Late Cretaceous Polar Marine Ecosystem

Life in a temperate Polar sea: a unique taphonomic window on the structure of a Late Cretaceous Arctic marine ecosystem

Karen Chin1, 2, *, John Bloch3, Arthur Sweet4, Justin Tweet1, Jaelyn Eberle1, 2, Stephen Cumbaa5, Jakub Witkowski6 & David Harwood7

1Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA
2Museum of Natural History, University of Colorado, Boulder, CO 80309, USA
3Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131, USA
4Geological Survey of Canada, Natural Resources Canada, Calgary, Alberta, Canada T2L 2A7
5Research Services, Canadian Museum of Nature, Ottawa, Ont., Canada K1P 6P4
6Palaeontology Section, Warsaw University, 00-927 Warszawa, Poland
7Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA

*Author and address for correspondence: Department of Geological Sciences, University of Colorado, Boulder, CO 80309, USA karen.chin@colorado.edu

Received 11 June 2008; Accepted 28 July 2008; Published online 19 August 2008

Abstract

As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada, that offers a snapshot of a ca 75Myr ago marine palaeoecosystem adapted to such conditions. Thick siliceous biogenic sediments and glaucony sands reveal remarkably persistent high primary productivity along a high-latitude Late Cretaceous coastline. Abundant fossil faeces demonstrate that this planktonic bounty supported benthic invertebrates and large, possibly seasonal, vertebrates in short food chains. These ancient organisms filled trophic roles comparable to those of extant Arctic species, but there were fundamental differences in resource dynamics. Whereas most of the modern Arctic is oligotrophic and structured by resources from melting sea ice, we suggest that forested terrestrial landscapes helped support the ancient marine community through high levels of terrigenous organic input.

ie the Polar Sea was a great big brown water ecosystem. Or at least boosted by one. I'd love to comment more, but can't.