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).
 
 
 
 
 
 
 
 
 
 
 
 
 

6 comments:

Craig Dylke said...

The last time I was at a conference Dr. Currie attended he alluded to the material really shaking up things with this animal... However that was in 2010. We'll just have to wait and see.

Mark Wildman said...

That's interesting to know - thanks for the information Craig.

emailmark said...

Phil Currie is presenting at the FPCS at the Royal Tyrrell in a couple of weeks time. If I get the chance I'll ask if there is any news.

Mark Wildman said...

Excellent Mark - it would be good to have some up to date news.

Anonymous said...

Weird, there have been rumours of 'another' find at least since 2008. And Tom Holtz, himself (when Yutyrannus was published), alluded to something that would shake things up a bit. At the time, I thought he was talking about Megaraptorids. The plot thickens.

Paul W.

Mickey Mortimer said...

Here's a thought. Those "hyoids" as figure 2 in the plate you used could be xiphisternal processes as in Struthiomimus. Compare to figure 1 here http://www.bio.ucalgary.ca/contact/faculty/pdf/russell/20.pdf . Both are paired and curved with one flat end and one tapered end, one element has an extra process for articulation, and they're wider than the gastralia. It would also make sense that something around the pectoral area was preserved instead of something around the skull.

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