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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?"
Reptiles have perfectly good immune systems: in the case of alligators, they're better than human ones. However, since reptiles are cold-blooded, the seasonal temperature variation means reptiles have suppressed immune function during cold periods, so they'd be predisposed to higher mortality from disease after a meteorite strike or extensive volcanic activity puts enough debris in the atmosphere to reduce the Earth's temperature.
The Black Death spread across Europe and the Mideast in less than 4 years -- individual diseases can move very quickly. The idea that the rise of a class of disease vectors, biting insects, might've gradually led to higher mortality, is interesting, and something I'd never read about.
Nostalgia's not what it used to be.
"Incest May Have Had a Hand In Dinosaur Extinction" and giggled myself silly.
For the last time, we did NOT evolve from monkeys!!!
Monkeys and humans share the same ancestor - thats all.
It's not a human disease.
Whatever its primary host is, it can't be as bad as it is to humans.
Wow, sent an e-mail as suggested when clicking on "use classic" banner, and got a fast response that addressed my msg
The biggest thing I got from the years I studied Earth History and Paleontology was that was that there were always multiple reasons for mass extinctions. People like to point to "the cause" for the end dinosaurs or the Permian extinction, or the late Ordovician crises but in reality there were many. A comet, or A huge volcanic eruption, or A climate crises, or A parasite, or A disease is not going to bring down a large group of diverse life forms. The K/T impact was the coup de' gras but there were other things happening as well. Maybe a rise of parasitic insects had a hand in it, but alone it wouldn't have wiped out everything that vanished across the K/T boundary. For example there were large numbers of animals under the ocean, from plesiosaurs to ammonites that disappeared at the same time. Insects could not have had anything to do with that.
You mean like how fleas carrying the plague made rats and humans extinct during the dark ages?
IIRC insects predate dinasaurs. Sorry, I'm a skep tick.
The book's author isn't a palentologist, he is with the Department of Entomology at Oregon State University. He is (like I am now) making claims he does not have the credentials for.
mcgrew's razor: Never attribute to stupidity that which can be explained by greedy self-interest
Uh, the species of rat which carried the Black Death did very nearly go extinct, and it wiped out one third of the population of Europe in just two years, in some areas as much as 60-75%. If that had been combined that with other pressures occurring simultaneously, like extreme changes in the environment, then yes, even two of evolution's greatest generalists could have been brought low.
I can't say I believe it, but I also don't find it inherently implausible.
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The moon recedes at about 4cm/year, and is currently about 40,000,000,000 cm away. So, assuming the rate of recession was constant (which it wasn't), and started within 35 feet of the Earth (impossible), the tall dinosaurs (and the short ones) would have had to duck or dodge the moon as it passed by them 10,000,000,000 years ago ... not 85 million years ago. As recent as 85 million years ago, the moon would have been a mere 1% closer to the Earth that it is now.
Dragonfly fossils with 70 cm wingspans have been found.
I prefer rogues to imbeciles because they sometimes take a rest.
Actually, there is no evidence that insects of the late Cretaceous got that large. The size of insects is limited by the concentration of oxygen in the air. This is because they do not have lungs per say but have a system that delivers oxygen to their tissues by diffusion. (This oversimplifies the actual case but you get the idea.) In the early Paleozoic there was much more oxygen in the air (about 30% vs, 20% now). This allowed insects to get much larger than today. Although I don't have figures on the concentration of oxygen in the air during the late Cretaceous, it probably was more similar to the air today (pre-Industrial revolution) than it was to the Early Paleozoic.
Early outbreaks of the Black Death killed 80% of the infected people and massively depopulated Europe. Nowadays you'd only have about 50% chance to die of it. Our immune system did evolve somewhat.
That's straightforward natural selection. A significant part of the world population is descendant of the surviving 20% which were naturally more resistant to the plague.
(Unless you are not a creationist, in which case you will have to find your own perfectly irrational explanation all by yourself.)
Antibacterial != antiviral. Their immune systems are very good at protecting against bacterial infection in those environments (and some reptiles, like the kimodo dragon actually have nasty bacteria living in their saliva that acts as a natural poison to weaken prey) but viral immunology is completely different. And viral mutations can move quickly though a population where they were previously benign.
Allow me to repeat something that has been said before:
Dinosaurs were not a tightly knit group, they were widely divergent. Any cause for the extinction must account for mosasaurs, elasmosaurs, icthyosaurs, pterasaurs and many mammalian groups as well. Plague by insect ain't that cause. For what it's worth, my degree is biology with specialization in entomology.
Its amazing how many come up with this solution independently when dealing with unwanted bees nests. Spraying soapy water is FAR more effective, less dangerous, though admittedly, not nearly as cruel or fun.
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Humans would not have been "brought low". There are plenty of humans outside of Europe.
Well, that much is pretty much obvious. That's how evolution happens.
A polar bear is a cartesian bear after a coordinate transform.
Reptiles have immune systems which work for them. They are cold blooded as was mentioned above. Reptiles (in general) have specialized cells which do phagocytosis (even very primitive organisms have this), lymphoid tissue (gut-associated etc) but not lymph nodes, lyphocytes differentiated into B cells and T cells. What they don't have is the variety of immunoglobulin classes that mammals have. ie Their antibody is IgM-like and IgG-like (IgY), but not IgD, IgE and class switching is either slow or non-existent. Birds were the first (phylogenetically) to exhibit lymph nodes and multiple Ig classes, and class switching. Furthermore reptiles don't seem to be able to do the memory (amnestic response) very well. To say that the reptile system is better (or as good as) the mammalian system is non-sensical. They both work have worked to keep species alive for many millions of years and they both continue to evolve. The key is that they work for each in their own envirnmoment. The immune system of a cold blooded animal is by necessity different from a warm blooded animal because bacteria have adapted to grown so much faster at warmer temperatures. If the immune system cannot respond rapidly (ie memory response) then that individual dies. If you look at the evolution of the immune response it appears to have taken several leaps rather than evolving gradually and steadily. These events coincide with changes which could alter the microbiological pressure on animal species. (see the Silurian period and the development of immunoglobulin and T-cell receptors, also the important RAG 1 and RAG2 genes). If reptiles were evolving into birds and there was a change from cold-blooded to warm-blooded at the same time you would expect to see a shift in the immune system capabilities --- and we do. Insects, while vectors of disease likely had little to do with this shift (Achem's razor) http://www2.ncseweb.org/kvd/exhibits/immune/immune_evo_annotated_bib.html
Wiki tells all. Researchers have debated whether a higher O2 content would be needed to support insects of that size. My guess is yes.
I prefer rogues to imbeciles because they sometimes take a rest.
It would...
Of course, it affected the Flying Reptiles (pternadon, etc.) as well, which weren't Dinosaurs.
And then there's the Marine Reptiles (ichthyosaurs, mososaurs, that lot), which weren't Dinosaurs.
A disease that could jump around that far across the biosphere probably isn't going to bypass a bunch of rats. Especially given that...
...the mammals weren't "newly arisen" - they'd been around for a hundred million years or so at that point.
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