Why was everything so darn BIG?
Here is a question which believers in the Bible can answer very easily. The FACT of oversize creatures (also referred to as "megafauna") fits in quite well with biblical chronology. After God created the world, and all of the various animals, including man, he said it was "very good". Even in the early chapters of Genesis, the "great creatures of the deep" are mentioned.

On Discovery Channel, we hear a lot about Dinosaurs, but much less reported is the fact that the fossils show that many species of animals as well as plants were jumbo proportions in earlier earth history.

Not Just The Dinos
Gigantic ferns, dragonflies with 3 ft. wingspans, (all the better to feed giant reptiles), humungous sloths, crocodiles as long as a London bus, and monstrous sharks all appear in the fossil record. Even fossil insects such as 5 ft. millipedes! Many of their shrunken relatives are still around today. Why were things so big at a former time, and why not now?

As I previously stated these things are expected, and even anticipated by those who interpret Genesis literally. Long ages are the prevailing pattern when the world was new, and the vegitation bountiful and healthy! Anyone who went to sunday school knows that Methuselah lived to be 960 years old! But did you realize that Adam, Noah, and many others also achieved longevity we might only dream of? It is a fact of biology that reptiles, unlike humans, continue to grow throughout their lives! Could this be why dinosuars AND so many other creatures which are NOT extinct grew so 'terribly' large?

Why shove it under the rug?
The evolutionst would like you to forget about the other humungous creatures and plants, and focus on Dinosaurs. Why? Because in this way they can paint the picture of a former time, when different types of creatures walked the earth. Thus explaining the difference in size. If everything were larger, that would require a different explaination. And it is proof that the environment and atmosphere can, and indeed have changed. Why is this important? Because Carbon 14 dating, and indeed many dating mechanisms are based on constants. A predicted quantity of a particular ingredient, decaying at a steady constant rate. If global changes have occurred in earth history, these dates could be vastly skewed. see Uniformitarianism

Oxygen Bubbles in Ancient Amber
Recent USGS analysis of the bubbles found in fossilized amber revealed an interesting surprise! The oxygen content was much richer than the present! Another interesting point is that this increase tapers off and assumes todays percentages shortly after the KT Boundary (between the Cretacious and Tertiary) where the dinosaurs are said to have gone extinct! More

Awww C'mon! Nobody lives to be nearly 1,000!
True! Not these days, anyway. But ancient Jewish Historian, Flavious Josephus, who wrote "Antiquities of the Jews" warned against dismissing the idea out of hand:

But let no one, upon comparing the lives of the ancients with our lives, and with the few years which we now live, think that what we have said of them is false; or make the shortness of our lives at present an argument, that neither did they attain to so long a duration of life, for those ancients were beloved of God, and [lately] made by God himself; and because their food was then fitter for the prolongation of life, might well live so great a number of years: and besides, God afforded them a longer time of life on account of their virtue, and the good use they made of it in astronomical and geometrical discoveries, which would not have afforded the time of foretelling [the periods of the stars] unless they had lived six hundred years; for the great year is completed in that interval.

Next, from that same passage, he adds that these things can be alternately confirmed by other listed sources (from ancient Greece and elsewhere), to the tune of no less than 11 other sources!

Now I have for witnesses to what I have said, all those that have written Antiquities, both among the Greeks and barbarians; for even Manetho, who wrote the Egyptian History, and Berosus, who collected the Chaldean Monuments, and Mochus, and Hestieus, and, besides these, Hieronymus the Egyptian, and those who composed the Phoenician History, agree to what I here say: Hesiod also, and Hecatseus, Hellanicus, and Acusilaus; and, besides these, Ephorus and Nicolaus relate that the ancients lived a thousand years.

So Where'd They All Go?
So what happened to all these giant plants and animals from the past? Well, extinction for one. Unlike the evolutionary creation of NEW creatures, extinction is a pattern which is observed today. During our lifetimes, many species now alive will become extinct. But it seems that there might have been a heavier force at work than the intermittent reduction of species that we see today. In fact there was a geological period which reflects this very thing. Massive boneyards, large coal seams (created by dead organic plant matter), and the complete loss of many "kinds" of animals, including the dinosaurs. Why did they die out? Well, a couple of very funny reasons have been proposed. I want to state that I think these to be entirely ridiculous, but will present them anyway as evidence of just how far some people will go to avoid the "F" word:

Extinction by Impotence (too bad they didn't have Dino-Viagra!)

And that one is only topped by this one:
Extinction by Flatulance (that's good ol' farts, for the layperson...)
Yes, it's true methane gasses caused by the dinosaurs diet, might be the true cause of their mass extinction! This is too funny. Maybe the ancients could have produced "Dino-Beano" to keep this problem in check! Haha!

But what was the real reason that could have caused all this calamity? I'll give you a hint: It involves water... and plenty of it...