Prolecanitida

Systematic Paleontology Class Cephalopoda Subclass Ammonoidea Order Prolecanitida

The Prolecanitida constitutes an order within the Ammonoidea with a range that extends from the Late Devonian to the Late Triassic, with the Sageceratidae included. Prolecanitid shells (conchs) vary from discoidal to thinly lenticular with goniatic to ceratitic sutures which characteristically form auxiliary lobes. Outer rims (venters) may be smoothly rounded, flat, or longitudianally grooved. Sharp (oxyconic) in the case of Prodomites if included.

Siphuncles, as with their nautiloid ancestors as well as with the Anarcestida and Clymeniida, are retrochoanitic in which septal necks point to the apex of the shell; unlike the Goniatida, Ceratitida, and Ammonitida which are prochoanitc, their septal necks at least in the outer whorls pointing toward the aperture.

Two superfamilies are included in the Prolecanitida, the Prolecanitaceae which has a range extending from the Late Devonian to the Middle Permian, and the Medlicottiaceae, its range extending from the Late Mississippian (Early Carboniferous) to the Late Triassic, if the Sageceratidae belongs.

References Treatise on Invertebrate Paleontology Part L, 1957; pp L69 --L74