Astreptoscolex anasillosus Mazon Creek Polychaete Worm
with Preserved Bristles

Astreptoscolex anasillosus

Phylum Annelida, Class Polychaeta, Order Phyllodocida, Family Nephtyidae

Geological Time: Pennsylvanian (~300 m.y.a.)

Size: 22 mm long

Fossil Site: Mazon Creek, Pit 11, Francis Creek shale, Braidwood, Illinois

Astreptoscolex anasillosusWorms of the Annelid phylum appear in the fossil record in the Cambrian. Those of class Polychaeta are also called bristle worms, are one of several classes of Annelids. Their bodies have paired lobes called parapodia that have many bristles. Polychaeta literally means "many bristles". Bristle worms extant with more than 10,000 described species. They live in many environments, including deep portions of the ocean, in the shallows, and burrowed into mud and sand of beaches.

Astreptoscolex anasillosus was an Annelid worm that lived during the
Pennsylvanian (318.1 - 299 million years ago), and many have come from the Mazon Creek Lagerstatte. Many examples preserve a pair of conical teeth, unlike those of any bristle worm except other modern members of the Nephtyidae. The genus derives its name from the Greek word forinflexible, a reference to its seemingly stiff appearance.

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