How Plant-Eating Dinosaurs Nearly Destroyed the Earth

Time to diet

I've always been an amateur naturalist, and always wondered (nerd that I am) what actually killed the dinosaurs 65 million years ago. An entire order of animals was wiped out, the world over -- not one species in any size or ecological category survived. That's incredible. Circa 1980, a scientist name Alvarez advanced the hypothesis that an asteroid killed the dinosaurs. An asteroid did strike the planet 65 million years ago, and iridium in the soil strata is consistent with that fact. The Alvarez theory became a 'darling' of the science establishment and has since been pretty well embraced. I never liked it because it didn't address some issues:

- Why did dinosaurs die, but other large, even cold-blooded creatures sailed thru with flying colors -- crocodiles, alligators, komodo dragons and sharks, to name a few
- Why did dinosaurs die completely, in every niche? seems like some smaller species could've squeaked by
- By 65 million years ago, there were only a handful of dinosaur species remaining; some process had already wiped out their numbers. An asteroid would merely have been the coup de grace. Why had they already dwindled so severely?

I did some research, and found that the Alvarez theory isn't universally accepted, there are many contrarians like me who disagree with it. Also, in my research I learned about an ecological disaster, created by highly evolved (for that time) animals that nearly threw the Earth's life cycle out of balance. Humans like to think that we are the worst thing that has ever happened. With pollution, strip mining, deforesting, hunting etc, we've caused immense destruction to the Earth. But nothing we've done compares to the damage of herbivorous dinosaurs. You see, in the Age of Dinosaurs, the land was covered with lush, fern forests. Angiosperm plants had not yet evolved. Dinosaurs would make a meal of the fern fronds, and all was good. Well, good except for the ferns. Ferns need their fronds to photosynthesize, and the leaves contain spores for plant reproduction. Dinosaurs would devour leaf, as well as stem, stripping the fern of its ability to grow or reproduce. A busy brontosaurus could probably strip a grove of trees in one day. With ferns getting depleted, it created starvation conditions for giant plant eaters. Furthermore, it threatened the entire planet by upsetting the exchange of gases between plants and animals. Fauna had become a serious threat to flora.

Natural Selection answered the dilemma in a couple of ingenious ways. The reader can decide for himself whether Natural Selection (NS) operates by intelligence or random selection, but suffice it to say NS did some brilliant things. (See my earlier blogs, God Talk and Amazing Blue Marble). Angiosperm plants developed rather suddenly. They offered fruits, berries and nuts to unobtrusive squirrels and newly evolved birds. Their leaves were tiny and inedible to ravening dinosaurs. This was a "win win" for nature. At the same time, nature developed T-Rex and velociraptors -- efficient killing machines, however unpleasant their demeanor. An ailing brontosaurus, trying to digest a meal of hackberry leaves, was no match for a vicious carnivore. Between starvation and predation, the herbivores vanished. One can only speculate that the small, nimble land animals surviving were inadequate food supply for T-Rex, and so it also starved.

Even in today's Cenozoic era, large animals are at risk for hunting, predation and starvation. Whales and elephants exist mostly at the mercy of, and as a curiosity to humans. But those species are very 'in check' -- they pose no ecological threat. Humans are indeed a threat to world ecological balance. It will be interesting to see how Natural Selection answers that call -- randomly or otherwise.

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