Time: Carboniferous, Westphalian Stage
mm = 1 inch): Millipede fossil is 63 mm on a 30 mm by 62 mm nodule pair
Mazon Creek, Francis Creek Shale, Braidwood, 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.
This fine example is one of the spiny millipedes known as Euphoberia
tracta, and comes from Mazon Creek itself. The fossil history of millipedes
dates back to the Silurian, with some fossil burrows which may be
attributed to millipedes having been found in the Devonian. Since
millipedes live in habitats such as moist forest floors, fossilization
is a very chancy occurrence. It is thought that they made the transition
to fully terrestrial forms early in their evolutionary history. These
are thought to have led a cursorial existence in more open habitats
where their spines would have aided in warding off would-be predators.
Note that there are many preserved limbs, and the finely segmented
abdomen is quite evident in this part/counterpart specimen. I have
recently been able to procure specimens from a family who has been
collecting this material in the field for three generations, and will
continue posting material as it becomes available to me.