How reliable is the dinocyst genus Svalbardella as a temperature proxy: implications for paleoclimatological studies of the late Paleogene

Currently the dinocyst genus Svalbardella is represented by two formally described morphotypes: Svalbardella cooksoniae (type species) and S. partimtabulata. However, anumber of informal Svalbardella-like species have been registered from the northernhemisphere settings. Notably, some of these Svalbardella-like forms show features typicalfor the Paleocystodinium genus. It is generally accepted that Svalbardella spp. differsfrom Paleocystodinium spp. in having bluntly rounded apical and antapical horns andindications of paratabulation other than the archeophyle.Svalbardella is known mainly from late Middle Eocene to Oligocene deposits of northernhigh latitudes (e.g. 1,2). The first appearance of Svalbardella in the Northern Atlantic isdated to 41.9 Ma (2). The paleogeographic distribution of Svalbardella suggests anaffinity with cold, arctic water masses (3), and thus the genus is commonly applied as acold(er) water indicator. In addition, Svalbardella–rich intervals described from Early andmid-Oligocene strata have been linked with the two Oligocene glacial maxima, the Oi-1aand the Oi-2b, respectively (4,5).However, a recent study based on organic biomarkers (6) have shown that an intervalyielding S. partimtabulata in the Middle Eocene of Denmark corresponds with elevatedsea-surface temperatures. This is just one of several examples illustrating that consideringthe entire genus of Svalbardella as a proxy for sea surface cooling may be misleading.This study aims to recognize and describe key species within the Svalbardella genus,and to assess their potential as paleoclimatological proxies.