Dakotas continue to yield paleontological treasures

Two hundred years ago Lewis and Clark's Corps of Discovery laid the groundwork for a good deal of scientific research with its descriptions of territory acquired through the Louisiana Purchase. While Thomas Jefferson was said to be disappointed by the absence of living megafauna, the area ultimately yielded a wealth of Late Cretaceous fossils. A new volume published by the Geological Society of America makes clear that the process of discovery continues.

The Geology and Paleontology of the Late Cretaceous Marine Deposits of the Dakotas, GSA Special Paper 427, offers a new state-of-the-science overview of a stretch of land along the Missouri River. Included are the Greenhorn, Pierre, and Fox Hills Formations.

"Intense study of this area over the past twenty years led to assembly of this volume," said lead editor James Martin of the Museum of Geology and Department of Geology and Geological Engineering, South Dakota School of Mines and Technology. "The time was right to consolidate some significant breakthroughs and make them readily accessible."

Breakthroughs documented in the volume include:

• Elevation of the Pierre Shale to group status
• Naming of new Pierre Shale members
• Correlations based on geochemistry of bentonites and rare earth elements
• Identification of the stratigraphic source of the first reptile collected from the American West based on rare earth element analysis

Also examined are invertebrate fossils including some associated with a shell-crushing marine reptile, the first clear recognition of a North American mosasaur (Hainosaurus), a new species of short-necked plesiosaur, and a new species of diving bird.

Source : Geological Society of America