The nautiloid Family Eothinoceratidae from the Floian of the Central Andean Basin (NW Argentina and South Bolivia)

Abstract

A single confidently dated species of cephalopod is so far known in the Tremadocian of the southern Central Andean Basin (NW Argentina and southern Bolivia). This species belongs to the Eothinoceratidae and has a strong affinity mainly with Avalonia. During the Floian, a notable increase in diversity took place, with the appearance of a variety of families represented by several genera, in particular, within the Family Eothinoceratidae. In addition to the previously described species from southern Bolivia, we evaluate the other records of that family from the Central Andean Basin, and propose the following new taxa: Saloceras sikus sp. nov., Saloceras quena sp. nov., Mutveiceras gen. nov., and Mutveiceras cienagaensis sp. nov. We also describe Margaritoceras diploide, Margaritoceras sp., and Mutveiceras sp. From a palaeogeographic perspective, the cephalopod fauna shows affinities mainly with those of England, Wales, and the Montagne Noire (cold water Gondwana and periGondwana). As with other cephalopod faunas of mid to high palaeolatitudes, eothinoceratids occur along with other cephalopods forming assemblages of low morphological diversity. We interpret the forms described here as demersal with a subvertical poise, but capable of making rapid buoyancy changes, living in a wide spectrum of shallow offshore to shoreface settings.

Characterization of two new superorders Nautilosiphonata and Calciosiphonata and a new order Cyrtocerinida of the subclass Nautiloidea; siphuncular structure in the Ordovician nautiloidBathmoceras(Cephalopoda)

“…Flower (1964) assigned this family to the suborder Cyrtocerinina that was said to include two additional families: Cyrtocerinidae Flower 1946 and Eothinoceratidae Ulrich et al (1944). This suborder was said to be characterized by thick connecting rings that have concave outer surfaces (concavosiphonate), and "collars or lobes of various shapes" that extend from the connecting rings into the siphuncular cavity (Chen & Teichert 1987, p. 157;Cichowolski et al 2014). The Cyrtocerinina was placed in the order Ellesmeroceratida.…”

First record of a nonpaleotropical intejocerid cephalopod from Darriwilian (Middle Ordovician) strata of central Spain

“…The absence of critical internal structures in many of these specimens does not allow for a taxonomic identification at genus or species level and many taxa are in need of a revision. Hopefully, the recent reappraisal of early Paleozoic peri-Gondwanan cephalopod faunas from elsewhere (e. g. Kröger et al, 2012;Evans et al, 2013Evans et al, , 2015Bogolepova et al, 2014;Sone, 2014, 2015;Aubrechtová, 2015;Cichowolski et al, 2015Cichowolski et al, , 2018Ghavidel-Syooki et al, 2015;Rolet and Plusquellec, 2016;Aubrechtová and Turek, 2018;Manda and Turek, 2018;Ebbestad et al, 2019;Fang et al, 2019) will stimulate future research on the Iberian cephalopods. specimen MGM-8187O, lateral view.…”

Radiation, diversity and environmental expansion of Early Ordovician ostracods: a view from the Southern Hemisphere

“…, ; Salas ; Balseiro & Waisfeld ; Cichowolski et al . ; Benedetto & Muñoz , ; Toro et al . ; Waisfeld & Balseiro ; Albanesi & Ortega ; Muñoz & Benedetto ; Meroi Arcerito et al .…”

“…A wealth of palaeontological information, including the biostratigraphical context, systematics of different invertebrate groups, and palaeobiogeographical and palaeoecological analyses, is available from ostracod-bearing units (e.g. Benedetto 2003;Benedetto et al 2009Salas 2011;Balseiro & Waisfeld 2014;Cichowolski et al 2014;Benedetto & Muñoz 2015Toro et al 2015;Waisfeld & Balseiro 2016;Albanesi & Ortega 2016;Muñoz & Benedetto 2016;Meroi Arcerito et al 2017;Tortello et al 2016, among others).…”