Wednesday, July 6, 2011

Skeleton holes suggest active dinosaurs

Somewhere on the area of your thigh bone, there is a minute hole. It’s called a “nutrient foramen”. A blood vessel passes through this gap, suffusing the bone with blood and oxygen. The hole is established in all thigh bones, from those of birds to lizards, and it always fulfils the similar task. But it can also twice as a keyhole into the past, allowing us to peek at the lives of animals long extinct. Roger Seymour from the University of Adelaide has use the size of these holes to demonstrate that many dinosaurs of all sizes led dynamic lifestyles.
Seymour calculated the nutrient foramina in the thigh skeleton of approximately a hundred animals, and establishes that, in general, bigger animals have bigger bones and bigger holes. But those of mammals are just about twice as big as those of similarly sized reptiles. Combined with the details that mammal blood has a higher pressure than reptile blood and carries additional oxygen, Seymour estimates that mammal skeleton obtain about 54 times more oxygen than reptiles ones do. This all makes intelligence. When they’re doing exercise, mammals have superior metabolic rates than reptiles and they require additional oxygen to fuel their behavior.

There are two exceptions. Seymour establishes that in terms of foramen size, monitor lizards clustered with mammals. These lizards are lively hunters that can still chase down mammal victim. Thanks to a sole “gulping” method of breathing, monitor lizards have extraordinarily high metabolic rates for reptiles, and their thigh skeleton have abnormally large foramina to contest.

Seymour too showed that the foramina of 10 dinosaurs, from Centrosaurus to the very tall Girraffatitan, were still larger for their size than individuals of mammals, and much bigger than those of similar reptiles. Seymour says that these dinosaur fossils holes “maintain the ever-growing verification that some dinosaurs were greatly active animals” that ate a lot, grow quickly, and was capable of strong bursts of movement.

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