Gumdrops

insitu Prasopora Lexington Formation, KY

Bryozoans are some of the most common fossils found in the Upper Ordovician deposits of the Kentucky Bluegrass. Prasopora falesi?,  closely related to P. simulatrix Ulrich, of the Monticuliporidae family is found only in Kentucky in rocks of  Kirkfieldian and Shermanian. Specimins have been found in the Grier Member (which spans the Kirkfieldian and Shermanian stage boundries), Brannon Member, Sulphur Well Member, Tanglewood Member, and through the Shermanian Stage portion of the Clays Ferry Formation.

Specimen has a 7cm diameter base

The hemispherical growth habit of P. falesi has lead to its more colloquial name the “gumdrop bryozoan” OR "chocolate drop" to local fossil collectors.

Another fun aspect of the growth habit of these bryozoans is when examining their underside you can often tell what they were living on... a bivalve perhaps? a silty muck? reworked clasts?

Specimens from left to right have a 5cm and 7cm 

diameter base.

In reading through Karklins, 2010 I am also entertaining the possibility that the specimens photographed above could also be Mesotrypa angularis Ulrich, 1893. I will be doing thin sections or acetate peel to investigate this further. If you have any thoughts or suggestions on the genus please comment below. Thanks for checking out Ordovician Weekly.

Reference: O. L. Karklins, U.S. Geological Survey professional paper, Issue 475, G.P.O, 1984, University of Michigan, Digitized Feb. 22, 2010.