Chapter 5: The truth of why Dinosaurs died out (2)

The minimum speed required to achieve flight is expressed as Vmin and can be calculated as Vmin = ((W/A) constant)0.5 , where A=wing area and W=weight. The W/A is known as the wing load. The constant is determined by the shape of the wing; a well-designed wing would have a constant of about 0.9kg/m3. If the constant is 0.9kg/m3, the formula Vmin = (1.1 x wing load)0.5 holds true.

Based on this formula, if a flying object becomes twice as large, the minimum flying speed increases 1.4 times. In other words, as the body becomes larger it requires a higher speed to get off the ground. The albatross is one of the largest birds flying today. It has a wing load of 150/N/m2 and has an estimated minimum flying speed of 13m/S, 47km/h. When it takes off, it has to run at full speed into the wind to maximize the windflow over its wings, and flies off looking very heavy. This take-off speed may almost be the limit at which animals can attain flight.

Let's apply this formula to the pterosaur known as Quetzalcoatlus. Pterosaurs have a very distinctive structure--their bones are hollow which make them very light compared to its body size. Therefore we can't simply apply the square-cubed rule to birds and pterosaurs.

Quetzalcoatlus has a wingspan of about 12m and weighs only about 90kg. Assuming a weight of 90kg and using the illustration in the Royal Tyrrell Museum as a reference, its wing area can be calculated to be 4.3m2, with a wing load of 209N/m2 which would give a minimum flying speed of 15m/S, or 54.6km/h. There is no way that such a lean pterosaur, with a wingspan of 12m, could have achieved this take-off speed. While albatrosses receive an assist from strong winds off the Pacific Ocean, Quetzalcoatlus lived in the interior and could not have become airborne unless it was very gusty. Furthermore, albatrosses flaps its wings to gain additional speed, but with its hollow bones and a 12m wingspan its was quite unlikely that pterosaurs was able to flap its wings.

A minimum flying speed of 54.6km/h means that it could not go below this speed, even while landing. Otherwise it would have crashed. So even if it had been able to take off, pterosaurs, with their thin bodies, could not have survived landing at this speed.

As one can see, dinosaurs and pterosaurs could not have existed in an 1G environment. As further proof, no large creatures have appeared to fill the niche left open by the extinction of the dinosaurs for 65 million years. It is common knowledge among biologists that when a species dies out, another species will come to take over the niche it had occupied. And this applies to organisms that live in the air as well as those on the ground.

The niche left open since the extinction of the pterosaurs is yet to be filled. To avoid any misunderstanding, let me clarify that the pterosaurs and ichthyosaurs belong to completely different families from dinosaurs.

Could it be a coincidence that dinosaurs, pterosaurs, and ichthyosaurs--completely different, large creatures--had existed at the same time. It would be understandable if it had been only the dinosaurs that died out, but it was a simultaneous extinction of huge creatures in three different ecologies--on the land, in the sea, and in the sky. The niches that were left open has not been filled by other species, except in the sea, where the influence of gravity is less of a problem due to the buoyancy of water.

Chapter 6: Ammonites and coral

Let's look at marine animals now. Many species also died out in the oceans. Even the ammonites that were among the most successful organisms in the sea along with the ichthyosaurs, also died out at this time.

Although the extinction of ammonites can be explained by the environmental changes wrought by the asteroid impact, many researchers admit that there is an inconsistency, related to the presence of coral. As can be seen from the current death of many coral reefs from environmental disruption, coral is very susceptible to changes in its environment. However, despite the dramatic global environmental changes that caused the extinction of ammonites, there is little evidence to show that the coral were affected.

There was, however, something unusual happening to the ammonites even before their extinction. During the late Cretaceous, abnormally coiled ammonites appeared in great numbers, and which may provide clues to its demise. Many such abnormal ammonites have been found in Japan, and some of you may have seen them in places like museums.

These ammonites were affected during their growth by a sudden increase in the gravity. Thus it would be natural to see a mass outbreak of this affliction. Coral, on the other hand, are made up of microscopic coral polyps. On the whole they are very solid and would have been able to endure changes in gravity. Since large coral reefs are made up of these hardy microscopic coral polyps they would not have been affected by gravitation change.

Translated by Rie Ishida