Archive for June 12th, 2011

Wooster’s Fossil of the Week: A strange little echinoderm (Ordovician of Russia)

June 12th, 2011

This small fossil was completely new to me when I found it during my research trip to the Ordovician of Russia in the Fall of 2009.  A side view is shown on the left of this conical skeleton, and the top view is right.  I could tell it was an echinoderm because it has a characteristic structure in its calcitic skeleton known as the stereom (a network of tiny passageways inside the crystals).  Other than that, it was a mystery to me.

My Russian colleague Andrey Dronov showed me that it is of the genus Bolboporites, a strange relative of the crinoid found only in the Ordovician of the Baltic Region and North America.  As you can see in the reconstruction on the right below, it probably lived in the sediment as an upwardly-flaring cone with a single feeding arm (the brachiole) collecting suspended organic matter from passing water for food.  In the fossil view above and right, you can see the hole where the missing brachiole fit; inside of that you can just make out an opening that is likely the mouth.

Bolboporites likely originated on the paleocontinent of Baltica and then migrated to North America.  As far as I can tell it is vanishingly rare over here — I’ve never seen Bolboporites before in the field or in collections.  Now Wooster has one of the very few of these little treasures.

References –

Rozhnov, S.V. 2009. Eocrinoids and paracrinoids of the Baltic Ordovician basin: a biogeographical report. IGCP Meeting, Ordovician palaeogeography and palaeoclimate, Copenhagen, p. 16.

Rozhnov, S.V. and Kushlina, V.B. 1994. Interpretation of new data on Bolboporites Pander, 1830 (Echinodermata; Ordovician), p. 179-180, in David, B., Guille, A., Féral, J.-P. & Roux, M. (eds.), Echinoderms through time (Balkema, Rotterdam).