In the asteroid impact theory of the extinction of the dinosaurs, they died off largely because?

Question

In the asteroid impact theory of the extinction of the dinosaurs some 65 million years ago, the dinosaurs (and over half of all the other species on the earth at that time) died off largely because:

a)the impact caused massive earthquakes and volcanic activity worldwide.
b)of injuries suffered from direct hits of pieces of the asteroid or comet.
c)dust settled on the leaves of plants, making them inedible, so the animals died of starvation.
d)dust injected into the stratosphere from the impact absorbed visible light from the Sun, causing global temperatures to plummet.

Answer 1

the atmosphere was heavily clouded with dust that took a very long time to settle out. This caused a drastic cooling of the surface temperature of the earth. Dinosaurs, being cold blooded, could not survive that drastic a climatologic change. In fact, it is posited that an ice age began as a result of the impact and dust. If you look at major volcanic eruptions over the past few hundred years you can see the same phenomenon occurring with regard to temperatures.

Answer 2

There are any number of extinction theories for both the dinosaur and modern times. One of the factors common across many of these theories is the idea that something is sent into the air. That something is sent up on such a scale large enough to effect world climate. This could be short term, or long term; in either case would effect temperature, ultra violet from the sun, and food growth. Is this what happened to the dinosaurs, quite likely.

Answer 3

Most physisists believe it is "D". However, if you look at the animals that did NOT go extinct at the K-T boundary (at the end of the cretaceous), we can find out more. So....
--Who would be most affected by "D": smaller animals, like amphibians, birds, small reptiles like turtles, lizards, snakes etc.
--Who would NOT be as affected by "D": Large terrestrial vertabrates would succumb to "D" long after smaller animals.

So knowing this, lets look at what actually is indecated via fossil evidence (what has been collected at the K-T boundary).
--Who went extinct: Dinosaurs larger than a housecat, all marine reptiles, all flying reptiles.
--Who survived: Amphibians, Reptiles, Birds, Mammals.

Okay. SO what was different about these creatures that helped them to survive? That's the tough question. But most paleontologists now say the extinction went something like this:
*At the end of the Cretaceous, dinosaurs were already dwindled in number by desease, and other factors. Pterosaurs were loosing resourse competition with birds. When a comet struck the gulf of Mexico, populations were reduced already, and might have been the final blow, to cause these animals to go extinct. But those that survived (mentioned above) suffered no losses at all. And surely, if you affect them with "D", they would last much shorter than larger dinos. So the impact must have been locally devastating, but not a global catastrophe to the degree that many physisists claim. It was probably no fun, but it wasn't Armageddon.

Answer 4

C & D...this is my personal opinion. Atmosphereic change didn't happen overnight. The dust blocked affected all aspects of the planet. It was ground level, causing plant life to be inedible but, I don't believe dinosaurs would have ceased eating because their food was dirty. Meanwhile, atmospheric dust absorbs all sunlight, thus killing of plant life. I think the dinosaurs slowly starved to death in a planet that was slowly freezing

Answer 5

The answer is definitely d). The Earth cooled dramatically, killing most plants, causing the plant eating dinosaurs to die off, causing the meat eating dinosaurs to flourish, but only until all of the corpses were consumed. Everything that weighed more than 20 lbs was starved out of existence, with one exception: Crocodiles.

Answer 6

I believe all the alternatives are correct, for all of them are possible (with exception, perhaps, of the alternative B).

First of all, nobody really knows what caused the mass extinction that took place some 65 million years ago. The asteroid impact theory is one of some theories that try to explain it, but is no more than that: A theory (nonetheless, a very feasible one, in my opinion). So, if the theory in itself is speculation, the same applies to the details of this theory. Scientists that study this possibility speculate about the details of it, and every alternative you have mentioned are also mentioned on those speculations (except, perhaps, alternative B, that is mentioned, but not widely supported by scientists as a major cause of death). Remember that this theory is studied and supported by many scientists, so it has many versions.

About the mentioned alternatives, some observations are due:
A) It is widely believed that earthquakes an tsunamis caused by a great asteroid impact may not have directly extincted species (or, at least, many species). Earthquakes and tsunamis may kill a lot, but there are always survivors. It is necessary only a few of each (with luck, only two) so that the specie continue. But the intensity and the consequences of earthquakes and tsunamis due to asteroid impact are not known. And even if earthquakes and tsunamis may not be directly responsible for species extinction, large changes on ecosystems, caused by the great mortality of earthquakes and tsunamis, may. So, they may be indirectly responsible.
The same for the volcanic activity. Volcanic activity injects gases and dust in the atmosphere. The gases and the dust spreads all around the world, and the dust settles down on the earth surface. Gases and dust may intoxicate species, absorb sun light and cause climate changes. All of that may cause indirect species extinction.
B) This possibility was raised, but it is not largely supported by scientists. Rocks would have caused great mortality around the impact region, but not farther away. Minor pieces of the major rock that would have been re-ejected into the space and re-collided to the earth would have been dismantled by the atmosphere. Greater pieces would cause localized damage, just like the main one. Some living beings would die directly of rock impact, but it is not feasible that some entire specie would have been extinct of that. But, who knows the speed and the size of the asteroid? Who knows how the schockwaves would travel by and devastate the world surface?
C) It is very likely that it happened. The dust, after rock impact, schock waves, hurricanes, earthquakes, tsunamis an other mechanical energy phenomena, would be the faster killing agent.
D) That is also very feasible. After dust intoxication, an side by side with climate changes and ecosystem changes, that would have been a great killing agent. But the altern mentions stratosphere. The dust would have been injected into all the lower layers of the atmosphere, not only into the stratosphere.

If I was told to choose on of those alternatives, I would choose alternative C. But not one of them can be rigorously discharged as the main cause of extincion (with exception of, maybe, alternative B).

My particular version of the theory is a killing network of events (since the events are inter-ligated):

Primary killing events:
1- Direct asteroid impact (localized mortality).
2- Air schocwave of the direct impact, along with land schockwave (earthquake) and sea schockwave (tsunamis) (unpredictable mortality).
3- Secondary asteroid impacts (localized mortality, but spread all around the world).
4- Secondary asteroid schockwaves (unpredictable mortality).
5- Volcanic activity due to major impact (localized mortality, spread around the major impact region).
Secondary killing events:
1- Intoxication caused by dust of primary and secondary impacts and volcanic activity (mass mortality).
2- Climate changes, including storms and hurricanes, caused by gases and dust injected into the atmosphere (mass mortality).
Tertiary killing events:
1- Lack of vegetables, privated of the sun by dust (mass mortality).
2- Ecosystems changes, which are caused by all prior killing and by climate changes (mass mortality).

How it is possible to measure the killing effect of each event?

Answer 7

d because of the enormous temperature and the change to the environment it cased the the extinction.

Answer 8

d

Answer 9

I've always been taught that it was reason "d"

Answer 10

Answer D, or boredom..