It is the most diverse and long-lived chimaera genus, with over 39 species found worldwide spanning over 140 million years from the Middle Jurassic to the Miocene.

[2] Complete specimens of I. quenstedti from the Late Jurassic of Germany most closely resemble the genus Callorhinchus amongst living chimaera genera.

[3] It is sometimes placed in the "Edaphodontidae", a unclearly defined group of chimaera with an uncertain position within the clade,[1] while other authors place it into Callorhinchidae along with Callorhinchus,[4] a position that has been supported by at least some phylogenetic analyses.

For example, I. bifurcatus with mandibular plate length of 3.2 in (8.2 cm) possibly belongs 5 ft 8 in (1.72 m) long specimen.

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