Sunday, July 18, 2010

Bryozoans of the Mahantango

Bryozoans were an integral part of the reef ecosystem during the Paleozoic and there are several good examples from the Mahantango.

By far the most common are the Fenestella type Bryozoans. These are basket or fan shaped lattices that are usually found as fragments due to their delicate nature. I've found some large examples of the fan shapes and a few that preserved the cone shaped base of the basket shapes.

This is a large piece of a fan type Fenestrella. You can see I had to glue together the piece from a few smaller bits.

Another commonly found genera is Sulcoretepora which is a branching type but they were flat instead of round as in other species. The first one still has some of the calcitic skeleton preserved while the others have had it dissolved away.

This sample from the Centerfield Reef member has as at least four different species (including two of Fenestella).

I think that the Bryozoans were more limited in genera within the Mahantango since much of it was a nearshore detaic environments. You find the most diversity when the rock becomes more limy indicating a transgression (rising) of the oceans and thus deepening and clarifying the water.

Here are some stick like Bryozoans that appear as tiny branches. They are too small for me to get a clear picture of for ID purposes but I think they are part of the Rhombopora genus.

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