Proper noun
Kasimovian
(geology, paleontology) A subdivision of the Carboniferous period.
The collapse of the rainforest ecology in the mid Pennsylvanian (between the Moscovian and the Kasimovian) removed many amphibian species that did not survive as well in the cooler, drier conditions. Source: Internet
The Missourian or Monongahela corresponds to the rest of the Kasimovian. Source: Internet