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.

Museums: Hauff Museum, Holzmaden

In this series I would like to share photographs of fossils and exhibitions from museums that I have visited. There won't be a lot to say about them so this will be mainly photographs of what I thought was pretty outstanding.

This post features some photographs taken in the Hauff Museum at Holzmaden. It is devoted to the palaeontology of the Posidonia Schieffer and exhibits a range of fantastic fossils, including invertebrates, marine reptiles, fish and pterosaurs. Enjoy.

The Hauff Museum featured a stepped profile of the stratigraphy through the Posidonia Schieffer. Each bedding surface featured a different fossil groups. You can see a marine crocodile (Steneosaurus) in the middle. It also featured plesiosaurs and ichthyosaurs.

An example of the most common fossils found in the Posidonia Schieffer; ammonites. These ammonites vary in size from a centimetre in diameter to around 40 centimetres (that we saw). 

This particular bedding surface exhibits the most spectacular of the fossils found in the shale. The long dark fossil is a piece of driftwood. Attached to it are crinoids (sea lillies). The wood along with the crinoids would have floated in the water column until the weight of the crinoids and bivalves became too much and the wood sank and became buried in the soupy sea floor.

This is a rather complete fossil of a hybodont shark. These sharks are easily recognisable from their fin spines that precedes their dorsal fins. The cause of death for this particular shark is believed to be that of greed. The palaeontologists here believe that this shark ate too many belemnites including the guards, which caused it to increase its weight, eventually the shark became to float and subsequently died. The belemnite guards are still in the stomach of the shark.

This is the fossil of one of the largest Ichthyosaurs. This is Temnodontosaurus, fossils of this are found throughout Europe, a skull is on display at the Charmouth Fossil Shop that was found in the Blue Lias. This animal would have been the top predator of the Jurassic seas. Sir David Attenborough's recent documentary on an Ichthyosaur from Lyme Regis is evidence that Temnodontosaurus hunted smaller Ichthyosaurs.

This is by far the most impressive specimen in the museum. This is an 18m long piece of driftwood that has been colonised by crinoids and bivalves. This makes visiting the museum well worth it.

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!