D Taxonomy is the classification of differing organisms into groups based on a set of defined characteristics that is common to all members of the group. Until recently, this study involved careful measurement of physical characteristics of an animal - for example, the size of various body parts or the organization and interaction of bones. The advent of molecular biology has added new characteristics for the taxonomist to consider. Unfortunately, taxonomists do not always agree as to the proper distribution of groups of animals.
Disagreements can arise because of a number of factors.
These include a changing evaluation of the relationships between groups, improvement in the techniques or measurements that are being used, a reassessment of the value of various characteristics, and additional data that reduces the significance of previous studies. As differences are brought up, discussed, argued and perhaps resolved, the nomenclature can change, although the organism in question remains the same. This evolution in names means that one species may have been placed into a number of groups and called different names over time. This variation can make it difficult to find information about a specific animal, as it may have been referred to by a number of names since it was initially described. Being able to place animals in groups allows scientists to apply information that they discover about one animal to other, related animals and allows different scientists, perhaps thousands of miles or decades apart, to compare information without fear of inadvertently being led astray.