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ZoomDinosaurs.com
DINOSAUR ANATOMY AND BEHAVIOR
General Anatomy Size Teeth Herds, Packs Offense Defense Reproduction, Nests & Eggs Blood Pressure
Skeleton Tails Brains Male or Female? Skin Diet Locomotion Life Span Hot or Cold Blooded?

DINOSAUR LIFE SPAN

How old did the dinosaurs get to be? That question is very hard to answer.

Recently scientists have found that most dinosaur bones have growth rings (called lines of arrested growth, abbreviated LAG) that may answer this question. These lines are only visible using a microscope. The bones have to be sliced into thin section and viewed with a polarized lens in the microscope. It's a bit like looking at the growth ring of trees to determine the age of a tree. Each year of growth leaves a trace in the bone (or tree trunk).

Another way to estimate life span is based on body size, the known life spans of modern-day animals, and the fact that large animals generally live longer lives than smaller ones. It has been estimated that the huge sauropods, like Apatosaurus, Brachiosaurus, Diplodocus, and Supersaurus lived to be roughly 100 years old. Smaller dinosaurs probably lived shorter life spans.

Scientists have determined the following estimates:


Growth Rates:
Growth rates based on maximum growth rates of modern-day reptiles, even though there are probably major metabolic differences. Protoceratops: Adult 177 kg, hatchling 0.43 kg (hatchling weight calculated to be about 90% of the weight of 0.5 liter egg). Age to adulthood calculated to be roughly 26-38 years.

Hypselosaurus : Adult 5300 kg, hatchling 2.4 kg. Age to adulthood calculated to be about 82-188 years. If this is true, this would seem to indicate that dinosaurs either lived for an incredibly long time or else, using the growth rate of living reptiles is not appropriate, and Hypselosaurus grew at a much faster rate that modern-day reptiles (indicating that it had a much faster metabolism than living reptiles), or maturity came long before they reached their adult size.

References

Chimsamy, A. 1994. Dinosaur bone histology: implications and inferences; pp. 213-227 in G. D. Rosenberg and D. L. Wolberg (eds.), Dino Fest. The Paleontological Society, Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee.

Ricqlés, A. de. 1983. Cyclical growth in the long limb bones of a sauropod dinosaur. Acta Palaeontologica Polonica 28:225-232.

Varricchio, D. V. 1993. Bone microstructure of the Upper Cretaceous theropod dinosaur Troodon formosus. Journal of Vertebrate Paleontology, 13:99-104.

ZoomDinosaurs.com
DINOSAUR ANATOMY AND BEHAVIOR
General Anatomy Size Teeth Herds, Packs Offense Defense Reproduction, Nests & Eggs Blood Pressure
Skeleton Tails Brains Male or Female? Skin Diet Locomotion Life Span Hot or Cold Blooded?


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