Studying the early history af life in Greenland

Exceptionally preserved fossils of soft-bodied animals have always aroused particular interest within the geological community. Not only do they supply anatomical information not usually preserved, but they also provide insights into the structure of the living communities which are difficult to obtain from fossils preserved as hard skeletal elements alone. The importance of these soft-bodied or poorly skeletised forms is indicated by their dominance in present day environments where animals without hard parts make up more than two thirds of the number of species and individuals present (Conway Morris, 1986).

Exceptionally preserved fossils of soft-bodied animais have always aroused particular interest within the geological community. Not only do they supply anatomical information not usually preserved, but they also provide insights into the structure of the living communities which are difficult to obtain from fossils preserved as hard skeletal elements alone. The importance of these soft-bodied or poorly skeletised forms is indicated by their dominance in present day environments where animais without hard parts make up more than two thirds of the number of species and individuals present (Conway Morris, 1986).
The most famous assemblage of exceptionally preserved soft-bodied fossils occurs within the Middle Cambrian Burgess Shale of British Columbia, Canada. The locality was discovered in the early part in this century by the eminent American palaeontologist Charles D. Walcott whose many contributions to Cambrian geology are recognised by the land area of North Greenland which bears his name ( fig. 1). Burgess Shale fossils have been described by many authors, but most notably in a series of monographs by Walcott himself and by a group established at the University of Cambridge, England, under the leadership of Professor H. B. Whittington (see Conway Morris, 1986 for references). A recent 'best-seller' evaluates the significance of this "most precious and important of all fossil localities" in terms of the development of life during the 500 000 000 years since the Cambrian (Gould, 1989, p. 13). Gould suggests that the importance of the Burgess Shale assemblage has been underestimated since earlier work tended to interpret many of the fossils in terms of classifications largely based on present-day taxa, rather than recognising the diversity inherent within the assemblage itself.
The Burgess Shale assemblage contains more than 100 species, but only some 2% of the 40 000 individuals counted by Conway Morris (1986) contain hard parts capable of preservation under normal geological circumstances. This latter group includes trilobites and hyolithids, readily fossilised on account of their calcareous skeletons and thus familiar to students of Cambrian fossils. The remaining species consist of a wide range of Rapp. Grønlands geol. Unders. 148. 54-56 (1990)

Studying the early history af life in Greenland
John S. Peel animais ranging from arthropods, which dominate the collections both in terms of the abundance of species and individuals, to sponges and bizarre fossils which can not be accommodated within current schemes of classification. Many of these fossils preserve exquisite details of soft tissues, including limbs and gills.
One of the most interesting aspects of the Burgess Shale assemblage is its antiquity (more than 520 000 000 years). It provides a window through which the early evolution of highly organised life can be studied, occurring some few tens of millions of years after one of the greatest events in the history of life. This event, often referred to as the 'Cambrian explosion', took place near the Precambrian-Cambrian boundary (550000000 years ago) and resulted in the relatively sudden appearance of highly developed organisms within the fossil record.
It is clearly of some consequence that an assemblage of Burgess Shale-like fossils some 20 000 000 years older than those preserved within the Burgess Shale has been discovered recently in Greenland. This assemblage was discovered by A. K. Higgins within the Lower Cambrian Buen Formation in north-westem Peary Land ( fig. 1) during the final stages of a regional geological project instigated by the Geological Survey of Greenland (GGU) in North Greenland (1978-1980 and 1984-1985). Unfortunately, the significance of the assemblage was not recognised until the collections were examined in Copenhagen early in 1986, by which time it was no longer possibie to revisit the locality within the logistic frarnework established for the North Greenland project.
Apart from sponges described by Rigby (1986) and many specimens of a single species of nevadiid trilobite, subsequently described as BuenelIus higginsi gen. et sp. nov. by Blaker (1988), the small collection made by Higgins contained a number of species of poorly skeletised arthropods. The discovery was reported and briefly described by Conway Morris et al. (1987). The assemblage was considered to be of special interest not only on account of its excellent preservation (cf. fig. 2) but also because it demonstrated the presence of an animal community of similar structure to that of the  MiddJe Cambrian Burgess Shale in subslanriaJly alder Lower Cam brian strata.
During July 19R9 a 4-man group revisited the locality to make Illrger coJiections and Io try and assess Ihe extent of the fossiliferous deposi{~. The expedition was made possibie by a generous grant from the Carlsberg Foundation, Copenhagen, and logistical support from GGU's geological mapping programme in North-East Greenland (see Henriksen, 1990). Dcspite problems with poor weather, a collection af more than 1500 rock smnples was secured. Almost all thc fossils were derived from approxim atcly 5 m af shale occurring at a single locality near J. P. Koch Fjord. The fossiliferous sha1cs apparelltly occur within the lo\ver part af the Buen Formation and not \virhin thc upper part. as had heen suggesled by Comvay Morris et ai. (1987).
The most cammon fossils within rhe more than 30 species <.:urrently recogniscd are arthropods, some of which must have cxceecled half a metre in length tIming life. Most conspicuous are large specimens of !he trilobite BuenelIus higginsi but bivalved carapace:-i ol" ostrac ouc-like species (Iength 1-2 cm) are numcricaJly dOIll-in3nl. Otber speejes vary from eJongate forms witil abundant segments to squac ovoid arthropods with fewer segments and large head and tai I shields af similiH proportions. Many specirnens of the hItter group prcscrve traces af limhs, gi lis and possibIe cnleric musculature ( fig. 2). Sponges and worms are well rcpresented but brachiopods and echinoderms are apparently absent. Molluscs are rcprescnted by a few Snlall capshaped shelIs af 1I1lcertain affinity. I-Iyolithids are also rare but same prescrve tbe operculum and appendages ('hekns'), Sevcral taxa currently defy c1assificarion. Most notable amongst these is li worm-hke species (Iength c. 5 cm) covcrcd with a dense thatch uf pointcd spines hut with larger ovoid plates at both extrcmitics. This remarkable taxon promises to bc the key to unravelling Lhc affinities of a number af described taxa af spine-hke microfossils whicb are common in Lower Cam brian strata from man y areas (Conway Marris & Peel, 1990).
The assemblage of poorly skeletised fossils from lhc Buen Formation is bc:ing studied by li group af palaeontologists centred amund tile University of Cambridge and the Geological Survey of Greenland. Tlle investiga· tians wiJl writc not only a new chapter an ancient life in Grccnland but also contribute to the understanding af the carly history of life an carth.