Appendix. Colophon

The animal on the cover of Enterprise Rails is a sturgeon. Although sturgeon is the common name for more than 26 species of fish in the Acipenseridae family, it is often used to identify the two most common generas in the family: Acipenser and Huso.

Among the most ancient of the bony fish, sturgeon first appeared in the fossil record more than 200 million years ago. They are found from the subtropic waters of North America all the way to the subarctic waters of Eurasia; their high tolerance for a wide range of temperatures and salinity (the amount of salt in the water) partially explains why the species has undergone very little morphological change since its existence was first recorded. Other reasons they have achieved the informal status of “living fossil” probably include the lack of predators that hunt them because of their size; and, as bottom-dwellers feeding in the benthic zone (the ecological region at the lowest level of water, including the sediment surface and some subsurface layers), they always have access to a wealth of prey.