GEOLOGY AND PALEONTOLOGY RECORDED BY THE CORPS OF DISCOVERY, INCLUDING THE FIRST FOSSIL REPTILE FROM THE AMERICAN WEST

Geological observations of the Corps of Discovery have received less subsequent attention than other aspects of natural history. While this may seem surprising in view of President Jefferson’s interest in agriculture and mineral resources, conventional interpretation has generally held that the expedition was so overwhelmed by the new discoveries and observations of plants and animals that geologic information was given less attention. Perhaps a more accurate view is that geologic observations are more subtle within the accounts. While subsequent analyses have been more focused on botany and zoology, it is also true that geological observations of great interest were recorded early in the expedition. Fortuitously, the geology of the route along the Missouri River afforded an astonishingly good introduction to a general section of Upper Cretaceous and Early Tertiary strata in sequence lower to upper, a fact now recognized, but obscured from the expedition itself. Fossil discoveries are so common there now, that it is difficult to understand why the expedition did not record more of them.

The Soldier River discovery of a fish fossil, Saurocephalus lanciformis, presumably moved from original context, has long defied complete interpretation, but the specimen still exists and is subject to further analysis. The more perplexing journal entries regarding a so-called petrified fish (September 10, 1804) almost certainly refer to a Cretaceous reptile, likely Tylosaurus sp., noting recent discoveries in the area. Unfortunately, no specimen has been found that would document the discovery.

As a footnote to history, the expedition’s naming of Corvus Creek, based on the observation of magpies there, ultimately bestowed the name Crow Creek on the Siouxan peoples whose reservation is one of the most scientifically productive two hundred years later.