Insects May Have Had a Hand In Dinosaur Extinction

eldavojohn writes "Everyone's got their favorite theories of Dinosaur extinction, but new speculation is rampant in a book that gives cause to believe it may have been disease-carrying insects. Due to the length of their slow and eventual extinction (the 'K-T Boundary'), it is argued that this would more likely be attributed to the spread of disease and the rise of parasitic insects like ticks or biting flies. Are our immune systems the only reason any animals survived?"

Comments

Three questions

[A nonymous Coward]

Why wouldn't this also affect mammals? Is there an implication that dinosaurs had more primitive immune systems? Is any of this more than mere speculation?

I also would have thought dinosaurs had thicker skin, if for no other reason than having a lot more meat to hold together than the puny mammals of the time. Is this not a factor? Do modern day elephants and rhinoceroses suffer from insect infestations even tho they have thick skins?

And lastly, I thought recent research had shown that the slow dying theory was just an artifact of the skimpy fossil record, that they did indeed die out very abruptly at the K-T layer. Is my memory wrong here?

Re:Three questions

[MightyYar]

Why wouldn't this also affect mammals?

And more importantly - why do we still have birds? Birds are supposed to be direct decedents of dinosaurs, and they seem to handle disease pretty well (judging by the state of NYC pigeons).

Re:Three questions

[ColdWetDog]

My question would be, if these insects were either large enough, or had the ability to penetrate the thick hide of a dinosaur, what chance would a small mammal have had from one of them?

A proto-mosquito the size of turkey is flying around.

OK, you're a six story tall dinosaur ...
Or a three inch tall proto-mouse.

Who's gonna get bit?

Re:Three questions

[MightyYar]

But don't we seem to get all sorts of human-only crap as well? Birds have managed to stick around this planet a lot longer than our 150,000 - 1 million years.

Re:Three questions

[lysergic.acid]

while i'm not a zoologist, i'd imagine that if the article is correct, and this was when insects first became a significant vector for disease transmission, then it's plausible that neither dinosaurs nor mammals would have had the immune system to defend themselves against illness.

it's much harder to adapt to a brand new class of diseases than it is to adapt to new variations of an existing form illness. so the attrition rate for evolving a suitable defense would have been extremely high.

as for why mammals would survive while dinosaurs didn't, it may have been because mammals reproduced much quicker. animals with shorter life cycles and higher reproduction rates tend to adapt to environmental changes much more easily. in the time it takes for a large dinosaur to go through 2-3 generations of changes, a small mammal such as a rodent may have gone through 20-30 generations or more. so in times of crisis small animals are much more likely to survive than larger ones.

another factor could be that, because mammals were at the bottom of the food chain, they tended to be nocturnal and live in burrows. being underground could perhaps have also protected them from the global catastrophes that were ravaging dinosaur populations. they probably didn't have as specialized of diets as the dinosaurs did, so when flowering plants began replacing the normal vegetation that herbivorous dinosaurs depended on, plant-eating mammals weren't affected. they also wouldn't have been affected by the mass population die-offs that would have starved the carnivorous dinosaurs.

lastly, insects would have provided a valuable new food source for primitive mammals. dinosaurs may have grown too large to do the same. and whenever animals at the top of the food chain are removed from an ecosystem, the animals at the bottom of the food chain flourish. so all of this would have contributed to the rise of the mammals.

Re:Three questions

[Chris Burke]

But my point was that when combined with other environmental pressures, the disease doesn't have to kill everyone by itself.

Yes the Black Death wasn't going to wipe out humanity. Yet it could have nearly done so to the human population in Europe if it had occurred at the same time as an environmental disaster that had it occurred alone would have threatened but not destroyed the population. Since we're talking about the K-T extinction, an event of many times greater magnitude than the Black Death, using as a point of initial comparison a disease that wiped out a third of a continent seems like a valid way to say "it could happen".

Re:Three questions

[SpiderClan]

Yes, at first glance it would. At second glance, perhaps birds and dinosaurs weren't so closely related as to make birds vulnerable to the particular pathogen(s) at hand. At third glance, perhaps many species of birds were severely damaged or wiped out by the same thing. At fourth glance, it could be that the carrier insects didn't like fighting through feathers to get to bird skin, so they stuck to biting dinosaurs.

I'm sure more glances would lead to even more explanations, ideas, theories or what have you and that someone who was actually looking would be able to prove the results of all my glances wrong without too much effort.

Re:Three questions

[Anonymous Coward]

You answered your own question: why do we still have birds? Birds are supposed to be direct decedents of dinosaurs.

Re:Three questions

[dwye]

> Dragonfly fossils with 70 cm wingspans have been found.

Contemporaneous with dinosaurs, or in the Carboniferous Period?

If they weren't around when the dinosaurs were, then they had no more effect than cavemen had.

Insects have been around a lot longer.

[jellomizer]

Insects actually beat us to land before us vertebrates. I would suspect that they would adapt to be parasites a lot earlier then it took for Dinosaurs to evolve. And Dinosaurs were actually very successful group that lasted for a long time (and had a wide variety of species) I doubt that even a potent parasite could kill them all off maybe just a couple of species.

Re:Insects have been around a lot longer.

[LWATCDR]

This whole thing is very short on facts as far as I can tell.
1. Dinosaurs and insects existed together for far longer than humans have been around.
2. Saying Dinosaur is like saying mammal. There is a HUGE variety in them. The idea that bugs wiped them out seems very far fetched.
3. Birds are still around and they seem to be the descendant of Dinosaurs.
So yea this is just a little far out. But then Dinosaurs becoming totally extinct is just way too odd but that did happen well except for the line that became birds.
I blame Homer.

Stupidity

[MightyMartian]

This is a dupe, and what's more, it may be the most inane and retarded theory of dinosaur extinction out there. Dinosaurs weren't a single group, but an incredibly large and diverse family. This is like claiming that a set of epidemics could kill off all mammals or all birds. It's fucking stupid people.

Fast extinction

[Geoffrey.landis]

Due to the length of their slow and eventual extinction

Do note that the "fact" that the Cretaceous-Ternary extinction event was "slow" is not well established; there are many palentologists who cite evidence that it was, in fact, extremely rapid, and the apparent "slowness" is a statistical artifact of the discontinuous nature of the fossil record. The microfossil record, which is much more continuous, seem to show very rapid extinction.

The dinosaurs lasted for about 165 million years. It seems rather unreasonable to think that they coexisted with insects prefectly well for 164.9 of those 165 million years, and then suddenly every dinosaur species died of insect-borne infestation in the last 0.1% of their reign-- including the ocean-dwelling dinosaurs. And including a lot of other marine life. And microbiota. And many species of plants.

What about the aquatic dinosaurs?

[wilkinc]

From the wikipedia page about the Cretaceous-Tertiary extinction event: Mosasaurs, plesiosaurs, pterosaurs and many species of plants and invertebrates also became extinct. Does this insect argument explain the fact that plesiosaurs, plants and invertebrates also went extinct?

It's entirely possible...

[actionbastard]

That insects had absolutely nothing to do with dinosaur extinction.

Cretaceous period atmospheric O2 levels were near the highest level since the Cambrian period and CO2 levels were near a low point. Anybody who has taken biology knows that in order for photosynthesis to take place the atmosphere must contain a certain amount of CO2. Additionally, dinosaurs would not have grown to the large sizes that they did if the O2 content of the atmosphere was anywhere near where it is today.
Most likely scenario for extinction is a decline in CO2 levels caused a drop in photosynthesis rates which started a decline in available food plants for herbivores. Once their numbers started to drop the largest carnivores would have less to feed on so their numbers would start to decline. Then, coincidentally, this frisky asteroid decides that it would like to get to know Mother Earth, and the rest is geologic history. The insects were just a minor player on much larger stage.

Re:Mom, I'm saving humanity

[Inthewire]

Why is it not as cruel?