That dinosaur growth rings are so rare both in occurrence and in number implies that dinosaur metabolisms were fast. Walking dinosaur costume That they appear at all suggests dinosaurs differ in some modest way from tropical mammals and birds. Realistic dinosaur costume As noted above, birds seem to employ nonshivering thermogenesis less than mammals. Perhaps this form of heat production was less developed in dinosaurs, enough so that it occasionally affected growth. This is a very tentative idea. and the whole issue needs a lot more work.
ln 1979, Johnston found that theropod teeth had rings in their inner dentine like those of crocodilians, so he thought that they should be ectothermic.u On the other hand, these growth rings may have something to do with the constant tooth replacement practiced by theropods and crocodilians. Because the latter two groups’ teeth differ so much from the mammalian permanent adult teeth, they do not offer a clear test of physiologr.
We can tell that dinosaurs continued to grow as adults, albeit slowly, because their cartilage limb joints never ossified. Animatronic dinosaur costume This is often cited as a reptilian feature, but elephants never seem to completely stop growing either.