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
 Worms
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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