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Apart from the Phyllopod Bed of the Burgess Shale (Middle Cambrian) polychaete …


Biology Articles » Paleobiology » Paleozoology » The earliest annelids: Lower Cambrian polychaetes » The Sirius Passet Lagerstätte

The Sirius Passet Lagerstätte
- The earliest annelids: Lower Cambrian polychaetes

Whilst the Sirius Passet Lagerstätte (Conway Morris et al. 1987; Peel et al. 1992; Conway Morris 1998) does not match the richness of either the Burgess Shale or Cheng− jiang Lagerstätten it has yielded an impressive variety of or− ganisms showing exceptional preservation, notably trilo− bites ( Blaker 1988; Blaker and Peel 1997; Babcock and Peel in press) and other arthropods (Budd 1993, 1994, 1995, 1997, 1998, 1999; Williams et al. 1996; Budd and Peel 1998), halkieriids (Conway Morris and Peel 1990, 1995), and sponges (Rigby 1986).

All the fossils, including the annelids described herein, were collected at the south−western end of the broad valley connecting J.P. Koch Fjord and Brainard Sund in north−west Peary Land, central North Greenland (latitude 8247.6’ N, longitude 4213.7’W) at an altitude of 450 mabove sea level (Fig. 1). Almost 6000 fossiliferous slabs were selected dur− ing visits between 1985 and 2006 (Peel 1990; Peel et al. 1992; Conway Morris 1998) from extensive talus slopes de− rived from the lower part of the Buen Formation (Conway Morris 1998: figs. 52, 55).

The Buen Formation forms part of the southern shelf suc− cession of the Franklinian Basin of North Greenland and the Canadian Arctic Islands (Surlyk 1991). The formation (325 m thick) consists of a lower, sand−dominated, member overlain by an upper member dominated by dark grey−green mud− stones and siltstones in its type area in southern Peary Land (Peel and Sønderholm1991; Ineson and Peel 1997; Blaker and Peel 1997). It thickens to around 700 m in northern Peary Land where it comprises a mud−rich transitional succession into deep water trough deposits of the Polkorridoren Group (Peel and Sønderholm1991). Dark grey to black mudstones at the fossiliferous locality form part of this transitional succes− sion from the shelf to the slope. To the south they lie in faulted contact with pale dolomites of the underlying Portfjeld Forma− tion, and to the north with bioturbated mudstones and sand− stones of the Buen Formation.

The Sirius Passet Lagerstätte contains the oldest Lower Cambrian trilobites known from North Greenland. The occur− rence of Buenellus higginsi Blaker, 1988 indicates the Neva− della Zone as used in Laurentia (Palmer and Repina 1993; Blaker and Peel 1997; Babcock and Peel in press). This is now correlatedwith Stage 3 of the provisional Cambrian Series 2 in the emerging global stratigraphic scheme for the Cambrian (Babcock et al. 2005). In the upper member of the formation, the occurrence of the olenelloid trilobites Olenellus (Meso− lenellus) hyperboreus (Poulsen, 1974) and O. svalbardensis Kielan, 1960 indicates the Olenellus Zone of Laurentian usage (Blaker and Peel 1997), equivalent to the provisional Series 2 Stage 4 of the Cambrian (Babcock et al. 2005).


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