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Digital future for paleoclimate estimation from fossil leaves? Preliminary results

Peter M. Huff, Peter Wilf and Ebere J. Azumah
Digital future for paleoclimate estimation from fossil leaves? Preliminary results
Palaios (June 2003) 18 (3): 266-274


Leaf size and shape are selected by climate and are strongly correlated with climatic variables. Accordingly, fossil dicotyledonous leaves are considered to be among the most reliable indicators of terrestrial paleoclimates. However, the methods used have much potential for improvement. All currently rely on discrete, usually binary characters, but leaf morphology is better evaluated and more reproducibly measured using continuous variables. Digital leaf measurement offers the possibility of continuous, reproducible variables, with the potential to improve paleoclimate estimates as well as the ecological and evolutionary understanding of leaf form. Results are reported for five variables measured on 238 leaves representing the woody species from three living test floras--two temperate and one humid tropical. The variables are: shape factor (an area:perimeter ratio standardized to a circle); the ratio of feret diameter (diameter if leaf's area is contained in a circle) to major axis length; the ratio of tooth area to leaf area; tooth count; and tooth count standardized to leaf perimeter. It is well known that increased mean annual temperature is correlated with a high percentage of untoothed species. By extension, increasing temperature is expected to be associated with relatively undissected, more circular leaves (i.e., with high shape factor, low tooth-area:leaf-area ratio, and low tooth count). These trends were observed in the test floras, both between the tropical and the temperate sites and between the two temperate sites. Shape factor was the variable that resolved the three sites most significantly. The five variables show promise for testing on an expanded set of floras sufficient to develop statistical models for paleoclimatic studies.

ISSN: 0883-1351
Serial Title: Palaios
Serial Volume: 18
Serial Issue: 3
Title: Digital future for paleoclimate estimation from fossil leaves? Preliminary results
Affiliation: University of Michigan, Museum of Paleontology, Ann Arbor, MI, United States
Pages: 266-274
Published: 200306
Text Language: English
Publisher: Society of Economic Paleontologists and Mineralogists, Tulsa, OK, United States
References: 36
Accession Number: 2004-042891
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendices
Illustration Description: illus. incl. 2 tables
N39°43'00" - N40°13'00", W77°07'60" - W76°13'60"
Secondary Affiliation: Pennsylvania State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 200412
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