The final argument from the texture of bones derives from the growth rings.(realistic dinosaur factory) Most people are familiar with growth rings in oak and pine: thin, dark lines are winter wood; wide, pale bands are summer wood. Probably not too many people know that growth rings also form every year in animals. When winter comes, the snapping turtles burrow into the pond bottom to escape freezing. The bones nearly stop growing and lay down a thin, dark layer.(dinosaur factory)The following spring, the turtles start eating and growing and laying down a thick, light layer of growth in their bones. Deer also stop growing in the winter, and the slowdown is marked by a thin, dark line in the bone. Game wardens, in fact, use growth rings in the roots of teeth and in bones to enforce laws against shooting underage bears, moose, coyotes, and beaver. If the warden suspects foul play, he can have the growth rings counted at a lab, and obtain a conviction on the basis of them. Winter isn’t the only circumstance that can stimulate growth rings in bones or teeth; anything that cuts off food or water will have the same effect.
Could growth rings tell whether extinct animals were warm blooded or cold-blooded? Maybe, under careful analysis. Both warm-blooded and cold-blooded animals today can develop growth rings in habitats where winter becomes severely cold. (life size dinosaur for sale)But in warm climates where the dry seasons aren’t too extreme, cold-blooded species tend to have better-developed rings than warm-blooded species. So, if fossils came from an ancient habitat with a warm climate, it could be expected that warm-blooded animals would have more poorly developed rings on average. It must be remembered only the average condition is really significant because some warm-bloods will have well-developed rings. (dinosaur costume)Now, in many of the bones Armand de Ricqles cut from the primitive reptiles and amphibians of the Coal Age in Europe and North America, he found growth rings. The Coal Age environment was warm, tropical. He therefore concluded these growth lines were the products of typically cold-blooded physiology. But growth rings were much less common in dinosaurs, and so he concluded that dinosaurs must have had a more mammal-style rhythm of growth.