Corbinites (Subfamily Lithacoceratinae), a new genus for the giant western Canadian Late Kimmeridgian or Tithonian (Late Jurassic) ammonite Titanites occidentalis Frebold

The finding of two new specimens and a reappraisal of the single original specimen of the problematic giant Canadian Late Jurassic ammonite Titanites occidentalis Frebold results in the creation of Corbinites, n. gen. It is assigned to the ataxioceratid subfamily Lithacoceratinae largely because of the presence of variocostate and previously unrecognized ataxioceratoid ribbing in middle and late growth stages. With enigmatic ancestry and geographically removed other forms with similar characteristics, the species may have been endemic in the relatively isolated early Alberta foreland basin of western interior Canada.