PhysOrg.com—The larger an animal is, the more time it spends eating. This means an elephant hardly has time to sleep. It spends 18 hours every day satisfying its huge appetite. Professor Martin Sander from the University of Bonn explains:
This led us to one of the many riddles that gigantism of dinosaurs puts before us. They were just so large that a day would have had to have 30 hours so that they were able to meet their energy demands.
Martin Sander is a spokesman for an international research group, The Deutsche Forschungsgemeinschaft (German Research Foundation), which is looking for explanations for this and other paradoxes, and which has funded the project to date. Now for the first time, their research is offering a plausible answer to the question which the group sought to answer six years ago: why the giant long-neck dinosaurs were even able to exist. The researchers also explain why today’s terrestrial animals are nowhere near reaching the Jurassic size record. Mammals chew. Giant dinosaurs gulped.
Chewing helps to digest the food faster. By the grinding process it is broken down and at the same time its surface is enlarged. This way the digestive enzymes are able to attack the food more easily. Sander says: Chewing is a property of prototheria which no large herbivorous terrestrial mammal has got rid of. But chewing requires time—a resource that becomes scarce with increasing size. At the same time the the ones that chew need a large head, since molars and muscles have to be put somewhere. Not without reason elephants are quite big headed.
However, the herbivorous giant dinosaurs had relatively small, light skulls. Only this fact enabled them to grow extremely long necks. And these again helped them to make food intake as efficient as possible. So they did not constantly have to heave their 80 ton body over the Jurassic savanna while looking for their greens. They just remained on the spot and used their agile neck to browse their surroundings. This was particularly relevant for the heavy weights. Smaller dinos simply had far smaller necks compared to their body length.
New teeth every month
Horsetails were part of the sauropods’ diet, for, according to research by the group, they are exceptionally nutritious. However, only a few animals feed off them today. Horsetails contain a lot of silicate which acts like sandpaper, so they are hard on teeth. These dinosaurs did not chew them but just plucked them and gulped them down, offering no problem to teeth! Even so, scientists from the US have recently discovered that sauropods renewed their teeth exceptionally often, some even in a monthly cycle.
The digestion process itself probably took several days with the giant dinosaurs, due to the missing molars. However, their stomachs were so large that they still provided them with enough energy round the clock. Moreover, the metabolism of these giant animals was incredibly powerful. They possessed amazingly sophisticated lungs, which were far more effective than those of humans. The large number of air sacs which permeated the body cavity and vertebra of the dinosaurs played an important role in their function. Combined with a nifty system of valves they ensured that a gas exchange could take place while breathing in as well as while breathing out. A nice side effect was that the neck got significantly lighter this way. This was important for the statics of the animals. Sander says:
In the history of species the lungs of today’s birds and of the giant dinosaurs have the same origin. This effective air exchange principle was invented about 230 million years ago.
This is consistent with the fact that the earth passed through an oxygen trough at the time. The concentration only 12 to 15 per cent, ie a third less than today. So being able to pick out the few oxygen molecules in the thin air as rapidly and well as possible was a huge advantage.
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