Review of the Early to Mid Ordovician orthoconic cephalopods from Iran

A revision of the Ordovician cephalopod Bactrites sandbergeri Barrande: Systematic position and palaeobiogeography of Bactroceras

“…Specimens belonging to Bactroceras were described from Morocco (Krö ger and Lefebvre, 2012) and Iran (Evans et al, 2013). These authors reported that the studied specimens show similarities with B. angustisiphonatum and B. avus, respectively, but because of the lack of diagnostic characters, no species-level determination was possible.…”

“…However, as neither the surficial ornamentation nor the expansion rate are known, exact determination at the species level remains impossible (Krö ger and Lefebvre, 2012). The Iranian specimen assigned to the genus Bactroceras by Evans et al (2013) is a small portion of a phragmocone, showing three phragmocone chambers and a marginal siphuncle. However, the phragmocone chambers are very short for Bactroceras; thus, the present author considers the generic assignment of this specimen to Bactroceras questionable.…”

“…This group includes pelagic cephalopods that, owing to their morphology, were able to expand from their original, demersal niches to pelagic and deep-water realms. Soon, orthocerids became highly diversified and geographically widespread (Frey, 1995;Krö ger and Mutvei, 2005; and Evans, 2011;Evans et al, 2013;Krö ger, 2013). Consequently, understanding the origin of Bactroceras, its evolution, and the divergence of allied lines are crucial for elucidating the still poorly-known early radiation of orthocerid cephalopods.…”

Review of the Ordovician stratigraphy and fauna of the Anarak Region in Central Iran

“…By mid Katian time they spread along the western margin of Gondwana and arrived at the 'overlap zone' (Bassett et al 1999) where Hindella originally evolved as a component of the cold-water brachiopod associations. (Evans et al 2013). It was also recognised that this fauna was likely to have affinities with those of northern Gondwana (e. g. Armorica and Perunica), once those faunas are better known.…”

“…Potentially, these specimens might represent the more adoral portions of specimens of Wennanoceras. Equally, they may represent the remains of members of the endocerid family, Cyrtendoceratidae, known to occur in the Darriwilian of the Shirgesht Formation of the Derenjal Mountains and the Lashkarak Formation of the eastern Alborz (Evans et al, 2013). Without additional material the nature of this material is unlikely to be satisfactorily resolved, and it is included here for the sake of completeness.…”