living in trees, at the same time 'Lucy' was living on land."

No comments: