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Last month several people inquired about the availability of reprints of
my paper "Coevolution of cycads and dinosaurs" that appeared in Cycad
Newsletter vol.. 30, no 1, 2007, p. 6-9. The Introduction appears below.
I'll be happy to provide reprints either as a PDF file or as a hardcopy.
Just email me at email@example.com. My interpretation of the
paleobiology of cycads and herbivores is a bit off paleontology's beaten
path, and I welcome comments and criticisms.
Geology Department, Western Washington University
Cycads were a major component of forests during the Mesozoic Era, the
shade of their fronds falling upon the scaly backs of multitudes of
dinosaurs that roamed the land. Paleontologists have long postulated
that cycad foliage provided an important food source for reptilian
herbivores, but the extinction of dinosaurs and the contemporaneous
precipitous decline in cycad populations at the close of the Cretaceous
have generally been assumed to have resulted from different causes.
Ecologic effects triggered by a cosmic impact are a widely-accepted
explanation for dinosaur extinction; cycads are presumed to have
suffered because of their inability to compete with fast-growing
flowering plants that appeared during the mid-Cretaceous “angiosperm
explosion”. This paper explores a different hypothesis, i.e., that the
evolutionary fates of cycads and dinosaurs were inextricably
intertwined, and the Late Cretaceous extinction of these reptiles was
the triggering event that caused cycads to diminish to their present
status as “living fossils”. The main tenet of this hypothesis is cycads
depended on herbivorous dinosaurs to disperse their seeds, and the
disappearance of these herbivores led to a precipitous decline in the
geographic range and numerical abundance of cycads. Evidence comes from
the toxicology of extant cycads, their seed dispersal strategies,
anatomical characteristics of herbivorous dinosaurs, and the geographic
distribution and taxonomic diversity of modern and fossil cycads.