Palaeontology of SW Germany 3.1.14: spineless @ Hauff

This series of posts on the Palaeontology of SW Germany, where I grew up, has gotten a bit longwinded and confusing. Therefore, I’ll give you a linklist to those parts dealing with the Urweltmuseum Hauff.

So far I have concentrated on the vertebrates (hey, I’m a vertebrate palaeontologist, OK?), but now it is time for some amazing invert stuff. The lack of a spine doesn’t mean an animal is soft and squishy, but as usual the Posidonia Shale preserves a lot of squishy stuff on shelled and otherwise hard-tissued animals that elsewhere is normally lost. So now there will be a series of posts showing such fossils, and today’s topic are a group of cephalopods: belemnites. Let’s start it off with a rather non-special specimen.

Youngibelus tubularis and Acrocoelitis levis.
Longest rostrum is (I guestimate) some 15 cm!

That’s how we often find belemnites: the rostrum’s tough part, plus some crushed remnants of the hollow shorter part (the phragmocon), but nothing of the animal’s soft parts. Check out the nicest specimen I ever found here.

Or, if you are very lucky, you can find a fossil documenting how this typical preservation comes about in many cases:

Palassoteuthis laevigata

This belemnite got munched on by a predator, probably a shark or ichthyosaur. CRUNCH!!! Why the attacker dropped the soft parts with the fragments along with the tough massive rostrum I have no idea.

So, what do those superspecial belemnites with soft tissues look like?

better, hu? Here, Acrocoelites trisulculosus has a complete phragmocon. But that’s not really soft tissues. It gets better:

Palassoteuthis laevigata – the biggest known female with tentacles preserved. Note that the ink has spilled a bit, but that the mantle muscle is well constrained.

and here is Palassoteuthis laevigata, the smallest find so far. This one got into the jaws of some hungry predator. It is, I guess, about 33% of the size of the large female above.

Nice taphonomy story with this female Palassoteuthis laevigata: the heavy rostrum pulled the dead or dying animal down when the phragmocon was damaged the the air escaped. It penetrated the mud on the sea floor, whereas the lighter soft tissues settled on the mud surface. We will see something similar for vertebrates in future posts.

This is a longitudinal section, in which you can nicely see that most of the rostrum is solid, and that the widening phragmocon reaches into the solid bit only for a short distance. All the calcite crystals are radially arranged.

Now, finally, for a male of Palassoteuthis laevigata. You can recognize males by the two large hooks with which they grab and hold on to the females. This photo came out a bit greyish, and I did some photoshopping to make the animal stand out more.

The next specimens I need to show in context: the smallest known belemnite rostrum, from a juvenile about 30 mm long overall, next to the hooks of large males. Cool!