A LATE CRETACEOUS CONIFEROUS WOODLAND FROM THE SAN JUAN BASIN, NEW MEXICO

The Fossil Forest Research Natural Area (FFRNA) in New Mexico is the site of an exceptionally preserved fossil forest of Campanian age. This study combines paleoecological, taxonomic, and sedimentological analysis, together with GIS mapping of 68 fossil tree stumps and nine fossil logs, in order to...

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Bibliographic Details
Published in:Palaios 2011-02, Vol.26 (2), p.89-98
Main Authors: DAVIES-VOLLUM, K. SIAN, BOUCHER, LISA D, HUDSON, PATRICK, PROSKUROWSKI, A. YAEL
Format: Article
Language:English
Subjects:
Angiosperms
Campanian
Coniferales
Coniferous forests
Conifers
Cretaceous
Cupressaceae
Cupressinoxylon
depositional environment
Floodplains
floral studies
Forest conservation
forests
fossil forest
Fossil Forest Research Natural Area
fossil wood
Fossils
Fruitland Formation
growth
Growth rings
Gymnospermae
Kirtland Shale
lithostratigraphy
Mesozoic
New Mexico
Paleobotany
paleoecology
paleoenvironment
Plantae
San Juan Basin
San Juan County New Mexico
Senonian
sensitivity analysis
Spermatophyta
tree rings
Tree stumps
Trees
United States
Upper Cretaceous
Woodlands
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Summary:The Fossil Forest Research Natural Area (FFRNA) in New Mexico is the site of an exceptionally preserved fossil forest of Campanian age. This study combines paleoecological, taxonomic, and sedimentological analysis, together with GIS mapping of 68 fossil tree stumps and nine fossil logs, in order to provide a detailed description of this forest. Wood analysis of stumps illustrates that the forest is almost exclusively composed of conifers most likely related to the Cupressaceae. Reconstruction of the forest indicates that the conifers were mature and widely spaced, creating an open canopy woodland; however, leaf litter directly associated with the fossil woodland has not been preserved, so the detailed composition of its understory remains enigmatic. Analysis of the substrate in which the stumps were rooted suggests that trees grew in a gley soil under wet floodplain conditions. Mean sensitivity analysis of growth rings in the stumps indicates that small-scale environmental disturbances on the floodplain, such as periodic flooding, or regional environmental disturbances, such as volcanism, disrupted wood production. The death of the woodland was probably due to waterlogging and burial by suspended sediment associated with flooding. Despite the presumed dominance of angiosperms in disturbed, riparian environments during the Late Cretaceous, this study indicates that conifers were still dominant in some subenvironments at this time and could form mature open canopy woodlands on wet unstable floodplains.
ISSN:0883-1351
1938-5323
DOI:10.2110/palo.2010.p10-090r