caa a22 4500 388017481 CHVBK 20180307124915.0 cr unu---uuuuu 161130e199801 xx s 000 0 eng 10.1017/S002233600002401X doi S002233600002401X pii (NATIONALLICENCE)cambridge-10.1017/S002233600002401X Aguirre-Urreta María B. Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina (aguirre@tango.gl.fcen.uba.ar) The ammonites Karakaschiceras and Neohoploceras (Valanginian Neocomitidae) from the Neuquen Basin, West-Central Argentina [Elektronische Daten] [María B. Aguirre-Urreta] Three species of Karakaschiceras, K. attenuatus (Behrendsen, 1892), K. neumayri (Behrendsen, 1892), and K. lycoris (Leanza and Giovine, 1949), and one species of Neohoploceras, N. arnoldi (Pictet and Campiche, 1860), are described and figured from the Valanginian strata of the Neuquén basin in west-central Argentina. The large collection of fossils available for study shows wide intraspecific variation regarding ornament and whorl section in Karakaschiceras neumayri and Neohoploceras arnoldi, casting some doubts on the current systematics applied to species of these genera. The biostratigraphic position of the four species in the Neuquén basin corresponds to the Karakaschiceras attenuatus Subzone of the Olcostephanus atherstoni Zone. This subzone is correlated with the Mediterranean Karakaschiceras inostranzewi and Saynoceras verrucosum zones of Europe at the base of upper Valanginian sections. Copyright © The Paleontological Society Journal of Paleontology Cambridge University Press 72/1(1998-01), 39-59 0022-3360 72:1<39 1998 72 JPA https://doi.org/10.1017/S002233600002401X text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S002233600002401X text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Aguirre-Urreta María B. Departamento de Ciencias Geológicas, Universidad de Buenos Aires, Ciudad Universitaria, 1428 Buenos Aires, Argentina (aguirre@tango.gl.fcen.uba.ar) NATIONALLICENCE 773 0- Journal of Paleontology Cambridge University Press 72/1(1998-01), 39-59 0022-3360 72:1<39 1998 72 JPA CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge