Abstract Detail

Paleobotanical Section

Looy, Cindy V [1], Romero, Rosemary [1], Huynh, Tony L. [1], Parkinson, Dula [2], Goedert, James L. [3], Kiel, Steffen [4].

Timing the origin of Kelps.

Kelps (Laminariales) include the largest benthic organisms in the world, and are amongst the most successful groups of brown algae. Until recently it was generally thought that kelps radiated in the North Pacific following the onset of the late Cenozoic cooling. Molecular research, however, suggests that the Laminariales may have evolved during the Late Cretaceous, around 100 million years ago. The only hard fossil evidence for the minimum age of this group, though, is represented by 13 to 17 million-year-old Miocene deposits in California. These fossils have a branching morphology similar to kelp genera Nereocystis and Pelagophycus; close relatives of Giant Kelp. This indicates that large kelps, and most likely also the diverse communities that it commonly sustains, were already well established during the middle Miocene. Recently discovered kelp-like holdfasts in carbonate concretions of early Oligocene age from Washington State have the potential to show that kelps evolved and diversified significantly earlier than indicated by our current understanding of the fossil record. The preserved haptera (branching finger-like structures) of the holdfasts strongly resemble those within the Macrocystis-clade, which include Nereocystis and Pelagophycus. Light micrographs and electron microscope images of the of the split surface show the preserved internal casts of individual cells. Synchrotron-based X-ray Micro-Tomography of the holdfasts shows their 3D morphology, different tissue types and internal structure.

Broader Impacts:

1 - University of California, Berkeley, Department of Integrative Biology and Museum of Paleontology, Valley Life Sciences Building #3140, Berkeley, CA, 94720, USA
2 - Lawrence Berkeley National Lab, Advanced Light Source, 1 Cyclotron Road, Berkeley, CA, 94720, USA
3 - University of Washington, Burke Museum of Natural History and Culture, Box 353010, Seattle, WA, 98195, USA
4 - University of Göttingen, Geobiology Group, Goldschmidtstrasse 3, Göttingen, 37077, USA

Keywords:
Kelp
Laminariales
Oligocene
Washington
Paleobotany
x-ray tomography
morphology
holdfast.

Presentation Type: Oral Paper:Papers for Sections
Session: 16
Location: Melrose/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 11:00 AM
Number: 16011
Abstract ID:818
Candidate for Awards:Isabel Cookson Award