Fossil find puts ‘Lucy’ story on firm footing

By Jonathan Amos
Science correspondent, BBC News

New fossil evidence seems to confirm that a key ancestor of ours could walk upright consistently – one of the major advances in human evolution.

The evidence comes in the form of a 3.2 million-year-old bone that was found at Hadar, Ethiopia.

Its shape indicates the diminutive, human-like species Australopithecus afarensis had arches in its feet.

Arched feet, the discovery team tells the journal Science, are critical for walking the way modern humans do.

“[The bone] gives a glimpse of foot anatomy and function,” explained William Kimbel, director of the Institute of Human Origins at Arizona State University, US.

“It is the fourth metatarsal bone, which resides on the outside of the middle part of your foot, and which helps support the well-developed arches of the foot that we see in the soles of modern human feet.

“The bone that was recovered from the Hadar site has all the hallmarks of the form and function of the modern human foot,” he told the BBC.

Arch types
Palaeo-scientists knew A. afarensis spent some of its time standing tall; that much has been clear since 1974 when they first examined a skeleton of the species, famously dubbed “Lucy”, also found near the village of Hadar in the Ethiopian rift valley.

But the absence of important foot bones in all of the specimens uncovered to date has made it difficult for researchers to understand precisely how much time Lucy and her kin spent on their feet, as opposed to moving through the branches of trees.

Human feet are very different from those of other primates. They have two arches, longitudinal and transverse.

These arches comprise the mid-foot bones, and are supported by muscles in the soles of the feet.

This construction enables the feet to perform two critical functions in walking. One is to act as a rigid lever that can propel the body forwards; the other is to act as a shock absorber as the feet touch the ground at the end of a stride.

In our modern ape cousins, the feet are more flexible, and sport highly mobile large toes that are important for gripping branches as the animals traverse the tree tops.

Professor Kimbel and colleagues tell Science journal that the feet of A. afarensis’ say a lot about the way it lived.

It would have been able to move across the landscape much more easily and much more quickly, potentially opening up broader and more abundant supplies of food, they say.

“Lucy’s spine has the double curve that our own spine does,” Professor Kimbel said.

“Her hips functioned much as human hips do in providing balance to the body with each step, which in a biped of course means that you’re actually standing on only one leg at a time during striding.

“The knees likewise in Lucy’s species are drawn underneath the body such that the thighbone, or femur, angles inwards to the knees from the hip-joints – as in humans.

“And now we can say that the foot, too, joins these other anatomical regions in pointing towards a fundamentally human-like form of locomotion in this ancient human ancestor.”

A. afarensis is thought to have existed between about 2.9 million and 3.7 million years ago, and the Hadar area has yielded hundreds of fossil specimens from the species.

Long road
Commenting on the latest research, Professor Chris Stringer, a palaeoanthropologist at London’s Natural History Museum, said scientists were gradually filling in the detail of this creature’s position in the human origins story.

“Bipedalism in Lucy is established, but there has been an issue about how much like our own that bipedalism was,” he told BBC News.

“Was it a more waddling gait or something more developed?

“And certainly there’s evidence in the upper body that the Australopithecines still seemed to have climbing adaptations – so, the hand bones are still quite strongly curved and their arms suggest they’re still spending time in the trees.

“If you are on the ground all the time, you need to find shelter at night and you are in a position to move out into open countryside, which has implications for new resources – scavenging and meat-eating, for example.

“If the Australopithecines were on that road, they were only at the very, very beginning of it.”

Fossil female pterosaur found with preserved egg

By Jonathan Amos
Science correspondent, BBC News
It was the males which carried a crest, the latest research published in Science magazine suggests

For fossil hunters, it represents one of those breakthrough moments.

A pterosaur has been found in China beautifully preserved with an egg.

The egg indicates this ancient flying reptile was a female, and that realisation has allowed researchers to sex these creatures for the first time.

Writing in Science magazine, the palaeontologists make some broad statements about gender differences in pterosaurs, including the observation that only males sported a head-crest.

David Unwin, a palaeobiologist in the Department of Museum Studies at the University of Leicester, was part of the research team.

He told the BBC the discovery was astonishing: “If somebody had said to me a few years back that we would find this kind of association, I would just have laughed and said, ‘yeah, maybe in a million years’, because these sorts of things are incredibly rare.”

Pterosaurs, also sometimes referred to as pterodactyls, dominated the skies in the Mesozoic Era, 220-65 million years ago. Although reptiles like the dinosaurs were plodding on the ground below them, they were not actually dinosaurs themselves – a common misconception.

This particular specimen has been dated to about 160 million years ago.

It was found by Junchang Lü and colleagues and excavated from sedimentary rocks in the famous fossil-hunting grounds of Liaoning Province in China. Liaoning has yielded many of the great finds in recent years, including a series of feathered dinos that have transformed thinking on bird evolution.

The new creature is from the Darwinopterus genus, or grouping, but has been dubbed simply as “Mrs T” (a contraction of “Mrs Pterodactyl”) by the research team.

The state of the egg’s shell suggests it was well developed and that Mrs T must have been very close to laying it when she died.

She appears to have had some sort of accident as her left forearm is broken. The researchers speculate she may have fallen from the sky during a storm or perhaps a volcanic eruption, sunk to the bottom of a lake and then been preserved in the sediments.

“The most important thing about this particular individual is that she has a relatively large pelvis compared to other individuals of the same pterosaur, Darwinopterus,” explained Dr Unwin.

“This seems quite reasonable – females lay eggs, they probably need a slightly wider pelvis. And then the really exciting thing is that she has a skull which lacks any kind of adornment or decoration whatsoever. When we look at other individuals of Darwinopterus, we find quite a few individuals with a large crest on the skull.

“We’re very confident now that we’re dealing with two genders here – males with big crests and small hips, and females with no crest on the skull and large hips.”

The female fossil partially prepared (A). After being fully prepared (B), the egg is clear to see (red circle)

Jonathan.Amos-INTERNET@bbc.co.uk

Audio included on original page: http://www.bbc.co.uk/news/science-environment-12242596

Ancient human remains found in Israel

By DANIEL ESTRIN, Associated Press Daniel Estrin, Associated Press
Mon Dec 27, 6:13 pm ET
JERUSALEM –

Israeli archaeologists said Monday they may have found the earliest evidence yet for the existence of modern man, and if so, it could upset theories of the origin of humans.

A Tel Aviv University team excavating a cave in central Israel said teeth found in the cave are about 400,000 years old and resemble those of other remains of modern man, known scientifically as Homo sapiens, found in Israel. The earliest Homo sapiens remains found until now are half as old.

“It’s very exciting to come to this conclusion,” said archaeologist Avi Gopher, whose team examined the teeth with X-rays and CT scans and dated them according to the layers of earth where they were found.

He stressed that further research is needed to solidify the claim. If it does, he says, “this changes the whole picture of evolution.”

The accepted scientific theory is that Homo sapiens originated in Africa and migrated out of the continent. Gopher said if the remains are definitively linked to modern human’s ancestors, it could mean that modern man in fact originated in what is now Israel.

Sir Paul Mellars, a prehistory expert at Cambridge University, said the study is reputable, and the find is “important” because remains from that critical time period are scarce, but it is premature to say the remains are human.

“Based on the evidence they’ve cited, it’s a very tenuous and frankly rather remote possibility,” Mellars said. He said the remains are more likely related to modern man’s ancient relatives, the Neanderthals.

According to today’s accepted scientific theories, modern humans and Neanderthals stemmed from a common ancestor who lived in Africa about 700,000 years ago. One group of descendants migrated to Europe and developed into Neanderthals, later becoming extinct. Another group stayed in Africa and evolved into Homo sapiens — modern humans.

Teeth are often unreliable indicators of origin, and analyses of skull remains would more definitively identify the species found in the Israeli cave, Mellars said.

Gopher, the Israeli archaeologist, said he is confident his team will find skulls and bones as they continue their dig.

The prehistoric Qesem cave was discovered in 2000, and excavations began in 2004. Researchers Gopher, Ran Barkai and Israel Hershkowitz published their study in the American Journal of Physical Anthropology.

Eggs with the oldest known embryos of a dinosaur found

By Katia Moskvitch
Science reporter, BBC News

Palaeontologists have identified the oldest known dinosaur embryos, belonging to a species that lived some 190 million years ago. The eggs of Massospondylus, containing well-perserved embryos, were unearthed in South Africa back in 1976. The creature appears to be an ancestor of the family that includes the long-necked dino once known as Brontosaurus. The study in the Journal of Vertebrate Paleontology also sheds light on the dinosaurs’ early development.

While the embryos are only about 20cm long, the adults are thought to have reached some five metres in height

The researchers used the embryos to reconstruct what the dinosaurs’ babies might have looked like when they roamed the Earth. Having studied the fossilised eggs, the team, led by Professor Robert Reisz of the University of Toronto Mississauga in Canada, discovered that the embryos were the oldest ones ever found of any land-dwelling vertebrate. “This project opens an exciting window into the early history and evolution of dinosaurs,” said Professor Reisz. “Prosauropods are the first dinosaurs to diversify extensively, and they quickly became the most widely spread group, so their biology is particularly interesting as they represent in many ways the dawn of the age of dinosaurs.”

‘Awkward’ bodies
Massospondylus belonged to a group of dinosaurs known as prosauropods, the ancestors of sauropods – huge, four-legged dinosaurs with long necks. Having studied the tiny (20cm-long) skeletons, the researchers noted that the embryos were almost about to hatch – but never had the chance. Interestingly, the report says, the embryos looked quite different compared to the adult animals. Once hatched, the babies would have had rather long front legs, meaning that they would have been walking on all fours rather than on two legs like the adults. The embryos’ heads were also disproportionally big, but it is believed the adult Massospondylus, which were about five metres in length, had relatively tiny heads and long necks. The little ones’ anatomy would have changed with age. The paper stated that the rather awkward body of the embryos suggested that just like humans, the hatchlings would have required parental care – and if in this case, it would be the earliest known example of parental care.

Early Sauropod Dinosaur: First Complete Skeleton Found

ScienceDaily (Oct. 28, 2010)

Skull and lower jaw of Yizhousaurus, an early sauropod dinosaur from the Lower Jurassic (~200-million-years-old) of southern China.
(Credit: Bill Mueller)

Scientists have discovered in China the first complete skeleton of a pivotal ancestor of Earth’s largest land animals — the sauropod dinosaurs. The new species, tentatively dubbed Yizhousaurus sunae, lived on the flood plains around Lufeng in the Yunnan Province of South China about 200 million years ago. The species helps explain how the iconic four-footed, long-necked sauropod dinosaurs evolved.

Unlike the 120-foot-long, 100-ton sauropod giants that came later, Yizhousaurus was about 30 feet in length, but it shows all of the hallmarks of later sauropods: the beginning of a long neck, a robust skeleton and four-legged posture. It also comes with an intact fossilized skull — which is very rare and crucial for understanding its place in the evolution of sauropods.

“Sauropods have these big bones but their skulls are very lightly constructed and also very small,” said paleontologist Sankar Chatterjee of Texas Tech University. Chatterjee presents the discovery on Oct. 31 at the annual meeting of the Geological Society of America in Denver.

Yizhousaurus’s skull is broad, high and domed, less than a foot long with a short snout, eye sockets on the sides for scanning enemies. It has an unusually wide and U-shaped jaw, in top view, like that seen in later Camarasaurus, said Chatterjee. Numerous serrated and spoon-shaped teeth of the upper and lower jaws would shear and slide past each other for cutting plant material during feeding. The sturdy teeth and raised neck let the animal very easily nip small branches from treetops and then chew the plant material.

“Once the plant food was ingested, a gastric mill in the stomach probably provided further mechanical breakdown of the plant,” Chatterjee explained. Apparently the animal was well adapted to a life of eating plants to support its large body.

Besides its telltale physical features, Yizhousaurus was also found in revealing company. A half century ago spectacular specimens of prosauropod dinosaurs such as Lufengosaurus were discovered at the same location. This makes sense, since most paleontologists are of the opinion that prosauropods gave rise to sauropods, despite the fact that the transition has been very vague, Chatterjee said.

“This is why this new one (Yizhousaurus), may bridge this gap,” he said.

Abstract is available at http://gsa.confex.com/gsa/2010AM/finalprogram/abstract_175675.htm