The earliest leperditicope arthropod: a new genus from the Ordovician of Spitsbergen

Abstract

Abstract. A new leperditicope from the carbonate-dominated sequence of the Nordporten Member of the Kirtonryggen Formation, Spitsbergen, is the oldest confirmed representative of this group of bivalved arthropods. It occurs at a stratigraphical level low in the Floian Stage of the Early Ordovician, and below rocks bearing graptolites of the Pendeograptus fructicosus Biozone. Its occurrence emphasizes an ‘out of Laurentia’ palaeogeographical origin for leperditicopes, though there are no obvious antecedents in the earlier, Cambrian record of that palaeocontinent.

Bivalved arthropods from the Middle Ordovician Winneshiek Lagerstätte, Iowa, USA

“…Vannier et al (2001) noted that the earliest leperditiid is Eoleperditia ambigua Berdan, 1976 from the early Llanvirn of Utah—a similar age to the Winneshiek occurrence. The best preserved leperditicopes from other localities are uncrushed and in the round, preserving significant relief (Williams and Siveter, 2008). Silicified specimens can be released from limestone by dissolution; calcitic specimens have to be cracked out of limestones.…”

“…The affinities of leperditicopes are uncertain and will only be resolved with the discovery of preserved soft parts (Becker, 2005). Although traditionally assigned to ostracods (e.g., Berdan, 1984), such a relationship is controversial (Becker, 2005) and most authors now refer them only to arthropods (Vannier et al, 2001; Williams and Siveter, 2008). Frustratingly (in contrast to the small phyllocarids), no soft parts are preserved in the Winneshiek specimens.…”

Lower Ordovician trilobites from the Septembersø formation, North-East Greenland

“…These specimens potentially represent one of the oldest known occurrences of leperditicope arthropods in the fossil record. The current oldest known leperditicopes are from the Nordporten Member of the Kirtonryggen Formation from Spitsbergen, of early Floian age (Williams & Siveter 2008).…”