Saturday, 29 July 2017

Tyrannosaurus rex couldn’t run says new research

·       T. rex could not run due to its size and weight
·       T. rex was unable to pursue prey at high speeds
·       Even walking speed was limited due its impact on the skeleton
·       This changes the way we have to think about the way T. rex behaved
It is a classic chase scene in modern cinematic history. The image of a rampant Tyrannosaurus rex (T. rex) chasing Jeff Goldblum as he sits injured in the back of a 4x4 vehicle in Stephen Spielberg’s original Jurassic Park.
But could a T. rex actually move that fast, or even run at all?
New research from the University of Manchester says the sheer size and weight of T. rex means it couldn’t move at high speed, as its leg-bones would have buckled under its own weight load.
The research, in collaboration with the N8 High Performance Computer (NPC) research partnership, looks extensively into the gait and biomechanics of the world’s most famous Dinosaur and, using the latest in high performance computing technology, has created a new simulation model to test its findings.
Led by Prof William Sellers from the School of Earth and Environmental Sciences, the researchers have combined two separate biomechanical techniques, known as multibody dynamic analysis (MBDA) and skeletal stress analysis (SSA), into one simulation model, creating a new more accurate one.
Prof Sellers says the results demonstrate any running gaits for T. rex would probably lead to ‘unacceptably high skeletal loads’. Meaning, in layman’s terms, any running would simply break the dinosaur’s legs. This contradicts the running speeds predicted by previous biomechanical models which can suggest anything up to 45mph.
He explains: ‘the running ability of T. rex and other similarly giant dinosaurs has been intensely debated amongst palaeontologist for decades. However, different studies using differing methodologies have produced a very wide range of top speed estimates and we say there is a need to develop techniques that can improve these predictions.
‘Here we present a new approach that combines two separate biomechanical techniques to demonstrate that true running gaits would probably lead to unacceptably high skeletal loads in T. rex.’


The results also mean that the T. rex couldn’t pursue its prey in a high-speed chase as previously thought. He added: ‘Being limited to walking speeds contradicts arguments of high-speed pursuit predation for the largest bipedal dinosaurs like T. rex and demonstrates the power of Multiphysics approaches for locomotor reconstructions of extinct animals.’
Although the research focuses on the T. rex, the findings also means running at high speeds were probably highly unlikely for other large two-legged dinosaurs such as, Giganotosaurus, Mapusaurus, and Acrocanthosaurus.  
Dr Sellers adds: ‘Tyrannosaurus rex is one of the largest bipedal animals to have ever evolved and walked the earth. So it represents a useful model for understanding the biomechanics of other similar animals. Therefore, these finding may well translate to other long-limbed giants so but this idea should be tested alongside experimental validation work on other bipedal species.’
This isn’t the first time MBDA and SSA have been used to measure the walking and running ability of dinosaurs. However, it is the first time they have been used together to literally create a more accurate picture.


Dr Sellers explains: ‘Our previous simulations of theropod bipedal running did not directly consider the skeletal loading but these new simulations do calculate all the forces in the limb bones and these can be used directly to estimate the bone loading on impact.’
The fact that T. rex was restricted to walking also supports arguments of a less athletic lifestyle. This means the results could change the way we view the effects of how the size and shape of T. rex and other large bipedal dinosaurs alters as they grow.  Previous studies have suggested the torso became longer and heavier whereas the limbs became proportionately shorter and lighter as T. rex grew. These changes would mean that the running abilities of T. rex would also change as the animal grew with adults likely to be less agile than younger individuals.

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But Dr Sellers says these new findings show this probably wasn’t the case and we should apply this new model even wider: ‘It would be very valuable not only to investigate the gait of other species, but also apply our multiphysics approach to different growth stages within that species.’
You can download this paper for FREE from PeerJ, click this LINK

Friday, 11 November 2016

When is a fossil a fossil...

The most common form of fossilization produces remains that clearly record the biomineralised skeletons of prehistoric animals, the “hard parts” of these creatures, since the soft tissues usually decay and disintegrate soon after death. Dinosaur bones and teeth are such biomineralised skeletal features, as are the shells of molluscs, the external skeletons (exoskeletons) of insects, and the carapaces of crabs, to name only a few examples. Even biomineralised hard parts can be fragile and subject to decay or mechanical breakdown when they are small in size, which is why we are not up to our necks in fossils. The thin and often hollow bones of flying vertebrates such as pterosaurs, birds, and bats are notoriously fragile since they are built so lightly, and they are therefore comparatively scarce in the fossil record. Small mammals likewise have tiny bones that are easily fractured or otherwise broken down and lost to time. The only remains of many species, especially mammals, is often only their teeth. As with many animals, teeth are the hardest parts of their bodies and therefore the most resistant to post-mortem destruction. Many individual animals, especially the early record of mammals and some entire groups, are known only through finds of their fossilized teeth.

To extend our understanding of creatures known only through fossil hard parts, we use comparisons with modern life forms that appear to be structurally similar. This is the science of comparative anatomy, and it has been successfully applied by biologists and palaeontologists for centuries. We can also bracket extinct species with living species that are related to ancestral and descendant members of the extinct group, this is known as the extant phylogenetic bracket (EPB) and was developed by Larry Witmer (Ohio University, USA). In many cases we find additional evidence, such as the scars of muscle attachment on fossil dinosaur bones, which show that the EPB data appear to be appropriate. Combining such evidence and EPB with a liberal application of comparative anatomy, we can build an understanding of the complete prehistoric animal, as it was with its soft tissues intact. While evidence supports certain aspects of such extrapolation, in other respects this work is necessarily speculative. 

Fossilisation is a rare phenomenon that occurs only to a tiny fraction of a community’s population at any given place and period, but in most cases, no trace is left behind.. Nonetheless, if we consider the fossilization of skeletal elements as the standard, then the fossilization of soft-tissue structures is much rarer still. When these unique discoveries are made, this type of fossilisation literally “fleshes out” our understanding of the fossil record in many crucial ways. Even a single example of soft-tissue preservation can be of tremendous value in the interpretation of fossil animal types. These discoveries are of such special interest that it is worth reviewing some of the classic examples of this phenomenon. In each case, special circumstances prevented the ordinary loss of soft tissues. 

It is clear that some organic remains of life have been altered to a point that it is difficult to identify them as being a specific organism, however their organic origin is not brought into question. Once such group of organic compounds are hydrocarbons. A suite of economically important ‘minerals’ that have been altered so far, but still retain vestiges of organic compounds that reveals their origin. The body fossils (bone, shell, etc.) of dinosaurs and other vertebrates have both recognizable organic chemistry and morphology, they have not been processed to the point that they may be considered ‘products’ from the original organism. 

Fossils are indeed partially composed of chemistry that directly links them to the organisms from which the fossils remains came. They really cannot be considered minerals (a solid naturally occurring inorganic substance), but are truly ‘geobiological’ composites of both inorganic and organic molecules that were constructed through biological and post-burial processes that preserve the fossil through deep time. The alteration that occurs to the biological tissue through subsequent mineralisation rarely overprints the organic composition of an organism completely. Our team at the College of Charleston, University of Manchester and also at the Stanford Synchrotron Radiation Lightsource (Stanford University, USA) have been chemically mapping fossils using multiple imaging techniques to elucidate these geobiological composites we commonly know as fossils.

The carbon cycle is remarkably efficient at recycling organic material, but under certain preservational circumstances, some of the chemical building blocks of an organism make it through this taphonomic filter. In exceptionally preserved fossils, it is possible that remnants of structural proteins and associated organic molecules survive and can be mapped to help resolve original biological structures. The potential for new techniques to compositionally or spatially resolve such ‘chemical fossils’ is being realized with the recognition of elemental and organic residues that once comprised living tissue. Until the advent of techniques sensitive enough to resolve trace amounts of organic compounds and organically bound elements, it was difficult to untangle potential material transfer from microbes, geochemical fluids and the contamination from sampling/conservation techniques applied to a sample. However, the advent of synchrotron-based imaging and infrared spectroscopy has revolutionized sample analysis, enabling high-resolution scans that spatially resolve reaction aureoles, precipitates, etc. The suite of de novo techniques available to paleontology is completely changing our understanding of what constitutes a ‘fossil’.

Saturday, 29 October 2016

Imaging Life on Earth...




Archaeopteryx from the Late Jurassic of Southern Germany.
Since the dawn of time, our species has recorded images of life on Earth. Whether it be the beautiful cave paintings that captured our world over 17,000 years ago to the brush-strokes of Rembrandt, they share our species desire to capture the world around us. The origin and evolution of our own species has been preceded by billions of years of evolution that is complemented by a rich and diverse record of life on this planet. While there were no artists to record on canvas this rich tapestry of life through time, rare circumstances arose that would preserve the remains of life as fossils. Most have considered fossil remains as mere echoes of their former biological selves, but some fossil do preserve astoundingly high fidelity structures of both hard (e.g. bone, shell) and soft tissues (e.g. feathers, skin).

Fossils provide us with the evidence that narrates the story of decent with modification that is the evolution of life on Earth. Unravelling genomes and reconstructing molecular phylogenies can now precisely measure the evolutionary distance between organisms in the tapestry of extant species. The DNA that defines life is a fragile molecule, unable to resist even the gentlest ravages of geological time. The molecule of life is recovered from rare samples no older than 1 million years old, and then only in exceptional circumstances. The proteome might be the next logical focus, as proteins are more robust and might leave tantalizing evidence for the very building blocks of life. Here the frustration is also evident to those who study such ancient molecules, as anything older than 10 million years is rare. Is there another way that we can unpick the biological codec concealed within fossil remains?

However, the fossil remains that litter deep time are not so easy to characterize, but have the potential to constrain much of what we know record about the evolution of life on Earth.

The very atoms that construct biological materials can and do survive deep time, this is evident by the breakdown products of organic remains that drive our hydrocarbon-based economy. There is good reason that hydrocarbons are often termed ‘fossil fuel’. It is therefore strange that there is such amazement at the survival of organic remains within discrete biological structures, otherwise known as fossils.  Recent work has shown there are biomarkers that can be identified, mapped and quantified in both extant and extinct organisms (plants and animals). Such biomarkers are powerful tools when unlocking the puzzle of organismal biology, physiology and the very biosynthetic pathways that built, regulated and drove the evolution of life. The advent of synchrotron-based imaging techniques are now allowing us to piece together the complex relationships between trace-metals, rare earth elements that help study tissue types that comprise life, both past and present. The fragile paradigm that fossils merely represent shadows of past life is now being challenged, not with the promise of DNA or intact proteins, but from the fundamental building blocks of everything, elements. The chemistry of life is now helping reveal hitherto unseen 'chemical ghosts' by shining some of the brightest light in the universe upon fossils.

Synchrotron-Rapid Scanning X-Ray Fluorescence Map of Archaeopteryx scanned at beam line 6-2 at SSRL

Fossils are indeed partially composed of chemistry that directly links them to the organisms from which the fossils remains came. They really cannot be considered minerals (a solid naturally occurring inorganic substance), but are truly ‘geobiological’ composites of both inorganic and organic molecules that were constructed through biological and post-burial processes that preserve the fossil through deep time. The alteration that occurs to the biological tissue through subsequent mineralization rarely overprints the organic composition of an organism completely. Our team at the College of Charleston, University of Manchester and also at the Stanford Synchrotron Radiation Lightsource (Stanford University, USA) have been chemically mapping fossils (above) using multiple imaging techniques to elucidate these geobiological composites we commonly know as fossils.