Evolution of Birds

Evolution of Birds

Introduction

The main purpose of this paper is to make an analysis on the evolution of birds. It is proved that the birds have been evolved since centuries before. The first bird has been identified at the time of the dinosaurs. Thus, this paper is a reflection of how the birds have been evolved.

Discussion

According to the research, the bird's evolution has started in the Jurassic period. The first bird which has been evolved is the theropod dinosaurs. The birds have the categorization under the biological class which is named as Aves (Ali, 1968). From the class Aves, the foremost specie which has been discovered is the Archaeopteryx lithographica. This has been originated from the late Jurassic period, even though at that time the Archaeopteryx was not a commonly known bird. According to the latest phylogenies, the birds have the placements in the dinosaur clade theropoda. As per the recent prevailing consensus, the Aves and one of the sister group of Aves which is the order Crocodilia, are the only living members of Archosauria. The evolution of birds is greatly complicated by the fact that they have quite fragile bones which are poorly preserved. However, scientists agree that the ancestors of birds (as well as crocodiles and dinosaurs) were Mesozoic reptiles from the group thecodonts (Kurochkin, 1985). Apparently, some of these animals gradually adapted to life in the trees. The scales that covered the front limbs, have greatly grown and turned into feathers. Thus the ancestors of birds were first able to jump from branch to branch, then plan and, finally, conquered the air. One of the "candidates" to be the first bird is a fossil of the Jurassic period (Hou, 1984). This is a small animal like the size of a crow and had feathers, but the presence of teeth and the ventral fins, a long tail and fingers with claws, no keel, and pneumatic cavities in the bones brings him to reptiles. Perhaps Archaeopteryx could not maintain their body temperature at a constant level. Archaeopteryx lived in the trees; apparently, they could only schedule (Feduccia, 1996). These animals are so different from modern birds, that they are isolated in a separate subclass yascherohvostyh birds, as opposed to all other birds. Birds were commonly introduced by private individuals or by acclimatization societies for aesthetic or sentimental reasons. Acclimatization societies often kept detailed records, and some, like the Hui Manu in Hawaii, published newsletters documenting their activities (Blackburn, 2009). Other exotic birds were translocated for biocontrol purposes. These introductions were generally carried out by government agencies, which also documented their efforts. These data make exotic birds very useful model systems for examining evolutionary changes (Barlow, 1997). Birds have been preferentially introduced to islands. Islands are very amenable to examinations of evolution, as they are simplified systems that have fewer confounding factors (such as lower overall species richness and habitat diversity) than mainland areas. The reduction of these factors makes it easier to assign mechanisms to observed ...