Longevity Injuries and Disease

Nothing, living or non-living, can persist indefinitely. In the days of the transatlantic liners, the average 'life' expectancy of a glass tumbler was about 1.5 crossings. Presumably, few tumblers would have survived for more than five or six crossings although potentially they could last for centuries. Whatever the potential life of a dinosaur, most individuals would have been killed by predators, injuries or disease long before they died of old age. Growth rings in certain bones and teeth suggest that some of the giant sauropods may have lived for at least 120 years. Perhaps some even reached 200 years, but there is no way of finding out (Lambert et al. 1992). During Mesozoic times, the earth was spinning faster on its axis than it does now, so the days were shorter and there were more of them in a year.

The greatest authentic age reached by a living reptile is over 150 years. This reptile was a giant tortoise (Geochelone gigantea) brought from the Seychelles to Mauritius in 1776 when fully mature. It was accidentally killed when it fell through a gun emplacement in 1918(!) and its actual age has since then been estimated at not less than 180 years. The greatest age recorded for a crocodilian is only 66 years.

Many Mesozoic reptile fossils show bones broken by falls or when fighting, or damaged by infections or arthritis. Dinosaur palaeopathology has been reviewed by Rothschild (1997). Evidence for injuries and disease is restricted mainly to abnormalities of bone growth, erosion of articular surfaces due to cartilage defects and fractures that have begun to heal. Breakages less than a few weeks old would probably not be recognisable as having occurred during life. Although osteoarthritis has traditionally been considered to be a common disorder of dinosaurs,signs of this,as well as of dental pathology,are extremely rare in dinosaur skeletons. Gout has, however, been identified in the finger and toe bones of Tyrannosaurus, fusion of the cervical vertebrae in ceratopians, and tail tip fusion in hadrosaurs. Examples of tumours are very problematic. Eggs of Hypselosaurus with multilayered shells have also been found. Stress is known to cause thinning in the shells of birds' eggs by disturbing the hormones of the birds that are laying them. Erben et al. (1979) found progressive thinning in some Late Cretaceous dinosaur eggs, which they thought might indicate stress, but similar observations have not been made in the case of other species.

The factors that limit life span, such as increased susceptibility to infectious disease, do not usually affect the skeleton. Consequently,palaeopathology does not provide any clues as to the possible causes of extinction. Nevertheless, it is clear from the paucity of pathological evidence that the dinosaurs and the other Mesozoic reptiles must have been relatively healthy animals.

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