Could the Development of an Achilles Tendon give Hominids an Edge?

Recently, a team of scientists from the University of Manchester led by Dr Bill Sellers presented new evidence on the locomotion of bipedal theropod dinosaurs.  Their study involved the use of a powerful computer programme that analysed extant and extinct animal data and then calculated the top running speed of each animal tested.  The results did not reveal too many surprises.  The larger the theropod the slower it could run.

Running Speeds

The fastest dinosaur in this study proved to be the chicken-sized Compsognathus.  Measurements from the fossilised skeleton led the Manchester university computer to calculate that this tiny dinosaur could run at an impressive 40 mph.  A six tonne T. rex on the other hand could run at just 18mph (still fairly striking considering the size of the animal).

You can read the full article here:

Tyrannosaurus rex could run down David Beckham.

Early Hominids

The Manchester team went on to present a second study, this time with the focus on human evolution, their work suggests that if early hominids lacked an Achilles tendon, then they would have managed little more than an amble.

However, if the likes of Homo ergaster had evolved an Achilles then their ability to run would have been greatly enhanced.  Being able to run away from potential predators is an effective survival strategy, particularly in the dry Savannah environments where early hominids, such as H. ergaster lived.  But if they could run, could our direct ancestors have hunted?  Fossil remains of Homo ergaster have revealed teeth worn away in a pattern that indicates a diet of chewing at flesh.  Does this indicate that evolutionary advantages such as Achilles tendons allowed them to hunt?  If the likes of Homo ergaster were able to hunt or indeed to roam around their habitat efficiently so they could locate carcases and scavenge them, this would have permitted them to obtain a lot of protein from the meat they ate.

Our Achilles Heel?

Lots of protein is essential if you are going to develop a big brain, is the reason for our eventual success to be found in the tendon that links our heel to our calf muscles?

The Achilles tendon acts as a spring whilst running.  It stores and releases energy and greatly improves the running action.  Strong tendons can make a huge difference to how fast an animal is capable of moving, they are after all what gives the kangaroo its bounce.

The study by Dr Sellars involved inputting the anatomical details of an early human ancestor Australopithecus afarensis, postulated from the limited fossil evidence we have (the well-known “Lucy” fossil) plus additional evidence from footprints, preserved in volcanic ash at Laetoli (Tanzania).  The powerful bio-mechanical computer then analysed the evidence and came up with an efficient form of bipedal locomotion for our 3.5 million year old ancestor.  The research indicates that Lucy and her kind were already efficient walkers but their gait, limb bone measurements and the lack of an Achilles tendon would have severely hampered their ability to run.

Challenges Previous Studies

This study contradicts in part, the work done by Patricia Kramer of Washington University.  Her work focused on the relationship between the wide pelvis and shorter legs of A. afarensis.  According to this research, A. afarensis was actually a more efficient walker than modern humans.  Patricia and her team calculated that these early hominids “wiggled” rather than “waddled” when they walked and concluded that just because H. sapiens is the only surviving species of bipedal hominid; this did not mean that our way of walking was the best.

This Manchester team’s work, presented to the British Association for the Advancement of Science sheds new light on the cursory abilities of the earliest ape-men.  The problem is, the evolution of hominids is still poorly know, the lack of fossils is a real drawback.  Virtually all the material on the origins of mankind going back 6 million years could be easily fitted inside a single transit van, the fossil record of our own evolution is so poor.

Hominid Taxonomy

Scientists still debate how the various hominid species are inter-related, this new work which shows the importance of the Achilles tendon in terms of effective running speed does little to shed further light on how the hominid family tree shapes up.  Indeed, in apes the origins of the Achilles tendon is a very confusing issue.  Our closest living relatives chimps and gorillas lack an Achilles tendon, whereas gibbons the least closely related great ape to Homo sapiens has one.

It may be misleading to use the extant apes to review the evolutionary importance of running.  Chimpanzees and gorillas adopt a quadruped stance and spend a lot of their time on the ground.  Gibbons are largely arboreal and it may be this difference that is the real reason for the absence/or presence of the Achilles tendon in these genera.

Efficient Walkers

The Manchester University model shows that early hominids were quite efficient walkers, but were poor runners.  Effective running followed much later on our evolutionary path, once we could walk upright we had an advantage but the development of an Achilles tendon permitted our ancestors to run and perhaps hunt more effectively.

It seems that the old adage is true – “you must walk before you can run”.

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Tiny Mongolian Dinosaur may shed “Light on the Origin of Flight”

A combined team of palaeontologists and researchers from the North Carolina State University and the North Carolina Museum of Natural Sciences have published evidence that contradicts many scientists views on how dinosaurs may have evolved into birds.

A widely accepted doctrine had been that miniaturisation was one of the last stages in the long series of changes required in order for dinosaurs to evolve into flying animals, the first avians – birds.  However, the US team’s analysis of a small Mongolian dinosaur, recovered from Cretaceous deposits, throws an evolutionary spanner into the works.

Small Theropod Dinosaur

Dr Julia Clarke, assistant professor of palaeontology at the university, led the analysis of the new dinosaur species called Mahakala omnogovae (derived from the words for Lord Shiva), which had been discovered in the Gobi desert.  This small, basal Dromaeosaur was only 70 cms long and weighed little more than 2-3 kgs.  Although, the fossil is far from complete, the researchers are confident that this specimen represents an adult of the species and not a still growing juvenile, so Mahakala is one of the smallest dinosaurs known.

A Typical Small Theropod Dinosaur (Dromaeosauridae Family)

A scale drawing of the dromaeosaurid Atrociraptor marshalli.  An illustration of a typical small theropod dinosaur.

Picture credit: Everything Dinosaur

How to Fly

In order to achieve powered flight, animals have to become lighter so that they are able to take off under their own muscle power.  Modern birds (Neornithes) have a number of anatomical adaptations to help them fly, for example no teeth, a reduction in the number of digits, the development of a pygostyle and so on; all helpful in making their skeletons lighter and thus assisting in powered flight.  It had been thought that miniaturisation would have assisted the evolution of birds, with smaller and smaller dinosaurs able to run faster and leap higher into the air; and over many generations; slowly powered flight evolved from this.

However, with dromaeosaurs small size was relatively common well before the ability to fly evolved.  There are a number of small light-weight dinosaurs known from the Late Cretaceous, dinosaurs such as the 1 metre tall Bambiraptor from the Western United States and Byronosaurus.  These swift and agile hunters show many bird-like adaptations in their skeletons.  Perhaps there was a biological advantage in being small and fast running.  Clearly, such small fleet-footed animals would have not been on the menu of the large tyrannosaurs, even young Tyrannosauridae would have had little chance of catching them.  There would have been plenty of food around for such animals, many small mammals, lizards, snakes, insects, even larger dinosaur’s eggs.  The feathers on these small dinosaurs would have been essential for insulation, helping these animals to retain body heat.

The Evolution of Flight

The evolution of flight and the eventual rise of the birds may have been an “evolutionary side-shoot”, an indirect consequence of being small, feathered and nimble.  Many dinosaur families seem to have small members within them whose descendants got bigger not smaller as previously thought.  Small size in members of the dromaeosaur group occurs well before many other innovations in locomotion and growth strategy that would have helped these animals eventually evolve into true birds.

Dr Julia’s work has been published in this month’s edition of the journal “Science”.

The trouble with small, light weight animals whether they are true birds or the dinosaur ancestors of birds, is that they tend not to be found as fossils.  Their skeletons are light and delicate and not able to withstand the rigours of fossilisation.  Many animals are scavenged and their remains scattered, so there is little chance for scientists to recover an articulated specimen.    Chances are there were probably many thousands of different types of small theropod around in the latter stages of the Mesozoic.  The bipedal theropod body plan is a very successful design, after all it had been around for most of the age of reptiles with very few modifications.  These animals would have inhabited areas with plenty of cover such as forests and scrub-land.  Forest environments do not lend themselves to the prevailing conditions that allow rapid burial and fossilisation to occur.  Only in rare circumstances can such animals be preserved; such as the sediments that went on to form the lithographic limestone of Solnhofen that permitted remains of Archaeopteryx to be fossilised or the amazing fossils found in the Sihetun region of the Liaoning Province, China.

At best, we still have a very patchy fossil record of the evolution of birds and it may be many more years before scientists are able to piece together the relationship between true birds and non-avian dinosaurs.

The evolution of birds and the roles that certain groups of dinosaurs had to play in this is likely to remain contentious for sometime to come.  One puzzle is that an animal such as Archaeopteryx can be found in Late Jurassic sediments and yet more primitive avian features are found in specimens from the Liaoning deposits which are approximately 30 million years younger.

A Cast of an Archaeopteryx Fossil on Display at Liverpool Museum

Archaeopteryx fossil cast. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

A number of manufacturers have introduced feathered dinosaur models.  The American Museum of Natural History have approved a “tube of feathered dinos”, which includes animals such as a feathered Velociraptor, Dilong and Microraptor.

Our favourite feathered friend remains Archaeopteryx, a truly amazing and enigmatic animal with only 7 fossils known to date (one of them consists of a single feather)!

To see a collectible dinosaurs including feathered dinosaurs: Dinosaur and Prehistoric Animal Models.

Incredible Fish Fossil found in Oil Drill Core

Sometimes a scientific discovery can be down to pure chance.  Despite huge advances in the technology available to palaeontologists, the finding of a brand new species can have more to do with serendipity than with appropriate planning and correct scientific practice.

The discovery of a new species of Late Cretaceous fish is a typical example of how “lady luck” can intervene and help scientists shed more light on life in the Mesozoic.  In 1988, a Canadian oil company called Cequel Energy Inc. was sinking drill cores into a region of west-central Alberta, prospecting for fossil fuels.

A 75 mm wide drill was thrust more than 1,300 metres deep into the Albertan sediments.  When the drill core was pulled up and examined it revealed a beautifully preserved 96 million-year old fossil fish, neatly encircled by the cylindrical drill core.  Only the tip of the snout and the last part of the tail had been lost, the rest of the fish fossil neatly fitted into the diameter of core sample.

One very lucky fossil find – a Cretaceous Teleost

Picture courtesy of University of Alberta

Occasionally core samples do reveal fossils, such as the Plateosaur fossil fragments extracted by an oil company offshore Norway in May 2006, but to find a delicate fish fossil such as this is a particularly rare event.

To read about the Plateosaur remains found in the Nowegian drill core:

Norway’s First Dinosaur – Say Hello to Plateosaurus.

Fish skeletons are light and fragile, even if they avoid being scavenged and are rapidly buried, wave action and currents can quickly disperse the bones as the flesh rots away.  However, in this instance the skeleton is virtually complete and perfectly preserved providing further evidence on the evolution of teleosts.

The core was taken from an area of Alberta just south of Grande Prairie, the fossil was found in core material from the Dunvegan Formation and as a result of this the fish has been named Tycheroichthys dunveganensis (means lucky fish from the Dunvegan Formation).  This deep-bodied fish belonged to a now extinct group called the Paraclupeidae, which are related to modern herrings.  Fish fossils from this group have been found in Lebanon and Brazil but this is the first time that this family have been reported from North America.

This fish has been referred to as a holotype (a specimen on which the original description of the species will be based).  During the latter part of the Cretaceous, North America was effectively split in two by the shallow Western Interior Seaway.  This sea stretched from the Gulf of Mexico to the Arctic Ocean covering the majority of Alberta during the late Cretaceous (with a few notable exceptions such as the Dinosaur Provincial Park Formation and the Oldman Formation).

The fish fossil lay amongst the other core samples for many years, under the supervision of the Canadian museum of Nature.  Palaeontologists from the University of Alberta reviewed the core samples and realised the significance of the fish fossil.  Their work on this amazingly lucky find has just been published in the Canadian Journal of Earth Sciences.

Articulated specimens such as this are extremely rare and given the circumstances of its discovery, it really is remarkable how this little fish fossil has survived.  The fossil has now been treated to help its preservation and stored in the secure vaults in the Canadian museum.

For models and replicas of prehistoric sharks and other ancient fish: PNSO Age of Dinosaurs Figures.

Did Two Asteroids colliding in Outer Space seal the Fate of the Dinosaurs?

In 1980 the physicist Luis Alvarez and his son, geologist Walter Alvarez proposed a theory that an asteroid hitting the Earth might have caused the mass extinction that led to the demise of the dinosaurs.  High levels of the rare Earth element iridium had been found in sediments dating from the Late Cretaceous and this led the father and son team to postulate that an asteroid impact could have wiped out much of life on Earth 66 million years ago.

Impact from Space

Their theory was given further credence with the discovery, in 1990, of a huge impact crater found off the coast of Mexico.  Could this be the “smoking gun” evidence of an asteroid impact that led to the extinction of the dinosaurs?

The impact crater, now known as the Chicxulub crater (a Mayan word that translates to “tail of the devil”) is estimated to have been 112 miles (180 kilometres) across and was made by an object of around 6 miles in diameter (10 kilometres).  Evidence now suggests that there may have been a series of impacts around 65 million years ago.  Such a catastrophic bombardment would have resulted in global environmental damage, huge fires, acid rain and mega tsunamis.  Not surprisingly then that approximately 70% of life was wiped out.

This theory has been largely accepted by the scientific community, but debate has arisen as to where this asteroid object came from.  Now new research by a joint US and Czech team, published in the journal Nature points to an event between 140 mya (million years ago), and 180 mya that set in motion the asteroid collision that would spell doom for the non-avian dinosaurs.

Asteroid Collision

A collision between two large asteroids in an orbit between Mars and the outer planets may have sent huge splinters of rock hurtling towards Earth, including the one that hit 65 mya claims the team from the South-west Research Institute of Colorado.

The three researchers, William Bottke, David Vokrouhlicky and David Nesvorny created a computer simulation that plotted the paths and direction of many large objects in what is known as the “Asteroid Belt” between Mars and Jupiter.  The orbit of one large terrestrial object known as (298) Baptistina intrigued them, as it shared the same orbital path with a lot of smaller asteroids.

Using the computer model to study the trajectories of these objects in the past, the team noted that the Baptistina asteroid and these other rocks were once joined together as a giant asteroid over 100 miles across, cruising the innermost region of the asteroid belt.  Their studies showed that between 140 mya and 180 mya (160 mya is the time period stated with most confidence by the researchers), a time when dinosaurs were dominating the Jurassic period – this huge asteroid was “bumped” into by another monster rock some 37 miles across (60 kilometres).

For a lesson plan relating to asteroids and extinction events designed for Key Stage 1 and Key Stage 2 students: Why Do Asteroids Always Land in Craters?

From this soundless collision was born a huge cluster of rocks, including 300 bodies larger than 6 miles in diameter (10km) and 140,000 bodies larger than 1/2 mile in size.  Over the remainder of the Mesozoic these rock pieces found new orbits under the influence of the Yarkovsky effect (named after the Russian engineer who identified this phenomenon), thermal particles from the Sun give objects momentum.  As the group of rocks spread out, at least some of them were captured by the gravitational pull of the inner planets and they began their journey with many impacting on Mars, Earth and Venus.

One such lump ended up colliding with Earth and causing the Cretaceous/Tertiary mass extinction.  The joint US and Czech team identify other celestial craters that may have been caused by debris from the Baptistina collision, a number of craters on Venus may have been as a result of this event and the huge moon crater Tycho estimated to be 108 million years old may also have been caused by an asteroid sent on its course by the initial impact 250 million miles away and approximately 60 million years earlier.

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