Tuesday, May 16, 2006

DINOSAURS WERE WARM BLOODED ANIMALS

Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for more than one hundred and sixty million years, earliest appearing about two hundreds and thirty million years ago. For many years, scientists started to search evidence showing that dinosaur may be warm blooded. The evidence used include the way dinosaur stood straight-legged like mammals, the big rib cages that could have held mammal-like hearts and lungs, and bones that had channels for quick blood circulation as found in the bones of the warm-blooded animals. Dinosaurs were dynamic creature, and not just overgrown lizards.

The fossilized heart of Dinosaurs was found in the Northern part of South Dakota in 1993. Dinosaurs were classified under reptiles for many years until this view was seriously challenged by John Ostrom professor of palaeontology at Yale University and Robert Baaker. The two scientists from North Carolina States, Reese and Bill showers got a way. Reese and Bill determine the extremities of dinosaurs were sustained with same temperature with its body core or not. Scientists have used the isotopes method to determine the temperature of the body. Bones consist of mineral calcium phosphate (CaPO4); the calcium phosphate has an oxygen atom which occurs naturally in the form of two isotopes, 16O and 18O. the bond are formed by 18O (O Oxygen) atoms according to physists language this is the effect of isotopes, the oxygen atom taken up into newly formed bone tend to be preferentially. Barrick and Showers compared dinosaurs and reptiles. There was little or no difference between tail and rib in 16O/18O ratios. The unmineralized interior of Terex bones (T bones) rule out possible artifacts, the same results were obtained. The fossils of the reptiles were found in the same deposit showed similar characteristics of the cold blooded animals. The dog of the same size with dinosaurs indicated similar constancy of 16O/18O.

Horner teamed up with Armand de Ricqles in an effort to investigate bone structure as a means to differentiate between endotherms and ectotherms. The two scientists did studies that analyzed the differences in bone structure during the growth series of a dinosaur, from embryo to adult. Through comparative anatomical studies of micro-thin sections of bone from dinosaurs, modern birds, and reptiles, the scientists found that both the dinosaur bones and the modern bird bones contained vascular canals within the bone, for blood vessels. This evidence suggested that there is a very significant similarity among bird and dinosaur bone, which indicated that the dinosaurs were warm blooded.

The studies of tiny dinosaur baby bones in hadrosaur were conducted by Jack. Results showed that Dinosaurs grow very fast. Horner showed that it reaches substantial size while still in the nest. Furthermore, evidence for rapid dinosaur growth can also be found in the microscopic structure of the bones. The bones of the dinosaurs were reached in the passage ways known as Halverson canals that transport nutrient laden blood to the cells that lay new bone. The fast growing bones of warm blooded mammals have the same high density of Halverson canals, whereas the slow-growing bones of cold blooded reptiles have far fewer.

Ruben hauled a 70-watt ultraviolet lamp to Salerno, Italy to study the fossil of Scipionyx samniticus. It is the best preserved soft tissue of a dinosaur in the world. The fossil showed that the baby dinosaurs had a large intestine, liver, windpipe and muscles. The UV light allowed Ruben and his team to see that the liver and guts of the Scipionyx were separated from the lungs and heart, which indicate the presence of a diaphragm, a layer of tissue found in mammals and modern crocodiles. A diaphragm also allows for high levels of oxygen exchange.

Beverly Eschberge believed that dinosaur have been only the warm blooded animals due to the structure of the bone and histology, growth rates, predator to prey ratios speed and agility, rate of evolution, similarities with birds as well as insulation. Most of the dinosaur bones which have been studied appear like the bones of modern ectodermic. Dr Russell, a palaeontologist of North Carolina State University has indicated that the images of its chest which has enhanced suggested that it was a four chambered double pump heart with a single systemic aorta. The heart was more similar to of birds or mammals than reptile. “Willo’ fossilized heart suggested that the circulatory system was more advanced than that of the heart of reptiles. Longer periods of high activity were one of the vital aspects of warm blooded.

Evidence indicated that dinosaurs were very active which was able to move in high speed. The findings by Reuben indicated the presence of a diaphragm, a layer of tissue found in mammals. The way dinosaurs stood straight-legged live mammals. The bones that contained channels for quick blood circulation as found in warm blooded animals. The evidence which have been provided by scientists clearly indicates that the dinosaurs were warm blooded animals.

References

Chang G (1999). Dinosaurs were hybrid of cold-blooded, warm-blooded animals [internet] 2006 May 09, 11:30 UTC [cited 2006 May 10] Available from: http://www.exn.ca/Html/Templates/topicpage.cfm?ID=19990122-51&Topic=Dinosaur
George J (1997). The isotopes in their bones suggest that dinosaurs were warm blooded [internet] 2006 May 09, 14:30 UTC [cited 2006 May 10] Available from: http://www.txtwriter.com/onscience/Articles/dinoblood.html
Morell V (1987). Were Dinosaurs warm-blooded? Evidence supporting the claim that dinosaurs were warm blooded from strongest to weakest [internet] 2006 May 07, 11:30 UTC [cited 2006 May 10] Available from: http://www.cheathouse.com/essay/essay_view.php?p_essay_id=12829

Wikipedia Contributors. Insects’ behaviour, The free Encyclopaedia [internet] 2006 May 06, 08:30 UT C [cited 2006 May 08] Available from: http://en.wikipedia.org/wiki/dinasaurs

Masiya Kedibone
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