My Collection #2

Small Kosmoceras jason on a piece of Oxford Clay with a tiny
belemnite to the left.

These fossils were collected from Must Farm Brick Pit in Whittlesey, near Peterborough in Cambridgeshire, UK in June 2016.

Kosmoceras ammonites are known from Callovian age Oxford Clays of the Late Jurassic Period in Europe. These ammonites therefore date back to around 163 Ma. As with these two fossils, they are commonly found flattened in the clay, rarely it is possible to find three dimensional casts of the shell. The maximum diameter known from fossils is about ten centimetres. There is evidence of sexual dimorphism in these ammonite, the more decorated males have a smaller shell than the females, the purpose of the ornamentation is unknown.

Calcitic Kosmoceras jason from Kings
Dyke Brick Pit.

A larger iridescent Kosmoceras jason on a piece of Oxford Clay

The preserved phragmocone of a belemnite from the
Oxford Clay.

Cylindroteuthis is a belemnite known from the Early Jurassic, ~200 Ma, to the Early Cretaceous, ~140 Ma. This specimen is rather common, being found in Asia, Europe, North America and New Zealand. The calcitic guard of the belemnite is what is commonly found, lengths range from ten centimetres to twenty-two centimetres. Rarer fossils exhibit traces of appendages and an ink sac, showing their relation to squids. The guard would be an internal feature as traces of blood vessels have been found on the surface of the guard. This fossil is not to be confused with the shell of the belemnite, this is found within the guard, as shown in the photo to the right.

The largest of the Cylindroteuthis belemnites in my collection from the Oxford Clay at Kings Dyke Brick Pit.

This is a fragment on a bone from the giant fish Leedsichthys. This member of the pachycormidae is known from Callovian sediments of the late Jurassic. Discovered by Alfred Leeds in 1889 when the Peterborough brick making industry was taking off and quarries were being opened in and around the city, Leeds collected various marine fossils from the Oxford Clay in this time. Fossils have been found in England, France, Germany and Chile. In 2002, another individual was discovered in the Must Farm pit in Whittlesey by students at Portsmouth University. An excavation led by Jeff Liston of Yunnan University, revealed thousands of delicate bones, including the pectoral fin. A lot of the skeleton would have been composed of cartilage and so it doesn't fossilise. Size estimates put the fish at around twelve metres long. It is believed that a spike in planktonic populations were the reason behind the size of the Leedsichthys. Being a filter feeder, water would have been forced through gill rakers that removed the plankton from the water.

A small fragment of Leedsichthys problematicus from the Oxford Clay at Kings Dyke Brick Pit.

The larger and more complete Gryphaea
in my collection.

Also known as the Devil's Toenail, Gryphaea is an extinct genera of bivalve mollusc. Their geological range is from the late Triassic through to the Eocene. These bivalves are some of the more common finds in Jurassic marine deposits of Europe. They possibly lived in small colonies as shown in the photograph to the right. The bivalve had a larger hooked valve and a smaller, flatter lid. The
larger valve would be embedded in the sediment whilst the lid remained exposed. It is one of the only bivalves that have one valve larger than the other.

A broken Gryphaea from the Oxford Clay.

The underside of the above Gryphaea.

Messel Grube Pit

The first visit while I was in Germany was to the Messel Grube UNESCO World Heritage Site, near the town of Darmstadt. The strata within the quarry itself is of Eocene age, approximately 47 Ma. This was a period in time when the earth was experiencing temperatures much higher than today. At the time of deposition, the Messel Grube area was a lake environment with a diverse fauna of fish, reptiles and mammals, the latter of which were washed into the lake to be preserved under anoxic conditions. The area is believed to be volcanically active, periodically releasing poisonous gases into the waters and nearby forests.

The pit was originally dug for the exploitation of hydrocarbons, with the discovery of brown coal and bituminous shales, when handling the rock you find that you are quickly covered from head to toe in oil. Once the pit had become disused the local government used it as a landfill site for local industries. After a lengthy campaign from the local community, the site was designated a UNESCO World Heritage Site for its diverse palaeontology. On the plus side, the rubbish that was placed in the pit is now a perfect habitat for a population of bats.

There are only two museums that are allowed to dig in this quarry, Darmstadt and Senckenberg (Frankfurt). We were fortunate enough to be allowed in under supervision to excavate some fossils.

The fossils here are incredibly delicate. The nature of the oil shale means that once exposed to air it begins to dry rapidly, in the process the rock, and subsequently the fossil, begin to curl up. This led to the development of the transfer technique, this is where the fossil is taken and placed in resin then the rock is removed in the lab to reveal the fossil.

When we arrived, we set about removing the overburden to reveal the shale. This had been put there to keep the rock moist. We then used wedges and the spades to break the rock into large slabs and moved them away from the excavation site to be split further. The rock itself was soft enough to split with a large knife.

Getting to work removing the overburden to expose the oil shale and find exceptionally preserved Eocene fossils.

Our finds included, several bowfin fish (Cyclurus), a number of gar pikes and even a bird wing. By far the most common find was coprolite (fossilised faeces). The gars and bird wing was quickly taken away to be treated in order to be preserved.

After this we went on to visit the Darmstadt Museum to see the true diversity of the Messel Pit. I will show some of these fossils in my museum series.

Dotternhausen and the Posidonia Schieffer

While on my third year residential fieldtrip to Southern Germany we visited to early Jurassic strata known as the Posidonia schieffer (shale). The rock here is somewhat akin to the Blue Lias of Lyme Regis and Charmouth, however the rock here is much more uniform and does not feature Milankovitch Cycles. This particular outcrop was in a quarry just outside Dotternhausen.

Everyone hard at work counting ammonites, you can see the
enthusiasm in the picture.

The shale was deposited under anoxic marine conditions, the sea floor would have been a soupy mud that supported no benthic fauna. This is perfect for exceptional preservation. Ammonites, crinoids, ichthyosaurs, pterosaurs, sharks and fish all would fall into this mud and sink. Due to the lack of oxygen aerobic bacteria would not be present and therefore decay would be inhibited. This leads to the preservation and discovery of fossil logs with crinoids attached and ichthyosaurs with skin outlines and embryos in the womb, just to name some examples.

The morning was spent at the Werkforum Museum at the cement works in Dotternhausen. Here we got a brief background to the fossils found in the quarry and what the environment would have been like 185 Ma.

So while visiting the Dotternhausen Quarry it was to be expected that as a cohort of 20 students we should find something between us.

Dactylioceras in one of many sheets of split shale.

Phylloceras from yet another sheet of shale.

Our first task was to collect and tabulate the number of ammonites with epibionts living on them. Myself and three of my close colleagues set to work splitting shale "sheets" and counting every ammonite in sight. Here I had my first find, a beautifully preserved fish fin, encircled by the disarticulated 'horseshore' structure of a Lytoceras ammonite.

The well preserved fish fin with the Lytoceras horseshoe
in the top of the picture.

I would have been happy to come away from the entire field trip with just this one find. But a few layers down, I come across a very small bone, about a centimetre or so in diameter. What we know is this is an Ichthyosaur vertebra. What we believe is that it is a tail vertebra of a juvenile because of how small it is. Unfortunately this was an isolated bone. Fortunately, it doesn't need any mechanical preparation as it is already well presented on the slab of shale it came from. Already I have had more success here in an hour than I have in three years of fossil hunting across numerous sites on the south coast of England.

The small tail vertebra from the ammonite exercise.

The small Ichthyosaur vertebra, in need of a
little treatment to protect it.

An hour or two after we arrived to the quarry we had all just about finished the exercise, and not a moment too soon with the day only getting hotter and hotter! And so, true to form with this class, we enthusiastically scrabbled over freshly blasted rock from the quarry wall in search of the fossils we had seen in the museum that morning.

I chose to split larger blocks bit by bit in the hope that there would be a bone or two preserved inside. A few blocks in, I start on one particular piece and put it on its side and begin hammering. It split a little too easy and at an odd angle, revealing a line of bones in the piece that had come away. Turning it over, I found that there was a line of vertebrae, criss-crossed by slender ribs. This was a disarticulated Ichthyosaur. Just on this block there was around 15 vertebrae. Definitely not complete but certainly exciting to find! It took three of us to move this block out so that the rest of the class could see what had been found.

The first block to be found in the quarry, with
some of the offcuts to the right.

The two main blocks and offcuts that we
managed to find and bring back to the
UK for preparation.

Meanwhile, the search continued for the rest of the animal. After shifting some rock, another block with a single vertebra and some definition of ribs was found. Still not complete but unfortunately there was no more of the Ichthyosaur to find. At first, I thought that the museum, or at least the cement works, would want this find for themselves. Some quarry owners in the UK confiscate fossils and sell them as profit, I assumed this was the same here. But, I was told that I would be allowed to keep them and bring them back to the UK to prepare the bones myself.

Side view of one offcut that thankfully fits back onto the
rounded block quite nicely

The two blocks are jam packed with bones, still not complete unfortunately. I believe that the centre of the skeleton is preserved, the tail and head unfortunately missing, possibly eaten by a much larger Ichthyosaur.

There's always one piece left over, no idea how this fits onto
either block. But it'll still make a nice addition to my collection.

I spoke to Professor Dave Martill about why the bones are scattered in the block as opposed to being articulated like the specimens we have seen before. He said that this is probably due to the final resting position of the animal in the Jurassic. It may well have come to rest on its ventral side and not be completely buried in the sediment, therefore decay would have taken place. Therefore you know have vertebrae that are elevated above the sediment and becoming loose due to the decay process. They will begin to fall out and land on the sediment in seemingly more random orientations. The same is true for the ribs.

The local museum has very kindly allowed me to use their equipment to prepare this find. Work will begin on the 27th June. I plan to upload nightly on the progress of the day even if it is just a photograph of what has been revealed so far. Needless to say, I'm very excited!

The Devonian Period

An artist's impression of the Devonian landscape. Image credit:
Karen Carr

The Devonian period began 416 Ma and came to a close around 358 Ma. It is commonly referred to as the Age of Fishes, despite plants and insects taking great leaps forward in evolution. 

In the Devonian, Gondwana had begun its drift into lower latitudes, set on a collision course with Euramerica. By the end of the Permian these two continents will collide and form the supercontinent Pangaea. The Caledonian Orogeny was continuing in Euramerica, however, the mountains were being rapidly eroded, this caused vast deposition in shallow ocean basins. The climate was also warming up and so the planet was quite dry. 

Because of the continuation of the formation of shallow sea environments, extensive reef building could be found on the perimeter of the continents, the reefs were continuing to thrive from the Silurian Period. 

The Placoderms that first appeared in the Silurian grew to great lengths, up to 10 metres. This made them the top predators of the oceans. The most famous of which is

Skull of Dunkleosteus. Note the bony extensions at the
front of the mouth, these are not teeth. Image credit:
cmnh.org

Dunkleosteus, this fish did not have crushing teeth instead these were extensions of bone from the armour on the animal's head. The trilobites and brachiopods were joined by the coiled molluscs; these were the first ammonites. By the close of the period we also see the emergence of sharks and rays that diversified from cartilaginous fish. 

Fish also underwent massive evolutionary success. Here ray finned fish (Actinopterygii) and lobe finned fish (Sarcopterygii) had evolved. These fish had evolved true bones, teeth, swim bladders and gills. Actinopterygii have fins supported by thin bones whereas the Sarcopterygii fins were fleshy and had phalanges that were joined to an ulna and a radius on the pectoral fin and a fibula and tibia on the pelvic fins. These two bones where then joined to a humerus on the pectoral fin and a femur on the pelvic fin. You'll notice that these are the same bones that we have in our limbs. This is because Sarcopterygii fish are widely accepted as the common ancestor for all tetrapods. But despite being the more numerous in the Devonian, the Sarcopterygii widely died out, except for the Coelacanth and lungfish that still exist today. 

Plants had taken hold of the land in the Devonian. Ferns, lycophytes and horsetails had evolved from the primitive plants of the Silurian. Plants were evolving incredibly quickly, their size and lifestyle was changing completely. A good example of this is

Artist's impression of Archaeopteris. Note
that the leaves are not true leaves they are
in fact fern-like in appearance. Image credit:
go2add.com

Archaeopteris which grew to a massive 30 metres with a 3 foot diameter. From the fossils of this plant we can see that it shed its fern like branches, a change in lifestyle from the primitive Cooksonia of the Silurian. Archaeopteris was the first deciduous tree. The expansion of greenery across the landscape meant that Carbon dioxide levels fell and Oxygen soared, this was a key characteristic of the following period the Carboniferous. 

The earliest true insect appeared in the Devonian, Rhyniella praecusor was a flightless hexapod that evolved between 412 and 391 Ma. Tetrapods also began to crawl out of the water, the first tetrapods are more closely related to amphibians. Tiktaalik rosae is believed to be the link between the Sarcopterygii and the Tetrapods. This animal was mostly aquatic but had powerful hind limbs that were jointed to a fish-like pelvis. This enabled the animal to propel itself while out of the aquatic environment. It was also able to breathe air through nostrils, an adaptation not previously seen in animals. 

The Devonian period was one of the big five extinctions in geological history (I will cover the big five extinctions in a separate post tomorrow). It is hypothesised that this extinction was two prolonged events rather than a single instantaneous eradication of species. Firstly, the Keilwasser Event which took place in the late middle Devonian. This is where great amounts of corals, the jawless fish went extinct, whilst the number of trilobite species were dramatically reduced. The second event, the Hangeberg Event, took place on the Devonian-Carboniferous boundary. Here the Placoderms and many species of early ammonite were pushed to extinction. Despite 70% of invertebrate life going extinct, vertebrates and plants were relatively untouched by these two events. The extinctions are believed to have been caused by global cooling and the first forest fires caused by Carbon dioxide depletion.  

The Ordovician Period

The Ordovician is the second geological time period of the Palaeozoic era, spanning from 485.4 to 443.4 Ma. The Ordovician is named after the Celtic tribe the Ordovices. This period was the stage for a number of revolutions in the world's flora and fauna.

Ordovician oceanscape. Image credit: dustdevil on DeviantArt

For most of the Ordovician, the climate was warm and wet. This caused the sea levels to rise 600 metres above todays levels, this created new habitats such as inland seas and freshwater areas.

The fauna still dominated the planet's oceans. After the Cambrian extinction, coiled cephalopods, called a Nautilus, exploited the empty niche and became successful and effective predators. A straight cephalopod also evolved to become one of the larger predators of it's time, this was the Orthocone. Trilobites and cnidarians also continued to thrive.

Fossil fish became more abundant in the Ordovician. The jawless mouths of these fish are found positioned on the ventral surface of the head. This suggests that they sucked up their food from the sea floor rather than being active and swift predators. We also find the early evolution of armour plating in fish in the Ordovician, the fish depicted above have bony armour plates on their heads. These fish are the ancestors of lampreys and hagfish that we have today.

Crinoids also find their origins in the Ordovician. They pinnules filtered the Ordovician waters for plankton. To read more about Ordovician crinoids, see my post 'My Collection #1' where I discuss a crinoid fossil that I have.

Life also began to make advances on land as well. Hard bodied arthropods; Eurypterids, also known as sea scorpions. could survive on land for short periods of time. This was due to the ability to diffuse gases across their exoskeleton. The living fossil Horseshoe crabs are also believed to have ventured onto land to spawn as they still do today.

Horseshoe crabs spawning, scenes like this would have
been common during the Ordovician. Image credit:
capeandislands.org

The very first terrestrial plants are seen in the Ordovician. They likely evolved from green algae. They appeared as tiny non vascular plants, that resemble Liverworts. Evidence for these plants comes from not only their fossils, but the fossils of their spores that have been identified in Upper Ordovician sediments. This shows that the plants were immediately exploiting the land, using reproductive methods that allowed for rapid expansion across the barren landscape.

The Ordovician was closed with the second largest mass extinction in the Earth's history. It is believed that this event took place between 447 and 444 Ma.

Chronostratigraphical Timescale of the
Ordovician. Image credit:
keyword-suggestions.com

A massive 49% of marine fauna was pushed to extinction, while other phyla saw individual numbers fall dramatically. This is commonly attributed to an ice age. Research by Page et al states that temperate climates did not return until the end of the Silurian. The ice age's trigger is disputed, the more popular hypothesis is that as Gondwana drifted over the South Pole, ice caps formed over where Africa would have been location on the supercontinent. This locked up vast amounts of the Earth's water, sea levels consequently dropped, destroying shallow sea habitats. The falling temperatures also pushed tropical species to extinction. An alternative hypothesis that was put forward by Melott et al in 2004 suggested that a gamma ray burst of a mere 10 seconds destoryed the ozone layer. This exposed the life on Earth to great amounts of radiation. This radiation is believed to have triggered a sharp fall in global temperatures, trigging an ice age.

Palaeoart: Leedsichthys

Today I've got two pieces of artwork from the same artist and of the same subject. The Jurassic leviathan, Leedsichthys problematicus. The artist is the great Robert Nicholls, the artist of the Ichthyosaur piece that I shared yesterday. I think we can agree that Nicholls is a fantastic artist who really does these animals justice when he brings them back to life in his artwork.

The Leedsichthys is a prehistoric fish of the family pachycormidae, an extinct group of ray finned fish. The animal is known in the Jurassic deposits in the Peterborough area where thousands of fossils have been found in the Oxford Clay quarries. The first was found by local Palaeontologist and farmer, Alfred Leeds, the man the fish is named after. However, in 2002, students from the University of Portsmouth found more remains, a team led by palaeontologists Dr Jeff Liston and Dr Dave Martill uncovered over a thousand bones, making it the most complete specimen to be found despite only finding a small proportion of the animal. Size estimates are around 11 to 14 metres (37 to 49 feet). 

This first piece shows a lone Leedsichthys with an Ichthyosaur in the background. This gives us a nice sense of scale, although the Ichthyosaur is in the background it is clear to see that it is dwarfed by the fish. This raises an interesting question, would smaller animals follow giants like this as a form of protection? Another thing I like about this piece is Nicholls' choice of colouration for the Leedsichthys, a dark dorsal surface and white underneath. This is very similar to the colouration of modern sea animals including Great White Sharks. The sharks of today are coloured as such so that from above they are camoflaged with the murky depths and from beneath they blend in with the bright surface of the water, this makes it more difficult for prey to spot the incoming predator. But Leedsichthys was not a predator, it was a filter feeder like the Whale and Basking sharks of today, this is shown by the giant gape of the fish's mouth which is collecting tiny plankton. The reason for the a peaceful giant like Leedsichthys to be coloured this way is for its own protection, a predator would have difficulty making out the outline of the fish from above or below, making a successful attack more risky.

The seond piece I've chosen is another lone Leedsichthys in the Jurassic Ocean by Robert Nicholls. This time rather than being accompanied by an Ichthyosaur, there is a group of smaller fish surrounding the giant, the species is possibly Caturus. This is interesting as it shows the vast range in size between the two types of fish, which helps to visualise the length of this gentle giant. As with the last piece, it appears that smaller animals are staying close to the Leedsichthys for protection from predators. This behaviour can be seen in fish today that surround Whale Sharks.

Overall, both artworks are impressive in the way they show us the scale of this fascinating fish. If you want to read more about this wonder, then pay a visit to the new website created by a team at Peterborough Museum, the link will be left below.

www.bigjurassicfish.com