However there is no reasons why we have no conclusive answer to the mystery of the K-T event. Several complications that make work hard for the scientist/detectives trying to crack this case:
The Fossil Record:
Most data on the K-T event comes from North America, which one of the few areas is known that has a somewhat continuous fossil record (remember, fossils are only formed under certain rare conditions, and are only found in sedimentary rocks). The infamous Hell Creek locality in Montana is one such continuous site enclosing the K-T boundary. The secret to the K-T event may lie within our collections; who knows! Anyway, we don't know much about what was occurring in the rest of the world at the time of the K-T event. The marine fossil record gives us great hints about what was occurring within the sea, but how applicable is that to what went on in the terrestrial realm?
The Nature of Extinction:
Extinction is not a simple event; it is not simply the death of all representatives of a group. It is the cessation of the origination of new species that renders a group extinct; if species are constantly dying off and no new ones originate through the process of evolution, then that group will go extinct over time no matter what happens. New dinosaur species ceased to originate around the K-T boundary; the question is, were they killed off (implying causation, especially a catastrophe), or were they not evolving and simply fading away (perhaps implying gradual environmental change)?
Determining the age of rocks or fossils that are millions of years old is not easy; carbon dating only has a reasonable resolution when used with organic material that is less than about 50,000 years old, so it is useless with the 65 million year old K-T material. Other methods of age determination are often less accurate or less useful in certain situations. So we don't know exactly when the dinosaurs went extinct, and matching events precisely to give a picture of what was happening at a specific moment in the Mesozoic is not easy. Thus, the ultimate question of a gradual decline of dinosaurs vs. a sudden cataclysm is almost intractable without a wealth of good data.
To truly understand the situation of the dinosaurs around the K-T boundary, we need to understand the paleoecology of that time on Earth. Paleoecology is an extension of the discipline of ecology, attempting to understand the interactions of organisms with their environment, using geological (the rocks tell you what the soil was like, and thus tell a lot about the abiotic (non-living) environment) and pal ontological (what plants and animals are found as fossils tell you a lot about the biotic (living) environment) evidence. With the problems of the fossil record and time resolution, it is difficult to understand the paleoecology of a region at a specific time in the past.
The Signor-Lipps Effect:
This concept helps us to understand the limitations of the fossil record. The theory states that groups of organisms may seem to go extinct in the fossil record before they actually do; this is an artifact of the fickle nature of the fossil record rather than actual extinction. Thus, it is possible that some groups of organisms did not go extinct at the K-T boundary, and also possible that some organisms that seemed to have gone extinct earlier may have survived up to the boundary, and then gone extinct. This matter further complicates the important issue of the selectivity of the K-T extinction.
Even with the best hypothesis, such as the impact hypothesis, it is very difficult to prove or disprove whether the dinosaurs were rendered extinct by an event that occurred around the K-T boundary, or whether they were just weakened (or unaffected) by the event. This is not to say that all extinction hypotheses are not science; many are excellent examples of good science, but a linkage of direct causation is a problem. "Why" questions, such as "Why did the dinosaurs die out", or "why did dinosaurs evolve?" are among the most difficult questions in paleontology. Ultimately, a time machine would be required to see exactly what killed the dinosaurs.
Source from great site: http://www.rareresource.com
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Posted by Dinosaurs World at 11:16 PM