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.

Ichthyosaur Preparation Diary #1

BEFORE: The underside is the side
 that I will be preparing from, 
far too much rock
for a small drill to get through.

The first major work that needed doing to the Ichthyosaur was that it needed cutting down to size. The blocks were very thick and very heavy. Plus, I plan on mechanically preparing the bones by going from what looks to be the bottom. This is because the bones are exposed on the top surface, great for spotting them in the field, not so good for their preservation. Some of the vertebrae in the long block are badly worn but going from the other side will reveal them at their best.

The round block was easy enough to split. The stratification was completely parallel to the bedding surface and split like a dream. On the underside, there are another three rather large vertebrae waiting to be revealed.

AFTER: The thickness of the rock has been greatly reduced,
making it easier for the drill to get to the better preserved side
of the bones.

The long block didn't want to play as nicely. The position of some of the bones had created cylindrical structures which split vertically rather than horizontally. Unfortunately, it broke into three pieces, not beyond repair but something that would have been better avoided.

Next step was gluing the off cuts, and now broken pieces back onto the main blocks so that the bones were complete when they are prepared out. Again the round block went back together with little to no fuss. One piece was guided in by a handy belemnite that had broken in two and stuck to either piece of shale. The long block was proving difficult again. The larger of the broken pieces was thicker than the main block and so the other end is being propped up to stop it snapping again. The rest was repaired with no problem, another three vertebrae added to this block with numerous ribs completed.

Block 1 after the repairs. The glued piece at
bottom of the picture is the large broken piece.
The glued slab on the right of the block has
three more vertebrae in it and numerous ribs, it
also completes a number of vertebrae along the
glued line.

Block 2 much more neatly glued and split with
the three large vertebrae revealed in the centre.
There is also potentially a fourth near the
tape measure but we will have to wait and see.

BEFORE: The small odd piece that doesn't fit
anywhere

But there is one piece that just does not fit anywhere. A shame but in this small piece of shale there are two vertebrae, at different angles. One appears to be squashed anterio-ventrally and the other is half complete. But once prepared it'll make a nice display piece.

Although the epoxy glue looks unsightly, I have smeared it onto the side that will be face down when it comes to preparation so this will not be seen.

AFTER: The small odd piece after splitting, this brings
the bone closer to the surface. The first vertebra is
clearly seen in cross section here.

The second vertebra is harder to see, it is in the centre of
the rock in side view, the lip around the centrum is rather
prominent.

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!

Lyme Regis (and a passing visit to Charmouth)

In this second part to the Dorset Fieldwork I will show you all the world famous Lyme Regis Lias outcrops. These were incredibly interesting both geologically and palaeontologically. Our trip leader, Professor David Martill found something very exciting when making our way back to the coach.

We visited the beach to the west of the town of Lyme Regis, Monmouth Beach.

Lyme Regis (with a quick stop at Charmouth):

Map of West Dorset showing the location of Monmouth Beach.
(Source: Google Maps)

The alternating succession of shales and argillaceous
limestones at Monmouth Beach. (Source:
https://www.shutterstock.com/video/clip-5416676-stock-
footage-the-blue-lias-beds-and-limestone-pavement-on-
monmouth-beach-cliffs-lyme-regis-on-the-jurassic.html)

The limestone ammonite pavement, or ammonite
graveyard. (Source: https://chandlerscottage.co.uk/1
125x750-lyme-regis-0772/)

In the morning after a rather lengthy drive from Swanage, we arrived in Charmouth. Although we didn't actually go onto the beach to see the cliffs up close, we got a pretty good view of the geology. I have also visited this site a number of times and will post the fossils I found in my collection series.

When standing at the Charmouth Heritage Centre, if you were to look to the west towards Lyme Regis those dark clay cliffs are called Black Ven. To the east you have Stonebarrow and the Golden Cap.

Charmouth is a Jurassic succession being deposited during the Sinnemurian to Pliensbachian ages of the lower Jurassic, approximately 190 Ma.

Black Ven is highly fossiliferous with ammonites being the most common fossil you will find. If you are very lucky you can also find crinoids, Ichthyosaur and Plesiosaur remains. A complete dinosaur, Scelidosaurus, has also been found here and is on display in the Charmouth Heritage Centre. Another must see is in the fossil shop, where they have on display a large Temnodontosaurus skull.

This is also one of the sites that Mary Anning collected from, finding marine reptiles and the pterosaur, Dimorphodon macronyx, later described by Sir Richard Owen.

After this brief talk we then drove a bit further west into Lyme Regis and walked down onto Monmouth Beach. Here you will notice, similar to Kimmeridge Bay, a repeating pattern in the cliffs between shales and argillaceous limestones, another example of Milankovitch Cyclicity.

But the really interesting thing to see here is in the wave cut platform that is formed by one of these bands of limestone. It is covered in hundreds of ammonites, the majority are of the genus Coroniceras. This was a single event where all of these ammonites died at the same time, this was gradual, possibly they returned to the same site seasonally. Ammonites won't be the only fossil you find here, you can also spot nautiloids, crinoids and gastropods. A complete Plesiosaur was even found in the pavement some years back.

If you wet the limestone around an ammonite you will find dark marks in the rock. These are fossilised burrows. Some are branching 'Y' shapes, this is formed by a shrimp, the name given to these burrows is Thalassinoides. Others will be two circles next to each other (Diplocraterion), straight burrows (Planolites), and some very fine burrows. These very small burrows are called Chondrites and show that the water had become anoxic for a period.

On the walk to the next locality, Professor Andy Gale found a large nautilus, preserved in three dimensions, a very nice find indeed. It was picked up by a course mate on the way back to the coach.

The next site was geologically of interest. This was the boundary between the limestone dominated White Lias, to the shale of the Blue Lias. The interesting part is, lithologically speaking the boundary is very clear, you can see a pale limestone become a dark shale. You would be forgiven for thinking that this is simply the boundary between the Rhaetian of the Triassic and the Hettangian of the Jurassic.

But to date the rock to confirm this is very difficult. The use of lavas of similar ages are regularly used to radiometrically date rock, however, there are no lavas to use. So dating could be done with the fossils, using relative dating. The change in the ammonites present between the White and Blue Lias represents a biological boundary. This is higher in the succession than the lithological boundary.

On the way back, Professor Dave Martill came across some Ichthyosaur remains in a limestone band of the Blue Lias. Unfortunately I did not see it but there was enough articulated material to warrant him going back to recover it.