Archive for April 15th, 2016

Wooster’s Fossil of the Week: An atrypid brachiopod from the Devonian of Spain

April 15th, 2016

1 Atrypid dorsal Lr Couvinian M Dev El Pical Leon SpainOur featured fossil this week is another gift from brachiopod enthusiast Clive Champion of England. This fine specimen of Atrypa sp. was collected from the Middle Devonian (Lower Couvinian) exposed at El Pical, Leon, Spain. Atrypa is the emblematic genus of the atrypid brachiopods, which were common in the Devonian around the world. They were also prominent in the Late Ordovician of the Cincinnati region, as seen here and here. We are looking at the dorsal valve in the above view.

2 Atrypid spiraliaThis particular specimen is not notable for its special beauty (it is, after all, exfoliated and a bit misshapen), but for the view it provides of an internal feature: the spiral brachidium, sometimes called the spiralia. This was a ribbon of calcite that supported the lophophore, a tentacular apparatus used in filter-feeding. We see it here because the dorsal valve eroded away, exposing the inside of the shell. Our friends at The Falls of the Ohio have another specimen showing the spiral lophophore of an atrypid.

3 Atrypid ventralThis is a view of the flat ventral valve of our atrypid brachiopod. Inside during life the spiral lophophore would have looked like two springs perpendicular to the floor of this valve.

Thank you again, Clive, for the beautiful and inspiring brachiopods!

References:

Bose, R. 2013. A geometric morphometric approach in assessing paleontological problems in atrypid taxonomy, phylogeny, evolution and ecology, p. 1-9. In: Biodiversity and Evolutionary Ecology of Extinct Organisms. Springer, Berlin and Heidelberg.
Rudwick, M.J.S. 1960. The feeding mechanisms of spire-bearing fossil brachiopods. Geological Magazine 97: 369-383.