New fossil worms from the Lower Cambrian of the Kinzers Formation, Pennsylvania, with some comments on Burgess Shale-type preservation

Abstract

Two new fossil worms are described from the Lower Cambrian Kinzers Formation of southeast Pennsylvania. Both are unique specimens.Kinzeria crinitanew genus and species has a body divided into three regions. The head bears a prominent set of elongate tentacles, presumably employed for feeding. The elongate trunk tapers slightly in a posterior direction. It contains a prominent intestinal tract, the contents of which indicate a deposit feeding habit. The tail is an expanded structure, with either a spatulate or sagittate outline. The mode of life ofK. crinitais uncertain, but the animal may have been semi-sedentary.Atalotaenia adelanew genus and species is more poorly known, lacking the anterior. The preserved body is vermiform, with external annulations and a rounded posterior. There is a prominent internal strand, consisting of a probable intestine and an associated fibrous unit, possibly representing muscles. This worm may have been infaunal. These discoveries extend further our understanding of the ancient diversity of Laurentian Burgess Shale-type faunas. In common with the Burgess Shale itself and the Sirius Passet fauna (Peary Land, Greenland) the location of fossil-Lagerstätte [see Shields (1998) for a discussion of the terminology of Lagerstätten] of the Kinzers Formation adjacent to a prominent escarpment reinforces earlier evidence of the paleotopography exerting an important control on the distribution of Burgess Shale-type faunas. Whether this is a result of localized faunal abundances or taphonomic control is, however, uncertain.