Tree-dwelling apes in Europe strode upright around 5 million
years before members of the human evolutionary family hit the ground walking in
That’s the implication of fossils from a
previously unknown ape that lived in what’s now Germany about 11.6 million
years ago, say paleontologist Madelaine Böhme of the University of Tübingen
in Germany and her colleagues. But the relation, if any, of these finds to the
evolution of a
two-legged stride in hominids by perhaps 6 million years ago is hazy (SN: 9/11/04).
Excavations in a section of a Bavarian clay pit produced 37 fossils
from the ancient ape, dubbed Danuvius
guggenmosi by the investigators. Bones from the most complete of four
individuals represented by the new finds cover about 15 percent of that
creature’s skeleton, including nearly complete specimens from the forearm and
lower leg, Böhme’s
team reports online November 6 in Nature.
Earlier research had generated age estimates for fossil-bearing sediment in the
spine and body proportions indicate that it could hang from branches, like
present-day orangutans and gibbons, as well as walk on two legs slowly, somewhat
like hominids that originated in Africa roughly 6 million to 7 million years
ago, the researchers say. No other fossil or living ape has moved in trees and
on the ground precisely as Danuvius
did, they conclude. An ape built like Danuvius
likely served as a common ancestor of great apes and hominids that emerged
roughly 7 million years ago or more, Böhme contends.
If true, Danuvius’ body
design would upend the long-standing idea that hominids evolved an upright
stance after splitting from a common knuckle-walking, chimplike ancestor in Africa.
The new finds also challenge an argument that hominids evolved from ancient
apes built much like modern orangutans, which walk upright on tree branches
while grasping other branches for support (SN:
A Danuvius link to
hominids would fit with evidence that a
4.4-million-year-old hominid called Ardipithecus
ramidus combined an upright gait with adept tree climbing (SN: 4/2/18). But A. ramidus weighed about three times as much as Danuvius, which ranged from an estimated
17 to 31 kilograms, Böhme’s team says. Based on available fossils, the
considerably smaller and older Danuvius
was designed for less efficient walking and better climbing than A. ramidus was, says paleoanthropologist
Scott Williams of New York University who was not involved in the new study.
Despite those differences, “upright walking preceded the
great ape/human split and likely started in Europe,” Böhme says.
Many fossil apes dating to between 13 million and 5.3
million years ago have been found
in Europe (SN: 5/22/17) and, to
a lesser extent, Africa (SN: 8/9/17).
Those finds, however, included no completely intact limb bones.
Measurements of three Danuvius
limb bones, two of which come from the same adult male, indicate that this
extinct ape relied equally on its forelimbs and hind limbs. Comparisons of two Danuvius spinal bones with those of
fossil and living apes suggest that the newly discovered animal had a
relatively long, inwardly curving back capable of supporting an upright stance.
Grasping, opposable big toes helped to stabilize flat feet while walking, the
researchers say, while curved fingers, much like those of present-day chimps
and other apes, would have aided climbing and maneuvering in trees.
Danuvius’ big toes
were long and strong enough to grip thin branches and hanging vines in trees, Böhme
says. As a result, Danuvius could
have held itself in place in a thicket of branches or vines to hide from large,
predatory cats, she speculates.
If further fossil finds confirm that Danuvius and perhaps other ancient tree-dwelling apes stood
upright, “it would show that our [human] lineage never did go through a
hunched-over stage of walking because we were always upright,” says
paleoanthropologist Jeremy DeSilva of Dartmouth College.
It’s possible, though, that Danuvius independently evolved a form of upright walking on tree
branches that had nothing to do with the appearance of a two-legged gait in
hominids, says DeSilva, who was not a member of Böhme’s team.
The latter possibility appears most likely, Williams says. Danuvius shares enough of its known
anatomy with modern African and Asian monkeys, gibbons as well as other fossil
apes for scientists to question whether the German creature had any direct
influence on hominids’ upright stance, he says.
Still, the discovery of Danuvius
“adds an exciting piece to the puzzle” of ancient ape evolution, Williams says.
Credit: Source link