TWO COEXISTING, PERMINERALIZED ALETHOPTERIS MORPHOLOGIES FROM IOWA AND A NEW METHOD FOR DIFFERENTIATING THEM BASED ON LEAF GEOMETRY
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This research focuses on a new morphology of Alethopteris, the frond of a Carboniferous seed-fern tree, based on a series of orthogonal cross-sections of the leaflets, which are preserved in coal balls. The coal balls, which are chunks of coal saturated in calcium carbonate, were recovered from the Williamson No. 3 Mine in Lucas County, Iowa. From close examination of already prepared and sectioned coal balls, I identified criteria that distinguish the new Alethopteris morphology from other Alethopteris morphologies in the same coal bed and even coal balls. These criteria consisted primarily of measures made on orthogonal cross-sections. Results of comparisons of two populations of Alethopteris from the Williamson No. 3 Mine using the student t-test suggest that the two morphologies differ significantly and hence, are different species. I compared the new Williamson No. 3 Alethopteris morphology to Alethopteris species known from other coal ball localities. The new Williamson No. 3 Alethopteris is different from all these species, and represents a new species.
Subjectcoal ball Alethopteris pteridosperm permineralized Carboniferous seed fern leaf geometry paleobotany
Wehner, Matthew (2011). TWO COEXISTING, PERMINERALIZED ALETHOPTERIS MORPHOLOGIES FROM IOWA AND A NEW METHOD FOR DIFFERENTIATING THEM BASED ON LEAF GEOMETRY. Available electronically from