Washington, April 17 : Scientists have studied alligators to analyze what life may have been like for dinosaurs at low oxygen levels of 12 percent during pre-historic times.

The scientists chose the alligator as a test subject for the study because they are believed to be the modern relatives of the dinosaurs.

"We knew testing the effects of different oxygen levels would work with alligators because crocodilians have survived in their basic shape and form for 220 million years. They must be doing something right to have survived the oxygen fluctuations," said scientist Tomasz Owerkowicz.

Choosing to start at the beginning of alligator development, the scientists decided to try incubating alligator eggs at different oxygen levels, to find out how the youngsters grew and developed.

Receiving newly laid alligator eggs from Elsey at the Rockefeller Wildlife Refuge, Owerkowicz divided the eggs into groups incubated at 12 percent (low) oxygen, 21 percent (normal) oxygen and 30 percent (high) oxygen, and waited to see what would happen.

After almost 10 weeks of waiting, the eggs began hatching and Owerkowicz could see that there were no obvious differences between the alligators that developed in normal and high oxygen atmospheres.

But, he was in for a shock when the low oxygen level hatchlings began to emerge.

The tiny alligators' bellies were enormously swollen. They had failed to absorb all of the egg yolk food supply, leaving them with huge yolk-distended bellies.

In some casesm the bellies were so big that the animals' legs could not reach the ground, and the alligators had to sit around until they had burned off the yolk and could begin moving.

Owerkowicz suspects that there was not enough oxygen for the developing embryos to consume the yolk.

The low oxygen level youngsters' organs were much smaller too, all except the heart, which was relatively large, presumably to maximize use of the youngsters' limited oxygen supplies.

Next, Owerkowicz was curious to see how the alligators performed after 3 months in their respective atmospheres.

When Owerkowicz checked the size of the 3 month old low oxygen youngsters' lungs, he could see that they had caught up with his expectations and were larger than those of the normal oxygen alligators.

The alligators' lungs were enlarged to compensate for the low oxygen supply, allowing the alligators to increase their metabolic rates, but not as much as the normal or high oxygen alligators.

Owerkowicz admits that although his results can't tell us what life was like for his alligators' prehistoric predecessors, it is clear that `their growth and metabolic patterns would have been significantly different'. (ANI)