Wednesday, 31 August 2011

Wren's Nest Under Threat

You will forgive me if I deviate from the usual bill of fare for this blog but, every now and then, something crops up that you have to make people aware of and do your bit – and now is one of those occasions.

The Wren’s Nest National Nature Reserve is a renowned geological site of international importance. For those of you unfamiliar with locality, the Wren’s Nest is located in Dudley, near Birmingham in the UK and has significant historical value to the disciplines of both geology and palaeontology.

The Wren’s Nest exposes rocks of Silurian age – about 420 million years old and represents coral reefs within a tropical sea with a diverse marine community that includes crinoids, brachiopods, trilobites and many other animals. Their fossils are found in the limestone exposures and are often well preserved.


Image courtesy of Ashley Dace

The importance of the site cannot be denied. More than 700 different types of fossil have been recovered, of which 186 were first found and described here and, even today, there are 86 taxa which are totally unique to the Wren’s Nest.

One of the pioneers of geology, Sir Roderick Murchison, was a frequent visitor during the 1830’s and his landmark work, The Silurian System, was published in 1839 and featured extensive descriptions and illustrations of the fossils recovered from the site.

The Wren’s Nest became the UK’s first geologic National Nature Reserve back in 1956 because of its unique geological and palaeontological features. Further protection arrived in the form of the venue being declared a Scheduled Ancient Monument in 2004 and the future of the site seemed assured.

But, as incredible as it sounds, there are now plans to build a new housing estate actually in the reserve. There are to be eighty houses in total and will be built on the exposures of the Coalbrookdale Formation which, even today, is comparatively little known or researched and underlies the limestone strata.

I do not intend to go into the politics and drama of the issue but suffice to say that money is the root cause of the problem and the fact that these plans have been put into motion for more than twelve months now without anybody being made aware is significant. Only recently have plans been put into action to mount a serious campaign of opposition.

Amazingly, this housing project has been instigated with seemingly blind ignorance of further plans to develop the Wren’s Nest as part of the Strata Project – a geotourist scheme that has gained both local and national support. The project links other geological features such as the Steps Cavern, the limestone mines and the canal tunnel that links the Nest with Dudley Castle.

A modern research centre with laboratories, a visitor centre, restaurant and even a small hotel are included in the plans that would accommodate some of the 50,000 forecasted visitors per year. It has been suggested that perhaps those planning the housing estate were unaware of the Strata Project but does anybody seriously believe that?

Only recently, top geologists from the International Subcommittee on Silurian Stratigraphy visited the Wren’s Nest and confirmed the international significance of the venue and simply described it as “…the best.”

You can help in trying to overturn this ludicrous decision by voicing your opposition to the housing scheme by doing one of the following:

Send your written objection to;

The Directorate of the Urban Environment,
Planning Services,
3, St. James’s Road
Dudley,
West Midlands
DY1 1HZ

Alternatively you can email your objection to:
development.control@dudley.gov.uk


Please quote Re: Planning Application Number: P11/0652 in all correspondence

The supporters of the Wren’s Nest will be grateful for your help and a special word of thanks to geologist Chris Darmon for bringing this to our attention.







Wednesday, 24 August 2011

Prep News 2


Some of you may be familiar with the fact that we have some new plesiosaur material that we are currently preparing and looking at. The material was found in association in the Oxford Clay representing what appears to be a juvenile animal from an as yet unspecified taxon.

The animal is represented by multiple elements including one virtually complete forelimb, both femora and ribs. There are cervical, dorsal and caudal vertebrae represented but not many with processes and other large unidentified elements which are probably attributable to the pelvic or shoulder girdle. Some disassociated digits and other elements complete the recovered bones.

Unfortunately no skull material was recovered and we could not find a single tooth, which was disappointing. Cryptoclidus eurymerus is the most common plesiosaur recovered from this formation but there are subtle morphological differences in some bones which suggest this animal is something else. It is similar, however, to C. richardsoni and this is a very rare taxa indeed which may make this specimen quite important.

It s almost certainly not Muraenosaurus since that appears to be a much more robust animal. So the animal remains indeterminate at the moment and although I am erring on the side that it is possibly C. richardsoni, there is an outside chance that it may be a new taxon and that would be really exciting. We hope to get back to the site at some point and see if we can possibly locate any skull material and anything else that may help to identify the animal. The fact that the humerus is considerably larger than the femora is diagnostic of cryptoclidid plesiosaurs.

The material appears well preserved and heavily mineralised but it all has a proportion of matrix adhering to the surface in varying degrees of thickness. Some of it is merely compacted clay that is easily removed but other matrix is encrusted by calcite with remnants of both shell and belemnite embedded within and this has compacted and solidified to form a crust that is almost flint-like and is much tougher to remove.

Removal of this material is exacerbated by the fact that it almost blends into the bone and it is extremely difficult to take it away cleanly without damaging the fossil. The bulk of this material is removed mechanically but the remainder has to be removed very delicately, almost grain by grain to prevent damage and this is very much a time consuming process. The last specks are gradually eased out with needles but even at this stage they are extremely hard to remove and patience is paramount.

However, having said all that, some of the bone preservation is outstanding and this humerus is as good an example as any I’ve ever seen. This form of preservation is thought to be attributable to the fact that the Oxford clay sea was shallow and the organic material that the animals were buried in was exceptionally rich and fissile and virtually sealed in the fossils, thus enhancing preservation.

Unfortunately, many vertebrate remains are contained within calcite concretions and these are often well preserved but they are almost impossible to remove from the concretion without damaging the specimens. The plesiosaur discussed here also had a concretion in situ which had split and revealed a series of vertebrae running through it. Despite our best efforts, the concretion was so heavy that we were unable to extract it without mechanical help.


However, before extraction could be arranged, the site was covered over with spoil and the nodule seems to have disappeared but we are hopeful that it will eventually be relocated and we are optimistic the site will “reappear” after more spoil movement and, of course, more natural weathering and erosion.

After the humerus is finished being prepared, the radius and ulna are next up for preparation and these will clean up much quicker since they are much smaller elements to work on and do not appear to be too heavily encrusted with matrix. I’ll publish updates as we go along eventually unveiling the forelimb in its entirety once all the associated paddle elements are finished and, of course, any other news on the identity of the animal as we get it.

Footnote

We have recently been informed that the quarry has undergone extensive remodelling recently and that the layout has changed considerably which unfortunately lessens the chance of finding any more remains of this animal. This is regrettable but, until we are able to visit the site again, it is impossible to predict if we will be able to find any more of our plesiosaur.

Sunday, 21 August 2011

Told You So.........

I recently blogged about the possibility of setting up some form of judicial framework for the UK’s dwindling fossil  resources, something similar to the Paleontological Resources Preservation Act in the USA. The post met with mixed reaction, both here on the blog and also via personal communication. It has been very much a positive episode for me and appears to have at least made some people think and discuss the issue.

However, at the risk of saying “I told you so”, I recently received some correspondence which again bears out my belief that something will need to be done. Fossil hunter extraordinaire and all round   top man Cliff Nicklin ( a Quarry 4 & 5 colleague) recently took a family vacation on the south coast near Lyme Regis and Charmouth and, of course,  not only did he spend some quality time relaxing, but also did a little fossil hunting  – well you would wouldn’t you? But here is an excerpt from his recent correspondence:

It is becoming difficult to find anything, speaking to collectors, one has not been out for three months and another six months, and they are now waiting for the usual autumn/winter storms and, of course, land slides. Collecting has become an issue, as I lay on the beach (wife was with me), I noticed everyone walking past had a hammer.

I spoke to several party leaders regarding fossil trips and business is good at £5 per go, so we know why pickings are down………..”


So despite the fact that the Jurassic Coast is a UNESCO world heritage site and despite the recently launched self-imposed code of practice and everything that it represents, I suggest that my protestation that legal protection for the UK’s fossil resources is needed at some point in the future is wrong. It is needed NOW!

Wednesday, 17 August 2011

Hadrosaurs - Underrated Yet Spectacular (Part 1)

The International Hadrosaur Symposium takes place next month at the Royal Tyrrell Museum of Palaeontology in Alberta and is an eagerly anticipated event. It’s a busy time for the conference circus with the SVPCA in Lyme Regis running from the 12th to the 17th of September, the Hadrosaur Symposium on the 22nd to 23rd and, of course, the 71st SVP meeting is in LA from November 2nd to 5th.

There is going to be so much material and data floating around from these conferences that there will be no shortage of discussion, hotly contested debates and surprises for the palaeoworld to digest for the weeks and months that follow. The early word from SVPCA is that it will be an excellent event this year and SVP is always full of superb material but, I have to confess, that the Hadrosaur Symposium is the one I’m looking forward to more than most.

Hadrosaurs are fascinating dinosaurs. For me, they are some of the most interesting and underrated dinosaurs that have ever evolved. So they didn’t have sharp teeth, spikes or horns but, in the case of lambeosaurines, they have an amazing array of crests, grow extremely large and are extremely well represented in the fossil record with some species represented by a full ontogenetic life history from egg to adult.

Hadrosaurs can be defined by a number of unique traits and are split into two sub-families known as the Hadrosaurinae and Lambeosaurinae. For example, both groups have lost the first digit of the manus, the antitrochanter on the ilia is pronounced and robust for attachment of large muscle and the skulls display a suite of specialist characteristics.

Hadrosaurids have a worldwide distribution thus emphasising their spectacular success as a group. They are also recovered from various formations that demonstrate their adaptability to survive in different environments. These include, but are not restricted to, delta and flood plains and both lower and upper coastal plains.

In size, hadrosaurs varied enormously but the biggest such as Shantungosaurus were huge animals and were the size of the largest tyrannosaurids. Other recently recovered hadrosaurs from China are equally massive. Take a look here at Dave Hone’s recent images of Shantungosaurus – awesome animal, very impressive. Some recent work by Cooper (2008) again demonstrates that hadrosaurs grew extremely fast – at mammalian-like endothermic rates and attained adult size within 8 to 10 years.

But it is the superb dental arrangement that enabled the hadrosaurs to attain what was virtually global domination of the Late Cretaceous forests and flood plains. Vegetation was cropped by a highly efficient and rugose premaxilla that was covered by a horny sheath – or rhamphotheca to give it its proper name. This was then passed to the dental batteries for processing.


The dental battery of Edmontosaurus 

Hadrosaurs employed a unique method of chewing that was a remarkably efficient mechanism, grinding vegetation to pulp. Jaw movement was multi directional made possible by a hinge that was located between its upper jaws and the rest of its skull. This enabled the maxillae to be pushed outwards and sideways, while the dentary teeth ground against the upper maxillary teeth. This grinding action of tooth against tooth ground and shredded the vegetable matter before being swallowed for digestion. This process of oral mastication appears totally unique to hadrosaurs

Interestingly, this process seems to confirm that hadrosaurs had cheeks because if the maxillae hinged outward during chewing, it would seem likely that food would have simply fallen out of the mouth without them! It appears they may have looked a little like they were chewing the cud when eating but, of course, not using the same chewing arrangement as mammals do today. Not for nothing are they known as the cows of the Cretaceous (a rather unflattering description in my opinion).

The tails of hadrosaurs are remarkable feats of structural engineering. A latticework of ossified tendons stretched from the thorax to the anterior tail section and these were held in place by sections of soft tendon which, in tandem with the muscles from the trunk, provided rigidity and stiffness.

This enabled hadrosaurs to be able to walk bipedally by being able to hold the tail horizontal, anchored almost directly from the extremely strong sacral region. The ossification of tendons was an extremely efficient mode of support and acted like a form of cantilever bridge because it was this inflexibility that supported both the tail and torso when the animal moved.

Next time I’ll look at hadrosaurid crests and also discuss the old belief that they were semi-aquatic and how this theory just might be making a bit of a comeback.

Reference

Cooper, LN., Lee, AH., Taper, ML. & Horner, JR. (2008) Relative growth rates of predator and prey dinosaurs reflect effect of predation. Proc R Soc Lond B Biol Sci 275:2609–2615.



Wednesday, 10 August 2011

Endothermania!

This is very strange. No sooner have I published the previous post on warm blooded dinosaurs than none other than Greg Paul made a very interesting contribution on the DML. In it, he refers to a paper by Spicer and Herman (2010) that was looking at the Late Cretaceous environment of the Arctic by using plant fossils to determine the conditions at the time.

Migrating dinosaurs are something that has been alluded to in this blog on more than one occasion, usually to explain the occurrence of monotaxic bonebeds that may sometimes contain the remains of hundreds, perhaps thousands of animals. One of these migrations has been suggested to explain animals whose fossils have been recovered from the northern Alaskan slope, in as much that perhaps they spent the summer in northern latitudes during a time of plenty and then returned south before the Winter set in.

Paul points out that conditions in these latitudes were never that warm, with average July temperatures of 50° Fahrenheit (10°c), occasionally hitting 70°f (21°c). A blanket of cloud covered the land, only with occasional breaks, and this combination of average cool temperatures and very little sun were not exactly ideal conditions for ectothermic reptiles and Paul points out that there have been no remains found of crocodile, lizard or turtle on the Alaskan slope.

Winter at these latitudes was hard, at least three months without sun, perpetual darkness and prolonged sub-zero temperatures. Paul interprets these conditions as evidence that dinosaurs were well equipped to deal with such conditions, regardless of whether they were small or large animals, and cites bone histology that displays fast growth which is on a par with dinosaurs living in warmer climates.

And, as Paul points out, there would be no point for dinosaurs at lower latitudes to migrate north since it would be sunnier, warmer and there would be more food simply by remaining where they were. The dinosaurs of the north were resident all year round and maximised the summer season by consuming as much food as possible in preparation for the colder months ahead.

Paul interprets this as powerful evidence of endothermic dinosaurs with a high metabolism that were able to survive in many different environments and suggests that the Spicer paper is, more or less, the final nail in the coffin for those who persist with any notion of ectothermian dinosaurs.

Firstly, it has to be said that Greg Paul loves to throw a notion into the ring to provoke a reaction and this has certainly been the case with this one – just take a look at the follow up emails at the DML, still going strong. Secondly, even if you subscribe to the suggestion that there was no north to south migration, this does not mean that there was not any migration of some description. Surely the huge herds of both ceratopsians and hadrosaurs would have had to keep on the move to some extent otherwise local vegetation would have been quickly exhausted. This is one of those big mysteries that is one of the hot topics of the moment since there appears to be no obvious answer.

It is also worth pointing out that no matter how well sampled a formation may be, something will always turn up that surprises you and it is always a possibility that other reptilian remains have simply not yet been discovered, but this does seem unlikely. As I mentioned earlier, for a full gamut of argument and counter-argument, head over to the DML. Regardless of the evidence, Greg Paul, just like Bob Bakker, loves to get his ideas out there and really stoke up the palaeoworld, which in turn promotes healthy discussion, and I think that can only be a good thing.

Lastly, Paul’s summation echoes my own final words from the previous blog post:

And the hypothesis of low metabolic rate dinosaurs is dead, dead, dead. Bakker was right.”

Amen.

Reference

Spicer, R. A. and Herman, A. B. (2010). The late Cretaceous environment of the Arctic: A quantitative reassessment based on plant fossils. Palaeogeography, Palaeoclimatology, Palaeoecology, 295(3-4), pp.423–442.



Wednesday, 3 August 2011

Return of the Warm Bloods


A couple of recent studies have raised the always interesting question of whether dinosaurs were endothermic or not. Robert Eagle et al of the California Institute of Technology in Pasadena used a technique known as clumped isotope thermometry to discover if the fossilised teeth of sauropods, such as Giraffatitan, Diplodocus and Camarasaurus, could be indicative of body temperature.

What is clumped isotope thermometry (CIT)? In simple terms, CIT measures the reaction and bonding of carbon and oxygen. The technique was being used to determine the temperature of the earth during the prehistoric past when checking for carbon dioxide that was contained within minerals. The isotopes carbon₁₃ and oxygen₁₈ will clump together in low temperatures.

This technique was adapted to measure the mineral bioapatite, which makes up the enamel in teeth and, because bioapatite acts as a thermometer, it was possible to analyze at what temperature the teeth were formed. The results reveal body temperatures in large sauropods ranging from 36° to 38° - exactly the range found in mammals.

Of course, this does not mean that this is conclusive proof of endothermy in dinosaurs but it is further evidence ( if indeed any was needed) that large dinosaurs had a high body temperature and confirms the generally accepted theory that large animals quite naturally have elevated body temperatures anyway. No, the problem is how did animals the size of sauropods actually cool down bearing in mind the variables in sauropod physiology?

In an earlier post I commented that sauropods are engineering marvels and that when the secrets of the sauropods are solved, then we will have answered nearly every other question posed by the dinosaurs all at the same time. Elephants, rhino, hippo and whales suffer from overheating and even sunburn if they are not careful. Elephants cool down because they can pass blood through their greatly enlarged ears and back into the body as it cools. They also wallow in mud and dust which is cooling and gives an element of protection for the skin. And, of course, they are not averse to standing under the odd tree when they can find them.

But sauropods were so big that it is extremely unlikely that they could do any of the above. If they got down to wallow in mud it would seem unlikely that they could ever get up again. They couldn’t cover themselves with dust or mud although there have been the odd theories suggesting that sauropods may have bore a similar trunk to elephants but this seems unlikely and was recently disproved, as do having large ears since only mammals have external ears.

So it seems likely that sauropods had some other way of keeping cool – a technique that is unknown to us at this time. Eagle et al speculate that they may have discharged heat through their long necks and tails or via special air sacs situated below the skin. Worth noting that none of the above take into account the environmental temperature at the time or, something that I’ve been considering for some time, the make up of the atmosphere which was considerably different from today.

More experiments using CIT are to be used on both small and medium sized dinosaur teeth and this will prove very interesting indeed. If the results display enamel forming temperatures that are also at elevated temperatures similar to the sauropods then this would be pretty compelling evidence for endothermy in dinosaurs as a whole.

What do bones tell us?

Another recently announced paper has also added weight to the argument that dinosaurs were endothermic. Roger Seymour et al from the University of Adelaide have discovered that the size of nutrient foramina in human femora is relative to the amount of aerobic activity that can be achieved. The authors have now applied this same technique to determine the aerobic activity of dinosaurs and, unlike the previous work, a range of dinosaurs of different shapes and sizes have been examined.

Blood is supplied by the main artery in the bone through the nutrient foramina to keep the bones in ideal condition and also to effect any repairs that are required. The more active the animal, the more conditioning and repair for the bone is needed, thus the greater the blood supply needs to be. So if the foramina are large, it would appear to show that a much greater degree of metabolic activity was achieved.

Before anything could be determined about dinosaurs, the authors measured multiple femora of extant mammals and reptiles of all sizes, from the smallest to the largest and the results were unequivocal – the larger the foramina, the higher the metabolic rate. Not only that, but the foramina in mammals are about ten times the size of those found in reptiles. So how did the bones of dinosaurs measure up?

Well it turns out that the foramina in dinosaur femora are relatively bigger than even mammals. This has surprised the research team because it indicates that dinosaurs were even more active than the mammals and provides yet more indication that dinosaurs were extremely active creatures and, in all probability, endothermic animals.

The theory regarding hot blooded dinosaurs was part of the original dinosaur renaissance way back in the seventies. It’s been interesting to follow the whole dinosaurian physiological and metabolic argument since Bob Bakker’s original (and groundbreaking) suggestion (Bakker 1972). We have gone through so many different studies and discussions that it has almost become accepted that dinosaurs were something in between ectothermic and endothermic – such as Scott Sampson’s Goldilocks hypothesis (Sampson 2009).

I used to think of this as a cop-out because, despite all the evidence to the contrary ie limb posture, bone histology, fast growth and world wide distribution of dinosaurs, it has generally been hard to accept dinosaurs as fully endothermic. I too have erred on the side of caution and settled for mesothermy – the safe option.

But now, with another two lines of evidence pointing strongly yet again to dinosaurs being highly active, fully developed endothermic animals, how long will it be before we come to accept endothermic dinosaurs? Indeed, how long will it be before we go to Bob Bakker and say “You know – you were right all along!” I hope I’m around to see it.

References

Bakker, R.T., 1972. Anatomical and ecological evidence of endothermy in dinosaurs. Nature 238:81-85.

Eagle, Robert A., Thomas Tütken, Taylor S. Martin, Aradhna K. Tripati, Henry C. Fricke, Melissa Connely, Richard L. Cifelli, and John M. Eiler.  Dinosaur Body Temperatures Determined from Isotopic (C₁₃-O₁₈) Ordering in Fossil Biominerals. Science 23 June 2011: 1206196 Published online 23 June 2011 [DOI:10.1126/science.1206196]

Sampson, S.D., 2009. The Goldilocks Hypothesis. In: Sampson, S.D., Dinosaur Odyssey. Fossil Threads in the Web of Life. University of California Press, pp. 175-191.

Seymour, R.S., S. L. Smith, C. R. White, D. M. Henderson, D. Schwarz-Wings. Blood flow to long bones indicates activity metabolism in mammals, reptiles and dinosaurs. Proceedings of the Royal Society B: Biological Sciences, 2011; DOI: 10.1098/rspb.2011.0968