Cranial photographs of mammals on the web: the Mammalian Crania Photographic Archive (MCPA2) and a comparison of bone image databases

Abstract

The Mammalian Crania Photographic Archive (MCPA2) is a website (http://1kai.dokkyomed.ac.jp/mammal/en/mammal.html) that includes a collection of 10,950 photographs of mammalian crania, which have been taken with a high-resolution digital camera. In the present report, we outline the characteristics of MCPA2 and how it was created, and make brief comparisons with several similar websites currently accessible via the internet. The archived MCPA2 materials include 1825 cranial specimens, ranging from insectivores to elephants, which have been macerated in Japan during the past 35 years and prepared for osteological study. Of the 16 orders represented in the database, primates comprise the major group with 704 specimens. Each cranium was placed with the orbitomeatal (Frankfort) or palatine plane horizontal, and was photographed in six perpendicular views from a long distance using a telephoto or telemacro lens. These long-distance shots decrease perspective distortion that lead to measurement errors when studying cranial profiles and landmark positions, and enable detailed observation and measurement of specific bony characteristics on a computer screen. From our website, images can be searched using (1) the taxonomic table, (2) Japanese name, (3) English name, and (4) scientific name. In the page of search results, in addition to the images, four caliper measurements and additional text (taxonomy, sex, and age) are available for every specimen.