Soft Tissue Preservation in Late Cretaceous Dinosaur Bones
When Everything Dinosaur team members were first informed of a paper being published that reported on “blood cells and soft tissue” having been discovered in dinosaur fossils the day before the film “Jurassic World ” was released, there was some scepticism around the office. Amid the inevitably lurid and rather dramatic headlines which have been seen in some publications we thought it a good idea to try to put this fascinating piece of research into a wider context. The study was undertaken by scientists at the Imperial College London, their findings were published in the academic journal “Nature Communications”, it is not going to herald the establishment of a number of genetically engineered dinosaur themed safari parks, but it does suggest that even poorly preserved body fossils may contain more than just permineralised materials.
Bones and Teeth Alone are Not Enough
Most of what we have learned about the Dinosauria has been gained from studying their bones and teeth. Trace fossils too have proved useful, even permitting researchers to speculate on behaviours such as social groupings and pack hunting, but if traces of soft tissue could be analysed, then our understanding could move forward exponentially. Such a study could provide valuable insights into dinosaur physiology, it would for example, provide strong evidence with regards to the endothermy versus ectothermy debate (warm-blooded versus cold-blooded). Importantly, the link between the Coelurosauria and birds could be established beyond doubt. In short, it could be proved that the Robin perched on your bird table is indeed a distant relative of Tyrannosaurus rex.
Dr. Susannah Maidment One of the Authors of the Study Holding a Stegosaurus Skull Cast
Dr Susannah Maidment, one of the authors of the study holding a cast of a Stegosaurus skull.
Picture Credit: Laurent Mekul
A point that we frequently make is that dinosaur biology remains very much a mystery. What we have learned has come about through some very remarkable research that utilises techniques and scientific methods that were undreamed of even a few years ago. It is the collaboration between different scientific disciplines that is providing so much new information on dinosaurs and other extinct creatures. The use of computerised tomography (CT), for example, has enabled palaeontologists to explore the three-dimensional structures of fossil bone, even when it has been embedded in extremely dense rock. In this study, samples from eight dinosaur bone specimens were subjected to scanning electron microscopy (SEM) to provide exquisite images of the fossil structures in minute detail. A number of samples were studied using a focused ion beam (FIB), an imaging and resolution technology more at home in a materials science lab but now finding an increasing number of applications in other scientific areas of enquiry including vertebrate palaeontology. It is the adoption and application of different scientific methods, drawn from a whole variety of research fields that is enabling academics to make some remarkable discoveries, shedding light, or in this case electrons and ions on those most enigmatic of extinct creatures – the dinosaurs.
Any Old Fossils?
The novel approach undertaken by the Imperial College scientists sets up an intriguing possibility, one that allows us to use an analogy from the “Jurassic Park” franchise to explain. The eight fossils used in this study came from the Natural History Museum (London), which is conveniently located just a few hundred metres away from the College. Specifically the fossils come from two collections at the Museum, all of them relate to Late Cretaceous dinosaur fossil material from North America (Dinosaur Provincial Park and Lance Formations respectively). The fossils studied represent a claw bone from an unknown species of meat-eating dinosaur, a partial rib from an indeterminate duck-billed dinosaur and other bits and pieces of assorted dinosaur that would not have got a second glance had they been on display. That’s the point. Evidence for soft tissue preservation in a number of vertebrate fossils have been reported before, even in the Dinosauria. This area is not without controversy, but here evidence has been presented for the potential preservation of organic remains from reptiles that died more than seventy million years ago.
Dinosaur Claw Bone used in the Study
Manual ungual (dinosaur claw) from an unknown species of Theropod used in the Imperial College London study.
Picture Credit: Laurent Mekul
If these fragments of fossils can possibly contain proteins and other biological structures, then maybe, just maybe there is a lot more preserved within the fossil record – we just have not been looking for it.
Let’s use that “Jurassic Park” analogy to look at this intriguing aspect further. In the original book, written by Michael Crichton and published in 1990, the InGen scientists (the team behind the creation of various dinosaurs using DNA recovered from blood-sucking insects preserved in amber, mixed with amphibian genetic material and so forth), come up with what they think to be an infallible method of ensuring that all their engineered dinosaurs stay on their island home. Each animal’s position is tracked and movements can be recorded using a simple receiver. With three hundred dinosaurs on the preserve, it is just a case of asking the software that tracks the animals’ comings and goings to find three hundred dinosaurs. Every day without fail, when asked, the computer read out states that there are three hundred dinosaurs on the island. The flaw in this safety precaution is pointed out by Dr. Ian Malcolm, a mathematician who has been brought to the resort in order to validate it prior to the park opening to the public. The good doctor, asks the computer programme to find three hundred and one dinosaurs, and sure enough the software reports on that number. Dr. Malcolm continues to interrogate the team behind the computer programme asking repeatedly for the software to detect more and more dinosaurs. The doctor, a specialist in Chaos Theory, had predicted that the biological preserve would fail “nature finds a way” as he so eloquently states in the film. Despite the entire dinosaur population starting out as female, the animals had started to breed and that was why there were more dinosaurs recorded than expected.
Just like in the example above, scientists may have been asking the wrong questions. Soft tissue preserved in the fossil record of long extinct creatures might be more common than previously thought. Similar structures have been observed before, but for most of the time, the research was focused on investigating the range of criteria that were believed to have existed to have led to the preservation of organic remains, these specimens were treated as the exception – could they be the norm?
Tiny egg-like shapes identified deep within a dinosaur claw bone that have a resemblance to red blood cells, certainly deserve further analysis and investigation. Admittedly, the red and green images of the structures with the different colours reflecting varying material densities can be confusing, after all, if a lay person reads a headline in a magazine stating that dinosaur blood may have been found and sees a picture covered in red, he or she may jump to one very obvious conclusion. Mass spectrometry analysis, another relatively recent addition to the palaeontologist’s ever increasing technical armoury, this time from the laboratory of an analytical chemist, threw up tantalising results when the red blood cell-like materials were scrutinised. Four different regions from the same fossilised Theropod claw were compared to the mass spectrometry report for Emu blood. The resulting data suggested that there were indeed chemical similarities. If this really is some form of preserved, (although quite probably severely degraded), remnant of a Theropod dinosaur’s blood then, as Ratites such as the Emu are believed to be closely related to the Theropoda then similar mass spectrometry results could be anticipated.
Potential Evidence of Preserved Red Blood Cells in Dinosaur Bone
Evidence of potential red blood cells preserved in 75 million year old dinosaur bone.
Picture Credit: Laurent Mekul
Microscopic Fibres – More Caution Advised
Fibres or fibrous-like structures were reported from half the samples studied. In one specimen, a fragment of rib bone from an unknown dinosaur revealed a structure within it that resembled collagen. Further chemical analysis revealed traces of amino acid fragments such as glycine, alanine and proline. This is consistent what you would expect to find if you were analysing collagen. If a fragment of collagen could be recovered, then that would be a remarkable discovery indeed. Like blood and other organic materials these substances are believed to degrade relatively quickly after death. However, if a protein based structure like collagen could be found in the fossilised bones of a dinosaur then this would open up an entirely new area of research into the Dinosauria.
Potential Collagen Structures Preserved in Fossil Bone
Fibrous structures preserved in fossilised bone.
Picture Credit: Laurent Mekul
The scientists behind this paper are keen to point out that further study is required. Two of the fossil bones used in this research revealed no traces of any potential soft tissue components, a point missed by a number of media outlets that covered this story. However, if poorly preserved fossil material can retain microscopic traces of blood and other organic materials then it will change our science forever. Dig sites will be subjected to forensic procedures, perhaps a clean room will be have to be set up in the field to help minimise the risk of organic cross-contamination. What about the use of glues and resins that act as fossil bone stabilisers? Could the over enthusiastic use of super glue at a dig station compromise the chances of retrieving viable traces of organic material later, back in the prep lab?
If other institutes can repeat these experiments and produce the same results consistently, then this has some dinosaur-sized implications for palaeontology. If it can be concluded that the structures observed and analysed within the samples do indeed originate from preserved proteins from the extinct animal, then we may have an opportunity to study soft tissues in long dead creatures. A more complete understanding of dinosaur biology may be within our grasp.
Now that would be something to make a movie about.