cordylina Mazon Creek Polychaete Worm Fossil
Annelida; Class Polychaeta
Time: Pennsylvanian (~300 m.y.a.)
mm long on a 40 mm by 30 mm and 23 mm by 35 mm nodule pair
Site: Mazon Creek, Pit 11, Francis Creek shale, Morris, Illinois
Polychaeta (Bristleworms) have a diverse representation in the Mazon
Creek Lagerstätte. The segmented bodies of the Polychaeta have
paired lobes called parapodia which have a function in locomotion
or respiration. The parapodia bear numerous bristles that are the
source of the name of the class (Polychaeta means many bristles).
The polychaetes are thought to be paraphyletic, meaning they share
a common ancestor. This Didontogaster is thought to have been a predatory
species, as are many modern-day bristleworms. Its generic name means
“two tooth stomach”, in reference to a pair of jaws that
the worm had.
fossil pictures to enlarge