Analysis of 3.2-million-year-old Toe Bones Indicates Walking Tall A. afarensis

One of the many fascinating puzzles surrounding the evolution of hominids is at which point in their evolutionary development did they stop behaving like apes and started to adopt recognisable human traits such as leaving an arboreal lifestyle and adapting to a life, walking the open grasslands.

A team of American scientists, analysing a single toe bone, dating from around 3.2 million years ago, have suggested that one of our earliest known ancestors Australopithecus afarensis may have been an obligate walker, with foot arches to cushion movement as they walked along.  Such evidence, if the controversial interpretation is accepted, suggests that these early hominids had evolved adaptations suited to walking and not for climbing trees.  Perhaps the first steps on the pathway to the evolution of ground dwelling human ancestors.

Australopithecus afarensis

According to researcher William Kimbel, (Institute of Human Origins at Arizona State University), one of the authors of this new study, A. afarensis had a permanently arched foot and walked essentially the same as our own species.  The fossil of the fourth metatarsal, ascribed to belonging to A. afarensis suggests that these hominids had a foot designed to cushion the effect of walking.  This indicates that this particular species was an obligate walker.

The research team’s work is published in this months edition of the academic journal “Science”.  The team concludes that this research resolves the debate between palaeoanthropologists who think that this species was a biped and those who believe that A. afarensis was a stepping-stone between a tree-climbing ape and full bipedalism.

Commenting on the research, Kimbel stated:

“This fourth metatarsal is the only known of Australopithecus afarensis and is a key piece of evidence for the early evolution of the uniquely human way of walking.”

The fossil was found in Ethiopia, at Hadar, the famous location of Late Pliocene aged strata that has yielded a number of exceptional hominid fossils, some more than 3.5 million years old.  The area is so important in terms of  its fossil hominid remains, that the site is known as the “home of the first family”.  The village of Hadar, in the Awash river valley has given its name to the rock formation that yields these fossils – the Hadar Formation.

Researcher Carol Ward, another author of the study, stated:

“Understanding that the foot arches appeared very early in our evolution shows that the unique structure of our feet is fundamental to human locomotion.”

However, not all the scientific community agree with the paper’s findings.  Some scientists have suggested that it may be better to assess the degree of arching found in some of the larger toe bones such as the big toe (first metatarsal) before making such claims.

Australopithecus Model (Bullyland Figures)

At home on the plains putting their best foot forward a model of Australopithecus.

To view models of ancient creatures: Bullyland Prehistoric Animal Models and Figures.

Bones of a human foot showing the uniquely arched configuration of the foot bones, and where the fourth metatarsal is located. The 3.2-million-year-old bones from Ethiopia reveal the foot arches in the ancient hominid Australopithecus afarensis.

An almost complete set of hand bones for A. afarensis is known.  This fossil was also found at Hadar, it dates from approximately 3.3 million years ago.  Metacarpals as well as proximal and distal phalanges are known.  This set of bones seem to suggest that A. afarensis had hands close to but not resembling human ancestors.  They show characteristics of both an arboreal tree-climber and a ground-based animal.  Of course, since no species is fixed, over the time that Australopithecus afarensis existed it is possible that they adapted to a drier climate with less trees and become more accustomed to living on the ground.  Over generations, natural selection would have led to modifications such as adaptations to a more ground based existence.  Whether or not these relatively small animals walked the same way as we modern humans do, is open to debate.  They may have been upright and competent bipeds, but they probably had a different gait.

Oldest Fossil Lagomorph on Display to Commemorate Year of the Rabbit

On Thursday, 3rd February to mark the Chinese New Year, we put up an article about prehistoric rabbits, just a snippet in recognition that according to the Chinese astrological calender, this was the start of the year of the rabbit.

At the time we professed that none of the Everything Dinosaur team members knew anything about rabbits and their ancestors in the fossil record.

To view this article: Rabbits and the Chinese New Year.

We did not think it would be long before a Chinese museum or research institute put a fossilised lagomorph on display to mark the year of the rabbit, and sure enough, shortly afterwards, we were told of a Eocene Epoch rabbit skull going on display last week, to mark this special occasion in the Chinese New Year.

The fossil is a beautifully skull and jaws of a prehistoric rabbit dating from approximately 54 million years ago.  It is on display at the Palaeozoological Museum of China in Beijing.

Fossil Lagomorph

The fossil was discovered three years ago in the Eren Basin region.  It represented a new species of lagomorph, the oldest known in the fossil record.  It was formally named and described as Dawsonlagus antiquus.  The Chinese exhibition celebrates the rabbit in China’s culture and traces the origins and evolution of the rabbit family.  So if you want to see the earliest known ancestor of Bugs Bunny hop over to Beijing.

To view models and replicas of prehistoric animals made by the Chinese company PNSO: PNSO Age of Dinosaurs Models and Figures.

Manchester Researchers Reveal Secret to Dinosaur Tracks

A team of researchers based at Manchester University (England) have identified the ideal conditions needed for dinosaur tracks to be preserved as trace fossils.  Footprints and trackways are known as trace fossils.  These preserve evidence of the activity of animals, they have one major advantage over the other main type of fossil – body fossils, they are direct in situ evidence of the environment at the time and place the organism lived.  If you were to stand in the preserved, fossilised footprint of a dinosaur, you will literally be “walking with dinosaurs”.

Dinosaur Tracks

University of Manchester researchers used computers to simulate prehistoric creatures making tracks in different types of mud.  This university has developed an extensive range of software programmes which have led to insights into dinosaur travel speed and locomotion.  The team found that soil conditions had to be perfect for different dinosaurs to leave fossil footprints behind.

Computers Used to Assess Dinosaur Trackways

Picture credit: Manchester University

Dubbed the “Goldilocks effect”, scientists say it explains why tracks were left at some sites and not others.

Dr Peter Falkingham, who led the research team stated:

“By using computer modelling, we were able to recreate the conditions involved when a 30-tonne animal makes a track.”

He went onto add:

“Now we can use this Goldilocks effect as a baseline for exploring more complicated factors such as the way dinosaurs moved their legs, or what happens to tracks when a mud is drying out.”

The Diversity of the Dinosauria

Dinosaurs were incredibly diverse over their 160 million year reign, ranging from leviathans that weighed upwards of fifty tonnes to tiny, bipeds such as Compsognathus from Germany and Microraptor from China.  However, different sites and different strata have yielded different tracks.

The Paluxy River site in Texas, USA – where one of the most famous sets of fossil prints was found – only reveals prints of larger dinosaurs.  Using computer modelling, the team simulated up to twenty different dinosaurs walking in different conditions.  What they found was that heavier dinosaurs only left lasting tracks in thick, shallow mud.

In deeper, softer mud, only lighter dinosaurs could leave prints while larger animals would become stuck and trapped in the soft mud they could die.

Dinosaur Tracks Reveal Secrets

A theropod print compared to an ornithopod print.

Picture credit: Everything Dinosaur

The findings also suggest that significant sites such as Paluxy River could have been host to a larger number of creatures than the tracks themselves show.  The fauna of an area was probably a lot more diverse than the footprint record reveals.

Dr Falkingham commented:

“A skeleton is the remains of a dead animal; the footprints are the remains of a living animal, something made during life.  That’s what is absolutely fascinating for me about dinosaur footprints.”

For models and figures of dinosaurs and other prehistoric animals: Dinosaur Models and Prehistoric Animal Replicas.