Biodiversity

Monday, May 15, 2006

BIRDS ARE THE LIVING RELATIVES OF DINOSAURS

The birds are the phylum chordate, from the class Aves. They are the avian dinosaurs and theoretically considered as reptiles. The birds descended from diapsids dinosaurs. The earliest species of the class Aves to be known was Archaeopteryx. They are characterized by “the bony beak without teeth, the laying of hard – shelled eggs, high metabolic rate and a light strong skeleton” (1). The most important characteristic of the bird is flight or that they fly (2).


The dinosaurs were the subphylum of chordates, specifically, those with “backbones or spinal columns that conquered the terrestrial ecosystem over 160 million years” (3). The dinosaurs were a group of diapsids reptiles that firstly evolved from archosauriform ancestor during “the olenekian, like modern crocodilians” (3). They firstly appeared about 230 million years ago, and became extinct 65 million years back at the time of cretaceous. After their extinct they were no longer dominant on land. “The clade maniraptoran is the group of the theropod dinosaurs that many paleontogists believe birds were derived from some 150 or so million years ago, in the Jurassic period on the other side of the phylogenetic taxonomy birds are by definition maniraptoran and other maniraptoran are their closest relatives” (3).


The birds are the direct descendants of meat eating dinosaurs (eoraptor). However, the dinosaurs are not birds or reptiles at all. The dinosaurs are having straighter legs. They had unique movement, “walked with their legs underneath them” (1). The little dinosaur meat-eaters were probably the ancestors of birds. The dinosaurs also laid eggs, even though their eggs differ somewhat from those of birds, and at least some dinosaurs nested in colonies and cared for their young in the nest as the birds do, they take care of their young one until they are able to fly on their own” (2).


The birds and the dinosaurs were somehow comparable. The birds have hollow bones, and so did pterosaurs. Dinosaurs walked upright as birds do. The meat-eating dinosaurs had very similar skulls to birds. Some of the smaller dinosaur had bodies and arms that are similar to birds. The first bird known as, archaeopteryx, looks the same as the small meat-eating dinosaur. The different between the archaeopteryx and the small meat eaters was the feathers (1).


The birds share many characteristics with their extinct relatives and those characteristics enable them to fly. The birds have evolved remarkable specializations for flight. They resembled the flight from the Ornithomimids and other small theropods. They also resembled a unique breathing system, light yet strong hollow bones. They resembled a skeleton in which many bones are lost and “powerful flight muscles and -- most importantly – feathers” (2).


References:

[1]. Dinosaurs. TM & © 2006-1996 Scholastic Inc. All rights reserved, 10/05/2006, 09:00. Available from: http://teacher.scholastic.com/researchtools/articlearchives/dinos/evolut.htm.

[2].The link between birds and dinosaurs. 10/05/2006, 09:40. Available from: http://learn.amnh.org/courses/dinosaurs.php.

[3].The wikipedia contributors, Coordinated Universal Time [Internet], Wikipedia, The Free Encyclopedia; 2006 May 10, 10; 00 UTC [cited May 2006]. Available from:
http://en.wikipedia.org/wiki/Dinosaurs.


[4].The wikipedia contributors, Coordinated Universal Time [Internet], Wikipedia, The Free Encyclopedia; 2006 May 10, 11; 00 UTC [cited May 2006]. Available from:
http://en.wikipedia.org/wiki/Phylogenetics.


Ms Evelyn Maleka
CILLA CSIR
P.O. Box 395
Pretoria, 0001
Tel: (012) 841 2133
Fax: 012 842 7024.
Email: emaleka@csir.co.za
http://malekaevelyn.blogspot.com/

4 Comments:

  • Okay...

    First off, your reference section is incomplete (you have URLs, but no titles, etc.). Secondly, your essay is a collection of paragraph-length direct quotes - none of it is really your own work! even more confusingly, you sometimes have direct quotes attributed to two different references - this is a logical impossibility, unless obth said the EXACT same thing...

    Nick

    By Blogger NcK, at May 18, 2006 9:13 AM  

  • This comment has been removed by a blog administrator.

    By Blogger Maleka Evelyn, at May 18, 2006 12:04 PM  

  • Hi Nick

    Thanks and i have edited it, i will not repeat the same mistakes in the next assignment.

    By Blogger Maleka Evelyn, at May 19, 2006 1:46 PM  

  • You still have some referencing problems,especially with your reliance on direct quotes. It is much mproved, though. The structure and flow could still use some work.

    Nick

    By Blogger NcK, at May 29, 2006 12:09 PM  

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