Wednesday, 27 October 2010

An Introduction to the Oxford Clay - Part 2

In the first part of this mini-series, we looked at how the Oxford Clay was deposited and took an overview of the general climate, palaeoecology, and fauna of this highly complex ecosystem. Now I am going to look at some of the more important marine reptiles that have been recovered from this very important rock unit.

For more than 100 years now, the brick-making industry has given us a unique insight into the ancient Jurassic seas. The mud and sediment that accumulated on the sea floor formed the Oxford Clay, and this has been extracted from the brick pits on a massive scale which, in turn, has revealed a myriad of saurian remains.

In England, the area in and around Peterborough has proven to be a rich source. Alfred and Charles Leeds were probably the most significant of the early collectors. The Leeds brothers gathered, en masse, an extensive collection in the early 1900’s and these form the backbone of the marine reptile collections at both the British Museum of Natural History and the Hunterian Museum in Glasgow.

John Phillips was another important collector during the 1920’s and some of his finds reside at the Peterborough City Museum & Art Gallery, as do the more recent discoveries made by Alan Dawn during the 80’s and 90’s. Bedford, Aylesbury and St.Ives in Cambridgeshire are all museums that also hold small collections of Oxford Clay vertebrates.

Also worthy of mention are the substantial collections held at the University of Leicester, which was placed in the repository by both David Martill and Roy Clements, and in the National Museum of Ireland (see Araujo et al 2008).


There are several superb specimens of international significance in the Peterborough collection and these are on permanent display at the Priestgate venue. Amongst these is a virtually complete specimen of the marine crocodile Steneosaurus durobrivensis, more correctly termed a thalattosuchian. This was recovered by Phillips in 1923 and is displayed three dimensionally.

Dogsthorpe Quarry was one of the better known Oxford Clay quarries and during its time was extremely prolific. A more or less complete specimen of Cryptoclidus eurymerus was extracted from Dogsthorpe back in 1984 by Alan Dawn and a group of volunteers from the museum. The skull of this specimen is regarded at the best preserved and most complete ever found.


Even when Dogsthorpe was finished as a clay producing quarry and was being turned into a waste landfill site, it still produced the odd surprise. An employee of Shanks and McEwan, the company who managed the site at the time, discovered the magnificent pliosaur that is Simolestes vorax. This too was excavated by Dawn along with Gordon Chancellor, the then curator at Peterborough Museum. This specimen was virtually complete and well preserved, especially the unique skull which eventually featured as one of the subjects in Dr Leslie Noe’s Phd thesis on Callovian plesiosaurs (2001).

King’s Dyke was another well known and productive quarry. In 1994, yet another new genus of pliosaur was discovered, once more by Alan Dawn. Again largely complete, the skull and cervical vertebrae were almost perfectly articulated and undisturbed, although the rest of the post crania was not. This was the holtype of Pachycostasaurus dawnii and provided yet more new data on plesiosaurian evolution.

Another quarry in the vicinity was Star Quarry, one that I have visited on one occasion and was only flooded last year and is now inaccessible. In 1996 this quarry produced a magnificent, virtually complete specimen of Opthalmosaurus icenicus. This was unusual in as much as the ichthyosaur was recovered from the Middle Oxford Clay (Stewartby Member), much like a previous specimen from King’s Dyke, although this was a far superior example. Originally found by an amateur collector, Nigel Truss, this specimen is also on display in the Peterborough Museum.

Star Pit became the subject of nationwide interest during 2001 when students from Portsmouth University found the remains of the giant fish Leedsichthys problematicus. Estimated at the time to be almost 100 feet long, it is now generally believed to a more conservative, although still massive, 30 feet long.

Once funding had been obtained, Dave Martill, Leslie Noe, Jeff Liston, Darren Naish and students, along with local volunteers from a local geological society began the excavation. Some of this was broadcast nationwide on Channel 4 via their mini-series The Big Monster Dig during 2003.

So it can be seen that not only have these clay quarries had an extremely important social and economic influence in the local area but also gave us a window through time, back to the primordial Jurassic seas. Most exciting of all, as can be seen by the discovery of Pachycostasaurus, there is still so much we don’t know and still discoveries to be made.


There may not be the amount of quarries remaining now but the odd few that remain will continue to produce and it is important that any new discoveries of scientific importance are protected and deposited into the correct repository for both study and for future generations.

Referances

A.R.I. Cruickshank, D.M. Martill and L.F. Noè A pliosaur (Reptilia, Sauropterygia) exhibiting pachyostosis from the Middle Jurassic of England
Journal of the Geological Society.1996; 153: 873-879

Andrews CW. 1913. A descriptive catalogue of the marine reptiles of the Oxford Clay, Part Two. London: British Museum (Natural History) 206pp.

Araujo, R; Smith, A.S. and Liston, J. 2008. The Alfred Leeds fossil vertebrate collection of the National Museum of Ireland - Natural History. Irish Journal of Earth Science, 26, 17-32.

Dawn, A. 1997. Fossil marine reptiles of the Peterborough brick pits. Mercian Geologist, 14, (2), 90-93.

Geoffroy Saint-Hilaire, É. 1825 Recherches sur l’organisation des Gavials, sur leurs affinités naturelles desquelles résulte la nécessité d’une autre distribution générique. Gavialis, Teleosaurus, Steneosaurus. Mémoires du Muséum Histoire
Naturelle 12, 97–155.

Liston, J. 2004. An overview of the pachycormiform Leedsichthys. In Arratia, G. & Tintori, A. (eds) Mesozoic Fishes 3 - Systematics, Paleoenvironments and Biodiversity. Verlag Dr. Friedrich Pfeil (München), pp. 379-390.

Lydekker, R. (1889) Catalogue of the Fossil Reptilia and Amphibia in the British Museum, Part II; Containing the Orders Ichthyopterygia and Sauropterygia. British Museum (Natural History), London, 307 pp.

Martill, D. M. (10) Marine Reptiles. In Martill, D. M. & Hudson, J. D. (eds) Fossils of the Oxford Clay. The Palaeontological Association (London), pp. 226-243.

Noè, L.F. A taxanomic and functional study of the Callovian (Middle Jurassic) Plesiosauroidea (Reptilia, Sauropterygia). Ph.D thesis, University of Derby, Derby. UK

Phillips, J. 1871 The geology of Oxford and the valley of the Thames. Oxford. Clarendon Press.

Seeley, H.G. 1874b On the pectoral arch and forelimb of Ophthalmosaurus, a new ichthyosaurian genus from the Oxford Clay. Quarterly Journal of the Geological Society of London 30,696–707.


Image shows a recently recovered Leedsichthys rib from Quarry 4.

Thursday, 21 October 2010

First Life

Sir David Attenborough, at the age of 84, still shows no sign of slowing up or retiring. And I'm pleased to say that his next mini-series, First Life, will be airing on the BBC during November.

Any series made by Sir David is always eagerly awaited but this is a welcome return to a palaeo-themed programme, which is something that has always been close to his heart and is his first series of its type since Lost Worlds, Vanished Lives which I consider to be amongst the best of any general audience palaeontological series, along with Alan Charig's Before the Ark (which I would love to see again).

First Life focuses on the very origins of life and both examines and compares fossils with descendant and extant living relatives. Sir David travels the world on a journey of discovery, meeting palaeontologists' along the way who reveal the latest techniques utilised to help uncover the secrets of the origin of life.

I'm not too sure when this will air over the pond but I'm hopeful that you may be able to view it on BBC I-player. Incidentally, Sir David is also making a special on pterosaurs called Flying Monsters 3D to be shown on Sky's new 3D channel in the not too distant future.

video

Thursday, 14 October 2010

SVP 2010 - A Brief Review

Now that the 70th SVP meeting in Pittsburgh has drawn to a close (very successful as well I’m told), I thought I’d mention a few things that came up during the meeting and that I’m looking forward to hearing more about in the coming weeks and months.

This year’s abstracts were full of goodies covering a wide range of subjects but there were some highlights. Starting off with the in vogue ceratopsians and there was yet more on the morphology, ontogeny and homology of these totally fascinating dinosaurs. And yet still more, as well, on Triceratops and, yes, Torosaurus – things keep rumbling on.

Certainly synonymy and, the latest buzz-word, anagenesis featured highly at this years meeting and there is continuing discussion, at all levels, regarding these very high profile subjects.

Ankylosaurids got some deserved attention this year as did the sauropods which included work on titanosaur evolution and rates of teeth replacement within the group. Hadrosaurs got a bit of attention, again mainly anagenesis and morphological issues and there was an interesting report on a particular edmontosaur bone bed in Wyoming.

I’ve become more interested in micro vertebrate sites during the last year and there were yet more interesting presentations including anthill sampling and other work in the Hell Creek formation. There were also a couple of detailed posters for preparators’ that I’m interested in and the preparators’ session, in general this year, was very well received.

Tyrannosaurids were well represented with detail mainly concerned with ontogeny, evolutionary trends and morphological data as well as some very cool information on their palaeogeographical distribution and what appears to be a couple of new taxa.

Other theropods were well represented including work on a new basal theropod, a new dromaeosaur and ongoing research into abelisaurs. Other bits and pieces included a new pachycephalosaur and some fascinating insight into hypsilophodont feeding techniques.

Not so many presentations on marine reptiles this year although mosasaurs and pliosaurs were represented and there was some detail concerning ichthyosaur extinction. However, the one presentation that fascinated me above all others was about cryptocleidoid plesiosaurs and the fact that there appears to be evidence of a tail fin! I hope to discuss this, and many other issues mentioned above, further in the not too distant future.

Tuesday, 12 October 2010

Misty Bluff - Another First


April 2009 arrived and it was soon time to return to the Bluff. Again it was another trip without any new scrapings so we would be looking over old exposures, but at least there had been another winter of wind, rain and frost to help uncover any new prospective remains.

I arrived early and was disappointed to see a contingent from the Isle of Wight again, but this time there were only four of them. However, the one guy I found so disagreeable from the previous trip was one of them. So be it then. I quickly signed in and made my way to the Bluff.

I still haven’t got used to the fact that it hadn’t changed again. Previously there would always have been a scraping or some form of quarry work that would change at least one of the facies, but not now – not until the quarry is working again.

As usual I dropped onto the south easterly reptile beds and began to prospect. The winter had washed away the previous year’s excavations although you could just make out where they had been. I’d only been looking for a few minutes when the IOW group arrived. I could hear them before I saw them – quiet they aren’t!

They walked around me, shouting away to each other but I was lucky this time and they soon headed toward the far side of the quarry. Once they’d gone, I settled on a plan. After finishing this face I would cross the quarry road and search the same reptile beds that do not get as much attention. Then I would go to my fish spot and search for scales and bone. I refer to it as my spot since I know for a fact that I am the only person to spend any time there.

After this I would scavenge the area where all the bone pieces were recovered the previous autumn. I didn’t want to do that straight away since I was waiting to see if the guy who originally worked the spot was returning to carry on the excavation. Some of us still have scruples!

It was soon apparent that the south east face, despite by no means being worked out, would need some significant work to reveal new material. How we are all hoping the quarry reopens soon! I quickly made my way across the quarry road to the part of this bed that is not scavenged as much.

After a quick preliminary look, nothing of size was apparent so I decided to do some “up close and personal” prospecting, carefully examining the sediment at extreme close range, slowly moving along the face, hoping to catch any visual clues that may lead to a fossil.

It wasn’t long before I came across a cracking little crocodile tooth. Unfortunately it had obviously been exposed for some time and had become a little weather beaten, and almost all of the enamel had been lost. It still retained its shape and striations, however, and I was encouraged by the find.

Only a couple of yards away I found another tooth. This was much smaller and well worn, although it retained a blue hue under the eye glass. It was recurved in shape but the tip was rounded off. It’s difficult to identify and will need further comparison and study under the microscope.

Once I was happy that there was nothing else to be found, I made my way across the bottom of the quarry to the fish beds. As usual there had obviously been no-one prospecting since I was last there, and I expected to find material again. I therefore wasn’t surprised when I found a few lepidotid scales and a rare vertebrae, although not as much as I had expected, especially with a harsh winter behind us.

I sat down for a while and had something to eat and a drink. I looked toward my next destination and was pleased to see the bed devoid of other prospectors. I was soon making my way to the face and to the spot where all the bone had been recovered previously.

Incidentally, it pays to keep a photographic record of all locations for future reference, especially working quarries. Before the Bluff was mothballed, great swathes of clay would be removed between visits and previously worked sites were rendered unrecognisable. A photographic record will at least ensure that you can return to productive areas since, at the very least, you can use land marks on the horizon (as per Currie and his albertosaur bed albeit on a much smaller scale) as the fixing points.

Referring to the photograph I was able to walk right to the bone bearing bed and start looking. I started to locate bone fragments in the spoil heap straight away and recovered more material immediately below the heap. Whilst none of the material was diagnostic in any way, a couple of the better pieces do support the previous assertion that this is rib bone, but from what creature is anyone’s guess.

Satisfied there were no more surface finds to be had, I dug into the bed a little further to see if there was any more material to be uncovered. It was soon apparent that this wasn’t going to be the case so I moved on scouring the same bed for more bone, but nothing was forthcoming. Eventually I headed back to the south east face for another look before finishing for the day.


As I approached the face I became aware of some great excitement at the top of the ridge. On their previous trip here, the IOW group had decided to excavate into a bank that abutted the south eastern reptile beds. They had dug an enormous gulley and made significant inroads into the face. They had found nothing, which didn’t surprise too many people since, even during the years I’ve been coming here, this face has turned up very little. Indeed, the only fossils I saw from here were a big slab of clam shrimps.

This time, after their initial forays onto the Bluff, they decided to carry on with their excavation, only with startling results. After more excavating they began to uncover some excellent dinosaur tracks, a first for the Bluff. They were mainly theropod tracks, although there was one good ornithopod track. These had been removed individually and at the moment it is hard to know if a track way is involved.

For me, this is the Wealden at its best. Classic examples of dinosaurs strolling about on the flood plain and, since this is the type locality for Baryonyx, it’s a nice thought that maybe one or two of these tracks may have been laid down by the very same animal.


What happens now is unclear. It’s tempting to arrange for the removal of the overburden to see if a track way is involved and, at time of writing, neither the funds or inclination are there to proceed in this direction. It may be beneficial to wait for the quarry to reopen since the quarry owners are palaeo-friendly and it should be fairly simple to arrange the removal of the overburden.

Also it will be of benefit to perhaps wait until later in the year when, almost certainly, there will be further manual excavation into this bed. And no matter how many volunteers there are and how strong they may be, the clay is extremely tough and it takes a lot of hard labour to remove the spoil. I don’t believe that this will be detrimental if a track way is involved, but we’ll see.

At this point I should also say a big “well done” to the IOW boys. Despite my earlier criticism of their attitude and overall mannerisms, it has taken them hours of hard work for this reward and they have definitely earned it. So hats off to them, but let’s hope they show some humility now since everyone else congratulated them on their find.

After taking some images of the tracks I said my goodbyes and moved off site, leaving them to continue with their excavation although they were looking tired and I reckoned that they wouldn’t be there for much longer.

The Bluff is unique in the country. I know of no other locality on the mainland with such a varied flora and fauna, and from different environmental habitats. There are animals from the air, land, swamp and river, and the Bluff gives us a unique window into the early Cretaceous world of 125 million years ago.

Thursday, 7 October 2010

SVP 2010 - Pittsburgh


On the eve of the SVP meeting in Pittsburgh later this week, I just want to wish those of you who are going this year, a great meeting and I hope you really enjoy yourselves. I especially wish those of you who are presenting for the first time, whether poster or oral presentation, the very best of luck.

Earlier this week, I actually prepared a short concise blog entry which was a preview of some of the topics coming up for discussion during the meeting, mainly those that were of personal interest to me. As an active SVP member, I am well aware of the embargo regarding any form of coverage of abstracts and upcoming presentations during the meeting. I thought that I could construct a piece that was both informative and interesting without giving anything away, mentioning no names and no great detail.

I think it came out really well but the more I read it, the more the doubts started to creep in. I really believe that there is nothing in it that would provoke anger from anybody, it certainly reveals nothing specific – indeed it is nothing more than a taster. No, less than that – a hint of a taste.

Be that as it may, discretion is the better part of valour (stupidity?) and I’ve decided to shelve the piece until next Thursday, after the meeting has finished, and then I’ll be able to discuss things in more detail anyway, so it’s best not to chance it.

SVP 2011 – Enjoy!!!