Fossil Geese of the McKittrick Asphalt Deposits

• Main Author: Ross, Roland Case
• Format: Others
• Published: 1932
• Online Access: https://thesis.library.caltech.edu/5505/1/Ross_rc_1932.pdf; Ross, Roland Case (1932) Fossil Geese of the McKittrick Asphalt Deposits. Master's thesis, California Institute of Technology. doi:10.7907/2YAN-DQ47. https://resolver.caltech.edu/CaltechTHESIS:01082010-091209877 <https://resolver.caltech.edu/CaltechTHESIS:01082010-091209877>

<p>The geese although widespread in Recent times and well known have always been difficult of classification. Richard Lydekker (1910) says: "Although it has been attempted to divide the members of the order (Anseres) into several distinct families, the whole of them are so nearly allied that it seems impossible to do more than group the genera of the one family Anatidae under several subfamilies, and even some of these are very difficult of definition." The Anserinae or geese are one of these intergrading subfamilies.</p> <p>The difficulties encountered in the determination and classification of modern geese from osteological criteria alone have severely handicapped the recognition of fossil members of the Anserinae. The present problem involved (1) an attempt to obtain a series of structural characters in the major skeletal elements by which specific types or geese can be distinguished, and -- (2) an application or these distinguishing characteristics in the study of the fossil goose material from the McKittrick Pleistocene with a view to determining the types of geese present in the fauna from these asphalt deposits.</p> <p>As a result of the critical examination of modern types, sufficient data are assembled to show the intergradation of twelve native races. The same studies are being applied to foreign geese, bringing the races under observation to a total of twenty-four, which is 72% of the known Anserine species. The interspecific gradation is found to arise in a remarkable range of individual variation, coupled with sex, age and possibly health variations. Because of this variability within a species the criteria of current usage, length and stoutness, are seen to be mostly incorrect, and seldom usable. However, these data are quite useful in showing the extent of variation within particular species of geese, as follows.</p>