Pterospathodus, Walliser, 1964

Waid, Christopher B. T. & Cramer, Bradley D., 2017, Telychian (Llandovery, Silurian) conodonts from the LaPorte City Formation of eastern Iowa, USA (East-Central Iowa Basin) and their implications for global Telychian conodont biostratigraphic correlation, Palaeontologia Electronica 42 (6), pp. 1-37 : 19

Genus PTEROSPATHODUS Walliser, 1964

Type species. Pterospathodus amorphognathoides Walliser, 1964 .

Diagnosis. The apparatus of Pterospathodus as reconstructed by Männik (1998) is composed of 13 paired elements and one un-paired element. Most element morphologies are consistent with Sa, Sb 1, Sb 2, Sc 1, Sc 2, Sc 3, M 1, M 2, Pa, Pb 1, Pb 2, and Pc designations. Other elements described as carnuliform, carniciform, and “curved element” do not conform to the locational analogies of Sweet and Schönlaub (1975) when included in the apparatus. Pa and Pb elements are primarily used for differentiation of species and subspecies. Pa elements have a straight to slightly-curved blade, and most species have an inner, anteriorly oriented process, which may bifurcate. Some older species in the genus also have an outer process (e.g., Pt. eopennatus ssp. n. 1 sensu Männik, 1998, morph 5). Younger species have a platform developed under the blade and lateral processes. Pb 1 elements are angulate, may be slightly bowed, have a prominent central cusp, and a flared basal cavity. Pb 2 elements are angulate or dolabrate, and may have a slightly prominent to minor cusp. Their basal cavities are not as expanded as those in Pb 1 elements, but extend along the entire length of the element.

Remarks. If the apparatus reconstruction of Männik (1998) is correct, then the Pterospathodus apparatus contains more than twice as many elements as any conodont apparatus that has been reconstructed based on bedding plane assemblages or fused clusters (e.g., Phragmodus ). Elements formerly classified as Carniodus were included in the Pterospathodus apparatus by Männik because each taxa has the same stratigraphic range, and each displays parallel evolutionary patterns (each species of Pterospathodus occurs with a distinct set of Carniodus elements). No elements similar to the carnuliform, carniciform, or curved elements were found in this study, which may be due to the recovery of relatively few Pterospathodus specimens.