In Adam related news a process that was begun well over a year ago has finally culminated in me being awarded permanent residency status in South Africa. This is good news because it means I’ll be able to devote more time to all the wonderfull discoveries we made over the past two weeks while moving the BPI collections into the newly refurbished collections room (We’ve got compactuses and sliding drawers now!). Maybe I should blog about them sometime.
This tube belongs to one of the odder forms of Mollusca that this diverse phylum has thrown out.
Believe it or not (and yes, that’s its real name) this tube with what vaguely resembles the flower-attachment of a watering pot at one end, is a bivalve. A clam shell. Indeed ther bizarre group of bivalves to which it belongs are known as the watering pot shells (the proper taxonomic name for the group is the Clavagelloidea). To understand how such a major departure from the normally conservative two-part clam shell could have evolved it is important to note that many bivalve animals outgrow their shells. Just look at this geoduck.
With this in mind the tube of the clavagelloid becomes easier to understand. What needs to happen is for the shell-secreting mechanisms that secrete the ancestral shell to go crazy and extend way beyond the boundaries of the ancestral valves and coat the entire animal in a shelly tube. Indeed a closer look at the tube will reveal a pair of tiny ancestral valves embedded within it.
So in this picture the tube is upside down: the long siphonal tube that would reach up to clear water through the sediment is pointing to the bottom of the page.
Of course growing the tube isn’t quite as simple as extending the shells, for one thing the tube is underlain by the periostracum – a flexible, non-mineralised sheet that lies on the outside of the valves (so anatomically speaking the tube lies above the valves – even though they are embedded in it – go figure). Just how the tube of watering pot shells is secreted has been a matter of debate. Surprisingly no one has ever found a half-grown watering pot, all that is known is a single tubeless juvenile specimen of just one species, all other known watering pot specimens belong to adults with fully developed tubes. So jusy how they grow is still a bit of a mystery. I spent a lot of time earlier this year learning all I could about these fascinating bivalves, so I will be returning to them several times. Eventually I can tell you why.
Since I’m getting this blog off the ground again, I think I must clear up some old business. Firstly I’ve already dealt with my nomenclatural blunder in the previous post. Readers may also remember this picture from the old DracovenatorPictured is my wife, Celeste, as a newly appointed preparator to the IHE (Institute for Human Evolution) working away at a hush-hush important fossil that had to be deleted from the picture. So what was it?
……the holotype skull of Australopithecus sediba. Its not every day that your handy-work is displayed on the front cover of Science. Well done Celeste! (Yes, I know I’m three months late on this post).
If you’ve been following this blog (what little of it there is to follow) since the old version you may remember me going on about some fossil cowries from South Australia that I had named. Well as it turns out one of them already had a name. Lyncina (Austrocypraea) cadella Yates 2008 was actually named Austrocypraea rumballi way back in 2003 by Dirk Fehse. So sincere apologies to Dirk for not being aware of his work. In my defense Austrocypraea rumballi was published in a difficult to find newsletter of a shell club, and thorough searching by myself before publication failed to produce any reference to it. I don’t mind too much after all I’ve known Wayne Rumball, the guy the species was named after, since I was in high school and apart from being a thoroughly pleasant fellow has donated much of his time volunteering at the South Australian Museum. I just thought I might have had a more substantial number of taxa under my belt before I hit the almost inevitable synonym. The other species named in the paper, Umbilia caepa, still stands as valid as does the description of L. (A.) rumballi and the biogeographic/diversity conclusions.
Fehse, D. (2003) Katalog der fossilen Cypraeoidea (Mollusca: Gastropoda) in der Sammlung Franz Alfred Schilder. III.I. Die Gattung Austrocypraea Cossmann, 1903
I don’t have much time for an involved post but it would be remiss of me not to mention that my friend and supporter of Dracovenator, Dave Hone, has a new paper out in PLOS One. Dave and several of his colleagues have been looking at famous Liaoning fossils under UV light in order to see what structures may become visible that you can’t see under ordinary white light. The technique has been used to great effect by Helmut Tischlinger (one of the authors on the present paper) on pterosaurs from Solnhofen, revealing all sorts of structures like soft tissue crests, and keratinous beak-tipped jaws.
The present paper answers a very specific question. A halo of non-preservation seems to occur between the skeletons and the feathery plumage of feathered theropods from Liaoning. Is this halo real or just a preservational artefact? Hone et al. looked at one of these theropods, Microraptor, and decisively found that it is indeed a preservational artefact. Under UV light the feathers in the halo region show up nice and clearly, the rachis (‘stem’) of large flight feathers making a connection with their supporting bones, just as in modern birds. This means that a) the flight feathers, even those of the hind wing, were rooted firmly to the skeleton and b) were longer than we had previously realised. If you want to read more check out Dave’s own blog posts here and here. Otherwise download the paper itself – its free.
Hey everyone, since its been a long time since I posted I’m giving you an extra bonus picture of the day post. This was taken at our rented holiday house at D’Estree’s Bay on Kangaroo Island. It depicts one of those special moments that happen between fathers and their sons and a random squamate.