Gingkos and multituberculates: evolutionary interactions in the tertiary.
The genus Ginkgo is a north temperate gymnosperm taxon represented by fossilized leaves and wood from the early Jurassic through the Pliocene, and by the living species G. biloba native to eastern China. Seeds produced by this widely cultivated tree consist of an odoriferous, vesicatory coat surrounding a hard-shelled "nut." Dispersal of ginkgo seeds is a two step process: repulsion of predators by the toxic coat, followed by attraction of dispersers by the edible "nut." Based on anatomical and distributional evidence, extinct mammalian multituberculates in the genus Ptilodus are plausible consumers and dispersers of ginkgo seeds during the Paleocene and the Eocene. From the Oligocene through Pleistocene, seed-caching rodents are the most likely dispersal agents of ginkgo. Among extant genera in the class Coniferopsida which produce fleshy, animal-dispersed seeds, there appear to be two distinct evolutionary lines: (1) those with relatively large (greater than 20 mm), odoriferous diaspores dispersed primarily by mammals; and (2) those with relatively small (less than 10 mm), visually attractive diaspores dispersed primarily by birds.
Del Tredici
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Department of Biology, Boston University, MA.
D000818:Animals; D005075:Biological Evolution; D004463:Ecology; D008322:Mammals; D012639:Seeds; D014197:Trees