Tuesday, 23 February 2010

White-Out at Quarry 4

Quarry 4 has a definite stay of execution. There are a few reasons for this which I shall relate in a later post but suffice to say that the quarry will now not be flooded until August 2010 at the earliest, and that is only a tentative date at this moment. The quarry will continue to be worked for its organically rich clay over this period but on a reduced scale.

However, this still means fresh exposures for a few more months at the very least. This pleasing development has led to a few bonus field trips over the winter but the weather this year has been particularly hard and conditions have proven difficult time and time again and, to be honest, prospecting has been tough.

There have been a few pieces recovered during this time but nothing of consequence although Carl’s previously highlighted Liopleurodon tooth is a definite highlight. Also, some associated ichthyosaur material is slowly coming to life, particularly parts of a skull. Already recovered are an excellent basioccipital, exoccipital, and sclerotic plates. We are hopeful that more of this skull will weather out although, as of this moment, there appears to be no associated post cranial material.

As you can see from our most recent trip to the quarry, snow made prospecting almost impossible. It’s hard to believe that the conditions only 24 hours earlier were perfect. And yet, even in such conditions, Carl still managed to winkle out an ichthyosaur neural process (nothing to do with the aforementioned specimen). I think we’ve all had enough of winter now and look forward to Spring – it cannot arrive soon enough. And with further trips to Quarry 4 and the new Quarry 5 in the offing we are, as always, optimistic about the years prospecting.

Thursday, 18 February 2010

Prep Jobs for a Rainy Day

I love theropod teeth. There’s a beauty about them that provokes your imagination into overtime. For a start, in the right formation, they can be fairly commonplace. They vary in size, colour and shape and are often well preserved. It never fails to amaze me how amazing the enamel detail can be after millions of years have passed.

They are also much more intimate than bone. For me, when you pick up a tooth in the field, your mind instantly alerts you to the fact that this tooth was in a theropod mouth and undoubtedly aided the animal in killing its prey and for eating meat (and bone in some cases). The tooth was either shed during a meal or perhaps, when the animal died, became disassociated from the rest of the carcass. Yes, teeth, for me, are fascinating and they can tell us so much.

Because teeth, like all fossils, can be found in various states of preservation, they all represent different challenges when it comes to preparation and conservation. Take for instance the Daspletosaurus tooth in the image above and those that follow below. It’s unusual to find teeth of this size anyway, but this dentary tooth is exceptionally well preserved. Aside from some gentle pick work to remove matrix, light brushing and a gentle hand polish (with no solvents or chemicals I hasten to add), this tooth needed nothing in the way of restoration.

For conservation purposes though, the base of the crown and a few cracks were cleaned thoroughly and stabilised with a consolidant. But this really was as much as was needed for this tooth. Incidentally, this tooth was identified as Daspletosaurus torosus but I’m not so sure and have temporarily labelled this tooth as Daspletosaurus Sp. The superb serrations are tiny for a tooth this size – I’ve never seen anything like them before and am looking forward to studying the tooth in more detail.

These next teeth are also tyrannosaurid teeth, but this time from the Hell Creek formation in Montana.These are two teeth that were recovered in a disassociated state and highlights how different the challenges can be. The first example simply does not have enough substance to form a tooth again whilst the other went together reasonably well and, although there are obviously parts missing, it isn’t too bad a specimen for a reconstruction job. It could be restored a lot more if required but I prefer such teeth as they are and these are useful for comparative study.

This next image shows another example – probably a tooth from Tyrannosaurus rex, since this is from uppermost Maastrichtian deposits of Montana. This, on the face of it, is a fairly large tooth and there appears to be enough substance for a decent reconstruction. The fragments on the left of the image have been separated out because they all have a blue hue and should piece together as a base for the entire reconstruction. Being a large tooth obviously aids the rebuild. And then you get to the jobs for a rainy day – a very rainy day!

These next images show two dromaeosaurid teeth – probably Saurornitholestes. When teeth get this small, an enjoyable part of reconstruction can suddenly become a nightmare scenario. I mean, there’s fiddly and then there’s really fiddly, and fragments of these proportions are incredibly hard to work with. There is no immediate rush for these at the moment and it will have to rain very hard for me to consider working with them although they will be looked at eventually. If I had to make an evaluation of these two teeth now, I'd say the first tooth almost certainly does not have enough substance for reconstruction but the second tooth has a chance.

In any event fossil teeth, as well as fossil bone, in such a fragmentary state represent a significant challange to the preparator. A combination of both lateral and three dimensional thinking, as well as anatomical knowledge is required and, of course, a bit of luck is always welcome!

Tuesday, 2 February 2010

An Unusually Well Preserved Vertebra from the Hastings Group

First of all let me apologise for the lack of entries over the last couple of months. It’s been a pretty hectic time to be honest, but I have been keeping an eye on the palaeo-blogosphere and, boy, has it been busy out there or what? Lots of new critters already and it’s only the beginning of the year!

What I have done, however, is finished preparation of a cracking vertebra that was recovered in 2008 from the Wadhurst Clay (Hastings Group), not too far from Bexhill. It is Lower Cretaceous in age (Valanginian), about 135 million years old.

Unusually for a vert from the clay it obviously had some processes preserved and intact. This is really unusual since, although vertebrae from this formation are not exactly rare, they are often poorly preserved and water worn. This was obviously a special bone and I was very keen to do it justice.

The matrix that had encrusted the bone had also been its saviour and it was quite tough in places to remove but it was also, on occasion, surprisingly easy to remove. The centrum was fairly easy to clean but the processes were especially tough to clear. Surprisingly perhaps, the neural canal was easier than I expected to clear out.

Throughout the whole procedure, there was only the one repair required – one of the tips on a prezygopophysis came away but this was easily stuck back together with B72. Other than that, a light dressing of B76 was all that was needed to finish the job. Overall the bone was nice to work with and rather forgiving when it needed to be.

What we have here is an anterior caudal vertebra from Iguanodon (MWB-014.0408). It’s hard for me to reduce it to the species level although I’m almost certain it is bernissartensis but, for now, Iguanodon Sp. will have to suffice.

The images will give you a brief idea on the process involved. I hope you enjoy the images as much as I enjoyed prepping it.