The orthocerid Dawsonoceras? (Nautiloidea) from the Lipeón Formation (Silurian, Northwestern Argentina)

Abstract

Turic et al. (1982) erected the name "Rectogloma" zaplensis for a problematic fossil found at Las Capillas River, 20 km northeast of San Salvador de Jujuy city (figure 1). The fossil was collected from beds belonging to the Lipeón Formation (Turner,1960), on the western flank of the Zapla range (Subandean Ranges). Based on the work of Antelo (1978), the Lipeón Formation was assigned to the Llandovery-Wenlock interval. The fossil was assigned to the problematic genus Rectogloma, described by Tuyl and Berckhemer (1914) for R. problematica but based on a more complete ornamentation and the presence of sinuous striations, which denotes its better preservation state, they defined a new species: "Rectogloma" zaplensis (Turic et al., 1982). A restudy of the specimen indicates that the fossil is a nautiloid cephalopod that can be assigned with reservation to the genus Dawsonoceras Hyatt, 1884.