Longibelus Gen. Nov., a New Cretaceous Coleoid Genus Linking Belemnoidea and Early Decabrachia

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Longibelus Gen. Nov., A new Cretaceous coleoid genus linking Belemnoidea and early Decabrachia

ARTICLE in PALAEONTOLOGY · SEPTEMBER 2013 Impact Factor: 2.24 · DOI: 10.1111/pala.12036

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Dirk Fuchs Christina Ifrim Hokkaido University Universität Heidelberg

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Tomohiro Nishimura Helmut Keupp Hobetsu Museum, Hokkaido, Japan Freie Universität Berlin

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Available from: Christina Ifrim Retrieved on: 18 October 2015 [Palaeontology, 2013, pp. 1–26]

LONGIBELUS GEN. NOV., A NEW CRETACEOUS COLEOID GENUS LINKING BELEMNOIDEA AND EARLY DECABRACHIA by DIRK FUCHS1*, YASUHIRO IBA2, CHRISTINA IFRIM3, TOMOHIRO NISHIMURA4, WILLIAM J. KENNEDY5, HELMUT KEUPP1, WOLGANG STINNESBECK3 and KAZUSHIGE TANABE6 1Freie Universit€at Berlin, Institute of Geological Sciences, Branch Palaeontology, Malteserstr. 74-100, Berlin, D-12249, Germany; e-mail: [email protected], [email protected] 2Departement of Natural History Sciences, Hokkaido University, Saporro, 060-0810, Japan; e-mail: [email protected] 3Institut fur€ Geowissenschaften, Universit€at Heidelberg, Im Neuenheimer Feld 234, Heidelberg, D-69120, Germany; e-mail: [email protected] 4Hobetsu Museum, 80-6, Hobetsu, Mukawa, Hokkaido, 054-0211, Japan; e-mail: [email protected] 5 Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK; e-mail: [email protected] 6 Department of Historical Geology and Palaeontology, The University Museum, The University of Tokyo, Hongo 7-3-1, Tokyo 113-0033, Japan; e-mail: [email protected] *Corresponding author.

Typescript received 25 January 2012; accepted in revised form 7 February 2013

Abstract: The phylogenetic origin and the timing of orig- species of Naefia, and ‘N.’ matsumotoi, the new genus ination of the Decabrachia are controversial. This is due to Longibelus has been erected. Besides a redescription of a poor understanding of character complexes relating to Longibelus (‘Naefia’) matsumotoi, we describe the first Ma- the shell, which causes difficulties in establishing homolo- astrichtian occurrences of this species from Hokkaido gies among different taxa. One central problem concerns a (northern Japan) and Alaska. Among the type material of clear differentiation between belemnoids and early spirulids. N. neogaiea from the Maastrichtian of Chile, we found one A comparative analysis of shell structures of well-preserved specimen that unambiguously belongs to Longibelus gen. specimens including types and new material of Cretaceous nov. Similarly, two specimens from the Maastrichtian of spirulids Groenlandibelus, Naefia and Cyrtobelus, as well as Mexico previously determined as N. neogaiea also belong to selected taxa of aulacocerid, belemnitid and diplobelid be- the new genus. Also, we can reinterpret material from the lemnoids, revealed a set of 14 characters. Seven characters Cenomanian of India as Longibelus gen. nov. New material (apical angle, chamber length, dorsal and ventral sutures, from the Albian of India likewise assignable to Longibelus is orientation of septa, direction of the dorsal part of the sep- described for the first time. Finally, we introduce the first tal neck, primordial rostrum) are not or less diagnostic, records of coleoids from Zululand (South Africa). These whereas the seven remaining characters can be reliably used specimens belong to Longibelus as do specimens from the to distinguish between the Decabrachia on the one hand Aptian of Caucasus (previously described as ‘Naefia’ kaba- and Belemnitida and Aulacocerida on the other hand. novi). A phylogenetic approach suggests that Longibelus gen. These diagnostic characters are as follows: (1) presence/ nov. is derived from diplobelid-like belemnoids and gave absence of a mural flap; (2) position of the siphuncle; (3) rise for the Decabrachia or at least groenlandibelid spiru- shape of the dorsal soft tissue attachment scar; (4) pres- lids. This strongly supports earlier ideas on a close relation- ence/absence of tabular nacre in the conotheca; (5) pres- ship between Cretaceous Decabrachia and belemnites and ence/absence of a rostrum proper; (6) presence/absence of a simultaneously challenges opinions that Decabrachia origi- narrow rod-like proostracum; and (7) presence/absence of a nated in the Carboniferous. caecum. Diplobelida and ‘Naefia’ matsumotoi, however, exhibit a mosaic of decabrachian and belemnoid characters. Key words: Cretaceous, Coleoidea, Spirulida, Naefia, Long- Owing to striking differences between N. neogaiea, the type ibelus gen. non., shell morphology.

SINCE Jeletzky (1966), reviews on the origin and evolution an orthoconic low-angled phragmocone with conspicu- of the Decabrachia have constantly referred to the Creta- ously long chambers. Owing to the absence of a solid ros- ceous genera Naeﬁa and Groenlandibelus. Both taxa exhibit trum, which is diagnostic for aulacocerid and belemnitid

© The Palaeontological Association doi: 10.1111/pala.12036 1 2 PALAEONTOLOGY belemnoids, these taxa obviously play a key role in discus- that provide a clear discrimination between belemnoids sions on the phylogeny of the Coleoidea (Jeletzky 1966; and spirulids. It is therefore the objective of the present Donovan 1977; Reitner and Engeser 1982; Doyle et al. analysis to compare the type material of Groenlandibelus 1994; Haas 1997, 2003; Fuchs et al. 2012b). Surprisingly, and Naefia with unambiguous spirulids and belemnoids, their systematic position is nevertheless unclear. to determine diagnostic characters that clearly delimit Wetzel (1930) described the first phragmocones of spirulids and belemnoids. Finally, we discuss the phylo- Naefia neogaiea from the Maastrichtian of Chile. He rec- genetic, stratigraphic and biogeographical impact of our ognized their peculiarity and therefore considered Naefia observations. as a belemnite without a rostrum. Birkelund (1956) indicated similarities between Naefia neogaiea and Groenland- ibelus (‘Belemnoteuthis’) rosenkrantzi (Birkelund, 1956) MATERIAL AND METHODS from the Maastrichtian of Greenland. Hence, she accepted belemnoid affinities. Jeletzky (1966, p. 104) was the first Material to classify both N. neogaiea and G. rosenkrantzi as early spirulids owing to the presence of a Spirula-like caecum The main source of this comparative analysis represents in one specimen, which he believed is identical to G. ro- the type material of Naefia neogaiea from the Maastrich- senkrantzi (see below and Fuchs et al. 2012b). Biro- tian of Chile, Naefia matsumotoi from the Cenomanian– Bagoczky (1982) and Stinnesbeck (1986) presented new, Campanian of Hokkaido (northern Japan) and Groenland- better-preserved material of N. neogaiea from Chile. Both ibelus rosenkrantzi from the Maastrichtian of Greenland. followed Jeletzky (1966) and accepted spirulid affinities. Additionally, we included in this study Naefia kabanovi Over the following years, our morphologic, stratigraphic from the Aptian of the Russian Caucasus (original mate- and biogeographical knowledge on Naefia-like specimens rial of Doguzhaeva 1996), Naefia-like phragmocones from has continuously increased, but without a significant pro- the Albian of Zululand (South Africa) and Tamil Nandu gress in understanding their systematic and phylogenetic (southern India) and from the Maastrichtian of Chile, affinities (Doyle 1986; Stilwell and Zinsmeister 1987; Mexico (original material of Ifrim et al. 2004), Alaska and Hewitt et al. 1991; Hirano et al. 1991; Hayakawa and Japan. The phragmocones of these taxa have been com- Takahashi 1993; Doguzhaeva 1996; Hewitt and Jagt 1999; pared with unambiguous representatives of the Spirulida Haas 2003; Ifrim et al. 2004; Vartak et al. 2010). Bandel (Recent Spirula, Spirulirostra from the Eocene of northern and Stinnesbeck (2006) reconsidered the phragmocone Germany, Cyrtobelus from the Campanian–Maastrichtian morphology of Naefia and concluded that both Naefia of Canada and Greenland), the Diplobelida (types of and Groenlandibelus would represent a morphologically Conoteuthis hayakawai from the Turonian of Japan and isolated group not nested within any other coleoid group. Diplobelus belemnitoides from the Tithonian of the Czech Fuchs and Tanabe (2010) found remains of tabular nacre Republic), Belemnitida (Belemnitella bulbosa from the Ma- (which is generally considered to be diagnostic for belem- astrichtian of North America, Pachyteuthis sp. from the noids) in the conotheca of Naefia matsumotoi from Japan Bathonian of Central Russia) and Aulacocerida (Aulacoc- and therefore confirmed the observations made by Hewitt eras timorense from the Carnian–Norian of Timor, Chiti- et al. (1991). Although Fuchs and Tanabe (2010) retained noteuthis sp. from the Ladinian of Greece). We also Naefia within the Spirulida, they indicated – similar to examined sepiids (Palaeocene Ceratisepia, Eocene Belose- Bandel and Stinnesbeck (2006) – that a mosaic of belem- pia, Recent Sepia), but excluded them from the analysis noid and spirulid characters prevents an unambiguous owing to their strongly modified phragmocones. classification. Recently, Fuchs et al. (2012b) introduced Cyrtobelus hornbyense and Cyrtobelus birkelundae from the Campanian–Maastrichtian of Canada and Greenland and Methods placed them within the Spirulida. From the latter study, it became clear that the systematic status of Groenlandibe- The phragmocones have been examined, measured and lus and Naefia needed to be re-evaluated. photographed with a digital Microcam. Shell ultra- These systematic and phylogenetic inconsistencies com- structures have been investigated with SEM in Spirula, bined with the new morphologic insights obtained from Spirulirostra, Naefia matsumotoi, Cyrtobelus hornbyense, the genus Cyrtobelus led us to reinvestigate the type mate- Belemnitella bulbosa and Pachyteuthis sp. Selected speci- rial of Groenlandibelus rosenkrantzi, Naefia neogaiea and mens have been whitened with magnesium oxide (MgO) Naefia matsumotoi. New undescribed material from India, to enhance the visibility of characters. South Africa, Alaska, Mexico and Japan helped us to bet- Our results are largely based on our own observations, ter understand their shell morphologies and particularly except for the ultrastructures of aulacocerids, where we to recognize phylogenetically relevant character complexes added data from the literature. FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 3

Annotations concerning the determination of some course of the suture lines. Ventrally, boundaries between characters two chambers often exhibit lobe-like notches on the steinkerns (Fig. 1B) suggesting a deep ventral lobe, but Chamber distance (= ratio chamber length:diameter). White these structures have been caused by the septal necks, bands on the inner conotheca surfaces mark the attach- which were situated close to the conotheca; not by the ment sites of the septa, the mural parts. The adapical part suture line itself. Hence, only the adoral margins of the of each mural part is ridge-like (=mural ridge, mural ring mural parts (= septal line in other terminologies) unam- or septal ring in other terminologies). On the steinkerns biguously reflect the existence of lobes or saddles. (internal moulds), each ridge caused a sharp boundary between two chambers, that is, the distance between two Position of the siphuncle. Septal necks, which are almost ridges clearly reflects the chamber length (see Fig. 1B, G). in contact with the shell wall, generally created deep Accordingly, in specimens with semi-transparent shell notches on the ventral steinkerns (Fig. 1B). We therefore material preserved, the chamber length can be measured considered the presence of a deep ventral notch as equiv- between the adapical margins of the mural parts (Fig. 1C, alent of a marginal siphuncle. Phragmocones without or H). For phragmocones that are still invested by the usually with just a weak notch on the ventral steinkerns are nontransparent sheath, the chamber length is not deter- therefore considered to have a submarginal siphuncle minable. Also, the chamber diameter is not measurable in (Fig. 1G). fractured chambers or in partly embedded phragmocones. Mediodorsal attachment scars (Fig. 1C, H). Attachments Suture lines. The existence of lobes and saddles is visible scars are observable either as imprints on steinkerns or (if only by the help of well-preserved mural parts. Steinkerns preserved) on the inner surface of the conotheca. The without preserved mural parts do not reflect the exact shape of the scars is usually easily determinable (even in

B CDE A

G H IJ F FIG. 1. Schematic comparison and explanation of characters allowing to distinguish between Belemnitida (A–E) and Late Cretaceous Spirulida(F–J). A, absence vs F, presence of a mural flap. B, marginal vs G, submarginal siphuncle. C, stripe-like vs H, rectangular attachment scars. D, presence vs I, absence of a rostrum proper. E, spatulate-like proostracum (1/4) vs J, rod-like proostracum (1/16). Abbreviations: b, boundary; bk, bipartite keel; br, bipartite ridge; chl, chamber length; co, conotheca; df, dorsal furrows; mdf, mediodorsal furrows; mds, mediodorsal scar; mf, mural flap; mp, mural part; n, notch; rp, rostrum proper; sh sheath; sk, steinkern; sn, septal neck; vl, ventral lobe. 4 PALAEONTOLOGY poorly preserved specimens) by whitening with MgO or zontal septa on the other hand occur in most belemnoids analysis under oblique light. and in many spirulids. Diagnostic characters unambiguously delimiting Late Institutional abbreviations. AMNH, American Museum of Natu- Cretaceous Spirulida (Groenlandibelus, Naefia, and Cyrt- ral History; CPC, Coleccion Paleontologica de Coahuila, housed obelus) from Aulacocerida and Belemnitida are as follows: in the Museo del Desierto, Saltillo, Mexico; GPIK, Geologisches (1) presence of a mural flap (Fig. 1A, F); (2) submarginal € und Palaontologisches Institut of the University of Kiel, Ger- position of the siphuncle (Fig. 1B, G); (3) rectangular many; HMG, geological collections of the Hobetsu Museum, shape of the mediodorsal soft tissue attachment scar Hokkaido, Japan; KY and KX, geological collections of the Uni- (Fig. 1C, H); (4) absence of tabular nacre in the conot- versity of Oxford, UK; MB, palaeontological collections of the heca; (5) absence of a rostrum proper (Fig. 1D, I); (6) Institute of Geological Sciences, Freie Universit€at Berlin, Ger- many; MMK, collections of the Geological Museum Copenhagen presence of a narrow rod-like proostracum (Fig. 1E, J); (now Statens Naturhistoriske Museum), Denmark; MU, Ehmine and (7) presence of a caecum. It is worth noting that the University, Masuyama, Japan; NSM, National Museum of Nat- position of the siphuncle and the shape of the dorsal ure and Science, Tokyo, Japan; PIN, Palaeontological Institute of attachment scar are regularly preserved even on poorly the Russian Academy of Sciences; Q, geological department of preserved steinkerns. the University of Conception, Chile; UANL-FCT_MAA, Facultad Identification of a rostrum proper is well accessible as de las Ciencias de la Tierra of the Universidad Autonoma de long as the phragmocones are preserved in association Nuevo Leon, Mexico, Maastrichtian collection; UMUT, the Uni- with a solid rostrum (e.g. as in most Belemnitida s.s.). versity Museum, the University of Tokyo, Japan. However, identification of phragmocones with thin and short rostra is problematic, as one must clearly distinguish between the presence of only one or two shell layers RESULTS that cover the primary shell wall (conotheca) from out- side: the primordial rostrum and the rostrum proper (see We found 14 characters that could be observed in Fuchs 2012). The presence of two external shell layers (almost) all studied taxa. Question marks especially still indicates the presence of a rostrum proper irrespective of exist in rare diblobelids, Naefia neogaiea and Groenland- the morphology of the latter. According to Fuchs (2012), ibelus rosenkrantzi. A list of these characters and their the presence of only one external shell layer defines the character states are given in Table 1. presence of a sheath and consequently the absence of a Seven features yielded no (primordial rostrum/sheath), rostrum proper. overlapping (apical angle, ratio chamber length:diameter) The width of the proostracum can be reconstructed or unsorted (dorsal suture, ventral suture, orientation of from forward projecting growth striae in more or less septa, dorsal part of the septal neck) character distribu- well-preserved specimens with shell preservation. Detec- tions. tion of the characters mural flap, nacreous layer and cae- The characters apical angle (i.e. the general shape of cum is difficult and requires SEM-investigation of the phragmocone) and ratio chamber length:diameter can unaltered shell material. help to identify the systematic position of a coleoid Table 1 clearly shows that the Diplobelida and ‘Naefia’ phragmocone, but their qualitative determination is prob- matsumotoi do not fit in this robust identification scheme lematic. High variability in measurements leads to the as both taxa display a mixture of belemnoid and spirulid conclusion that both characters depend on the measure- characters. Diplobelida are belemnoid-like in having a ment method and/or the state of preservation and should narrow stripe-like attachment scar and in the absence of a therefore be considered only as tentative. caecum (Fuchs et al. 2012a). On the other side, diplobe- Besides the fact that suture lines are usually poorly pre- lids and early spirulids share a submarginal siphuncle and served, the diagnostic value of lobes and saddles is also the absence of a rostrum proper. ‘Naefia’ matsumotoi is equivocal. Dorsal lobes and saddles as well as ventral belemnoid-like in having a marginal siphuncle, a narrow lobes (ventral saddles are unknown) can be developed to stripe-like attachment scar and the presence of tabular varying degrees within each group under consideration. nacre in the conotheca. Vice versa, ‘Naefia’ matsumotoi For example, Pachyteuthis has straight dorsal sutures, Be- exhibits similarities with spirulids in having a mural flap lemnitella bulbosa, in contrast, exhibits distinct dorsal sad- and in the absence of a rostrum proper. Both the Diplo- dles similar to diplobelids. Similarly, dorsal septal necks belida and ‘Naefia’ matsumotoi are unique in having a seem to vary in different subgroups. proostracum that encompasses one-eighth of the The orientation of the septa as well as the direction of phragmocone circumference. the dorsal part of the septal necks obviously bears no Owing to striking morphologic differences between Nae- diagnostic value. Oblique septa occur in some diplobelid fia neogaiea – the type species of Naefia – and ‘Naefia’ mat- belemnoids and in some spirulids (e.g. Cyrtobelus). Hori- sumotoi, it is reasonable to remove the latter species from TABLE 1. Matrix comparing the character states of 14 characters.

1. 2. 3. 4. 5. 6. 7. Apical angle Chamber Dorsal Ventral Orientation of Mural ﬂap Dorsal part of length: suture suture septa septal neck diameter

‘Belemnoidea’ Aulacocerida Aulacoceras 5–10 degrees 0.50 Weak Weak Horizontal Absent Prochoanitic

Chitinoteuthis saddle (?) saddle (?) FUCHS Belemnitida Pachyteuthis 20–25 degrees <0.20 Saddle – Weak lobe Horizontal Absent Retrochoanitic Belemnitella straight

Diplobelida Conoteuthis 20–40 degrees 0.15–0.20 Saddle Straigth Horizontal- ? Retrochoanitic AL ET Diplobelus inclined – –

??‘N.’ matsumotoi 10 13 degrees 0.37 0.5 Straight Distinct lobe Horizontal Present Prochoanitic C NEW A GEN., N. LONGIBELUS .: DECABRACHIA Spirulida Groenlandi- Groenlandibelus 0.4–0.46 Straight Weak lobe Horizontal ? ? belidae Naeﬁa 13–19 degrees 0.26–0.37 Straight Weak lobe Horizontal ? ? Cyrtobelus 17–20 degrees 0.27–0.33 Weak lobe Weak lobe Slightly inclined Present ? Spirulidae Spirula / 0.5–0.6 Straight Distinct lobe Horizontal Present Retrochoanitic

8. 9. 10. 11. 12. 13. 14. Position of Dorsal scar Tabular Primordial Rostrum Proostacum Caecum siphuncle nacre rostrum/sheath proper width

‘Belemnoidea’ Aulacocerida Aulacoceras Marginal Stripe Present Present Present 0 Absent Chitinoteuthis Belemnitida Pachyteuthis Marginal Stripe Present Present Present 1/4 Absent Belemnitella Diplobelida Conoteuthis Submarginal Stripe ? Present Absent 1/8 Absent GENUS COLEOID RETACEOUS Diplobelus ??‘N.’ matsumotoi Marginal Stripe Present Present Absent 1/8 ? DECABRACHIA Spirulida Groenlandi- Groenlandibelus Submarginal ? ? Present Absent 1/16 ? belidae Naeﬁa Submarginal Rectangular ? Present ? 1/16 Present (?) Cyrtobelus Submarginal Rectangular Absent Present Absent 1/16 Present Spirulidae Spirula Marginal Rectangular Absent Present Absent Absent Present

Character states unambiguously diagnostic for spirulids are shown in italics; those of the Belemnitida and Aulacocerida in Bold. 5 6 PALAEONTOLOGY the genus Naefia and to establish a new genus. We there- Diagnosis. Phragmocone longiconic with an apical angle fore erected the genus Longibelus gen. nov. ‘Naefia’ kaba- of 13–14 degrees and a ratio chamber length:diameter novi as well as the specimens from southern India and between 0Á4– and 0Á46. Suture lines almost straight. Septa Mexico, which have been originally classified as Naefia not inclined. Siphuncle submarginal. Sheath apically neogaiea, Naefia cf. neogaiea or Naefia sp., belong to this thickened and high-conically elongated; adorally thin, new genus. Also, the South African specimen can be placed investment-like. Rostrum proper inclusively apical line along with Longibelus gen. nov. Furthermore, checking absent. Proostracum very narrow, rod-like, less than one- specimens for these characters identified one specimen sixteenth of the phragmocone circumference. Protoconch from the Chilean material that is dissimilar to Naefia neo- ovoid (slightly emended from Fuchs et al. 2012b). gaiea and closer to Longibelus gen. nov. With respect to the obvious dominance of Longibelus gen. nov., it is possi- Comparisons. Groenlandibelus is unique in having a high- ble that the Naefia-like specimens recorded from Antarc- conically shaped sheath apex. Furthermore, it differs from Naefia tica (Stilwell and Zinsmeister 1987) and California (Hewitt and Cyrtobelus in having higher chambers and a slightly smaller et al. 1991) are likewise closer to Longibelus gen. nov. apical angle. The septa of Cyrtobelus are slightly inclined, in con- The present results considerably affect the diagnosis of trast to Groenlandibelus. Groenlandibelus can be distinguished the family Groenlandibelidae as well as those of the gen- from Longibelus gen. nov. by the presence of a weak ventral lobe, submarginal siphuncle and a narrower proostracum. era Groenlandibelus and Naefia.

Occurrence. Upper Maastrichtian of Greenland. SYSTEMATIC PALAEONTOLOGY

Groenlandibelus rosenkrantzi (Birkelund, 1956) Subclass COLEOIDEA Bather, 1888 Figure 2A–E Superorder DECABRACHIA Boettger, 1952 Order SPIRULIDA Haeckel, 1896 v. * 1956 Belemnoteuthis rosenkrantzi n. sp. Birkelund, p. 17, Family GROENLANDIBELIDAE Jeletzky, 1966 pl. 1, fig. 9a–g. p 1966 Groenlandibelus rosenkrantzi Birkelund, 1956; Jeletzky, p. 92. (non = Cyrtobelus birkelundae Fuchs Type genus. Groenlandibelus Jeletzky, 1966. et al., 2012b) non 1974 Groenlandibelus rosenkrantzi (Birkelund, 1956); Diagnosis. Phragmocones ortho- to longiconic or slightly Birkelund and Hansen, p. 26. (= Cyrtobelus birke- cyrtoconic with an apical angle of 13–20 degrees and lundae Fuchs et al., 2012b) ratio chamber length:diameter of 0Á20–0Á50. Dorsal v. 1986 Groenlandibelus rosenkrantzi (Birkelund, 1956); sutures straight or with a weak lobe; ventral sutures with Doyle, p. 136, fig. 5. weak lobes. Septa not or only slightly inclined. Mural flap non 2000 Groenlandibelus rosenkrantzi; Doguzhaeva, p. 401. present. Ventral septal necks retrochoanitic, dorsal septal (= Cyrtobelus birkelundae Fuchs et al., 2012b) necks variable. Siphuncle submarginal. Mediodorsal p 2006 Groenlandibelus rosenkrantzi (Birkelund, 1956); attachment scars rectangular. Conotheca without a layer Bandel and Stinnesbeck, p. 24. (non = Cyrtobelus of tabular nacre. Sheath thin investment-like, apically birkelundae Fuchs et al., 2012b) cone-like thickened. Rostrum proper absent. Proostracum non 2006a Groenlandibelus rosenkrantzi; Fuchs, p. 12, fig. 3a–b. width narrow, rod-like, less than one-sixteenth of the (= Cyrtobelus birkelundae Fuchs et al., 2012b) phragmocone circumference. Protoconch ovoid with cae- v. 2006b Groenlandibelus rosenkrantzi; Fuchs, p. 122, fig. 3. cum and prosiphon (emended from Jeletzky 1966). non 2010 Groenlandibelus rosenkrantzi (Birkelund, 1956); Var- tak et al., p. 181, fig. 4a–b. (= Cyrtobelus birkelundae Fuchs et al., 2012b) Included genera. Groenlandibelus Jeletzky, 1966; Naefia Wetzel, v. 2012 Groenlandibelus rosenkrantzi (Birkelund, 1956); 1930 and Cyrtobelus Fuchs et al., 2012b. Fuchs et al., p. 3, fig. 1A–C Occurrences. Campanian–Maastrichtian of Chile, western Can- ada and Greenland. Holotype. MMK7758, the original of Birkelund (1956, p. 18, pl. 1, fig. 9a–g).

Genus GROENLANDIBELUS Jeletzky, 1966 Type locality. Agatdalen Valley, Nuussuaq, West Greenland.

Type and only species. Belemnoteuthis rosenkrantzi Birkelund, Type horizon. ‘Oyster-ammonite-conglomerate’, upper Maas- 1956, by monotypy. trichtian (Upper Cretaceous). FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 7

Redescription of the holotype. The specimen consists of three inaccurate preparation. The apical angle is approximately 13– pieces: the largest piece represents the phragmocone; the two 14 degrees. The preserved length of the phragmocone (includ- smaller pieces the external moulds of the phragmocone. The ing the apical sheath) is 27 mm; the maximum chamber phragmocone consists of 27 chambers including the proto- diameter 65 mm. The ratio chamber length:diameter varies conch and the apical part of the sheath (Fig. 2A). The un- between 0Á40 and 0Á46. In lateral view, the septa are not or usual curvature of the phragmocone has been caused by scarcely inclined. The dorsal sutures are almost straight,

A DE

FIG. 2. Groenlandibelus rosenkrantzi (Birkelund, 1956), holotype, MMK7758, late Maastrichtian of West Greenland. A, lateral view, scale bar represents 5 mm. B, ventral view to show weak ventral lobes; scale bar represents 1 mm. C, dorsal view to show forward curved growth lines (dotted line) and two mediodorsal furrows (mdf); scale bar represents 1 mm. D, dorsal view of the protoconch and the apex of the sheath (sh). Note there is no evidence of either concentric growth lines or an apical line; scale bar represents 1 mm. E, external mould of the dorsal side of the phragmocone with attached remains of the periostracum and/or sheath. The bipartite ridge (br) caused the mediodorsal furrows in C; scale bar represents 1 mm. 8 PALAEONTOLOGY whereas the ventral sutures are weakly lobate (Fig. 2B–C). The Naefia neogaeia Wetzel, 1930 siphuncle appears to be submarginal; septal necks are in any Figures 3A–E, 4A–H case not visible through the semi-transparent conotheca. Medi- odorsally, the conotheca bears two narrow and slightly diverg- v. * 1930 Naefia neogaiea n. sp. Wetzel, p. 92, pl. 14, fig. 3 ing furrows. Lateral to these furrows on either side, forwardly 1966 Naefia neogaiea Wetzel, 1930; Jeletzky, p. 104. curved growth lines indicate a very narrow rod-like proostra- v. 1982 Naefia neogaiea Wetzel; Biro-Bag ozky, p. 20, fig. 1. cum (Fig. 2C). The maximum width of the proostracum is non 1986 Naefia aff. neogaiea Wetzel, 1930; Doyle, p. 134, 1 mm. It can be traced backwards up to the second chamber. figs 1–5. (= Longibelus cf. matsumotoi (Hirano The oval protoconch measures 1Á5 mm in length and does et al., 1991) not deviate from the longitudinal phragmocone axis (Fig. 2D). ?1986 Naefia neogaiea Wetzel; Stinnesbeck, p. 222, pl. 6, The apex of the sheath (=‘guard’ in the terminology of Birkel- figs 6–7. und (1956) is high conical and shifted to the ventral side. ?1987 Naefia; Stilwell and Zinsmeister, fig. 3B. The distance between the posterior tip of the sheath and the non 1991 Naefia neogaiea Wetzel; Hewitt et al., p. 49, figs protoconch is 3Á8 mm. An apical line typical for a belemnite – rostrum proper does not exist (in contrast to the original 1 3. (= Longibelus matsumotoi (Hirano et al., 1991) description given by Birkelund (1956)). The maximum thick- 1997 Naefia neogaiea, Haas, fig. 1.4. ness of the solid part of the sheath is 1Á7 mm. There is no ?1999 Naefia neogaeia Wetzel, 1930; Hewitt and Jagt, evidence of concentric lamination as in a belemnite rostrum p. 319, fig. 3D. proper; instead, the prisms appear to radiate from the apex. non 2004 Naefia neogaiea Wetzel, 1930; Ifrim et al., p. 1578, Towards anterior, the sheath becomes rapidly thinner, but text-fig. 2A–B. (= Longibelus sp.) proceeds as a paper-thin investment as the counterparts indi- v. 2006 Naefia neogaiea; Bandel and Stinnesbeck, p. 22, pls cate. One of the two counterparts represents the dorsal side of 1–2. phragmocone, as forward curved growth striae suggest. Two longitudinal ridges in the mediodorsal line correspond to the Lectotype. GPIK 121b (subsequently designated by Jeletzky 1966, slightly diverging furrows observed on the outer surface of the p. 104). conotheca (Fig. 2E).

Paratype. GPIK 121a.

Genus NAEFIA Wetzel, 1930 Type locality. Cucaracha (lectotype) and Los Chilcos (paratype), Isla Quiriquina (Conception Bay, Bio-Bi o region, Central Chile). Type and only species. Naefia neogaeia Wetzel, 1930, by original designation. Type horizon. Quiriquina Formation, upper Maastrichtian, Upper Cretaceous. Diagnosis. Phragmocone orthoconic with an apical angle – of 13 19 degrees and ratio chamber length:diameter of Redescription of the lecto- and paratype. The lectotype (Fig. 3A– Á – Á 0 26 0 37. Suture lines almost straight. Septa not inclined. C) is 4 mm in length and includes six chambers preserved as Ventral part of septal necks short retrochoanitic; dorsal steinkerns (i.e. shell material is not preserved). The maximum parts still unknown. Siphuncle submarginal. Dorsal chamber diameter is 2Á5 mm; the minimum 2 mm. The apical attachment scars located apertural, short and rectangular. angle of the orthoconic phragmocone is 14 degrees. The ratio Existence of tabular nacre in the conotheca unknown. chamber length:diameter varies between 0Á29 and 0Á37. The Sheath thin investment-like. Rostrum proper absent. Pro- suture lines are indistinct owing to a poor preservation. The ostracum very narrow, rod-like, less than one-sixteenth of septa are oriented perpendicular to the phragmocone axis. In the phragmocone circumference. Protoconch poorly ventral view (Fig. 3A), each chamber offers a weak notch suggesting that the siphuncle was not entirely marginal. In known (?spirulid-like with caecum) (emended from dorsal view (Fig. 3B–C), the smallest chamber exhibits a Jeletzky 1966). rectangular structure that might be interpreted an attachment scar. Remarks. Owing to inadequate descriptions or insufficient The slightly larger paratype (Fig. 3D–F) is split and exposes preservation, generic attribution of the Antarctica and six chambers filled with sparry calcite. Longitudinally broken California material must be preliminary. We cannot cur- septal necks show that their ventral parts are clearly retrochoan- rently exclude the possibility that these phragmocones itic, whereas their dorsal parts are either achoanitic or even pro- belong to Longibelus gen. nov. choanitic (Fig. 3E–F). Connecting rings are not preserved; just their steinkerns. The latter are not in contact with the conotheca Occurrence. Maastrichtian of Chile (Wetzel 1930; Biro-Bagoczky indicating a submarginal siphuncle. 1982; Stinnesbeck 1986), possibly Campanian of Antarctica (Wetzel 1930; Stilwell and Zinsmeister 1987 and California (He- Morphology observed from additional material. The apical angles witt et al. 1991). of the orthoconic phragmocones vary between 13 and FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 9

A B

D EF

FIG. 3. Type specimens of Naeﬁa neogaiea Wetzel, 1930; upper Maastrichtian of Chile. A–C, lectotype, GPIK 121a. D–F, paratype, GPIK 121b. A, ventral view of the steinkern to show deep notches in the adoral part of each chamber indicating a marginal siphuncle; scale bar represents 1 mm. C, dorsal view; scale bar represents 1 mm. C, detail of C to show a rectangular mediodorsal attachment scar (mds); scale bar represents 0Á5 mm. D, dorsoventral fracture (part); scale bar represents 5 mm. E, dorsoventral fracture (counter- part); scale bar represents 5 mm. F, detail of E to show the marginal siphuncle; scale bar represents 1 mm.

19 degrees and the ratios chamber length:diameter between septa are hardly inclined. Polished specimen Q/3149 suggests 0Á26 and 0Á37. Specimen Q/3064 shows well that the suture short retrochoanitic ventral septal necks (see Bandel and Stin- lines are simple without distinct lobes or saddles; only a very nesbeck 2006, pl. 2, ﬁgs 4–5). The absence of a distinct ven- weak ventral lobe is perceptible (Fig. 4A–C). In lateral view, tral notch on the steinkerns suggests a submarginal siphuncle. 10 PALAEONTOLOGY

Adoral of each chamber, the steinkerns of specimens Q/3149 gular. Conotheca without a nacreous layer. Sheath thin and Q/3258 display mediodorsally rectangular imprints of soft and investment-like, adapically on top of the protoconch tissue attachments (Fig. 4D). Specimens Q/3578, 3064 and bulge-like thickened. Rostrum proper absent. Proostra- 3512 preserved remains of the conotheca. Forward projecting cum very narrow, rod-like. Protoconch ovoid with cae- growth lines weakly visible on the dorsal surface of specimen cum and prosiphon. Protoconch conotheca continues Q/3064 and Q/3578 suggest a very narrow rod-like proostra- into adult stages without interruption (from Fuchs et al. cum (Fig. 4A–C, E–H). The same specimens display two longitudinal furrows with a faint keel in between them. 2012b). In contrast to the latter specimens, specimen Q/3509 exposed distinct forward curved growth lines together with a Included species. Cyrtobelus birkelundae Fuchs et al., 2012b and mediodorsal bipartite ridge, which indicates that the latter C. hornbyense Fuchs et al., 2012b. juvenile specimen most likely preserved the sheath. None of the studied specimens preserved the initial chamber Occurrence. Upper Campanian – upper Maastrichtian (Upper (protoconch). Cretaceous) of Vancouver Island (British Columbia, Canada) and West Greenland. Remarks. In some respects, present observations differ from those of previous authors. Wetzel (1930), Biro-Ba- goczky (1982, p. 20), Jeletzky (1966, p. 104), Bandel Order and family UNCERTAIN and Stinnesbeck (2006) suggested apical angles between LONGIBELUS gen. nov. 12 and 15 degrees for the two types; our digital measurements varied between 13 and 19 degrees. Jeletzky Type species. Naefia matsumotoi Hirano et al., 1991. (1966, p. 104) concluded that the chamber distance is similar to the holotype of Groenlandibelus rosenkrantzi; Derivation of name. Longi- (Latin ‘longus’) meaning long; refers in contrast, we determined a significantly shorter dis- to the longiconic shape of the phragmocone; -belus (Greek tance in N. neogaiea than in G. rosenkrantzi. Bandel and ‘belos’) meaning bullet. Stinnesbeck (2006, p. 22) stated a siphuncular tube diameter of 30 per cent of its chamber diameter; this Diagnosis. Phragmocone longiconic with an apical angle – enormous diameter seems to be erroneous. A proto- of 10 13 degrees and chamber length:diameter ratio of Á – Á conch diameter of 4 mm, as Bandel and Stinnesbeck 0 37 0 50. Dorsal suture lines almost straight; ventral (2006, p. 22) measured from a single specimen, appears sutures with distinct lobe. Septa not inclined. Mural surprising as it is 9–10 times larger than any other fos- flap short. Dorsal part of septal necks achoanitic or sil and recent coleoids. Because the presumed presence prochoanitic. Siphuncle marginal. Dorsal attachment of a caecum is likewise unconvincing and needs further scars narrow and stripe-like. Conotheca with a thin confirmation; the detailed protoconch morphology must layer of tabular nacre. Sheath thin investment-like with remain open. a dorsal, bipartite keel. Rostrum proper absent. Proos- tracum width encompasses one-eighth of the phragmocone circumference. Protoconch morphology still Genus CYRTOBELUS Fuchs et al., 2012b unknown.

Type species. Cyrtobelus birkelundae Fuchs et al., 2012b. Included species. Longibelus matsumotoi (Hirano et al., 1991) comb. nov. and Longibelus kabanovi (Doguzhaeva, 1996) comb. nov. Diagnosis. Phragmocone slightly cyrtoconic with an apical angle of 17–20 degrees and a ratio chamber length: Á – Á Comparisons. Longibelus gen. nov. differs from groenlandibelids diameter of 0 27 0 33. Sutures lines with weakly devel- in possessing distinct ventral lobes, a marginal siphuncle, stripe- oped ventral and dorsal lobes. Septa slightly inclined. like mediodorsal attachment scars and in a wider proostracum. Siphuncle submarginal. Dorsal attachments scars rectan- From diplobelids, Longibelus gen. nov. differs in the slender

FIG. 4. Naeﬁa neogaiea Wetzel, 1930; upper Maastrichtian of Chile. A, Q/3509, dorsal view; scale bar represents 1 mm. B, Q/3064, ventral view to show a weak ventral lobe of the mural parts (mp) and weak notches (n) on the steinkern; scale bar represents 1 mm. C, same specimen in dorsal view to show straight suture lines; scale bar represents 1 mm. D, Q/3258, dorsal view to show short rectangular attachment scars (mds) on the surface of the steinkern (sk); scale bar represents 1 mm. E, Q/3578, dorsolateral view to show mediodorsal furrows (mdf); scale bar represents 1 mm. F, same specimen, dorsal view; scale bar represents 1 mm. G, Q/3509, dorsal view, whitened to highlight forward curved growth lines (dotted line); scale bar represents 1 mm. H, same specimen, dorsolateral view to show a mediodorsal bipartite ridge; scale bar represents 1 mm. FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 11 shape of the phragmocone, signiﬁcantly higher chambers, Occurrence. Aptian of Caucasus (Doguzhaeva 1996), Albian of absence of dorsal saddles that are overlaid by a keel, distinct South Africa and southern India, Cenomanian–Maastrichtian ventral lobes and a marginal siphuncle. of Japan (Hirano et al. 1991; Hewitt et al. 1991; Fuchs and

B C D

F G H 12 PALAEONTOLOGY

Tanabe 2010), southern India (Doyle 1986), Mexico (Ifrim chamber (Fig. 5C). Accordingly, unpaired attachment scars are et al. 2004) and Alaska. visible on the inner surface of each chamber (Fig. 5F). They are very narrow (stripe-like) and occupy the entire chamber length. It seems as if the mural parts of the septa cover the Longibelus matsumotoi (Hirano et al., 1991) comb. nov. scars. The semi-transparent conotheca consists of a thick inner Figure 5A–F prismatic layer, a thin intermediate layer of tabular nacre, a thin outer prismatic layer, and an outermost paper-thin and lamellar layer. Dorsally, the nacreous layer is absent. The outer v.* 1991 Naefia matsumotoi n. sp. Hirano et al., p. 205, pls 1–4. conotheca surface is smooth except for a mediodorsal longitu- 1991 Naefia neogaiea Wetzel; Hewitt et al., p. 49, fig. 1. dinal imprint. This scar-like imprint consists of two very shal- 1993 Naefia matsumotoi; Hayakawa and Takahashi, low furrows (UMUT 29686, 29687; MU 002/05HB0129). The pp. 6–31, fig. 2. two furrows on the outer conotheca surface are caused by a v. 2010 Naefia matsumotoi Hirano et al.; Fuchs and Tanabe, prismatic layer that is restricted the dorsal side, which bears an – p. 200, figs 2 8. inwardly directed bipartite ridge (Fig. 5F; = ‘inner sheath layer’ v. 2012 Naefia matsumotoi Hirano et al.; Fuchs et al., p. 14, in Fuchs and Tanabe 2010). The thin lamellar-organic perios- fig. 9C. tracum layer is situated external to the ridged layer. The periostracum layer is characterized by forward curved growth lines. Holotype. NSM PM7688 (original of Hirano et al., 1991, pl. 1, The proostracum encompasses one-eighth of the phragmocone fig. 1). circumference (Fig. 5E). The outermost shell layer, the sheath (= outer sheath layer in Fuchs and Tanabe 2010), is very thin, except in the mediodorsal region, where it is ornamented by a Paratypes. NSM PM7687, PM7689, (original of Hirano et al., bipartite keel (Fig. 5G). 1991, pl. 1 figs. 5–6).

Type locality. Kotanbetsu River, Kotanbetsu area, north-west Hokkaido, Japan. Longibelus matsumotoi (Hirano et al., 1991) Figure 6 Type horizon. Haborogawa Formation, Upper Yezo Group, uppermost part of the Inoceramus amakusensis Zone; upper San- Material. One phragmocone (HMG1532). tonian. Locality. Opposite outcrop H311 of Matsumoto and Toshimitsu ° ′ ′′ ° ′ ′′ Redescription (slightly modified from Fuchs and Tanabe (1995) (N42 48 37 E142 09 01 ), Kiusu, Hobetsu, Hokkaido, 2010). The apical angle of the longiconic phragmocone is 10– northern Japan. 12 degrees. The ratio chamber length:diameter varies between 0Á35 and 0Á5. The largest phragmocone studied has a maxi- Horizon. Unit IVc of Hakobuchi Formation, Gaudryceras izum- mum diameter of 12Á3 mm. Determination of a body chamber iense Zone (Shigeta et al. 2010), lower Maastrichtian, Upper is problematic as adoral chambers are mostly fragmentary; a Cretaceous. proostracum in situ is therefore still unknown. Both mural parts and their remains on steinkerns indicate distinct ventral Description. The longiconic phragmocone, which has been lobes and almost straight dorsal sutures (Fig. 5A–C). In lateral removed from the surrounding matrix, has a preserved length view, septa are hardly inclined. Adorally, each mural part is of 21 mm and includes 14 chambers. The earliest chambers overlapped by a short prismatic flap (mural flap), which is (including the protoconch) are missing. The smallest chamber formed by the inner prismatic layer of the conotheca. The ven- has a diameter of 2Á3 mm; the largest 6 mm. The chamber tral part of the comparatively short septal necks is retrochoan- length constantly increases from 0Á4mmto2Á5 mm. The ratio itic, whereas the dorsal part is prochoanitic. Steinkerns reveal a chamber length:diameter varies between 0Á37 and 0Á39. The comparatively deep notch (Fig. 5B). Steinkerns usually display apical angle is 13 degrees. The suture lines, which are visible mediodorsal stripe-like imprints of attachment scars in each through the semi-transparent conotheca, are dorsally straight

FIG. 5. Longibelus matsumotoi (Hirano et al. 1991) comb. nov., Cenomanian–Campanian of Hokkaido (northern Japan). A, MB- 723, ventral view; scale bar represents 5 mm. B, MB-724, ventral view to show distinct lobes (vl) of the mural parts (mp) and deep notches (n) of the steinkern (sk) indicating a marginal siphuncle; scale bar represents 1 mm. C, same specimen, dorsal view to show straight dorsal lobes and narrow stripe-like imprints of mediodorsal attachment scars (mds). The conotheca (co) is partly preserved; scale bar represents 1 mm. D, MB-726, dorsal surface of the conotheca to show dorsal furrows (df); scale bar represents 1 mm. E, MB-725, dorolateral view to show forward curved growth lines (dotted line), arrow head marks mediodorsal; scale bar represents 1 mm. F, MB-723, dorsal view of the inner surface of the conotheca (co) with mediodorsal attachment scars (mds), and the sheath (sh) with an inside directed bipartite ridge; scale bar represents 1 mm. G, MU 012/05HB1052a, dorsal view on the outer surface of the sheath to show the mediodorsal bipartite keel (bk) and forward curved growth lines (dotted line); scale bar represents 1 mm. FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 13

B CD

E FG 14 PALAEONTOLOGY

FIG. 6. Longibelus matsumotoi (Hirano et al., 1991) from the lower Maastrichtian of Hokkaido (northern Japan), HMG1532. A, dorsal view. B, lateral view. C, ventral view. Scale bar represents 1 mm. and ventrally slightly lobate (Fig. 6A, C). In lateral view, the Longibelus sp. A septa show no evidence of inclination (Fig. 6B). In ventral Figure 7 view, the steinkerns exhibit a distinct notch indicating that the septal necks are in touch with the ventral conotheca (Fig. 6C); Material. One phragmocone (AMNH-FI 82981). the siphuncle is hence marginal. Dorsal attachments are not visible through the conotheca. Posteriorly, the outer surface of Locality. Talkeetna Mts., Alaska (USA). the conotheca shows mediodorsally a pair of slightly diverging longitudinal impressions (Fig. 6A). The space between these Horizon. Pachydiscus kamishakensis Zone, lower Maastrichtian, furrows appears as a keel. The asymptotes of forward bended Late Cretaceous. growth lines correspond to these impressions. The distance between these asymptotes indicates a proostracum width of one-eighth of the phragmocone circumference. More anteri- Description. The phragmocone, which is embedded in the con- orly, the conotheca is partly covered by remains of a paper- cretion with the lateral side up, consists largely of its steinkern, – thin sheath, but only in the dorsal parts. Mediodorsally, the that is, shell material is only partly preserved (Fig. 7A B). The Á sheath bears a bipartite keel (Fig. 6A). A rostrum proper is longiconic phragmocone has a preserved length of 21 5 mm and absent. includes 11 chambers. The chamber length constantly increases from 1 mm to 2Á5 mm. The ratio chamber length:diameter is unclear because the chamber diameter is not entirely exposed. Comparison. The presence of a bipartite keel, a marginal sip- The apical angle is c. 13 degrees. Mural parts of the septa are huncle, a ratio chamber length:diameter of 0Á37–0Á39 and an poorly preserved, and details on the course of suture lines are apical angle of 13 degrees agrees well with the description of not available. Septa appear to be not inclined. A distinct notch L. matsumotoi (Hirano et al. 1991; Fuchs and Tanabe 2010). No on the ventral surface of the steinkerns suggests a marginal sip- signiﬁcant differences that may justify erection of a new species huncle (Fig. 7B–C). Spots of the conotheca are preserved in the have been observed. FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 15

B C

FIG. 7. Longibelus sp. A from the Maastrichtian of Alaska, AMNH-FI 82981. A, lateral view. B, ventral. C, detail of C to show a deep notch (arrow head) indicating a marginal siphuncle. Scale bars represent 5 mm in A and B, 1 mm in C.

ventral part of the phragmocone and, in a very few places, dorsolaterally forward curved growth lines indicating a proos- patches of the sheath cover the conotheca. There is no evidence tracum width of one-eighth of the entire phragmocone circum- of a rostrum proper. Because the dorsal part of the phragmo- ference (Fig. 8A–B). The dorsal sutures are straight, whereas cone is embedded in the matrix, diagnostic features of the dorsal the ventral sutures show a distinct lobe (Fig. 8C). A marginal side such as the shape of the mediodorsal attachment scars or siphuncle can be inferred from the well-visible septal necks, the width of the proostracum are not visible. The protoconch is which caused a deep notch in the steinkerns (Fig. 8C). More- not preserved. over, steinkerns exhibit mediodorsally narrow stripe-like attachment scars (Fig. 8D). Comparison. A comparatively low apical angle and a marginal siphuncle are diagnostic characters of the genus Longibelus gen. Comparison. A low apical angle, a high ratio chamber length: nov. However, a detailed comparison with the L. matsumotoi is diameter, a proostracum width of one-eighth of the entire hampered by the lack of diagnostic characters. The present phragmocone circumference, distinct ventral lobes, a marginal phragmocone differs from those of Groenlandibelus, Naefia and siphuncle and stripe-like attachment scars are diagnostic for the Cyrtobelus mainly by the presence of a marginal siphuncle. new genus, but a specific assignment is currently difficult because of the lack of further diagnostic characters. Affinities with Groenlandibelus, Naefia and Cyrtobelus are unlikely, as lat- Longibelus sp. B ter genera are characterized by a rod-like proostracum, weak ventral lobes, a submarginal siphuncle and rectangular attach- Figure 8 ment scars.

Material. One phragmocone (specimen Q/3525).

Longibelus sp. C Locality. Conception Bay, Bio-Bi o region, Central Chile. Figure 9

Horizon. Quiriquina Formation, upper Maastrichtian. 2004 Naeﬁa neogaiea Wetzel, 1930; Ifrim et al., p. 1578, text-Fig. 2A–B. Description. The longiconic phragmocone consists of ﬁve (clued) chambers and has a preserved length of 19 mm (Fig. 8A). Owing to a strong lateral compaction, measurements Material. Four isolated chambers (UANL CE MAAS-131-132, on the apical angle, the chamber length and diameter must CPC783-784) therefore be seen as approximate. The apical angle is c. 10 degrees, and the ratio chamber length:diameter is c. 0Á44. Locality. Loma Los Martinitos, 15 km south-east of Cerralvo The conotheca, which is preserved only in a few places, bears (north-eastern Mexico). 16 PALAEONTOLOGY

A B

FIG. 8. Longibelus sp. B from the lower Maastrichtian of Chile, Q/3525. A, lateral view. B, dorsolateral view to show forward curved growth lines (dotted line) on the external surface of the conotheca (co). C, ventral view to show a distinct lobe (vl) of the mural part (mp) and the deep notch (n) of the steinkern (sk). D, dorsal view to show the mediodorsal imprints of stripe-like attachment scars (mds) on the steinkern (sk). Scale bars represent 5 mm in A and 1 mm in B, C and D.

Horizon. Gansseri-zone, Mendez Formation, lower Maastrich- Longibelus cf. matsumotoi (Hirano et al., 1991) tian, Upper Cretaceous. Figure 10

Comparison. The comparatively large chambers (8Á8–10Á5mm Material. Three phragmocones (KY.5384, KY.4230, KY.4231). in maximum diameter) described by Ifrim et al. (2004) are represented solely by pyritized steinkerns (i.e. shell material is not Locality. Tamil Nandu (southern India). preserved). Many diagnostic characters are therefore lost; however, the steinkerns show three diagnostic characters: (1) The Horizon. Karai Formation, upper Albian, Upper Cretaceous. ventral suture is distinctly lobate (Fig. 9A); (2) the siphuncle appears to be marginal; and (3) the imprints of the dorsal Description. The comparatively large phragmocones are longi- attachment scars are narrow and stripe-like (Fig. 9B). Each of conic with a ratio chamber length:diameter between 0Á3 and 0Á5. these features is shared by the known species of Longibelus gen. Specimens KY.5384 (Fig. 10A–B) and KY.4230 (Fig. 10C) dis- nov. A specific assignment is currently difficult because of the play in ventral view a distinctly lobate suture line and a deep lack of further diagnostic characters. Affinities with Groenland- notch caused by a marginal siphuncle. In dorsal view, specimen ibelus, Naefia and Cyrtobelus are unlikely, as latter genera are KY.4231 (Fig. 10D–C) clearly exhibits a narrow stripe-like soft typified by weak ventral lobes, a submarginal siphuncle and rect- tissue attachment scar. angular attachment scars. FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 17

assumption is mainly based on the bipartite keel present on the sheath of C.46373 (compare Fig. 5G and Doyle 1986, ﬁg. 1d).

Longibelus sp. D Figure 11

1990 aulacocerid-like coleoid phragmocone; Doyle b, p. 268.

A Material. One specimen (KX-11759).

Locality. Locality 51, bed of Mzinene River, north of Hluhluwe, Zululand, South Africa.

Horizon. Bed k of Kennedy and Klinger (1975, p. 288), Mzinene Formation, upper Albian, Upper Cretaceous.

Description. The single specimen consists of the steinkern of a chamber, which is slightly compressed in dorsoventral direction. The diameter of the chamber is c. 18–20 mm; its length is c. 9 mm. The ratio chamber length:diameter is thus between 0.45 and 0.50. The estimated apical angle is <15 degrees. A suture line is not visible. The septa show no evidence of inclination. The ventral side of the steinkern is strongly corroded, but it B appears as if the deep position of the septal neck indicates a FIG. 9. Longibelus sp. C from the lower Maastrichtian of Mexi- marginal siphuncle (Fig. 11A). The dorsal side of the steinkern co, UANL CE MAAS-131. A, ventral view of the steinkern to exhibits very weak evidence of a narrow stripe-like attachment show the distinct ventral lobe (vl) as well the deep notch (n); scar (Fig. 11B). On both lateral sides, the specimen preserved scale bar represents 5 mm. B, dorsal view to show evidence of a shell material. On the left side, forward curved growth incre- stripe-like attachment scar (mds). ments are detectable indicating a proostracum that takes one- eighth of the phragmocone circumference.

Comparison. Similar to the Mexican specimens, the steinkerns Comparison. Despite the lack of many diagnostic characters, the from India preserve sufficient characters for identification at the present record can reliably placed within the new genus owing genus level. The combined appearance of a distinct ventral lobe, to the presence of a distinctly long chamber, a marginal siphun- a marginal siphuncle and a mediodorsal stripe-like attachment cle, an arrow stripe-like dorsal attachment scar and a proostra- scar is shared only by the genus Longibelus gen. nov. Affinities cum width of one-eighth. Each of these four features is absent with Groenlandibelus, Naefia, and Cyrtobelus can be excluded, as in Groenlandibelus, Naefia and Cyrtobelus. Belemnitids do have latter genera are characterized by weak ventral lobes, a submar- distinctly lower chambers and wider proostraca. Aulacocerids ginal siphuncle and rectangular attachment scars. lack a proostracum. The chamber diameter of 20 mm indicates the largest record of a phragmocone belonging to Longibelus Remarks. The three Indian specimens are pyritized and gen. nov. Based on a presumed apical angle of 10–13 degrees, strongly compacted. The ratio chamber length:diameter the phragmocone had a total length of at least 90–100 mm. must therefore be treated with care. The same character combination (distinct ventral lobe, marginal siphuncle, stripe-like attachment scar) has been Longibelus kabanovi (Doguzhaeva, 1996) comb. nov. also observed by Vartak et al. (2010) in specimens from the same region. Vartak et al. (2010) placed them in the v.* 1996 Naefia kabanovi sp. nov. Doguzhaeva, p. 694, genus Naefia, but in the light of this study, it is reason- text-fig. 2A–E, text-fig. 4A–C, pl. 6, figs 1–5, pl. 7, able to assume that they are congeneric with Longibelus figs 1–2, pl. 8, figs 1–4, pl. 8, figs 1–3. gen. nov. Taking into consideration the observations made by Doyle (1986) on ‘Naefia’-like specimens likewise Holotype. PIN 3871/124 (original of Doguzhaeva 1996: p. 694, from the Karai Formation, the Indian phragmocones text-fig. 2A–E, text-fig. 4A–C, pl. 6, figs 1–5, pl. 7, figs 1–2, pl. are even conspecific with Longibelus matsumotoi. This 8, figs 1–4, pl. 8, figs 1–3. 18 PALAEONTOLOGY

A B

CD E

FIG. 10. Longibelus cf. matsumotoi (Hirano et al., 1991) from the upper Albian of South India. A, KY.5384, ventral overview. B, detail of A to show the mural part (mp), the distinct ventral lobe (vl) as well the deep notch (n). C, KY.4230, ventral view to show the mural part (mp), the distinct ventral lobe (vl) as well the deep notch (n); scale bar represents 5 mm. D, KY.4231, dorsal view. E, detail of D to show evidence of a stripe-like attachment scar (mds). Scale bars represent 5 mm in A and C and 1 mm in B and D.

ABC

FIG. 11. Longibelus sp. D from the upper Albian of Zululand, KX-11759. A, ventral view; scale bar represents 5 mm. B, dorsal view to show evidence of a stripe-like attachment scar (mds). C, dorsolateral view to show forward curved growth lines (dotted line). FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 19

Paratypes. Two phragmocones (PIN 3871/125, 3871/126). mural flaps in sepiids is secondary (personal observations by DF). Type locality. Hokodz (north-western Caucasus, Russia). Position of the siphuncle. This character represents an Type horizon. Aptian, Upper Cretaceous. important diagnostic character that enables to distinguish Longibelus gen. nov. with a marginal siphuncle from Remarks. Longibelus kabanovi clearly differs from the Groenlandibelus, Naefia and Cyrtobelus, which exhibit a genus Naefia. In comparison with Naefia neogaiea, submarginal siphuncle (Fig. 1G). In ontogenetic early L. kabanovi is characterized by a smaller apical angle, chambers of Palaeocene, sepiid Ceratisepia also indicate a longer chambers and the presence of a narrow stripe-like submarginal siphuncle (see Meyer 1993; personal observa- dorsal attachment scar (Doguzhaeva, 1996). The same tions by DF). The marginal position of the siphuncle characters also exclude affinities with the genus Cyrtobe- present in highly specialized Spirula can be interpreted as lus. The general appearance of L. kabanovi is very similar derived. A marginal siphuncle (i.e. ventral parts of the to Longibelus gen. nov. (apical angle, chamber length, dis- septal neck are in contact with the ventral conotheca) is tinct ventral lobe, marginal siphuncle, stripe-like attach- typical for the Belemnitida and Aulacocerida (Fig. 1A2; ment scars). We preliminarily place L. kabanovi in the see Jeletzky 1966). Because diplobelids have a submarginal new genus, although the orientation of the dorsal part of siphuncle (Jeletzky 1966, Fuchs et al. 2012a), two ways of the septal neck observed in L. kabanovi (achoanitic) is dif- character polarization are possible: (1) Longibelus gen. ferent in Longibelus gen. nov. (prochoanitic). The pre- nov. is closer to the Belemnitida: a submarginal siphuncle sumed absence of tabular nacre might be another is then autapomorphic for a group including Diplobelida argument against this position, but this observation by and all subgroups of the Decabrachia. (2) Longibelus gen. Doguzhaeva (1996) needs further confirmation. In any nov. is closer to the Spirulida: in this case, the siphuncle case, the existence of mural flaps sets L. kabanovi sharply of both diplobelids and spirulids migrated independently apart from belemnites and instead closer to groenlandibe- towards dorsal as a result of similar requirements to their lids. life style and therefore is apomorphic for the Diplobelida and Spirulida (Fig. 12).

DISCUSSION Mediodorsal attachment scars. A comparison of attachment scars demonstrates a distinct character distribution. Phylogenetic implications Aulacocerida, Belemnitida and Diplobelida exhibit narrow stripe-like attachment scars (Fig. 1C), whereas Spi- In the following, we will approach the phylogenetic status rulida (i.e. Recent Spirula and Late Cretaceous Cyrtobelus of seven characters that help to distinguish between be- and Naefia) are characterized by wide rectangular scars lemnoids and phragmocone-bearing decabrachians. Char- (Fig. 1H). Ectocochleates have stripe-like attachments acters with a minor diagnostic value (apical angle, ratio similar to belemnoids (Kroger€ et al. 2005). We therefore chamber length:diameter, dorsal suture, ventral suture, consider stripe-like attachment scars to be plesiomorphic orientation of septa, dorsal part of the septal neck, within the Coleoidea and rectangular scars to be autapo- primordial rostrum/sheath) are considered to possess a morphic for the Spirulida (Fig. 12). The presence of wide limited phylogenetic relevance (at least at higher levels). rectangular scars in Eocene spirulids Spirulirostra, Spiruli- rostridium and Vasseuria support this polarization (per- Mural flap. The presence of a mural flap has been sonal observations by DF). In Recent Sepiida and described from Recent Spirula (Doguzhaeva 1996, pl. 3, gladius-bearing decabrachians, attachments have been lost fig. 3; Fuchs 2006, pl. 17), from Late Cretaceous Cyrtobe- in the course of their shell transformations. In case Dec- lus (Fuchs et al. 2012b, fig. 4) and from Early–Late Creta- abrachia is monophyletic, the presence of rectangular ceous Longibelus gen. nov. (Doguzhaeva 1996, p. 694, pl. attachment scars may even be autapomorphic for the 8, fig. 3; herein). Mural flaps have not been observed in Decabrachia. Accordingly, the stripe-like attachment scars belemnites nor in aulacocerids (compare Fig. 1A, F). observed in Longibelus gen. nov. indicate a plesiomorphic Although the presence of mural flaps is still unknown in character state. diplobelids, Naefia and Groenlandibelus, the phylogenetic value of the mural part appears to be high. We prelimi- Tabular nacre in the conotheca. Despite some contradic- narily consider the presence of mural flaps to be autapo- tory observations in the past, the lack of tabular nacre in morphic for a group comprising Longibelus gen. nov. and the conotheca of sepiids and spirulids has been estab- Decabrachia (Fig. 12). This assumption implies that lished (Doguzhaeva 1996, 2000; Fuchs 2006; Fuchs et al. (assuming Decabrachia is monophyletic) the lack of 2012b). Nevertheless, this view must be carefully evalu- 20 PALAEONTOLOGY

FIG. 12. Stratigraphic occurrence of coleoid subgroups and their phylogenetic relationships. Stratigraphic range of Belemnitida is modified from Iba et al. (2012). FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 21 ated because Hewitt et al. (1991) and Fuchs and Tanabe phragmocone circumference; the belemnitid one-quarter (2010) detected a thin nacreous layer in the ventral co- (Fig. 1E), the diplobelid one-eighth, and those of Late notheca of Longibelus (‘Naefia’) matsumotoi, which was Cretaceous Groenlandibelus, Naefia and Cyrtobelus one- previously believed to be a representative of the Spirulida. sixteenth (Fig. 1J). In Figure 12, we consider each step of Moreover, ultrastructural studies on unaltered speci- reduction as an autapomorphy of the respective groups. mens of Pachyteuthis sp. have surprisingly shown that in Presumed that the Decabrachia is monophyletic, the com- true belemnites, the nacreous layer also shows evidence of plete loss of the proostracum in post-Cretaceous spirulids reduction (own observation by DF). The ventral part of and in sepiids occurred independently. Under this the nacreous layer is indeed well-developed, but towards hypothesis of character evolution, Longibelus gen. nov. is lateral, it begins to peter out. Dorsolaterally, the nacre is closer to the diplobelid branch. visible only as a very thin layer; mediodorsally, it is absent. The same distribution of nacre has been observed Presence of caecum. According to the classical view, in the aberrant belemnoid Belemnotheutis by Fuchs et al. Recent Spirula inherited its caecum, the blind end of the (2007). It is still unclear, whether the nacreous layer in siphuncle that enters the lumen of the protoconch, aulacocerids or diplobelids behaves similarly, but this directly from its ectocochleate ancestors (Naef 1922; Jel- observation points to a general reduction in tabular nacre etzky 1966, p. 82; Fuchs 2006, p. 14, fig. 4.1–2). However, within the Coleoidea. In terms of this, we preliminarily Hewitt and Jagt (1999, p. 308) remarked the possibility of regard the dorsal reduction in tabular nacre as an autapo- a convergent development of the caecum as a result of morphy of the stem-group of the Coleoidea or a group similar hatching depths. Also, Fuchs et al. (2012a, b) comprising Belemnitida, Diplobelida, Longibelus and Dec- questioned the presumed homology owing to consider- abrachia; the further reduction as an autapomorphy of a able morphologic differences between spirulid and ammo- group containing Longibelus gen. nov. and Decabrachia noid protoconchs. One striking argument for this doubt (Fig. 12). Accordingly, the total loss of tabular nacre is an concerns the ultrastructure of the caecum, which is lam- autapomorphy of the Decabrachia. Further examination ello-fibrillar in spirulids and prismatic in ammonoids. on Groenlandibelus and diplobelids can verify this polari- Additionally, the ammonoid protoconch wall is – similar zation. The presumed (total) absence of tabular nacre in to belemnitids – known to peter out at the protoconch putative spirulids Shimanskya (Doguzhaeva et al. 1999) aperture, whereas in spirulids, the protoconch wall con- and Kostromateuthis (Doguzhaeva 2000) must be there- tinues without interruption into the postprotoconch co- fore re-evaluated according to these results. notheca. The latter difference particularly implies an enormous reorganization of the spirulid protoconch. Rostrum proper, primordial rostrum, sheath. A lot of con- Because of these differences and because the diplobelid fusion exists in the literature concerning the homology of protoconch apparently represents (although still insuffi- these three characters. Fuchs (2012) recently reviewed this ciently known) another coleoid protoconch type, we homology problem and concluded that the belemnoid question the homology between the bactritoid, ammonoid primordial rostrum and the spirulid and sepiid sheath are and spirulid caecum. Therefore, we preliminarily regard homologues (as a secondary shell formation) and that the spirulid caecum as an independent innovation and spirulids and sepiids lack a rostrum proper (which is con- therefore either as an autapomorphy of a group compris- sidered as a tertiary shell formation). According to Fuchs ing Longibelus and the Decabrachia, or exclusively for the and Niko (2010), Fuchs (2012) and Fuchs et al. (2012a) Decabrachia (Fig. 12). We are confident that future diplobelid Conoteuthis lacks a rostrum proper, too. records of well-preserved protoconchs in Longibelus can Hence, the possession of an aragonitic sheath (or primor- clarify this uncertainty. dial rostrum) and aragonitic rostrum proper is a symple- Our morpho- and phylogenetic approach on shell char- siomorphy within the Coleoidea. A calcitic rostrum acter complexes confirms that Groenlandibelus, Naefia and proper is autapomorphic for the Belemnitida (Figs 1D, Cyrtobelus are certainly on the decabrachian and most 12), and the lack of rostrum proper is autapomorphic for possibly already on the spirulid branch. Longibelus gen. a group consisting of Diplobelida, Spirulida and Sepiida nov., in contrast, is phylogenetically intermediate between (Figs 1I, 12). With respect to this character, Longibelus diplobelid belemnoids and the Decabrachia (Fig. 12). gen. nov. unambiguously belongs to the second group. Regarding Longibelus gen. nov. as a phylogenetic link implies a direct derivation of the Decabrachia from dip- Width of the proostracum. Within proostracum-bearing lobelid ancestors. This idea substantially contradicts previ- coleoids, there appears to be a trend towards reduction in ously proposed classifications and phylogenies (compare the forward projected proostracum. The phragmoteuthid Jeletzky 1966; Doyle et al. 1994; Young et al. 1998; Haas proostracum is known to encompass three-quarters of the 2003; Fuchs 2006), but supports the ‘belemnoid root- 22 PALAEONTOLOGY stock theory’ put forward already by Voltz (1830) and Stratigraphic implications Naef (1922) and more recently again by Hewitt and Jagt (1999, p. 308). As a result of our taxonomic revision, the genus Naefia is Derivation of the Decabrachia from Late Jurassic or represented by a single species and so far known only Early Cretaceous belemnoid ancestors requires the from the Maastrichtian of Chile (Fig. 13). The genus absence of true teuthids from the Jurassic fossil record. Longibelus gen. nov., in contrast, appeared in the Aptian According to the classical view, gladius-bearing coleoids and became extinct by the end of the Maastrichtian from the Jurassic of southern Germany or the Late Creta- (Fig. 13). It is worthwhile to note that there are no signif- ceous of Lebanon are ‘fossil teuthids’ (Naef 1922; Jeletzky icant fossil gaps between its appearance and disappear- 1966; Donovan 1977). However, numerous publications ance. Longibelus sp. D from the Albian of South Africa in the past 25 years have repeatedly shown that the gladi- fills the gap between the Aptian and Cenomanian. Long- us of these animals is only superficially similar to the ibelus matsumotoi occurred from the Cenomanian–Maas- teuthid gladius and that their well-known soft-part trichtian of Japan. Longibelus cf. matsumotoi from Chile, anatomy rather suggests vampyropod affinities (see e.g. Mexico, Alaska and Japan represents the latest records of Bandel and Leich 1986; Fuchs 2006, 2009; Fuchs and this genus in the Maastrichtian. Turonian–upper Campa- Larson 2011a, b). True teuthid gladii is therefore consid- nian fossil records of Longibelus are restricted to the ered to be still unknown from the fossil record. north-west Pacific (Japan). Consequently, we cannot find a strong argument that explicitly rejects a sister-group relationship between the Diplobelida and a group containing Longibelus gen. nov. Biogeographical implications and the Decabrachia. Regarding Longibelus gen. nov. as a stem-group representative of the Decabrachia implies a The taxonomic revision of the genus Naefia has also a mid to late Mesozoic origin of the Decabrachia, which is striking impact on the biogeography of groenlandibelids considerably later than previously believed (compare Dog- and Longibelus gen. nov. uzhaeva et al. 2010). This later origin is consistent with Our classification suggests a disjunct distribution of molecular data, which yielded a divergence between spiru- groenlandibelids. Naefia is restricted to the south-east lids and other decabrachiate orders at 150 (Æ30) ma Pacific (Chile), Groenlandibelus to the Arctic (Greenland) (Bergmann et al. 2006; Kroger€ et al. 2011; Warnke et al. and Cyrtobelus to the Arctic (Greenland) and the North 2010). Pacific (western Canada). Finally, a sister-group relationship between the Diplo- Longibelus gen. nov. has possibly its origin during the belida and a group including Longibelus gen. nov. and the Early Cretaceous in the Mediterranean Tethys (Fig. 13). Decabrachia also influences higher taxonomic levels, as Three occurrences during the Albian–Cenomanian suggest this idea makes the taxon ‘Neocoleoidea’ paraphyletic. A immigration into the Indian Ocean and the north-west monophyly has been presumed since Jeletzky (1966). Pacific. In the latest Cretaceous after extended migrations, Haas (1997) introduced the taxa ‘Neocoleoidea’ for a Longibelus existed in the Gulf of Mexico, the South and group of sucker-bearing coleoids and ‘Paleocoleoidea’ for North Pacific, and the Arctic (and possibly Antarctica). a group of hook-bearing coleoids commonly known as In the light of their biogeographical occurrences, the belemnoids. The presumed absence of suckers in hook- current fossil record of Naefia, Cyrtobelus, Groenlandibelus bearing belemnoids long prevented to consider the possi- and Longibelus gen. nov. suggests temperate and cold- bility of a direct derivation of neocoleoids (= all extant water preferences. The appearance of Longibelus in the coleoids) from belemnoid subgroups. The first record of Gulf of Mexico appears to be in conflict with this idea, suckers in a belemnoid, however, recently weakened the but Ifrim et al. (2004) connected the short-term invasion presumed monophyly of the ‘Neocoleoidea’ and simulta- of several cool or even cold-water faunal elements into neously enabled a belemnoid–decabrachian relationship the warm waters of the Gulf of Mexico to a major drop (Fuchs et al. 2010a). According to the present approach, in sea level, that is, a short cooling event during the early the Decabrachia evolved from diplobelid belemnoids, Maastrichtian. whereas the Vampyropoda derived from phragmoteuthid Longibelus gen. nov. was associated in the North Pacific belemnoids (Jeletzky 1966; Donovan 1977; Doyle et al. with closely related spirulid Cyrtobelus and with diplobelid 1994; Fuchs 2006). This idea fulfils the request formulated Conoteuthis (Fuchs and Niko 2010). In the South Pacific, by Boletzky (2003), who emphasized that the two differ- Longibelus gen. nov. co-occurred simultaneously with Nae- ent arm modifications present in the Decabrachia (4th fia. Interestingly, a Longibelus-Conoteuthis-co-occurrence is ventrolateral arm pair modified) and the Vampyropoda detectable at different periods and different parts of the (2nd dorsolateral arm pair modified) must have devel- world (Fig. 13). Both genera apparently coexisted in the oped from two different ancestors. Mediterranean Tethys during the Aptian (Doguzhaeva FUCHS ET AL.: LONGIBELUS N. GEN., A NEW CRETACEOUS COLEOID GENUS 23

FIG. 13. Stratigraphic and biogeographical occurrence of Longibelus gen. nov. (black bars), groenlandibelids (grey bars) and diplobelid Conotheuthis (white bars).

1996; Jeletzky 1981), in southern India during the Cenoma- ing neritic (inner and outer shelf) provinces (Stinnesbeck nian (Fuchs et al. 2010b; Vartak et al. 2010) and in Japan 1986; Hayakawa and Takahashi 1993; Doguzhaeva 1996; during the Turonian (Fuchs and Niko 2010; Fuchs and Ifrim et al. 2004; Vartak et al. 2010). Hence, these ani- Tanabe 2010). Furthermore, we found evidence that Cono- mals were, like belemnites, adapted to open waters. teuthis also coexisted with Cyrtobelus and Groenlandibelus Hewitt et al. (1991, p. 52) assumed a difference in the in the North American Province (Fuchs et al. 2012b). bathymetric distribution of belemnites and Longibelus Wherever these diplobelid-longibelid-groenlandibelid (their ‘Naefia’). On the basis of septal strength calcula- associations appeared, the belemnite fauna is obviously tions, the latter authors concluded that Longibelus might either poor (India, Greenland) or even absent (Chile, have lived 100–250 m deeper than belemnites. Belemnites Japan). Only in Antarctica, Naefia (or Longibelus?) appar- could have lived in epipelagic shelf waters, whereas Long- ently co-occurred with a comparatively rich belemnite ibelus inhabited, similar to Recent Spirula, mesopelagic fauna (Doyle 1990a). Most interestingly, belemnites s.s. waters above the continental slopes. The development of were entirely absent from the Late Cretaceous North Paci- mural flaps as an adaptation to withstand higher water fic (Iba et al. 2011), and it is conspicuous that the immi- pressures might support this idea. Hewitt et al. (1991, p. gration of Longibelus gen. nov. in the North Pacific 52) suggested a postmortem drift of the Longibelus shells (Cenomanian) appears shortly after the last belemnites from oceanic to neritic provinces. Serpulids that some- (Neohibolites) disappeared from the North Pacific. One times cover the outer surface of the Longibelus sheath might argue that Longibelus occupied the ‘open’ niches supports this assumption (own observations by DF). after the demise of belemnites.

CONCLUSIONS Palaeoenvironmental implications We conclude from our morphologic analysis on Phragmocones of Longibelus as well as those of groen- phragmocone-bearing coleoids that Longibelus gen. nov. is landibelids have been mainly found in sediments indicat- intermediate between belemnoids and Late Cretaceous 24 PALAEONTOLOGY

spirulids. Longibelus gen. nov. is belemnoid-like in having Nautilus pompilius: protein structure, gene organization, and a marginal siphuncle, stripe-like dorsal attachment scars evolution. Journal of Molecular Evolution, 62, 362–374. and a poorly developed layer of tabular nacre. On the BIRKELUND, T. 1956. Upper Cretaceous belemnites from – other side, the new genus is spirulid-like in possessing West Greenland. Meddelelser om Grønland, 137,1 28. mural flaps and lacking a rostrum proper. Diplobelid be- -and HANSEN H. J. 1974. Shell ultrastructure of some Maastrichtian Ammonoidea and Coleoidea and their taxo- lemnoids share with Longibelus gen. nov. the absence of a nomic implications. Det Kongelige Dansk Videnskabernes rostrum proper as well as a proostracum that takes one- Selskab, Biologiske Skrifter, 20,1–34. eighth of the phragmocone circumference. The latter BIRO-BAGOCZKY, L. 1982. Contribucion al conocimiento observation suggests a phylogenetic derivation of Late de Naefia neogaeia Wetzel, Coleoidea, en la formation Quiri- Cretaceous spirulids from diplobelid belemnoids via quina, Campaniano-Maastichtiano, Region del Bio-Bio, Chile, Longibelus gen. nov. This conclusion fundamentally chal- Sudamerica. Actas de la III Congreso Geologico Chileno. lenges the idea of a Carboniferous origin of the Spirulida Conception, Chile, 1,18–30. and instead supports the ‘belemnoid root-stock’ theory BOETTGER, C. B. 1952. Die St€amme des Tierreichs in ihrer suggested by Voltz (1830) and elaborated by Hewitt and systematischen Gliederung. Abhandlungen der Braunschweigis- – Jagt (1999) and Fuchs et al. (2012b). Longibelus gen. nov. chen Wissenschaftlichen Gesellschaft, 4, 238 300. appeared during the Aptian and disappeared after the BOLETZKY, S. V. 2003. Biology of early life stages in cephalopod molluscs. Advances in Marine Biology, 44, 143–203. Maastrichtian. The current fossil record further indicates DOGUZHAEVA, L. A. 1996. Two Early Cretaceous spirulid that Longibelus gen. nov. invaded the Pacific during the coleoids of the northwestern Caucasus: their shell ultrastruc- Cenomanian when the last belemnites left this part of the ture and evolutionary implications. Palaeontology, 39, 681– world. Biogeographically, the new genus had a worldwide 707. distribution. Longibelus gen. nov. as well as groenlandib- -2000. A rare coleoid mollusc from the Upper Jurassic of elid spirulids inhabited open waters above the continental central Russia. Acta Palaeontologica Polonica, 45, 389–406. slopes. -MAPES, R. H. and MUTVEI, H. 1999. A late carboniferous spirulid Coleoid from the southern mid-continent – Acknowledgements. The present study is part of the DFG-project (USA). 47 57. In OLORIZ, F. and RODRIGUEZ- FU 762/1-1 and JSPS-223840002. Our particular thanks go to TOVAR, F. J. (eds). Advancing research on living and fossil Sven Nielsen (Kiel, Germany), Neal Larson (Hill City, USA), cephalopds. Kluwer Academic/Plenum Publisher, New York, Sten Jacobson (Copenhagen, Denmark), Ajit Vartak (Pune, 566 pp. India), Vasili Mitta (Moscow, Russia) and Arturo Quinzio-Sinn --- 2010. Evolutionary patterns of Carboniferous (Concepcion, Chile) for facilitating access to specimens. Takeru coleoid cephalopods based on their diversity and morphologi- – Nakamura (Hobetsu Junior High School) and C. Metzler cal plasticity. 171 180. In TANABE K. et al. (eds). Ceph- – (Anchorage, Alaska) kindly provided Maastrichtian Longibelus alopods present & past. Tokai University Press, Tokyo, sp. from Hokkaido and Alaska. We are also grateful to Takashi 314 pp. Okamoto (Matsuyama, Japan) and Yasunari Shigeta (National DONOVAN, D. T. 1977. Evolution of the dibranchiate Cepha- – Museum of Nature and Science) for fruitful discussions. Many lopoda. 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