Wednesday, 16 July 2014

From the Toarcian to the Callovian Pt.3


 
The following day I decided to visit Whitby Museum and do a little scouting ahead of the next field trips. The museum is situated quite central in Whitby and is fairly well signposted but be aware that it is situated at the top of Chubb Hill which, if ascending from the sea front, can be quiet steep for those with mobility issues – or those who are just plain unfit.
The museum charges a modest entry fee of £5 and the museum not only caters for the fossil enthusiast but covers all aspects of Whitby’s local history which includes whaling, the local textile and agricultural industries, luminaries such as Captain James Cook and Dracula author Bram Stoker as well as a comprehensive natural history collection. But I came to look at the fossil collection and this is the first section you come to as you walk through the doors on the left hand side.
I was initially struck by how small the display area was considering the long history of collecting in the Whitby area and just how many specimens of note that had been found that we, as palaeontologists, were familiar with. But they did cram a lot of material into this area and there were specimens everywhere, the walls and cabinets were filled and there were even specimens tucked under the display cabinets for those of us who tend to look in these hidden caches of small museums. 
Some of the panel mounts were of particular interest and I spent quite a bit of time with a specimen of “Teleosaurus chapmani” which is synonymous with Steneosaurus bollensis and, as a result, was useful for comparing anatomy with some teleosaurid material we have been collecting elsewhere. Also of interest was the similarly panel mounted “Plesiosaurus propinquus” which, from today’s perspective, is so plainly a rhomaleosaurid that it is difficult to perceive it as anything else. But then we have to remember, that at the time this was first described, there was so much uncertainty, so many unknowns that it was clearly acceptable to label all long necked plesiosaurians as Plesiosaurus or similar – even if the skull was larger and much more robust than the standard plesiosaurian model.
Ichthyosaurs are well represented in the museum and taxa represented include Ichthyosaurus crassimanus, I. acutirostris and I. platydon and there are several other vertebrate specimens  as well. Unfortunately, many of the older specimens have suffered because of poor collecting methods and both primitive and unnecessary preparation techniques. I am not criticising our collecting forefathers you understand but merely pointing out that, by today’s standards, many fine specimens have been compromised by these older practices.
That being said, many specimens have undergone rigorous reconsolidation and preparation over the last twenty years or so  and are in a much better condition now but they still have to be regularly monitored since pyrite decay is a constant threat. All in all, Whitby Museum houses a fine collection of specimens and I would heartily recommend it to you.
I was not permitted to take photographs on this occasion but a quick Google search will enable you to see plenty of images of the museum and its exhibits. As an example, click here for a quick guide.
After my visit to the museum the sun shone and I decided to check out the quaint coastal village of Staithes, some 12 miles north of Whitby. You have to park at the top of the village and walk down to the harbour since there is extremely limited access  but it is also worth noting that this is also a very steep climb back – especially if you have a sack full of fossils. Staithes is another collecting location that is well known for its ammonites so I thought it worth checking out although I had already been tipped off previously that it was producing very little lately.
It was, unfortunately, high tide but I still decided to take a look to see what I could see. As I rounded the promontory from the harbour the tide was approaching its peak and there was very little coast for me to walk on. But even with the limited exposure available I could still make out belemnites and shell in the mudstones and I then decided to walk around to the other side of the harbour and check out the sea cliffs from there.
As I walked below a noisy gull colony and made my way out on the sea wall, the ancient sea cliffs rose in front of me. I could clearly see the headland at Penny Nab which is where most ammonites are recovered from and, even at high tide, it all looked rather tempting and I decided to return the following morning to prospect. Before I left I took advantage of the Cod and Lobster Inn, sat in the sun and sampled a fine pint of Black Sheep bitter. Life was good.

 
The following day I returned all geared up for another hunt. It was another dry day although rather murky and as I made my way down the steep hill into this picturesque coastal village I felt pretty optimistic. However, my optimism was soon dashed by the sight of around forty students who were attending an organised fossil hunt. They made a fine sight all resplendently dressed in their high visibility jackets and safety helmets as they were preparing to skirt the headland.
Now I have nothing against this sort of event – indeed I am very happy to support them and have done so on numerous occasions but I was looking for a little solitude this week and decided against sharing their excursion on this occasion. This left me in something of a quandary but rather than waste the day I quickly headed out of Staithes and headed back to the cove for another look but this time for a much more intense look.
I was delighted to see that, yet again, I had the cove to myself and I soon returned to the productive spot. To be honest I was not expecting to find too much since I had already gathered a nice collection of specimens previously, so I made a point of searching those areas that I had missed and even areas that I thought unproductive because they were so clearly over exposed.
Again I was delighted to find some more ammonite specimens throughout the entire exposure and even those spots I had considered probably not worthy of attention produced the goods. It was another lesson learnt and proved yet again that closer scrutiny of those spots that appear bereft of fossils will yield results. Nobody should be surprised by this and I have seen it that time and time again that a spot that has been searched maybe two or three times in the space of perhaps an hour will produce a fossil as if it had just been sitting there fully exposed to a fresh pair of eyes.
I admit to being surprised by my success considering the finds I had already procured on the two previous occasions and, again, I ignored many partial ammonites that I may have been tempted to pick up previously. I then determined it was time to leave for the day for I had truly scoured every part of this one section and, as I walked back up the cliff, I decided to visit one more venue the following day – one that had a particular reputation for being hard to get to but one where the rewards could be exceptional.

 

Tuesday, 10 June 2014

From the Toarcian to the Callovian Pt.2


 
The following day we decided to approach the bay from the south which was essentially the other side of the rock fall. Simon had already climbed up and around the fall to check out the other side to see if it looked fossiliferous. Simon was surprisingly quick and agile as he skipped over some extremely rough and acute terrain and never looked in danger of having an accident.
We had waited on the north side of the fall while he scouted and, after about ten minutes, he quickly reappeared and reported that the exposures looked similar to what we were looking through and suggested that there were almost certainly fossils to be found. This was good enough for us and seemed the sensible thing to do in light of their limited time in the north east.
And so, the next day, we dropped down a steep hill to the cove, about a mile south of our original bay, and prepared to head north. We believed that it would probably be a 30 to 45 minute walk along the coast to reach the desired spot although we would naturally look for fossils as we went since this whole coastline was remarkably rich in remains and decent specimens could crop out anywhere.
We had only just rounded the corner of the first promontory when we came across an exposed wave cut platform and straight away we could see several compressed ammonites and a couple of belemnites. Just beyond this was a very apparent and recent cliff fall displaying a patch of pebbles, rocks and large sandstone blocks not unlike the rock fall we had encountered the previous day. Immediately we found some bits of ammonite amongst the pebbles but as we approached the fall we could see, unsurprisingly, that other collectors had already been here and the remnants of split nodules  was indicative that the best specimens were already long gone. Or were they?
Amazingly, amongst all the debris, Simon managed to extract a large nodule that appears to have two very intact ammonites along the same bedding plane that should, if luck is with us, prepare really well and will be a superb display piece in due course. This will be almost certainly be prepared in the laboratory back at the NHM and so will have the best care and attention – fingers crossed that the ammonites are indeed as well preserved as they appear to be.
 
 
However, this was a rare find and we were soon heading off north for our intended destination. We scoured the headland as we walked but fresh exposures were not obvious and there was a growing increase in the amount of large sandstone blocks and debris we had to clamber over. We arrived at the next promontory only to be greeted by a sea of boulders and crevices that made walking tough and unforgiving. To add to our woes, the wave cut platform that was now exposed by the receding tide was extensively covered by seaweed and even getting to it was problematic.
Undaunted we pushed on over this never ending jumble of rock, mudstone and weed and, to be honest, it was physically extremely tough as well as being hard mentally since you were constantly concentrating on each and every footstep. A misplaced footfall might possibly mean a sprained ankle or even a broken leg and the weed and slime that covered the rocks and mudstones made the situation somewhat treacherous.
We decided to get to the next headland and hopefully we would be at the exposures we were aiming for. Imagine our despair as we rounded the headland to be greeted by another extensive field of rocks and boulders as bad as the field we had just negotiated, with the next headland appearing to be some distance off. Although we agreed that it was indeed likely to be our target spot we decided to call it quits and head back. This decision was not taken lightly but we had to take into account the amount of time it would take to get there, time to look for fossils and then the tide would have turned and we could not afford to misjudge our return south – especially with the terrain being so hard to negotiate.
We headed back south and began the long trudge back to the cove with our heads down to ensure we made it in one piece. Eventually we got back to where Simon had found his superb ammonite nodule and spent a little bit of time searching for more fossils but to no avail. We returned to the car and quickly back to base since Simon and Mark had to leave for London almost immediately. Saying our farewells, I immediately made preparations for the following day.
The weather deteriorated during the evening and another heavy sea mist closed in. I went for a walk along the top of the Lias cliffs and peered through the gloom but you could hardly make anything out. Only the sound of the waves broke the silence and for a moment I felt as if I was living back in the Jurassic. The great sea dragons abounded in the sea below me and pterosaurs flew all around me in the dense sea mist – the world must have been a truly awesome spectacle back in the Mesozoic.
The following day I descended down the cliffs, headed south and returned to the spot where the three of us had done well a couple of days previously. The sea mist was still pervading the atmosphere and you could not see probably a hundred metres either way but this just increased the sense of anticipation and, best of all, I had the entire cove to myself.
This time I decided to concentrate on this one area and spend a considerable amount of time on my hands and knees looking at every nook and cranny I could find. I would also check out some of the gullies and dips in the mudstone platform itself since they acted as collection points and there were many different rocks and stones that were trapped in all kinds of cavities.
Immediately this process began to pay dividends and I found a couple of nice ammonite nodules fairly quickly. When I extended the search onto the platform and began perusing the crevices for fossils I very quickly had one of those “wow” moments. As I peered around a boulder and looked down, there in a gully, just about sitting proud of the water was a wonderful pyritised ammonite glistening in the half light. It was almost as if somebody had placed it there waiting for me to find it and I took a couple of photographs of it in situ before gathering my prize.
 
 
Only fossil hunters understand the sheer buzz you get when you find such a fossil. That is not to decry the achievement of finding the vast majority of fossils but rather to celebrate that electric joy you get when you find a stunningly complete specimen, the glossy sheen of an immaculate tooth or, indeed, a gorgeous pyritised ammonite – there is no other feeling quite like it.
The platform gullies and crevices ended up being rather productive and, because they do not receive the attention that the foreshore generally receives, the fossils were often well preserved. Eventually the platform became decidedly weed covered and finding fossils problematic so I returned to the foreshore to continue looking amongst the gravels, rocks and boulders.
Throughout the rest of the session I recovered fossils including a couple of nodules that should contain complete ammonites. I know I often say this but getting onto your hands and knees and getting into spots that can seldom be seen from the standing or stooping position continues to pay dividends. One such very obvious boulder contained an ammonite nodule that must have been missed on countless occasions only because it was slightly exposed at the base and I only spotted it because I had my head stuck to the sand. Fortunately I managed to extract it safely and is another waiting for preparation.
Another fossil which I spotted in this fashion was a superb bivalve – the only example I found during the whole week. This too was secreted in a crevice and took some nifty chisel work to persuade its release from its ancient tomb. I really like this fossil and was thankful that I managed to find it. However, the elusive vertebrate fossils remained just that – elusive.
This is almost certainly due, in part, that you become focussed on finding ammonites and looking for nodules so you almost certainly miss other fossils. This is often the case in formations such as the Oxford Clay in which the sheer mass of ammonites and belemnites often preoccupies your line of vision and makes it difficult to differentiate other fossils – “noise” I call it.
However, I have no doubt that I was not missing much vertebrate material, if any, since I am very familiar with these kinds of fossils although I am nowhere near as familiar with these exposures as someone able to visit them on a regular basis. Regular prospecting at any site makes a tremendous difference to your find to visit ratio as you learn more and more about the exposures and the fossils they contain.
Gradually the mist dissipated and the sun began to shine and the day became a little warmer. I covered a very significant section of foreshore and amassed some very nice fossils indeed and I admit to being a little surprised that I was still able to glean a couple of nice ammonites quite higher up in the succession than expected.
Satiated for the day I made the long trek and climb out of the cove and did I know that I had had a good day as the weight of fossils on my back began to tell – the back pack seemed to gain more weight with every step up the steep trail. Eventually I made it back to base and took a look at my haul before washing them off and they made for a visually stunning display as they glistened with water. Soon it would be time for the next trip and I needed to decide on the location and eagerly began planning ahead.
 
 
 

Sunday, 1 June 2014

From the Toarcian to the Callovian Pt.1


 
The next few posts are really a light review of some recent fieldwork that myself and some colleagues undertook at the back end of April into early May. Don’t expect a technical treatise here nor are there any earth shattering developments or reviews – rather this is a very personal, almost diary-like, look back at what was some very welcome respite from what has been a very hectic period since January. I hope you enjoy them. 

At the back end of 2013 I had decided to plan a week’s fieldwork back in the north east to essentially chill out doing what I love but without the usual constraints of fieldwork and research under the auspices of our group. That does not mean I do not enjoy what we do but sometimes it is good to amble, looking for fossils as you go and smelling the hops along the way…..
So after Christmas I decided to look for accommodation in a fairly central location to the sites that I was quite keen to visit. I was fortunate that one of the first places I checked out was exactly where I wanted and looked ideal. I looked at the dates and settled for a late April excursion which appeared to me to be a fairly sensible time as it was after the Easter holidays and before summer really kicked in. Without further ado I booked the place up and I was all set.
Despite the fact I was booked to go on my own I let the other members of the group know of my plans and asked if anybody was interested in coming. It was unfortunate that so many members of the group were busy but in the end my colleagues Simon and Mark, from the Natural History Museum in London, said they would like to join me for the weekend and this was duly arranged.    
Eventually it was time to go and soon I was winging my way up the A1 headed northward with a car full of gear – mainly field gear it has to be said. Is there anybody that does not take more gear than is needed when field work is about to start? To be fair, I have rationalised my gear a great deal now and take a largely reduced set of kit for prospecting these days although it has to be said that the heavy duty gear and other equipment needed for a larger excavation remain in the vehicle in reserve. Well you just never know and I would hate going into the field under prepared – hate it.
As journeys go it was about as hassle free as it could get and I arrived in Whitby at lunchtime and stopped to pick up a few supplies and then grab a drink and a bite to eat. I noticed that I had a message on my phone from Mark and when I listened to it I was surprised to hear that they were already in the field getting a sneak preview – surprised because I was expecting them much later in the day.
I rang him back but there was no answer so I left him a message and duly went for some refreshment as planned. Whitby was rammed with people and it was a struggle to get parked but I did manage it eventually and walked into the old harbour. As I looked around I realised I had arrived bang in the middle of one of the major Goth Festivals that Whitby hosts twice a year. It was a great atmosphere as so many Goths dressed in their darkest finery mixed with everyone chatting away and posing for photographs. I was really taken in by it – it was wonderful fun!
Eventually I caught up with Mark and Simon in Whitby and, as we sat down for a coffee, they told of their brief field trip – brief because the tide was almost in and they had to beat a hasty retreat before it was too late. But even in this brief period they told they had picked up a few fossils and so the prospects looked good.
At this point it might be worth pointing out our aims for the trip – there weren’t any! This may sound a little surprising since our group is concerned with the recovery and research of marine reptiles but this was really a case of getting away from the intensity of our routine work and actually enjoying some time out with the added bonus of a fossil or two. We were not expecting to find any vertebrate fossils but we would certainly be looking for them but we would also be collecting ammonites as well.
The ammonite fauna of the north east is well known and they are incredibly abundant – at the right times. The local collectors are fortunate that they can be instantly on the scene whenever there is a fresh cliff fall or when there are storm conditions or when the big autumnal and spring tides scour the Lower Lias platforms to reveal their hidden treasures. I don’t blame them – so would I if I lived locally and exactly the same thing takes place in that mecca of British fossil hunting – Lyme Regis and Charmouth.
But this should not put anybody off searching for fossils at these locations. The local collectors certainly do not get all the best fossils and, with ammonites, they are often only interested in nigh on perfect specimens and ignore or discard those that are not as near as possible perfect. So there should always be a few fossils to be found – provided we look in the right spots.
After we settled in to our accommodation, which was spacious, well equipped and comfortable, we spent the evening in one of the local inns where we ate and drank and discussed all things palaeo. As usual, all of the talk focussed on the fossils found during the past and those we might find in the future. Topics included further field trips, especially a couple of large scale affairs abroad, what we could do to increase the chances of unearthing more marine reptile remains  and the importance of the public to palaeontology – watch this space!
Morning came and we set off early to make the most of the low tide. Our accommodation was situated rather well since we were only a matter of minutes from our first port of call. It had been raining and we were careful as we made our way down to the shore – conditions were very slippery. When we got to the bottom we headed north around some headland and aimed for some large boulders that were strewn across the shore since it was here that there was meant to be the chance of finding the odd bone and some fine ammonite specimens.
When I was last here there were lots of nooks and crannies that were holding areas for various rocks, nodules and fossils we collected some nice fairly intact nodules that clearly had ammonites inside them. But it was so different this time and it is no understatement that there were no nodules to find at all – indeed even ordinary rocks were conspicuous by their absence.  
Just why this should be the case is not known. I suspect that there have been no recent cliff falls to replenish the foreshore and it looks to me that there must have been several scouring tides since even the sand was missing. In any event we discussed the issue and decided not to waste any more time in the north and we duly headed south to the spot where Mark and Simon had picked up a few fossils during the previous day.
As we walked along the shore we could see that there had been an extensive rock fall further around the headland. Even at a distance we could see a great yawning chasm in the side of the cliff and, at the base of the cliff, huge sandstone boulders piled up on top of each other with a mixed covering of clay, shale, ironstone and other scree. We would have to have a look at that shortly.
Eventually we arrived at the spot where the fossils were found previously. It was a stretch of shoreline that was strewn with a mixture of mudstone boulders, sandstone and all sorts of other rocks and pebbles all intermixed with sand – this was much more like it. Ahead of the shore the exposed wave cut platforms of the Lias stretched out before us of which the platform exposed higher up on the coastline was free from the sea weed that covered the vast majority of it elsewhere.
We began to search and instantly began to find fragments of ammonites of which some were heavily eroded and others were pristine. We naturally spread into a line of three – Mark at the top of the line, Simon in the middle and I took the base of the unit where the shore abuts the platform. Mark found a couple of likely nodules straight away of which one he found by turning a likely looking nodule over with his boot. As he turned it over he uttered that gasp of pleasure as, displayed before him, was a superb example of the ammonite Dactylioceras commune which will clean up really well.
Encouraged by this we continued the search and we all found some nice examples. I was particularly struck how I managed to find three nodules that were exposed in one tight little section almost as if they had been placed there. As we progressed we decided to get a little pickier with what we collected since our collecting bags were starting to get a little heavy. As Mark and I continued to be engrossed Simon decided to push on and aimed for the rock fall zone determined to take a look.
After a while we looked up to where Simon was and we could see that he had already scaled the sandstone blocks and was busy looking through the spoil. Eventually Mark and I walked up to join him where we could see what had appeared to have happened. A lot of the sandstone was covered in seaweed which suggests the main fall must have happened some time ago but there had been a much more recent fall here which was evident by the amount of manmade quarrying mining there had been.
There were ammonite nodules in the shale and those that did not make the standard or had been damaged were left strewn all over the place. Simon had done well though and had managed to find a couple of decent specimens of which one looks particularly nice. Mark and I had a brief look although I felt that the two of us were not as comfortable as Simon was working in a spot which you could easily term as vulnerable to a further fall.
 
As we worked our way down and away from the rocks Simon decided to take a look on the other side of the rock fall to see what the exposures were like there. He soon bounded off, was very light on his feet and disappeared – “The Goat” Mark called him. While he was doing this we had a look at the wave cut platform below us while we could for the tide had turned. This platform is patchy as far as fossils go but we could see ammonites and belemnites in situ although these ammonites were nothing more than imprints but the belemnites were well preserved.
Eventually Simon caught up with us and suggested that the exposures on the other side were better accessed from the bay further south and so we formulated a plan to do that on the following day. It was now time to walk back with our spoils which was no mean feat. The climb out of this bay is one of the steepest you can encounter and we were really happy to make it to the top – good job we are all fit *cough*.
Soon it was time for food and drink and refining our plan for tomorrow because who knows what that might bring?

Wednesday, 2 April 2014

From the Vaults Pt.3


I love unusual aspects when photographing specimens and I particularly like this shot. This is a cervical vertebra, in ventral view, from Diplodocus carnegii and while I am not anywhere near being an aficianado of sauropods I do appreciate what a marvel of evolutionary engineering sauropods were - with a special admiration for the biomechanics of the sauropod neck.

There is still a degree of uncertainty regarding how these animals actually functioned and I have always thought that once we have solved the miracle of sauropod biology then the rest of dinosaur palaeobiology will fall into place. Well probably not as simple as that but I hope you understand where I am coming from.

Back to proper blogging soon and thank you for the visits and checking the blog out. It is very much appreciated!

Tuesday, 25 February 2014

From the Vaults Pt.2



Hadrosaurs are, quite simply, awesome. As a theropod man this may appear to be somewhat contrary but to anybody who spends time with the fossils of these remarkable animals, there is only a true appreciation of these wonders of nature. And their skulls, whether hadrosaurine or lambeosaurine, are magnificent.

The unkind epithet "Cows of the Cretaceous" is both undignified and is yet complimentary as it is easy to imagine great herds of hadrosaurs sweeping across the Late Cretaceous landscapes consuming vast amounts of vegetation. The well documented and super efficient jaw mechanism is a beautiful piece of evolved engineering although, I believe it fair to say, is still not fully understood and very much under appreciated by those who consider hadrosaurs mere theropod fodder.

I have come into contact with various hadrosaur skull bones that need preparation over the last few years and am now very familiar with them. I have three dentaries and one maxilla still to prepare (when time permits) and there are other bones in the cue but I am particularly fond of the jugal and quadrate. One quadrate, in particular, is exceptional and would come from a very large hadrosaur indeed. The predentary is another interesting bone with its castellated rim so perfect for nipping off fronds of vegetation.

The various crests of lambeosaurines are equally impressive and the range of ontogenetic and morphological extremes is fascinating and just what function they perform has long been debated although it is generally accepted that they were most likely used for intraspecific communications of some sort.   

The rest of the animal is pretty impressive as well - an ability to walk on both four and two limbs, to be able to rear up, and all supported by a magnificent framework of tendons and, lest we forget, an animal that exhibited a great deal of parental care that enabled hadrosaurids to proliferate throughout the Late Cretaceous.

Hadrosaurids deserve all the attention they receive and the sheer amount of fossils they left behind, including entire growth series from egg to adult, make them an appealing subject for research for any aspiring dinosaur palaeontologist.

Friday, 7 February 2014

From the Vaults Pt.1


Unfortunately, my increased workload is making blogging regularly somewhat difficult right now but just to keep things ticking over I will post some bits and pieces from time to time. This time I am glad to provide some cool images for the palaeoichnologists amongst you. Palaeoichnology has always been a fascinating discipline and is one of those branches of palaeontology that is certainly on the up as it increasingly benefits from digital technology.

Late last year a couple of us attended the Jehol-Wealden International Conference on the Isle of Wight and part of the conference entailed a field trip to visit some of the more famous fossil sites on the island. At Hanover and Brook we were very lucky to see many of the famous large dinosaur footprints and casts in situ - and very impressive they were too.  

It was great to discuss tracks with track specialist extraordinaire Martin Lockley, of the University of Colorado, and you could not fail to learn. So here are some of the track images from the day - enjoy!
 


 

 

 

 

 

Tuesday, 21 January 2014

More SVP Snippets


 
We are often fascinated by the large, some would say outsized, eyes in animals – particularly those in extinct animals such as ichthyosaurs. But do big eyes necessarily indicate a specific adaption to perhaps avoid being hunted by larger predators or, perhaps, do they serve multiple evolutionary driven functions? Lars Schmitz, of Claremont College in California, and his colleagues and have been looking at just that.
By testing a variety of theoretical models they compared the eyes of present day squid (the animal with relatively the biggest eyes of any organism) with those of ichthyosaurs by assuming that both squid and ichthyosaurs evolved their large eyes to avoid predation. They found, however, that large eyes are extremely useful for a number of key visual adaptations in low light level conditions and    that there is insufficient evidence supporting the evolution of large eye size due to predation.
Allometric testing was also indicative that actually both squid and ichthyosaurs do not actually have outsize eyes relative to their large body size within their respective clades.  This adds further weight to the argument that large eyes evolved naturally with large body size and helped the animals perform multiple functions in a light restricted environment although nobody doubts that they would indeed be useful in spotting a possible predator.
There were a few interesting presentations concerning phylogenetics during the meeting and Robert Sansom, of the University of Manchester, and Matthew Wills, of the University of Bath, threw a bundle of tinder wood onto an already burning fire and reinforced the necessity that we must all be alert to the external forces of fossilisation and the significant impact it can have on any phylogenetic tree.
The authors suggest that inherent loss of soft tissue during the fossilisation process causes morphological error. When comparing phylogenies of extant taxa that were filtered with those that are random by removing soft tissue data they found that these taxa actually dropped down lower in their respective phylogenetic trees.
Fossil filters, therefore, can cause significant signal loss which, of course, is the raw data utilised by phylogenetics and thus moves taxa down the tree causing the character states to appear more primitive. If this is the case then the element of caution when considering “parsimonious” character states would need to be greatly intensified.
To compound the issue for those of you involved in phylogenetics, Akinobu Watanabe and Mark Norell, both of the American Museum of Natural history Museum in New York, also highlighted the impact of poor sampling when variation within species occurs. In other words, intraspecific variance within species can cause character states to appear different from what they really are due to the lack of specimens.
A secondary taxon that is part of the same species that is different since it was not sexually dimorphic or ontogentically variant is known as a polymorph. To help combat the issues of polymorphic distortion, the authors have created a new script within TNT that simulates polymorphic sampling but replaces the polymorphic scores with single character states and then cross references the simulated results with the actual data.
The results are interesting albeit somewhat discouraging as the TNT variant recovers substantial differences in the organisation of phylogenetic trees. These discrepancies confirm what many palaeontologists have known for some time and that is that there is nothing that can be described as simple phylogenetics when dealing with extinct organisms and that sampling, not only from  the “more is better” standpoint,  but particularly of multiple specimens of the same species are essential to enable a clearer understanding of phylogenetic evolution.
More ichthyosaurs now which should not be a surprise since there is an abundance of research going on into these fascinating marine reptiles. It is well known that there was a significant extinction event across the Cenomanian/Turonian boundary during the early Late Cretaceous and, despite the odd rumour of ichthyosaur elements known from the Maastrichtian, it is generally accepted that ichthyosaurs went extinct at the end of the Cenomanian.
There are many theories on the cause of this extinction which also saw the demise of the spinosaurs, pliosaurs and, at the other end of the scale, the lepidotid fishes amongst many others. Whatever sparked this event led to depleted oxygen levels in the oceans and saw a rise in both sea and atmospheric temperatures.  And yet was the extinction of the ichthyosaurs a gradual decline or as a result of a sudden catastrophic event? Valentin Fischer, of the Royal Belgian Institute of Natural Science, has been looking at just this.
Re-examining the phylogeny, taxonomy and palaeoecology of Cretaceous ichthyosaurs has revealed some interesting data. Firstly, it has always been generally accepted that ichthyosaur diversity diminished after the Jurassic but we now know that this is not the case and that ichthyosaurs were much more common and diverse in the Early Cretaceous than generally thought.
Secondly this revision has also highlighted the fact that ichthyosaur extinction lasted throughout the Cenomanian and is indicative that marine ecosystems worldwide endured significant faunal turnover that affected many groups of marine animals. This is part of an increased amount of evidence we have that ichthyosaur extinction was part of a much wider reorganisation of marine fauna at the beginning of the Late Cretaceous which, although plesiosaurs survived the extinction event,  paved the way for the mosasaurs to become the dominant marine reptiles for the last 20 million years of the Mesozoic.
Staying with marine reptiles and Neil Kelley, of Vanderbilt University, has been examining the adaptability and morphological variation of various marine forms in the Triassic period. By analysing both dietary data and morphological characteristics of extant marine taxa with those of known Triassic marine reptiles (51 species), Kelly was able to ascertain that the data recorded and observed was generally comparable.
Unsurprisingly, perhaps, marine reptiles of the Triassic pursued a variety of dietary niches although it is interesting that as they got progressively larger in the Mid-Triassic that diets moved on from being mainly piscivorous to not only becoming more carnivorous but also specialising in invertebrate prey. After the Middle Triassic the specialist forms began to disappear whilst both the fish eating forms and the larger carnivores persisted.
The fact that open ocean forms continued to flourish in the Late Triassic may be indicative that there was a shortage of food resources in shallower waters near to shore. Because larger pelagic forms were able to persist into the Late Triassic may have ultimately led to a greater taxonomic diversity at the end of the period with many of the forms that dominated the seas of the Jurassic evolving during these very important stages.
Despite the data being assembled that led to these conclusions being comparable, much of it depends on assumption and the author rightly points out that the overall lack of fossil specimens does somewhat hinder this research and that there will always have to be a degree of conjecture.


 

References

Fischer, V. 2013. The extinction of ichthyosaurs is a facet of a major Cenomanian turnover in marine ecosystems.  Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2013, pp127.
Kelley, N. 2013. Ecomorphological diversity of Triassic marine reptiles.  Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2013, pp152
Sansom, R. and Wills, M. 2013. Fossilization filters result in significant loss of phylogenetic signal and cause organisms to appear erroneously primitive.  Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2013, pp205.
Schmitz, L., Motani, R. and Wainwright, P.C. 2013. Evolutionary drivers of giant eyes in large ocean predators. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2013, pp206 – 207.
Watanabe, A. and Norell, M. 2013. Tree building from Noah’s Ark: the impact of poor sampling within species on phylogenetic reconstruction. Journal of Vertebrate Paleontology, SVP Program and Abstracts Book, 2013, pp235.