Early Cambrian Arthropods from the Emu Bay Shale Lagerstätte, South Australia

Abstract

The Emu Bay Shale Lagerstätte, located on the north coast of Kangaroo Island, South Australia, is the most important Burgess Shale-type Cambrian fossil locality in Australia. In 1952, R.C. Sprigg first discovered fossils in the Emu Bay Shale near the Emu Bay jetty as part of the Geological Survey of South Australia regional mapping programme (Sprigg et al., 1954; Sprigg, 1955). However, due to an accident, Sprigg was unable to carry out detailed work to the east of Emu Bay. The Emu Bay Shale Lagerstätte site at Big Gully, located 3 km east of Emu Bay (Fig. 1), was discovered along the coastline immediately adjacent to Big Gully by B. Daily during his doctoral studies. The first fossils collected included superb articulated specimens of 'Redlichia' up to 25 cm in length. Daily (1956, p. 126) was also the first to publish information on the Lagerstätte, recording the presence of the trilobites 'Redlichia' n. sp. and cf. 'Lusiatops', plus 'Isoxys' n. sp., an unidentified crustacean and annelids; this represented his Faunal Assemblage 12. The trilobite species referred to as "cf. Lusiatops" by Daily (1956) was later described as 'Estaingia bilobata' by Pocock (1964), although the illustrated specimens were not sourced from the Lagerstätte. Jell (in Bengtson et al., 1990) formally described specimens of 'Redlichia' from Big Gully as 'R. takooensis' Lu, 1950. M.F. Glaessner, M. Wade and B. McGowran collected material (including nonmineralised taxa) in December 1956 (B. McGowran, pers. comm., December 2007), but no formal descriptions were published until Glaessner (1979) described the bivalved arthropods 'Isoxys communis' and 'Tuzoia australis', the palaeoscolecid priapulid 'Palaeoscolex antiquus', plus 'Myoscolex ateles' and 'Vetustovermis planus' of uncertain affinities. Glaessner (1979) noted that there were no signs of trace fossils in his material; he suggested deposition as a thanatocoenosis within a reducing environment.