How the Dinosaurs Died

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"How the Dinosaurs Died"
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The dinosaurs were the definitive survivors. They'd brushed off earlier extinction events, various planetary cataclysms, and were at the height of their diversity during the early Cretaceous period. They had characteristics of birds, mammals, and reptiles, and were easily the most efficient and adaptable animals ever. Their entire history was of filling niches and exploiting environments all over the world. They were usually prodigious breeders, and highly successful by any definition of the word.

So what wipes out the most diverse group of animals ever to exist prior to the mammals? It has to be something common to all members of the group. The one biological thing they all had in common was their egg laying cycle. (Ichthyosaurs were believed to breed live young, but this was probably more of an internal hatching methodology, dictated by the need for temperature to incubate eggs). An egg is a pernickety thing. To form an egg requires a supply of proteins, calcium, and to breed from eggs requires some work. Ask any crocodile.

The keyword is calcium. It happens that the end of the Cretaceous showed a decline in the diversity of dinosaurs, and some calcium deficient eggs. That's actually the worst sort of news for an egg laying species. Calcium deficiency isn't good for any living thing, but it's fatal for egg layers.

Calcium is an alkaline metal, one of the more abundant components of the biosphere, usually available in easily obtained amounts. It's used in muscle, nerves, brains, teeth, you name it, there's some calcium in it. The dinosaurs were adept users of calcium; you need to be pretty good with calcium to weigh several tons.

Meaning there's something more than weird about dinosaurs being calcium deficient. This is where the protein part of the equation comes in. Calcium and protein are codependent in all animals. The light metals are the basis of entire biological schematics in all organisms. It's not that easy to become calcium deficient. Egg layers in particular are not famous for it.

To wipe out the dinosaurs, therefore, and not wipe out everything else, means that they had to be suffering from something none of the other groups was afflicted by, and the affliction had to affect their entire life cycle.

Reproduction is based on the production of protein. To reproduce correctly, the appropriate proteins must be available, and to achieve that, the right enzymatic actions must occur. The dinosaurs, thanks to the reptile side of the family, were also pretty tolerant to mutation. It's only recently been established that reptiles are among the most prone to mutation of all animals. The dinosaurs produced so many viable speciations that it can be assumed this was another mechanism that wasn't causing them much trouble. They reproduced viably, in great variety, and if something came out looking a bit different it was probably OK.

However- In the Cretaceous there was a new element in the process; the flowering plants. Flowering plants, or angiosperms, are the most advanced plants, and they too are great users of calcium and protein.

They were also a real threat to the dinosaurs. They colonized like nothing before except fungi ever had. They took over areas opened up by dinosaur grazing. They also produced vast amounts of pollen, the first pollen ever seen on Earth.

Pollen is largely protein. It is pervasive, invasive, and worse, from the dinosaur perspective, chemically active. Plant chemistry is inextricably linked to calcium. So if you're a dinosaur, eating anything, it's now probably coated in pollen. Highly incompatible protein, which will react with calcium, and it's something your entire phylum has never encountered before. Flowering plants also extract calcium from the environment, into a form the dinosaurs can't use.

Result; scrambled eggs, full of cruddy contaminated enzymes, and some starving herbivores who like many other animals will extract calcium from their own tissues if it becomes unavailable. The trouble with calcium deficiency is that it will kill you. Eating calcium deficient animals isn't a great help to carnivores, either.

My bet would be that an examination of dino remains will show progressively higher incidence of ancient pollens in the deteriorating populations. If the flowering plants didn't get them the final straw, excuse the expression, would have been the advent of grasses, which are even more invasive and also calcium addicts.

This isn't in essence a new idea. It is however an ecologically reliable and consistent thesis. The calcium and pollen equation is trustworthy, although it would take some new technology, MRI, and someone looking for evidence of protein dysfunction to make it stick.

Now, here's the killer. Add an asteroid which flattens the remaining habitat, opens up huge areas of land to colonization by angiosperms, and there's nowhere to hide for the dinosaurs. The next generation might well come out of their eggs, as independent as ever, but the problem's by now established itself.

As mentioned by G.S. Paul in his thoughtful book, Predatory Dinosaurs, no one factor could have wiped them out. They really did have every survival tool they needed, for their normal environment. The flowers were the new element.

It's an insidious, difficult mechanism to which to adapt; billions of pollen grains, all different, all equally useless, non-metabolizable, and equally impossible to avoid. If you were looking for a traceless weapon, something with that capacity would kill anything. Humans have trouble with pollen; it's enough to trigger allergic reactions in about a third of the population. It's also sometimes considered the cause of a form of asthma, another decent percentage of humanity gets that.

If you're a dinosaur, you're able to take in very large amounts of pollen with your food. You probably can't digest it, if you can, it may not be efficiently, there are only so many things you can expect the rocks in your stomach to do. Your waste then creates compost for more flowering plants. Pretty tough deal. You also can't eat them.

Worse by far is the fact that this useless material in your gut is by now forming deposits right next to your reproductive equipment. Good old Nature, the ultimate mechanic at work. "If it can get in anywhere, it can be a problem." The material acts like a thousand spanners; there are proteins which your entire species and all its ancestors have never seen before, you don't have any working enzymes to deal with them, and you ain't feeling too good, nohow.

What about the marine dinosaurs? There aren't too many daisies in mid ocean. No, but a lot of pollen does get blown out to sea. Remember we're talking many millions of tons of the stuff, every year, all over Earth.

The other families, like mammals, reptiles, birds, insects, and the other plants, are immune to some degree due to high metabolisms, low metabolisms, advanced protein synthesis, in the case of mammals, which are better able to deal with exotic chemistry, being a more developed biology, and high adaptability and personal hygiene, in the case of insects, whose unwanted intake of pollen is proportionately low. Their body chemistry is also highly evolved, they predate all the other families on land. Birds, the dino-heirs, seem to have managed to avoid any of their predecessors' weaknesses, and were far more mobile.

In this case the supreme generalists, the dinosaurs, over generalized. Their spread actually defined their exposure. Where they went, the flowers went. They were migratory, they were herd members, the ratio of predator/prey more or less guaranteed maximum population stress, and life in the fast lane became death in the fast lane. Being great adaptors doesn't help if you don't have the proteins to adapt with.

They survived vulcanism, previous asteroids, continents breaking up like croutons, you name it. The one new element in the Cretaceous was the flowers. It may also be a weakness in egg layers; the entire new generation gets a dose of whatever the problem is. In mammals the risk is a bit better spread, and the birth rate a bit more dictated by time; eggs are laid on a roster basis, and if they happen to get addled, they get addled. Birds, again with super high metabolisms, have a higher risk but seem to have handled pollution and hormone based pesticides better than might be expected.

It obviously took a while, but the flowering plants were the only component in the dinosaurs' environment able to completely undermine their entire food chain and ecology.

According to the certificate, I'm a horticulturalist. Flowering plants are invasive opportunists, and very adaptable to conditions that ferns and pre-angiosperm plants can't handle. They exploit any available terrain, and thrive in areas of heavy concentrations of animal wastes. They opened up areas for other species, and as they did so, created no-go areas for the dinosaurs' traditional food plants. The steady reduction in grazing would have had a devastating effect on animals requiring massive intakes of food.

Add to this the fact that after an asteroid strike the flowering plants would have had all the advantages. Huge areas of new terrain to colonize. Ferns and cycads are primarily limited in habitat choices by the need for moisture, so the wrecked, aerated, landscape and layer of desiccating, dry, moisture robbing, ash would have been a major inhibitor. Ferns can grow anywhere, too, but without moisture in fairly large quantities, they're behind the eight ball.

Sooner or later, there will be a theory that really does fully explain the extinction, and meets all the facts. This is probably just yet another pensive stumble in the direction of the truth.


1. Gregory S Paul, New York Academy of Sciences, "Predatory Dinosaurs", Simon and Schuster, 1988. It is not inferred that Mr. Paul suggests or endorses my theory in any way. Quite the opposite; it got me thinking about a new factor in dinosaur environment.
2. I am not aware of any other published document relating to flowering plants and their impact on dinosaur extinction, and I did look. There is no intention to infringe on anyone's work, I do know the rules. If this document does so infringe, please inform me at for appropriate apologies and action.

More about this author: Paul Wallis

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