Fungal spores including the Late Cretaceous Pesavis parva and the Paleogene Pesavis tagluensis are notable age indicators. Paleogene taxa such as Woodwardia maxonii, Macclintockia, and Glyptostrobus dominate the flora. Paleocene indicators include macrofossils such as Platanus bella, Archeampelos, Hamamelites inequalis, and Ditaxocladus, and pollen taxa such as Paraalnipollenites, Triporopollenites mullensis, and Duplopollis. Analyses of plant macro- and microfossils suggest an early to middle Paleocene age for the Kanaka fossil flora. Detrital zircon dating is less decisive, yet indicates the Kanaka rocks are no older than Maastrichtian.
Palynology and plant macrofossils suggest the Kanaka Creek section is Paleocene rather than Eocene in age. Paleogene sediments of the Huntingdon Formation, a correlative to the Chuckanut Formation of neighboring Washington State, USA, are exposed in the greater Vancouver area, British Columbia, Canada. The Madygen fossils are nevertheless significant because they represent the second-oldest record of root nodules worldwide, predated only by permineralized mycorrhizal root nodules from the Triassic of Antarctica. The producer of the roots and the biological nature and affinities of the microorganisms inhabiting the nodules remain unknown. Here we report adpression fossils of slender roots from the ∼237-million-yr-old Madygen Formation in Kyrgyzstan, to which are laterally attached spheroidal protuberances up to 2.5 mm in diameter that we interpret as root nodules based on spatial arrangement and comparisons with other fossil and extant root nodules, along with several types of other plant structures exhibiting a superficially similar appearance (e.g., fertile organs, rhizome tubers). Documented evidence of root nodules in fossil plants is exceedingly rare, and thus the evolutionary history and paleobiology of these specialized structures hosting symbiotic microorganisms continue to be largely unresolved.
0 kommentar(er)
