Decapods today. It is high time I finally finish off the remaining fossils from the Urweltmuseum Hauff and post a final post discussing the museum as a whole, and one on the reconstructions shown – oh wait! There’s also the dinosaur models the museum has outdoors. Hm, seems this series will be going on for a while.
Anyways, here’s a very rare and very beautiful fossil from the rock-hard Lias ε II5. The beast is, I guess, some 20 cm long, a model decapod. I can’t tell if it is a complete animal or just an exuvia – the stripped-off exoskeleton and skin of an arthropod that has moulted. I tend towards the former, as it is not labelled as an exuvia. Genus and species unknown – crustacean taxonomy is tough enough for the extant stuff, I guess. German wikipedia even has a special page for just the taxonomy of the Malacostraca (lobsters, shrimps, krill, crabs, woodlice, etc.) here.
And this is Uncina posidoniae (PalaeoDB entry; may currently be down, you can use the mirror site). This one is an exuvia. As always, click on the photos for a larger version, it is worth it! If you want the full-size photos, tell me in comments and I will dropbox them to you.
Here’s two more Uncina posidoniae, the most beautifully preserved one (top), and the largest one (bottom), a 39 cm whopper. In fact, Uncina is common enough and so well known from beautiful fossils that there is quite some literature on it.
Ain’t they beautiful? As the photos show – and as anyone over the age of ten should know from school, but don’t get my started about biology in schools – a lobster, shrimp or other crustacean has a segmented body with an exoskeleton. The various segments can separate, both on decaying animals and on exuviae. And then you do not find perfectly preserved complete specimens, but some may have parts missing (as does the first Uncina shown above – no carapax!), or you find the individual parts separately. Because they have different sizes you may even get sorting by currents.
Coleia – not one carapax on its own, without the rest of the exoskeleton, but 18 of them in one slab of maybe 40 cm square!
OK, on to better preserved animals. Remember that that Lias-Sea was most of the time a shallow sea with an anoxic bottom? No wonder there are few crustaceans to be found in it. However, there are several layers with so-called sea-grass on them, which in reality are crustacean burrows infilled with slightly less dark sediment. I tried finding a nice photo on the net but failed, sorry. I have no idea what crustaceans made the burrows, but here’s another very nicely preserved one.
Proeryon giganteum – this Coleiid was a bit too big to have made the Seegrasschiefer burrows, I guess. But it looks awesome! Below is Proeyron hartmanni, a smaller species. This specimen is shown from the back, which is a bit unusual: Posidonia Shale fossils are normally prepared from the lower side, because it is better preserved, having been in contact with the sediment instead of exposed to the water before burial. And Proeryons tend to be found belly-down.
And that ends the Crustacean exhibit of the Urweltmuseum Hauff. Only a handful of specimens, but considering how rare they are an impressive show, which is probably overlooked by many visitors amid all the other awesome stuff. Next up are a bunch of ammonites!