Two Coleoid Jaws From the Upper Cretaceous of Hokkaido, Japan

Diversity, morphology, and phylogeny of coleoid cephalopods from the Upper Cretaceous Plattenkalks of Lebanon-Part I: Prototeuthidina

“…Fossil records of Cretaceous decabrachian and octobrachian coleoids from the North Pacific region are given in black circles. 1, Haboroteuthis (this study); 2, Yezoteuthis (Tanabe et al 2006); 3, Paleocirroteuthis ; 4, Nanaimoteuthis Tanabe and Hikida 2010; this study). Age after Cohen et al (2012).…”

“…Concerning the origin of Decabrachia, Fuchs et al (2013a) suggested that the Cretaceous belemnoid-like phragmocone-bearing coleoid Longibelus, which has a marginal siphuncle, stripelike dorsal attachment scars, and a poorly developed layer of tabular nacre, represents a sister taxon of the decabrachian clade comprising modern Spirulida, Sepiida, and Teuthida. Meanwhile, Tanabe et al (2006) described an extremely large coleoid upper jaw from the Campanian (Upper Cretaceous) of Hokkaido as a new genus and species (Yezoteuthis giganteus) and assigned its higher taxonomic position as Teuthida based on cladistic analysis of several characters with modern cephalopods. This study and others (Tanabe et al 2006Tanabe and Hikida 2010;Tanabe 2012) on the jaws from the Upper Cretaceous of Hokkaido and Vancouver Island (Canada) fill the gap in the relatively poor fossil record of the mainly soft-bodied coleoids (Fig.…”

“…Meanwhile, Tanabe et al (2006) described an extremely large coleoid upper jaw from the Campanian (Upper Cretaceous) of Hokkaido as a new genus and species (Yezoteuthis giganteus) and assigned its higher taxonomic position as Teuthida based on cladistic analysis of several characters with modern cephalopods. This study and others (Tanabe et al 2006Tanabe and Hikida 2010;Tanabe 2012) on the jaws from the Upper Cretaceous of Hokkaido and Vancouver Island (Canada) fill the gap in the relatively poor fossil record of the mainly soft-bodied coleoids (Fig. 8).…”

“…tential as a fossil even in taxa without a calcified chambered shell (Harzhauser 1999;Tanabe et al 2006Tanabe et al , 2008Tanabe and Hikida 2010) and has been extensively used in taxonomical studies of modern fauna (Naef 1923;Clarke 1962Clarke , 1986Clarke and Maddock 1988;Kubodera 2005). In modern cephalopods, the jaw apparatus consists of upper and lower elements (synonymous with beaks and mandibles) that are connected to each other by surrounding jaw muscles and housed within a globular-shaped muscular organ called the buccal mass in the proximal portion of the digestive tract (Nixon 1988;Tanabe and Fukuda 1999).…”

“…In addition to these flattened in situ jaws, unflattened isolated jaws referable to Coleoidea have recently been found from the Upper Cretaceous forearc basin deposits of Hokkaido, Japan (Yezo Group), and Vancouver Island, Canada (Nanaimo Group). Their comparative morphological examination with the jaws of modern coleoids allowed us to distinguish the following new genera and species (Tanabe et al 2006Tanabe and Hikida 2010;Tanabe 2012): Yezoteuthis giganteus of the order Teuthida, Nanaimoteuthis jeletzkyi and N. yokotai of the order Vampyromorpha, and Paleocirroteuthis haggarti and P. pacifica of the order Cirroctopoda.…”