Article: The Jurassic ammonite image database 'Ammon'

'Ammon' is an interactive database that incorporates taxonomic, morphological, stratigraphical and locality information as well as digitized images. When necessary, a user can measure morphological features directly from an image using the mouse to mark points on which are based the measurement of distances, the calculation of ratios and derivation of logarithmic spiral parameters. Features such as ribs can be counted using the mouse, and counts extrapolated automatically to a standardized unit of measurement such as a half whorl. 'Ammon' is also provided with a module that can measure features automatically once the image has been processed using edge detection, line thinning and tracing algorithms. The characterization of whorl shapes is a difficult problem best addressed by the use of elliptic Fourier analysis which not only faithfully mimics whorl cross sections but can also be animated to show, for example, the transition from one shape to another during ontogenetic development. 'Ammon' is a useful aid in fossil identification both as a retriever of species based on specified morphological, stratigraphical, and/or geographical information and as a way of assembling image collages of specified families, genera or species.Several general issues are raised by advances in computer technology and the growth in use of 'Ammon' and its kind. Paramount are: the universality of database design; completeness of taxonomic, stratigraphical and geographical coverage; efficiency of data entry; and the question of accessibility.