Fossil fruits and seeds from the early Eocene lower Lillebælt Clay Formation, Hinge clay pit, Denmark

Newly discovered fossil fruits and seeds from the lower part of Member L2 of the Lillebælt Clay Formation at Hinge clay pit, Denmark, provide the first diverse plant macrofossil assemblage from this unit. The material includes 39 specimens retrieved by sieving of approx. 5000 kg of a thin sapropel layer and adjacent clay occurring within the lower part of the Azolla-bearing interval and is dated to the latest Ypresian, Chron C22n, approximately 49 Ma. The assemblage includes named or tentatively named taxa assigned to five species in two (possibly three) genera of Vitaceae; Eurya sp. and Cleyera sp. (Pentaphylaceae); Rhamnospermum bilobatum (incertae sedis); Mastixiaceae; Magnoliaceae; Icacinaceae and 20 additional taxa of seeds, fruits or endocarps for which the modern relatives are unclear. The assemblage is notable for its occurrence in an offshore, bathyal depositional environment, implying long-distance transport from surrounding land areas into the eastern North Sea Basin. Comparison with Eocene floras from the United Kingdom and Germany (Messel) shows both similarities and striking differences. Several families common in coeval floras, including Menispermaceae and others, are not recorded in the Hinge assemblage. These absences are probably due mainly to taphonomic modification of the assemblage during the transport and early diagenesis, but rarity of taxa and preparation technique may also play a role. Other explanations for differences may be differing ages and/or ecologic distributions of the compared floras. The assemblage provides a rare window into late early Eocene vegetation around the North Sea Basin while also emphasizing the strong taphonomic filtering that shaped the fossil record at Hinge.