Thursday, 4 April 2013

Deinocheirus - The Truth ( Sort of )


From Osmolska & Roniewicz (1970)
 
Well I must say that I was glad that my April fool’s post was taken in the spirit I intended.  I was a little apprehensive since this was my first prank as a blogger and did not want to ruffle anyone’s feathers. I needn’t have worried and it made a pleasant change to have a bit of fun.
However, what the post has proven is that many of us have this insatiable thirst for the truth about Deinocheirus. It’s not hard to understand why. Since those forelimbs were recovered way back in 1969 we have all wondered about this enigmatic animal. I mean these forelimbs are eight feet long – eight feet!
Many of today’s palaeontologists and bloggers grew up in the dinosaur renaissance period – when dinosaurs really came to life as living, breathing, highly active animals. Throughout this period many dinosaurs went through rigorous reanalysis and restoration and we all got carried away with the hot blooded dinosaurs. Despite the renaissance somewhat levelling off throughout the eighties,  in 1993 Jurassic Park was released and was the spark for a whole new wave of interest and research into dinosaurs which has continued to proliferate into today’s fast moving science. And yet, in all of this, the truth behind Deinocheirus has remained hidden and the animal has held station as a more or less unknown quantity - except in phylogenetic analyses.
Before the onset of modern day cladistics and phylogenetics there was always the possibility that Deinocheirus was indeed a mega-theropod – built along the same basic blueprint as any theropod. But because it could not be imagined that any theropod could be THAT big it was thought that Deinocheirus may have been built along similar lines as a giant ground sloth and used its long arms in a similar way.
Of course, and in the same vein, the claws of therizinosaurs were also known at this time (in fact known since the 1940’s) and this animal too proved to be problematic for many years, initially being identified as probably being a turtle-like reptile. It was over twenty years before they were realistically identified as belonging to a theropod dinosaur. Fast forwarding a further twenty five years and new specimens turned up that allowed a pretty accurate restoration of therizinosaurs as a group.
But the so-called deinocherids have still not yet been satisfactorily classified and this for many, myself included, is really frustrating. So they may be primitive ornithomimosaurs but, realistically, we have not really progressed any further in nearly fifty years. Why is this?
Well, for me, and perhaps at the risk of sounding obvious, we do not have a lot of material. There is only the holotype that we have good material for and that, in real terms, is not a lot. However, back in 2008, Phil Currie relocated the holotype quarry, which was reopened, and there were was more bone collected. What this material consisted of is unclear but certainly some elements were subject of a paper published in 2012 (Bell et al 2012) which looked at feeding traces on these bones which were most likely made by a tyrannosaurid.
Now whether there is still more significant material from the quarry still being described is unclear at this moment in time but, as is the way, rumours persist. It may very well be that the Bell paper represents all that was recovered from the site and that maybe that. Until something concrete is published then Deinocheirus will remain the great unknown.
For me, this lack of fossils is actually one of the most interesting points regarding Deinocheirus and suggests that this animal most likely inhabited a completely different environment from the rest of the better known Nemegt fauna. Tarbosaurus, in comparison, is extraordinarily well known and fossils of this tyrannosaur are not uncommon. Tarbosaurus and its contemporaries lived in a warm, meandering fluvial environment and, for me, this is highly indicative that Deinocheirus was living elsewhere.
If Deinocheirus preferred a different, more upland environment then it could go a long way to explaining the lack of fossils. Dinosaur skeletons need to be buried quickly if they are to fossilise and the chances of any skeletal remains from any dinosaur making it through to fossilisation in an upland environment are massively reduced.
 
From Osmolska & Roniewicz (1970)
 
There is further, somewhat unfortunate evidence, to support this. Poaching and vandalism in the Nemegt is not uncommon and we are all aware of the stories. There are many instances, especially with Tarbosaurus, of skulls being removed from some good articulated specimens and the rest of the skeleton being vandalised or completely destroyed. This is very hard to police and despite the many vociferous displays of condemnation, fossils from Mongolia still end up on the open market whilst the very best examples are probably smuggled out and sold privately to the highest bidder.
But this does highlight just how rare any example of Deinocheirus must be. With the amount of illegal excavating there has been over the last twenty years, it is inconceivable that, if any decent material had been recovered, that someone would not have heard anything by now. There would be rumours - someone would know.
So unless anybody knows any different, then it is extremely unlikely that there is any other significant material from Deinocheirus in circulation. Of course it is possible that there may some material in an unopened jacket waiting to be discovered in the bowels of some institution but this is unlikely. So for me Deinocheirus will remain an enigma for some time to come.
Of course, we may simply be looking in the wrong place……..

References

Bell, P.R., Currie, P.J., & Lee, Y.N. (2012). Tyrannosaur feeding traces on Deinocheirus (Theropoda:? Ornithomimosauria) remains from the Nemegt Formation (Late Cretaceous), Mongolia. Cretaceous Research (37) pp. 186-190.
Osmólska, H. & Roniewicz, E. Deinocheiridae, a new family of theropod dinosaurs. Palaeontologica Polonica 21, 5-19 (1970).
 
 
 
 
 
 
 
 
 
 
 
 
 

Monday, 1 April 2013

Newly Discovered Skeleton of Deinocheirus Reveals Mega-Theropod


 
A new, virtually complete, specimen of the enigmatic theropod Deinocheirus mirificus, discovered in the Nemegt Basin of the Gobi Desert in Mongolia looks set to shake the world of theropod phylogenetics to the core. This specimen of Deinocheirus was recovered from Upper Cretaceous deposits not too far from where the original specimen was found at Altan Ula III and provides undisputed evidence that this animal represents a new gigantic sized coelurosaurian clade.
The specimen is currently being described and will be officially published later this year in the Proceedings of Earth Sciences – this current press release appears to be a taster of what is to come and is typical of some of today’s fast moving media-driven palaeoresearch.
 
“This has completely surprised us and we could hardly believe our eyes as the skeleton slowly emerged from the rock. A complete specimen of Deinocheirus is a palaeontologist’s dream and to find it so close to the quarry where the holotype was found is rather fitting.” said palaeontologist Dr. Pol T’Othewan, leader of the excavation and research team at the Nemegt Basin Research Centre (NBRC) in Dalanzadgad, Ömnögovi Aimag in Mongolia.
Deinocheirus is most famously known because of its huge forelimbs which are around 8 feet long. Although clearly a theropod dinosaur, the phylogenetic affinities of Deinocheirus have long been debated and the animal has been tentatively assigned as a megalosauroid, coelurosaur or, indeed, something in between the two. The most recent phylogenetic analyses return Deinocheirus as a basal ornithomimosaur but this new specimen looks set to confound the experts.  
“When Deinocheirus was originally discovered it was thought that because the forelimbs were so big that the rest of the animal could not possibly be of the same stature otherwise its size would defy imagination – they were wrong” said co-worker and palaeontologist Gotya Sukker – also of the NBRC.  “What we have now appears to represent an offshoot coelurosaurian clade displaying both primitive and derived characters and that Deinocheiridae is, indeed, a very distinct family. The size of the animal is astonishing and the skull alone makes the skull of Tarbosaurus look maniraptoran in comparison.”  
The specimen, which appears to be a fully mature individual, was found in the sandstones of the Upper Nemegt Beds and, despite being largely disarticulated, is essentially all there and appears to have suffered very little erosion which suggests that it had only been recently exposed at the surface before being discovered. The specimen was immediately identified as Deinocheirus, whose name means “terrible hand”, when the enormous forelimbs were excavated.
“Close examination has revealed several characters that are totally unknown in other dinosaurs – let alone other theropods. Certainly there is extensive remodelling in the vertebral column and a degree of pneumaticism only previously seen in sauropods and the hind limbs are incredibly long and strong” said another member of the team, Luke Anyulsee, of the University of Kehlsdorf in Austria.
Deinocheirus has always been an enigma in dinosaurian palaeontology but this skeleton, because of its completeness, will give us new insights into coelurosaurian evolution and has significant ramifications for dinosaurian phylogenetics as a whole.
“It has generally been accepted for some time that Deinocheirus was probably an over-sized ornithomimosaur with similar habits and lifestyle to its smaller cousins” Sukker said. “This specimen shows that, despite displaying ornithomimids traits in some parts of the skeleton, it was obviously something completely different. The skull is enormous – far bigger than any previously known theropod skull and the dentition is frightening. Deinocheirus would have unquestionably been the hyper-carnivore of its time”.  
Adult tyrannosaurs too, by comparison, were enormous animals and Tyrannosaurus was around 40 feet long with a skull approaching 5 feet long. Spinosaurus, despite being poorly known, is estimated to be around 50 feet long. When asked how they compare with Deinocheirus, T’Othewan is remarkably blunt in his response.
“They don’t – there is no comparison. Deinocheirus would have them sliced and diced and ready for breakfast before they knew it. This is now THE mega-theropod of the Mesozoic.”
This research is being funded by the Avril Tromper Foundation in Paris.