Post by Joe Botting on Feb 12, 2011 22:03:05 GMT -5
I can't resist posting something about this little darling. In the Builth Inlier it is practically everywhere - it's found from the oldest to the youngest beds, and in every environment except the shallowest water and inside magma chambers. Technically, it's Apatobolus? micula - an obolid (phosphatic) brachiopod that is roughly circular and except for one interval, doesn't get above 3 mm in diameter. The question mark on the genus is because it has so few features it's hard to say what it is!
micula cluster by joe with a camera, on Flickr
There are billions of them in the Builth mudstones. During my PhD I counted something like 11,000 of them for ecological purposes, and despite doing our best to ignore them, they've been showing up some interesting things. Firstly, they sometimes appear in clusters, as above. You'l notice that it's a cluster around a graptolite. We've had this at two sites, and it is always around a relatively rare species at each (both climacograptids), and never the common ones. Why? It's pseudoplanktic. These things were (in part) living attached to the graptolites, or to algae wrapped around them... presumably the specific graptolite preference is because the hosts lived at different water depths.
For something so abundant (in some places over 400 individual per 100 gof shale), it would be amazing if nothing ever ate them. And it looks like something did:
Apatobolus? micula, nibbled by joe with a camera, on Flickr
The something was clearly capable of breaking the shell, but just for once failed to kill the micula, which lived on to produce this weirdly healed shell. In other cases, the brachiopod definitely didn't make it. Here's a pellet made of crushed shells, and we've seen a few:
micula pellet by joe with a camera, on Flickr
So what was eating it? Something that had pretty specialist behaviour, and went (at least sometimes) only for one species. Something that had hard enough bits to be able to break a shell (excluding its jaws), which presumably means chelicerae or the like. And it was fairly small - the pellets are only a couple of millimetres across.
There are lots of trilobites at the site with the nibblings, but despite soft tissue preservation, we've not had any other definite arthropods besides ostracodes. So... probably a trilobite, we reckons. But we have no idea which one!
micula cluster by joe with a camera, on Flickr
There are billions of them in the Builth mudstones. During my PhD I counted something like 11,000 of them for ecological purposes, and despite doing our best to ignore them, they've been showing up some interesting things. Firstly, they sometimes appear in clusters, as above. You'l notice that it's a cluster around a graptolite. We've had this at two sites, and it is always around a relatively rare species at each (both climacograptids), and never the common ones. Why? It's pseudoplanktic. These things were (in part) living attached to the graptolites, or to algae wrapped around them... presumably the specific graptolite preference is because the hosts lived at different water depths.
For something so abundant (in some places over 400 individual per 100 gof shale), it would be amazing if nothing ever ate them. And it looks like something did:
Apatobolus? micula, nibbled by joe with a camera, on Flickr
The something was clearly capable of breaking the shell, but just for once failed to kill the micula, which lived on to produce this weirdly healed shell. In other cases, the brachiopod definitely didn't make it. Here's a pellet made of crushed shells, and we've seen a few:
micula pellet by joe with a camera, on Flickr
So what was eating it? Something that had pretty specialist behaviour, and went (at least sometimes) only for one species. Something that had hard enough bits to be able to break a shell (excluding its jaws), which presumably means chelicerae or the like. And it was fairly small - the pellets are only a couple of millimetres across.
There are lots of trilobites at the site with the nibblings, but despite soft tissue preservation, we've not had any other definite arthropods besides ostracodes. So... probably a trilobite, we reckons. But we have no idea which one!