55-1
Chapter One
Diversity in Anatomy and Physiology:
Clinical Significance
There are approximately 8900 species of living birds compared with only about 4200
species of mammals. In this chapter it is not possible to consider all aspects of anatomy
and physiology. Only those variations in the more clinically important parts of avian
anatomy and physiology will be considered, because knowledge of these is important when
carrying out surgery and autopsies or interpreting radiographs.
To the casual observer there are many obvious differences in size, ranging from the
hummingbird to the ostrich (Struthio camelus), in the varying forms of the bill and in the
colour and profusion of the plumage occurring in different species of birds. However
beneath this great variety of body form there is a greater degree of uniformity in the basic
anatomy and some aspects of the physiology of the class Aves than there is in many single
orders of other types of vertebrate. Even in the case of the large flightless birds, all present-day
living birds have originally evolved from a flying ancestor and the capacity to be able
to become airborne imp ... read full excerpt from Essentials of Avian Medicine and Surgery ebook
