Mark Wilson October 27th, 2013
DENVER, COLORADO–It’s that time of year for geologists when we collect at one of two major national meetings. Wooster geologists are always well represented at the Geological Society of America convention, this year held in downtown Denver. Meagen Pollock, Shelley Judge and I are here with nine enthusiastic Wooster students. Some events have already taken place (notably for me the paleontology short course and an epic annual banquet meeting of the Paleontological Society), and we’ve had our first student poster presentation.
Oscar Mmari is shown above with his poster entitled: “Syndepositional faulting, shallowing and intraformational conglomerates in the Mishash Formation (Upper Cretaceous, Campanian) at Wadi Hawarim, southern Israel“. Readers of this blog will remember Oscar’s summer work in the Negev measuring and describing sections. Oscar’s presentation went very well. Every time I stopped by the poster someone was in deep conversation with him.
Here’s an early morning view of the Colorado Convention Center in Denver where we’re doing our work and study (and socializing, truth be told). The weather this weekend has been fantastic, but a big change will come tomorrow morning.
More posts will follow!
Mark Wilson October 27th, 2013
Earlier this summer I participated on a pre-conference field trip of the International Bryozoology Association throughout Sicily. We had an excellent time and saw many wondrous things. At one stop on the western side of the Milazzo Peninsula in the northwestern part of the island we collected fossils from a fascinating foraminiferal ooze deposit known as the “Yellow Calcareous Marls” (Gelasian, Lower Pleistocene). Among the fossils in this unit were the objects pictured above. They looked like finger bones at first, but are actually the internodes (calcitic skeletal elements) of an octocoral known as “bamboo coral“. This particular species is Keratoisis melitensis (Goldfuss, 1826). I’ve never seen this group before in the fossil record. (Note, by the way, that these specimens are encrusted by foraminiferans and octocoral holdfasts. This means they rolled around on the seafloor for an extended period before burial.)
Bamboo coral belongs to the octocoral group and is only a distant relative of reef-forming “hard corals” or scleractinians. They are common today in deep seas because they do not need sunlight for photosynthetic symbionts like most hard corals do. They have multiple polyps for feeding, none of which can retract back into the skeleton. That is why the surface of these internodes is so smooth and without the usual corallite holes. Above is a colony of white bamboo coral (Keratoisis flexibilis); image from Wikimedia Commons.
Here we have a dried specimen of Keratoisis from the Florida Straits. You can see the white calcitic internodes of the skeleton separated from each other by the black nodes made of an organic material called gorgonin. This explains why our fossil specimens consist entirely of the isolated internodes — the chitinous parts did not survive fossilization. (Image from NOAA.)
Bamboo corals are long-lived, and it has been recently discovered that they incorporate trace elements in their skeletons as they grow, making them excellent specimens for studying changes in the chemistry and circulation of deep-sea waters. These fossils may thus someday be useful for sorting out the complex changes in the Mediterranean during the Pleistocene.
Langer M. 1989. The holdfast internodes and sclerites of Keratoisis melitensis Goldfuss 1826 Octocorallia in the Pliocene foraminifera marl Trubi of Milazzo Sicily Italy. Palaeontologische Zeitschrift 63: 15-24.
Sinclair, D.J., Williams, B., Allard, G., Ghaleb, B., Fallon, S., Ross, S.W. and Risk, M. 2011. Reproducibility of trace element profiles in a specimen of the deep-water bamboo coral Keratoisis sp. Geochimica et Cosmochimica Acta 75: 5101-5121.