Lissoceras is an involute, smoothly or finely vetrolaterally ribbed ammonite with a blunt, un-keeled venter included in the Haploceratidaefamily that lived from the Lower Bajocian to Middle Oxfordian (Middle to Upper Jurassic) ages in what is now Europe, south Asia, and southern Alaska.
Lissoceratoides, once considered to be a subgenus of Lissoceras, is indistinguishable morphologically from it.
References Notes
Bibliography Arkell et al., 1957 Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Part L. Geol Society of America and Univ Kansas Press R.C Moore (ed) 1957 D.T Donavan, J.H. Callomon, and M.K Howarth. 1981. Classification of the Jurassic Ammonitina. In The Ammonoidea. M.R. House and J.R. Senior, eds. Systematics Assoc. Pub Academic Press.