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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?"
It's all our fault.
someone get me a can of WD40 and a lighter.
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Do insects have hands?
On an insect?
The synecdoche no worky-worky.
Get thee glass eyes, and, like a scurvy politician, seem to see things thou dost not.--King Lear
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?
Infuriate left and right
Any disease that wipes out its host will have to evolve to be less deadly, or it will run out of hosts. So it's not really right to say that it's our immune systems that allowed animals to survive - the evolution of an immune system and the diseases that it fights go hand-in-hand. There is some competition, with diseases finding new ways to get around immune responses, but also some co-operation, as an overly-effective disease will destroy its own ecosystem and thus die out.
Dinsouar? What is a Dinsouar?
The dinosaur industrial revolution caused their extinction. It's entirely their own fault.
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.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
How could you? Just because your text is tiny is no reason to take out your frustration on those who have normal sized text!
Monstar L
I guess this throws a kink in my plans here....
Since we evolved from monkeys, are monkeys immune to those insects? I believe the first living being with AIDS was a monkey. Maybe the end to our species has just begun...
slashdot rocks
Short answer: Maybe... But if so, it is a small part of what let them survive...
Don't diseases and insects ALMOST ALWAYS follow other natural disasters where there are numerous dead and dying creatures on the land and in the water?
Besides, sharks have awesome immune systems (some scientists say they actually have the BEST immune systems) and many varieties of sharks also went extinct at the same extension period as well numerous species of plants...
Does the author mean to imply that plants also survived the insects and diseases because of their 'immune systems'? I did not realize that plants had immune systems??...
Guess I'll go RTFA...
They may have a hand in bringing them back from the dead.
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.
The world's burning. Moped Jesus spotted on I50. Details at 11.
parasites and disease don't generally lead to the extinction of their hosts, as you tend to go extinct yourself
after an initial population decimation, in which the hosts suffer, then the parasite/ disease suffers a dramatic population decrease. more resistant strains of host emerge, and then more benign strains of parasite disease emerge. the parasite/ disease can't afford to threaten its own existence by being too virulent and deadly
however, i am willing to bet we, us mammals, killed off the dinosaurs. nothing like a few little rodents chewing on the slowly reproducing eggs of nesting dinosaurs to decimate the population
in fact, the only surviving dinosaurs of the egg-chewing rodent crisis were the ones who could nest in trees, offering some protection from the ground dwelling egg chewers. of course, we call these dinosaurs birds today
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
I personally believe the distinction was caused by a bug riddled asteroid that caused volcanic eruptions when it crashed into the earth.
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.
"We can't say for certain that insects are the smoking gun, but we believe they were an extremely significant force in the decline of the dinosaurs," Poinar said. "Our research with amber shows that there were evolving, disease-carrying vectors in the Cretaceous, and that at least some of the pathogens they carried infected reptiles. This clearly fills in some gaps regarding dinosaur extinctions."
I'm failing to see any link between the rise of insects and the decline of dinosaurs. I accept that insects and their diseases were on the rise, and that plant life probably changed because of this. Still, though, we have a gap:
What about all the other life on earth?
I seem to recall being bitten by a tick once or twice in my lifetime. They're not dinosaur-exclusive.
Likewise, large animals other than dino's depended on that plant life, and many existed in astonishing numbers until the industrial revolution and gunpowder, etc.
For me to understand this, there really needs to be more explanation as to what fundamental differences killed off the dino's while mammals thrived under this same plague of insects.
"...speculation is rampant in a book that gives cause to believe..."
Speculation? In a book? Get back to me when there's evidence in multiple books and scientific journals. Speculation in one book isn't cause to believe squat.
(Could biting insects have caused deaths? Of course but extinction? Highly doubtful and, as I said, until it's discussed more widely than speculation in one book, I'll file that theory away as nothing more than what it is - speculation in one book.)
Sounds like a the African Killer Bees (tm) had been infiltrating. I live in South Africa by the way.
"Incest May Have Had a Hand In Dinosaur Extinction" and giggled myself silly.
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.
http://www.geoffreylandis.com
There's evidence that the environment was already stressed at the time due to unknown factors, possibly volcanic eruptions. Under such conditions, insects and infections may have increased their effects, similar to how drought results in beetle infestations in trees because the trees' defenses are weakened, which is a problem now in the US.
The meteor may not have been the sole cause, but it put the dinos over the top; a kind of perfect storm. It's possible that similar-sized meteors hit before without any noticeable extinction spike. But if one strikes when other sh8t is going down, then it can take its toll.
Table-ized A.I.
One day God came down and asked the dinosaurs if there was anything they wanted. They responded that they wanted to see what the future was going to be like. God opened a vision for them and at first they were excited at all the tasty bi-peds walking around and all the lush vegetation provided by global warming.
Then as the vision continued, they saw something they thought no living being should ever have to endure. They saw that Carlos Mencia was going to be famous and that people would eventually experience his comedy in one form or another. The dinosaurs decided that they would never subject their heritage to such atrocities.
They begged and pleaded for God to take their lives. God replied, "I love you and that is not my way." The dinosaurs were persistent and they begged and pleaded some more. God finally agreed, saying, "Since I love you, I will take your lives, but you must endure horrible plagues, famine, and natural disasters." For the dinosaurs, it was worth it and they agreed.
We can all learn something from our reptilian, bird-like ancestors.
Scientists have shown that the moon is moving away at a tiny yet measurable distance from the earth every year. If you do the math, you can calculate that 85 million years ago the moon was orbiting the earth at a distance of about 35 feet from the earth's surface. This would explain the death of the dinosaurs. The tallest ones, anyway.
Don't anthropomorphize computers. They *hate* that.
Warning - full (well.. kind of) frontal male nudity ahead!
which is totally what she said
http://www.hulu.com/watch/19210/the-simpsons-time-travel-nightmare
Well, I don't think it's necessarily that simple. There are plenty of diseases that outright kill.
Probably the most obvious example is the bubonic plague, a.k.a., the Black Death. It eventually killed all 3 types of hosts involved in plague outbreaks:
- the rats (which were eventually replaced by a different and more robust species of rat, as, yes, the old one almost went extinct),
- the flea (the bacteria essentially plug its stomach, so it ends up perpetually hungry, sucking blood until it barfs it right back and infests a new host. Eventually it starves to death.)
- the humans
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.
But if you combine it with other factors, e.g., a changing climate or whatever, and it could have driven a less resourceful species extinct. As I was saying, the black rats that were the co-hosts in those outbreaks did go pretty much extinct.
The bacterium itself, well, essentially the immense majority of those which caused such an outbreak, eventually died together with its hosts. You'd think that would be a very strong evolutionary pressure to evolve into something less suicidal. Essentially each outbreak ended up in a near wipe-out of the bacteria population. You have an advantage if you don't do that, no? But said evolution towards more benign versions just didn't happen. The humans evolved to have better chances of survival, but the bacterium seems to have stayed just as nasty as ever.
Basically what I'm saying is that there is no divine plan to save you, so to speak. The bacterium doesn't know whether it's heading towards extinction together with its hosts. As long as there are still _some_ available hosts, it didn't go extinct yet, and it can continue just as well.
Additionally, some bacteria can infect more than one host, or can survive decently in the ground without a host. For the latter, even killing all hosts immediately, still isn't really a problem. The former killing one of the hosts isn't much of an impediment either, as long as other hosts can survive (or breed faster than they're killed.)
So for example a hypothetical disease which could infest both dinosaurs and mammals, but only killed dinosaurs, could jolly well keep doing so ad infinitum.
Now I'm not saying that this is necessarily how the dinosaurs died out. Just that evolution works in perverse and mysterious ways.
A polar bear is a cartesian bear after a coordinate transform.
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.
http://blog.tiagocardoso.eu/artificial-intelligence/2008/02/11/were-dinosaurs-just-a-local-max-a-genetic-algorithms-intro/ :D
Well, at least is a nice article about genetic algorithms and how they can relate to real live.. and dinosaurs
Tiago Cardoso
Reptiles actually have great immune systems. Crocodiles are frequently injured in territorial fights, yet their open wounds do not get infected in the less-than-antiseptic environments they live in. Scientist are currently studying them to try to figure out why their immune systems work so much better than ours. Then again, they are one of the few families of reptiles that survived the extinction, so maybe that had something to do with it.
Support Right To Repair Legislation.
http://www.washingtonpost.com/wp-dyn/content/article/2006/05/17/AR2006051702158.html
"Kill 'em all and let Root sort 'em out"
Obviously the bugs deflected the meteorite onto them.
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?
Too busy to find refs at this time, but IIRC: crocodilians have a remarkable immune system, due to them living mostly in swamps (moist, warm and dirty!) and hurting each other frequently in territorial battles.
And they do have thick skins.
Mammals of the period were quite small, and presumably had much faster lifecycles than most dinosaurs... their immune systems would evolve faster. Also, the shorter lifecycle might prevent the disease from developing in a full-blown form: even if normal mice could catch AIDS, it wouldn't kill them because they'd die of old age before developing symptoms anyway.
Everyone knows it was disease, but it wasn't from insects. Homer just sneezed on a T-rex that was about to eat him.
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?
Yes, indeed, Immunoglobuline E which are responsible for combating parasites are only found in mammals. Not in birds (the other groupe of dinosaurs' descendants). Thus we could speculate that dinosaurs laked them.
That's one less way to combat them.
As a side note, IgE are also responsible for allergic reaction in modern humans. Probably we aren't exposed to lots of parasites in the developed world - in most people the IgE system just stays idle, but in a few individual who had the misfortune to inherit the wrong genes, this system gets overzealous and tries to functions against things that are supposedly inoffensive.
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?
Well that's a different factor but for an unobvious reason.
As modern birds and mammals aren't naked (for most of them. although a few evolved back to naked skin), they need to groom their fur (or feathers) and had evolved flexible backbones. (Which enable them to reach almost any surface with some member or another - even if it's a tail-used-as-a-fly-swater or a trunk). That also help them to bite and remove potential parasites, and made them more suited to survive to parasites.
Spines of dinosaurs seems a lot less flexible (don't need any when your skin doesn't require any maintenance).
Some species have even quite baroque decoration on their back (see Stegosaurus) that make them probably even less flexible than a modern day aligator, more like a turtle.
At least the turtle has a solid shell. But lots of dinosaurs would probably be left much more vulnerable to insects bites.
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?
Well, seems that every now and then a statistician comes up with a different interpretation of the few data we have available from that time. I really don't know which is currently the most popular
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
Birds indeed lack the anti-parasite IgE system.
But like mammals they need to groom their feathers/furs and birds have evolved flexible necks (like mammals have evolved flexible backs, or in elephant's case, flexible trunck), and thus they can bite and remove parasites.
"Sufficiently advanced satire is indistinguishable from reality." - [Tips: 1DrYakQDKCQ6y52z6QbnkxHXAocMZJE61o ]
Up until 50 years ago, dinosaurs were just large lumbering lizards. Now our knowledge is increasing and many of the assumptions are drying up. No doubt more of your current assumptions about "facts" are going to change.
I prefer the "u" in honour as it seems to be missing these days.
Bugs! If they can bring down dinosaurs, why not some mammoth software?
Glad no one is buying this. Way to publish the smut Princeton University Press! Who said the dinosaurs went extinct? One just took a crap on windshield. And who said a few million years was a long time? Maybe to a tick, but not to ticks.
How many Libraries of Congress is that?
better said than I
placental mammals did not accept a gradually emerging of proof that live young is superior to egg laying
placental mammals actively highlighted the egg-layer's weak link in their reproductive cycle by literally eating their eggs to extinction
that's the best theory of dinosaur extinction
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
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.
It was probably the butterfly. No one ever suspects the butterfly...
Do you have, like, a cartoon demonstrating how it works?
Don't know why nobody has said this yet, but...
I, for one, welcome our dinosaur-eating insect overlords.
Genocide Man -- Life is funny. Death is funnier. Mass murder can be hilarious.
Did Insects Kill the Dinosaurs? January 4, 2008.
You mean like how viruses affect windows more than linux because windows is more prevalent?
Insects and disease could have contributed to the speed of resolution, but it was not the cause.
...OR...Maybe it was an alien ship that crash landed, releasing destruction and a strange disease. And their feral dogs escaped and populated the world... Now that might be more fun to debate.
Below the K-T layer...Lots of Dinosaurs.
Above the K-T layer...No Dinosaurs.
Singular infectious disease event that eliminated that many species, with that many different DNA adaptations to different diseases does not indicate root cause.
The K-T disaster was still caused by a big rock impact.
a trait that will prove crucial to tipping the scales in your direction can emerge long before it actually serves its crucial role
lots of other things have to fall into place, such as a carnivorous prediliction for eggs, being especially tiny, fast, nocturnal, and crafty and smart, or for dinosaurs to "put all their eggs in one basket", pun intended, and prove to have such a horrible reproductive weakness exposed to the early mammals in such a way that the mammals do not as well have a weakness in their reproductive cycle the dinosaurs can exploit too (clumsy, weak, and especially small and helpless young fending for themselves, etc.). so it took time for the advantage to be fully taken advantage of. other traits needed to line up as well
but its probably no small coincidence that the only dinosaurs surviving today are birds, whose nests are above ground, or reptilians who bury their eggs, or guard them zealously, like crocodiles
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
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.
the butterfly...
If we don't make light of everything, we are just stumbling in the dark - Blank
And those durn tree-dwelling crocodiles!
Man, those things are scary. ^.^
Ceci n'est pas une signature.
are famous for zealously guarding their egg clutches, unlike many other reptiles which just leave their eggs to fend on their own, or abandon them at least temporariliy to forage for food
not female crocodiles. they will starve themselves in order to maintain constant vigilance over their clutch
go into any swamp today, and try to approach an egg mound with a bunch of crocodile or alligator eggs. i promise you a warm reception from the local 12 foot female crocodilian ;-)
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
mother nature provided something far worse to have nightmares about:
sarcosuchus imperator
the crocodile the size of a city bus
eek
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
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.
Not to mention that dinosaurs wouldn't have been able to figure out what was causing their deaths the way humans did with the plague. If it were over an evolutionarily "short" period of time, their immune systems wouldn't have had time to evolve and protect them as a species.
Although, to say "dinosaur immune system" is kind of funny, since there are so many different kinds of dinosaurs spread out over such a long period of time.
My beliefs do not require that you agree with them.
How mosasaurs, plesiosaurs, and other marine reptiles became extinct at the same time, or how many types of marine invertebrates became extinct (e.g., ammonites), or any of the many other creatures that became extinct that have nothing remotely to do with insects or dinosaurs. They don't call it a "mass extinction" merely because of the dinosaurs.
What's more, insects long pre-date dinosaurs, and the burst of insect diversity when flowering plants first show up also pre-dates the end of the dinosaurs. Dinosaurs have their peak diversity after the flowering plants and the first appearance of such insects as bees, ants, wasps, and termites. Dinosaurs grew up with insects. Why would their susceptibility to insect-borne pathogens suddenly change? Why would any pathogen be so impossibly thorough as to kill off all the dinosaurs, but not birds?
This extinction mechanism makes as much sense as the "mammals ate their eggs" story -- i.e. it doesn't make sense.
Typical reason people say dinosaurs died out was a meteor impact causing a "nuclear winter" type of event, cooling things down and reducing the dinosaur's food supply.
This could also be right though. I mean, dinosaurs that didn't die straight out could have had compromised immune systems (due to cold and also near-starvation). So it'd then be a 1-2 punch... insect-borne diseases would then be able to kill of dinosaurs that wouldn't have been affected if they were fully healthy.
If you start swatting insects off of yourself with your tail, and your tail is covered with razor-sharp spikes...
Improbable theories of dinosaur extinction keep popping up.
Dinosaurs disappeared because they stifled competition so efficiently that they became unable to adapt.
** The fat stupid monopoly syndrom **
They would have needed some kind of antitrust law to survive their own hubris.
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
the bugs!!
I was unaware that the 'dinos' went extinct. They seem to have evolved and some species have gone to dodo bird land but many are still here. I was also under the impression that species evolve and go extinct every day. Here's my completly uneducated theory; As the world got more crowded, there was not enough room for the bigger species to live/eat/hunt. So they died off or evolved to be smaller. But that's probably too simple of a theory to justify any government grants or sell vaccinations. Either that or they all got real sad and cried to death.
Chuck Norris Did Have a Hand In Dinosaur Extinction
0100111001100101011100100110010000100001
Perhaps diseases spread by bugs reduced the immune system. Add other stresses (say diminished food sources and competition from other animals) and you have a less favourable habitat for dinos, but more favourable for other species.
Engineering is the art of compromise.
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.
Sig this!
This might now be as far-fetched an idea as you might think. One proponent of the extinction-by-disease theory is Dr. Bob Bakker, a well-known dinosaur paleontologist. You've probably seen him a lot on TV, he's the excitable guy in the cowboy hat and crazy beard. According to Bakker, around the end of the Cretaceous, inland seas were drying up in the western U.S., creating land bridges and mixing between previously isolated populations. These populations would have had little immunity to each others' diseases, and insects are a common disease vector. Bakker seems to be in the minority in this opinion, though, as many paleontologists subscribe to the impact theory. The fossil record, however, shows that the dinosaurs were in decline for millions of years before the K-T boundary event. The Chicxulub impact may have only been the last straw, not the cause of the extinction itself.
>Are our immune systems the only reason any animals survived?
Insects, like dinosaurs and humans, are also animals.
Well, the insects wouldn't have to kill ALL species to destabilize the system. If just a few key species where strongly affected, the entire ecosystem, in land and water, may have collapsed in a chain reaction. Not only dinosaurs died, and this mass extinction wasn't the only nor the largest: http://en.wikipedia.org/wiki/Permian-Triassic_extinction_event . The point is that you don't really need special events to trigger the collapse and restabilization of a low-entropy system.
..please! The issue is pretty much settled from a scientific perspective. Dinosaurs were killed by a meteorite impact (something in the range of 10km in size), which can account for the iridium spike in clay deposits. A meteor which killed 70% of the biomass on earth, and all animals heavier than 20kg or so, which is obviously enough to reshuffle all the cards of evolution.
WTF, they even found the crater of the impact, which is in the gulf of mexico.
This site has a nice diagram of sexual reproduction in ferns. The spores of a fern have an egg and a flagellated SPERM! The sperm needs water to swim to the egg ( also located in the newly germinated spore )
So it would be an error to say that flowering plants reproduce more sexually than non-flowering plants. But non-flowering plants need water to reproduce sexually - that is all
...
They dinosaurs were to stupid to grab a can of RAID.