1938  Prohyattoceras Oyens: 1123 [nom.nud.].
pars1955  Demarezites Ruzhentsev: 703.
     1975  Hyattoceratinae n.gen., n.sp.  Lee: 182.
     1987  Eohyattoceras Glenister & Furnish: 988.
     1990  Leeites Bogoslovskaia: 72.

Type species: Eohyattoceras gerthi Glenister & Furnish, 1987, p.988; OD.

[Glenister & Furnish, 1987:] Ancestral hyattoceratids in which the fourth external lateral lobe (L2.2) is incompletely isolated,
and denticulation is confined to the bottom one-half of the lobes. Sutural formula for the type species is(Figure 2.3):
(V1 V1)L2 L1 (L2.1 L2.2) U2 U1.1:U1.2 U2 I2 I1 I2 DThe denticle that occurs at mid-height on the ventral flank of
the first internal lateral saddle of at least some advanced hyattoceratids (Figure 2.4) is unknown in Eohyattoceras.