Bizarre Amynilyspes Mazon Creek Pill Millipede Fossil
Subphylum Myriapoda, Class Diplopoda, Superorder Onsicomorpha
Time: Pennsylvanian (~300 m.y.a.)
inch): Fossil is 17 mm long by 7 mm across Matrix: 45 mm by 27 mm nodule
Mazon Creek, Coal City, Illinois
The Mazon Creek deposits of the region near Braidwood, Illinois
rival the other famous Lagerstatten of the Burgess Shale, Solnhofen,
and Liaoning for the variety of detailed life preserved. Many exquisitely-preserved
specimens are found in the ironstone nodules that make up the deposits.
of collecting areas are the spoil heaps of abandoned coal mines,
the most famous of which is Peabody Coal Pit 11. Pit 11 now serves
as a cooling pond for the Braidwood nuclear power plant, but with
over 100 other localities, specimens still come to light.
specimen is of a group not commonly seen from the Mazon Creek fauna
known as Amynilyspes, a pill millipede. In addition to the pill
millipedes, the Mazon Creek Fauna also has members of the euphoberids
and the xyloiulids. The pill millipedes have the capacity to coil
into a ball so tightly that they can be watertight when fully enrolled.
The pill millipedes persist to the present day, and are associated
with the forest floor. Note that this specimen has fronds of the
fern Pecopteris in association.
fossil pictures to enlarge