Post by Joe Botting on Aug 18, 2009 15:38:15 GMT -5
Thought this deserved a new thread. We've just been staying with Peter Van Roy in Dublin, and got some of the palaeoscolecids imaged in their mini backscattered SEM. The results are very mixed.
One specimen was really poorly preserved, with no detail beyond dark blobs where the plates had been. Another was similar butshowed really weird structures, as if some of the the plates had practically melted, and blurred together. Odd indeed.
The third one we tried was... rather better. Here's a wide-scale view. The blobs with no clear form are probably the undersides of the plates of the other surface, compressed onto that one. You can at least see the arrangement - rows of plates, separated by much finer-textured mesh.
Zooming in a bit, you can see the odd marks on each plate. Normally there are a clump of tubercles in one form or another, so this is not normal. It may well be new. You can also see that some of the background mesh is porous, but in places (e.g. adjoining the central plate) there are patches with microplates sitting in place in the mesh
A close up of the microplate area now; note the scale bar is 30 micrometres.
And finally, a real close-up of the structure. There are structures aty this scale that seem to be new in our understanding of the group, although some may be preservational. There are still some mysteries in palaeoscolecids - like, for example, what they were really related to (probably priapulids, but we're not completely sure), and what their plates were made of (partly phosphatic or entirely organic? It's still up for debate). This is the sort of material that can help to answer a few questions, and I reckon this is some of the finest preservation ever found.
The other three species are waiting to be sawn up and put in the SEM by Peter at some point. We're going to be looking for as many fragments as we can of these things - it might just be one of the most important palaeoscolecid faunas known.
As a final thought, we seem to have two genera that are very similar to species from... Australia. Combined with the sponge Pseudolancicula (and friends), this is starting to become an unsettling pattern. Either the record is incredibly incomplete, or there's something rather odd here... ;D
One specimen was really poorly preserved, with no detail beyond dark blobs where the plates had been. Another was similar butshowed really weird structures, as if some of the the plates had practically melted, and blurred together. Odd indeed.
The third one we tried was... rather better. Here's a wide-scale view. The blobs with no clear form are probably the undersides of the plates of the other surface, compressed onto that one. You can at least see the arrangement - rows of plates, separated by much finer-textured mesh.
Zooming in a bit, you can see the odd marks on each plate. Normally there are a clump of tubercles in one form or another, so this is not normal. It may well be new. You can also see that some of the background mesh is porous, but in places (e.g. adjoining the central plate) there are patches with microplates sitting in place in the mesh
A close up of the microplate area now; note the scale bar is 30 micrometres.
And finally, a real close-up of the structure. There are structures aty this scale that seem to be new in our understanding of the group, although some may be preservational. There are still some mysteries in palaeoscolecids - like, for example, what they were really related to (probably priapulids, but we're not completely sure), and what their plates were made of (partly phosphatic or entirely organic? It's still up for debate). This is the sort of material that can help to answer a few questions, and I reckon this is some of the finest preservation ever found.
The other three species are waiting to be sawn up and put in the SEM by Peter at some point. We're going to be looking for as many fragments as we can of these things - it might just be one of the most important palaeoscolecid faunas known.
As a final thought, we seem to have two genera that are very similar to species from... Australia. Combined with the sponge Pseudolancicula (and friends), this is starting to become an unsettling pattern. Either the record is incredibly incomplete, or there's something rather odd here... ;D
