Biodiversity

Friday, May 12, 2006

BIRDS ARE THE LIVING RELATIVES OF DINOSAURS

Birds have some characteristics which are similar to Dinosaurs. A Tyrannosaurus rex dinosaur that died sixty eight million years ago provided some of the strongest evidence that birds are the closest living relatives of dinosaurs. Dinosaurs had bone similar to female birds. Both Dinosaurs and birds shared common ancestors. Embryos of Dinosaurs were found without teeth.

The researchers said that a Tyrannosaurus rex dinosaur had soft thighbone tissues which strongly suggest that it was a female, and ready to lay eggs. The bone tissue was strongly similar to that made inside the bones of female birds (Chang, 1999). Mary Higby Schweitzer of North Carolina State University in Raleigh indicated that no other living type of animal, produces the hard shells of eggs just before they lay them. The emphasis was placed on gender, as it links the reproductive physiology of dinosaurs to birds very closely. It indicates that dinosaurs produced and shelled their eggs much more like modern birds (Discovery channel,1999).

"Mudge said that Dinosaurs were the ancestors of the birds or stock from which the latter have been derived by evolution"(George, 1997). The bones of the hind feet of a few species closely look like those of birds, some of the bones were hollow that indicates that other resemblances will be found and that birds were the outgrowth of reptiles. Dinosaurs had three toes like the birds, some of European and nearly all of the entire American dinosaurs, have a four and five toed structure. When four toes were seen in the dinosaurs, the fourth never rotated backward like that of the birds. Dinosaurs had the tibia and fibula which are separated always whereas the birds have these bones joined. The termination of the caudal vertebrata of the dinosaur was always small and did not tend toward the plowshare structure of birds (Morell, 1987).

Sinosauropteryx was the first non flying dinosaur to have proto feathers and it was the earliest bird-like dinosaur. This clearly indicated that feathers arose before flight. This also indicated the common ancestor of birds and dinosaurs. The fossil had features that the birds have for instance plumage.

Paleontologists have discovered two new bird-like dinosaurs with simple feathers and many other bird-like features. These findings strengthen the theory that birds evolved from dinosaurs. Although these new species had some form of primitive feathers, these feathers were symmetrical in cross-section which made them useless for flight. "The dinosaurs' arm-length was also insufficient for flight. The feathers were most likely used as insulation, keeping in body heat" (Morell, 1987).

These new dinosaurs Protarchaeopteryx robusta, and Caudipteryx zoui, together with the recently found Sinosauropteryx prima, have characteristics common to both theropod (beast-footed) dinosaurs and to birds. All three, plus many specimens of a very primitive bird (Confuciusornis Sanctus) were found in the period from 1996 to 1997 in an ancient lake bed in Liaoning Province, in China (Discovery Channel, 1999).

The carnivore dinosaurs had a complex system of air sacs similar to the setup of birds of nowadays. According to the research led by Patrick O'Connor of Ohio University, the lungs of carnivores that are bipedal with the feet similar to birds most likely pumped air into hollow sacs in their skeleton. "Comparisons between bird and dinosaur skeletons, as well as cladistic analysis, strengthen the case for the link, mostly for a branch of theropods called maniraptors "(Chang, 1999). Skeletal similarities include the neck, pubis, wrists (semi-lunate carpal), arm and pectoral girdle, shoulder blade, clavicle and breast bone.

A dinosaur embryo was found without teeth, which suggests some parental means was used to feed young dinosaurs, possibly the adult dinosaur putting nutrition into the mouth of a young dinosaur. This type of behaviour was seen in many modern bird species. "The skeletal similarities include the neck, pubis, wrists, arm and pectoral girdle, shoulder blade clavicle and breast bone" (Chang, 1999). A number of feathered dinosaurs provided clear evidence of the close relationship between dinosaurs and birds. Fernado Novas said that because birds are dinosaurian descenants, they are dinosaurs...birds are living dinosaurs.

References

1.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
2.Discovey Channel.1997. Bird-like dinosaur found in Aigentina[internet]2006 May 09,11:45 UTC [cited 2006 May 10]
3. 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

4. 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

5. Wikipedia Contributors.2006. Dinosaurs are warm or cold blooded, 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
CSIR PTA
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Cell No : 0824407982
Tel No: 012 8412123
Fax : 012 842 3676
E-mail :kmasiya@csir.co.za
Weblog: http://kedibone-kedimasiya.blogspot.com/

1 Comments:

  • Hi there

    Try to use fewer direct quotations, and rather restate things in your own words (while still citing the reference). Also, when using direct quotes, make sure that you quote exactly what appeared in your source. DO NOT reference the Discovery Channel, please.

    Your grammar has improved, but there are still some awkward phrases and many typos. But the main problem I have is that it's hard to find a main unifying theme in this piece that could tie your intro to your conclusion forcefully.

    Nick

    By Blogger NcK, at May 22, 2006 12:10 PM  

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