page_title: List of the Cenozoic life of Montana
section_title: I
hierarchical_section_title: List of the Cenozoic life of Montana / I
caption_attribution_description: Ischyromys oweni, Smithsonian National Museum of Natural History: Hall of Fossils.
context_page_description: This list of the Cenozoic life of Montana contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Montana and are between 66 million and 10,000 years of age.
context_section_description: †Ictidopappus
  †Ictidopappus mustelinus – type locality for species
  †Ignacius
  †Ignacius frugivorus
  †Ilex
  †Ilex acuminata – later renamed Ilex mormonica
  †Ilex mormonica – type locality for species. Formerly known as Ilex acuminata.
  †Intyrictis
  †Intyrictis vanvaleni
  †Ischyrhiza – or unidentified comparable form
  †Ischyrhiza avonicola
   †Ischyromys
  †Ischyromys douglassi – type locality for species
  †Ischyromys typus
  †Ischyromys veterior – type locality for species
  Isoetes
  †Isoetes trullata – type locality for species
  †Isoetites
  †Isoetites horridus
  Isonychia
  †Isonychia alderensis – type locality for species
caption: Mounted fossilized skeleton of the Eocene-Oligocene rodent Ischyromys
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