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“April showers bring May flowers.” So April’s been getting the credit all these years. Or maybe, just maybe, it was the dinosaurs!
The Dinosaur Herbivores
There are basically two kinds of plants, gymnosperms and angiosperms. All flowers – including May flowers - are angiosperms, and so are grains, grasses, cereals, sedges, fruits, vegetables, palms, oaks, hickories, almost every berry, etc. Today angiosperms dominate the planet. However, once upon a time, gymnosperms - like conifers and ferns - were king.
Then 140 million years ago, everything started to change. During the Jurassic, all the major herbivores were long-necked, tree-browsing dinosaurs (Brontosaurus, Brachiosaurus, Diplodocus, etc.). By the Cretaceous, almost all of those tree-browsers were extinct. In the Cretaceous, the major herbivores were low-browsing ground-feeders.
The Dino-Flower Theory
Robert T. Bakker in his famous book The Dinosaur Heresies postulated that this new dominant ground-browsing herbivore created an flower-favorable environment. A gymnosperm-dominated woodland would provide few available niches for early flowering plants to occupy. But if a herd of hungry Triceratops mowed down the ground cover, the net effect would reset all the ground cover back to square one. Ground cover would have to grow from scratch, similar to after a forest fire. Angiosperms with their faster growth and maturity rates would recover first and dominate the newly available niches. Flowering plants flourished. May flowers rule!
But Bakker has his critics too. For example, angiosperms first flourished close to the equator. Dinosaurs only sparsely populated this region, which would seem to diminish the effect of their appetites. Furthermore, angiosperms didn’t dominate the plant world until the Late Cretaceous, when dinosaur numbers already were starting to dwindle. Others believe that environmental factors may have aided angiosperms more than dinosaur herbivores. The Mid-Cretaceous was a period of increased volcanism and ocean floor production. Did increased temperature, CO2, and sea levels favor angiosperms over gymnosperms? Or did the rise of the pollinator insects (wasps, bees, and moths) during the Mid-Cretaceous give angiosperms their decisive advantage?
In any case, the world the dinosaurs left behind was angiosperm-supreme. The graves of dinosaurs were festooned with flowers.
Bakker, Robert T. The Dinosaur Heresies: New Theories Unlocking the Mystery of the Dinosaurs and their Extinction. New York: William Morrow, 1986.
Barrett, P.M. and Willis, K.J. Did dinosaurs invent flowers? Dinosaur-angiosperm coevolution revisited. Biological Reviews of the Cambridge Philosophical Society 76 (2001), 411-447.
Willis, K.J. and McElwain, J.C. The Evolution of Plants. New York: Oxford UP, 2002
Hello! My name is Heath Shive, content manager at ScholarFox. I'll be the author of most of the blog posts. I'm a former geologist and currently a freelance writer. The world is complex and seemingly crazy. Good! Because when you love to learn, you'll never be bored.