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Leaf shape is a key plant trait that varies enormously. The range of applications for data on this trait requires frequent methodological development so that researchers have an up-to-date toolkit with which to quantify leaf shape. We generated a dataset of 468 leaves produced by Ginkgo biloba , and 24 fossil leaves produced by evolutionary relatives of extant Ginkgo . We quantified the shape of each leaf by developing a geometric method based on elastic curves and a topological method based on persistent homology. Our geometric method indicates that shape variation in modern leaves is dominated by leaf size, furrow depth and the angle of the two lobes at the leaf base that is also related to leaf width. Our topological method indicates that shape variation in modern leaves is dominated by leaf size and furrow depth. We have applied both methods to modern and fossil material: the methods are complementary, identifying similar primary patterns of variation, but also revealing different aspects of morphological variation. Our topological approach distinguishes long-shoot leaves from short-shoot leaves, both methods indicate that leaf shape influences or is at least related to leaf area, and both could be applied in palaeoclimatic and evolutionary studies of leaf shape.
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North American Clovis Point Form and Performance: An Experimental Assessment of Penetration Depth
In Late Pleistocene North America colonizing hunter-gatherers knapped and used Clovis fluted projectile points. During their expansion the size and shape of Clovis points changed significantly. Archaeologists know that cultural drift contributed to this variation, but is it possible that this single source could alone generate so much variation so quickly? We present the first of several experimental studies exploring whether Clovis size and shape variation results in performance differences, focusing here on how deeply different Clovis point forms penetrate a target. Our ballistics experiment demonstrates that seven different Clovis point forms penetrated the same target with different effectiveness. Even after tip cross-sectional perimeter is accounted for, there are significant differences in penetration depths between two of the point types. These results are consistent with the hypothesis that Clovis people in different times and places may have chosen specific attributes to provide them with a selective functional advantage.
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- PAR ID:
- 10194537
- Date Published:
- Journal Name:
- Lithic Technology
- ISSN:
- 0197-7261
- Page Range / eLocation ID:
- 1 to 20
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1080/01977261.2020.1794358
