Introduction
The Cretaceous succession of the Haida Gwaii archipelago (formerly Queen Charlotte Islands) of western British Columbia, Canada, includes numerous abundant and well-preserved molluscan faunas, particularly in the Haida Formation, making this one of the best localities to study ammonite faunas of the North Pacific faunal province. The Haida Formation contains a number of important Albian ammonite taxa recognized elsewhere in the Pacific region and in some cases globally, including the genus Douvilleiceras and the species Anagaudryceras filicinctum (Whiteaves, Reference Whiteaves1876), “Anahoplitoides” [=Pochialayniceras Alabushev and Alabusheva (Reference Alabushev and Alabusheva1988)] yakounensis (Whiteaves, Reference Whiteaves1900), Arcthoplites (Lemuroceras) linaensis McLearn, Reference McLearn1972, Brewericeras hulenense (Anderson, Reference Anderson1938), Calliphylloceras nizinanum Imlay, Reference Imlay1960, Cleoniceras (Grycia) perezianum (Whiteaves, Reference Whiteaves1876), and Parasilesites laperousianum (Whiteaves, Reference Whiteaves1876). Among these, “A.” yakounensis, C. (G.) perezianum, and A. (L.) linaensis are all very interesting in representing typical Boreal faunal elements. The early Albian ammonite fauna of Haida Gwaii is thus a mixture of Tethyan and Boreal components in a broad sense and this mixed fauna has been called the North Pacific Fauna by Jeletzky (Reference Jeletzky1977).
Based on numbers of specimens collected over the past 140 years, ammonites of the genus Douvilleiceras form one of the most abundant and distinctive ammonite genera characteristic of the early Albian faunas of Haida Gwaii. The douvilleiceratids from the Haida Formation, particularly in the Maude Island section found in Skidegate Inlet, have been studied systematically by Whiteaves (Reference Whiteaves1876) and McLearn (Reference McLearn1972), who both recognized only one distinct species, Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876). Using an expanded set of morphological criteria, however, as well as large populations of specimens unavailable to the previous workers, we recognize five species within the genus Douvilleiceras in the Albian strata of Haida Gwaii.
Since Casey (Reference Casey1961) established the first modern biostratigraphic framework for the Albian, the European and Tethyan Albian ammonite zonations have been closely studied by numerous workers (e.g., Owen, Reference Owen1988, Reference Owen1999, Reference Owen2007; Hoedemaeker et al., Reference Hoedemaeker, Bulot, Avram, Busnardo, Company, Delanoy, Kakabadze, Kotetishvili, Krishna, Kvantaliani, Latil, Memmi, Rawson, Sandoval, Tavera, Thieuloy, Thomel, Vašiček and Vermeulen1990; Reboulet et al., Reference Reboulet, Rawson, Moreno-Bedmar, Aguirre-Urreta, Barragán, Bogomolov, Company, González-Arreola, Stoyanova, Lukeneder, Matrion, Mitta, Randrianaly, Vašiček, Baraboshkin, Bert, Bersac, Bogdanova, Bulot, Latil, Mikhailova, Ropolo and Szives2011) and, consequently, Douvilleiceras mammillatum has been recognized as an important zonal marker. As shown by Casey (Reference Casey1962), douvilleiceratid species are particularly abundant in the mammillatum Zone, the upper part of the lower Albian, of northwestern Europe. On a global scale, the stratigraphic range of douvilleiceratid ammonites is restricted to the interval from the Leymeriella (L.) tardefurcata Zone (L. acuticostata Subzone) (Kennedy and Kollmann, Reference Kennedy and Kollmann1979; Bréhéret et al., Reference Bréhéret, Caron and Delamette1986; Owen, Reference Owen1999) to the Lyelliceras lyelli Subzone of the Hoplites dentatus Zone (Owen, Reference Owen1971; Destombes, Reference Destombes1979), indicating the lower part of the lower Albian to the lower part of the middle Albian.
Geological setting
Highly fossiliferous strata of Albian-Turonian age crop out along the shores of Bearskin Bay in central Skidegate Inlet, Haida Gwaii, British Columbia (Fig. 1). These Cretaceous strata, referred to the Queen Charlotte Group (Sutherland Brown, Reference Sutherland Brown1968; Haggart, Reference Haggart1991), are well exposed along the south shore of Graham Island adjacent to the town of Queen Charlotte City, as well as along the shores of Lina, Maude, and other islands in Bearskin Bay (Haggart, Reference Haggart2004). The Albian section at Bearskin Bay is perhaps one of the best biostratigraphic reference sections for the Albian stage within the North Pacific region.
Figure 1 (1, 2) Location map of Haida Gwaii (formerly Queen Charlotte Islands), British Columbia, showing location of the Albian-Turonian succession preserved in Bearskin Bay, Skidegate Inlet (BBS; illustrated in inset 3). Circled letters in (3) indicate stratigraphic ranges of Albian fossil zones: A=Brewericeras hulenense Zone; B=Cleoniceras (Grycia) perezianum Zone; C=Mortoniceras – Desmoceras (Pseudouhligella) dawsoni Zone.
Lowermost Cretaceous strata exposed at Bearskin Bay consist primarily of conglomerate, sandstone, and alternating sandstone and siltstone. Collectively, these strata comprise the Haida Formation of the Queen Charlotte Group, and range in age from late early Albian to early late Albian (McLearn, Reference McLearn1972; Haggart, Reference Haggart1986, Reference Haggart1991). The Haida Formation grades upward into muddy siltstone and silty mudstone and shale of the informal Bearskin Bay formation, which ranges in age from late late Albian to late early Turonian (Haggart, Reference Haggart1986, Reference Haggart2004) (Fig. 1.3). The Bearskin Bay formation is in turn overlain, apparently conformably, by the poorly-fossiliferous Honna Formation (Haggart, Reference Haggart1991).
In addition to its relatively complete succession and simple structure, the Haida Formation displays an abundant and diverse molluscan fauna, including ammonites, bivalves, and gastropods. A basic biostratigraphic framework for the formation was established by McLearn (Reference McLearn1972) and Jeletzky (Reference Jeletzky1977), who recognized four local ammonite zones within the formation on Haida Gwaii. In ascending stratigraphic order these are: (1) the Leconteites lecontei Zone (=Leymeriella (L.) tardefurcata Zone in ammonite standard zonation of Reboulet et al., Reference Reboulet, Rawson, Moreno-Bedmar, Aguirre-Urreta, Barragán, Bogomolov, Company, González-Arreola, Stoyanova, Lukeneder, Matrion, Mitta, Randrianaly, Vašiček, Baraboshkin, Bert, Bersac, Bogdanova, Bulot, Latil, Mikhailova, Ropolo and Szives2011, lower lower Albian); (2) the Brewericeras hulenense Zone (=Douvilleiceras mammillatum Zone, upper lower Albian); (3) the Cleoniceras (Grycia) perezianum Zone (=Hoplites dentatus ~ Euhoplites lautus zones, middle Albian); and (4) the Mortoniceras - Desmoceras (Pseudouhligella) dawsoni Zone (Dipoloceras cristatum ~Arrhaphoceras briacensis zones, upper Albian). The Haida Formation at Skidegate Inlet, however, lacks the basal Albian Leconteites lecontei Zone (Fig. 1.3).
Douvilleiceras spiniferum (Whiteaves) is found commonly within a limited geographical and stratigraphical range in the upper lower Albian Brewericeras hulenense Zone on Lina and Maude islands (Fig. 1.2), and the northern part of Moresby Island (McLearn, Reference McLearn1972). In addition to D. spiniferum, we recognize several additional species of the genus Douvilleiceras from Haida Gwaii. All of these douvilleiceratids were obtained from calcareous concretions rich with the ammonite Brewericeras hulenense (Anderson, Reference Anderson1938) and plant fragments.
Systematic paleontology
Institutional abbreviations
BM=Natural History Museum, London; GSC=Geological Survey of Canada, Ottawa; GSM=Geological Survey Museum, London.
Dimensions
All measurements are given in millimeters. The following abbreviations are used for morphological features: D=specimen diameter; B=whorl breadth; H=whorl height; U=umbilical width; NR=number of ribs per whorl; NT=number of tubercles on each rib.
Sutural terminology
Sutural terminology follows the usage of Wedekind (Reference Wedekind1916) as augmented by Kullmann and Wiedmann (Reference Kullmann and Wiedmann1970), Wiedmann and Kullmann (Reference Wiedmann and Kullmann1981), and Korn et al. (Reference Korn, Ebbighausen, Bockwinkel and Klug2003): I=internal lobe; U=umbilical lobe; A=lateral lobe; E=external lobe.
Order Ammonoidea Zittel, Reference von Zittel1884
Suborder Ancyloceratina Wiedmann, Reference Wiedmann1966
Superfamily Douvilleiceratoidea Parona and Bonarelli, Reference Parona and Bonarelli1897
Family Douvilleiceratidae Parona and Bonarelli, Reference Parona and Bonarelli1897
Subfamily Douvilleiceratinae Parona and Bonarelli, Reference Parona and Bonarelli1897
Genus Douvilleiceras de Grossouvre, Reference de Grossouvre1894
Douvilleiceras mammillatum (Schlotheim, Reference von Schlotheim1813)
Figure 2 Douvilleiceras mammillatum (Schlotheim, 1813). (1, 2) GSC No. 21239, GSC Loc. 7598, lateral and ventral views of plaster cast. (3–8) GSC No. 10657, GSC Loc. C-303724; (3, 4) right lateral and ventral views of composite latex peel and plaster cast derived from external mold; (5, 6) left lateral and ventral views of composite plaster cast derived from external mold; (7, 8) ventral and left lateral views of actual specimen. All specimens coated with ammonium chloride.
Figure 3 Whorl sections of Douvilleiceras mammillatum (Schlotheim) from Haida Gwaii. (1), GSC No. 21239, GSC Loc. 7598. (2), GSC No. 10657, GSC Loc. C-303724.
1962Douvilleiceras mammillatum; Casey, p. 265, pl. 40, fig. 4, pl. 41, figs. 4a–b, pl. 42, figs. 6, 9a–b, 10a–b, text-figs. 94, 102a–b [with synonymy].
1962Douvilleiceras mammillatum var. aequinodum; Casey, p. 271, pl. 40, fig. 5, pl. 41, figs. 5–7, pl. 42, figs. 10a–b, text-figs. 94a–c, 95a–b, 102d, 103a–b.
1962Douvilleiceras mammillatum var. praecox; Casey, p. 272, pl. 41, figs. 8a–b, text-figs. 94d–e, 102c.
1962Douvilleiceras monile; Casey, p. 284, pl. 41, figs. 2a–b, pl. 42, fig. 5, text-fig. 102e.
1963Douvilleiceras mammillatum; Collignon, p. 109, pl. 283, figs. 1238–1239, 1241, pl. 284, fig. 1242.
?1963Douvilleiceras albense; Collignon, p. 112, pl. 284, fig. 1243.
1969Douvilleiceras mammillatum; Obata, p. 172–174, pl. 19, figs. 3, 5.
1972Douvilleiceras spiniferum; McLearn, p. 62 (pars), pl. 10, figs. 3A–C.
1979Douvilleiceras mammillatum mammillatum; Destombes, p. 69, pl. 4–21, fig. 1.
1979Douvilleiceras mammillatum var. aequinodum; Destombes, p. 71, pl. 4–4, fig. 1, pl. 4–5, fig. 2, pl. 4–21, fig. 2.
1979Douvilleiceras mammillatum var. praecox; Destombes, p. 71, pl. 4–21, fig. 3.
1979Douvilleiceras perchoisense; Destombes, p. 72, pl. 4–4, figs. 2a, b.
1983Douvilleiceras aequinodum; Weidich et al., p. 566, pl. 2, fig. 6.
1990Douvilleiceras mammillatum; Marcinowski and Wiedmann, p. 51, pl. 7, figs. 5, 6.
?2005Douvilleiceras cf. mammillatum; Myczyński and Iturralde-Vinent, p. 792, figs. 3–9, 5.1, 2, 3.
2005Douvilleiceras mammillatum; Prins, p. 31, CP46.
2008Douvilleiceras mammillatum aequinodum; Latil, p. 257, pl. 2, figs. 4, 5.
2010Douvilleiceras mammillatum; Courville and Lebrun, p. 28, pl. 1, figs. E, F.
2010Douvilleiceras monile; Courville and Lebrun, p. 28, pl. 2, fig. R, pl. 6, fig. A.
Type
Neotype, BM C12491, designated by Casey (Reference Casey1962, pl. 41, figs. 4a-b, text-fig. 102a), Folkestone Beds, main mammillatum bed, Copt Point, Folkestone, Kent (Coll. F. G. H. Price).
Description
The coiling is moderately involute and the umbilicus is moderately wide, with U/D=0.35. The whorl is depressed (Fig. 3). Multituberculate ribs on the outer whorl are rectiradiate and separated by interspaces a little wider than the ribs themselves. There are occasional intercalated ribs on the outer whorl of GSC No. 10657. The ribs number 26 per whorl on the outer whorl of GSC No. 10657. This specimen has eight rows of tubercles on each rib on the body chamber, but the inner row of ventrolateral tubercles on the left side of the shell is fainter than the other rows. This specimen shows an ontogenetic change in the number of tubercles on the outer whorl: six at less than approximately 50 mm in diameter, seven at approximately 50–70 mm, and eight at over 70 mm diameter.
Dimensions
See Table 1.
Table 1 Dimensions of specimens of Douvilleiceras mammillatum (Schlotheim, Reference von Schlotheim1813) from Haida Gwaii, British Columbia
All measurements in millimeters.
Measurements in parentheses are approximate.
* Indicating an additional row on each side of the venter.
Material
GSC No. 10657, from a sandy calcareous concretion collected at GSC Loc. C-303724. The specimen consists of approximately two-thirds of a whorl of an intermediate-sized individual, as well as the very well-preserved internal mold of the remainder of the whorl. A composite plaster cast-latex rubber mold recreates the full specimen of GSC No. 10657. Another specimen, GSC No. 21239 (figured previously as D. spiniferum (Whiteaves) by McLearn, Reference McLearn1972, pl. 10, figs. 3a–c; illustrated herein in Fig. 2.1, 2), comes from GSC Loc. 7598.
Occurrence
Whereas this species is found rarely in the lower part of the Haida Formation in Skidegate Inlet, it is widely distributed in the upper lower Albian (the mammillatum Zone) of the Mediterranean region.
Remarks
The shell ornamentation of GSC No. 10657 (Fig. 2.3–2.8), such as mode of tuberculation and ribbing, is similar to the neotype specimen of D. mammillatum, illustrated by Casey (Reference Casey1962, pl. 41, figs. 5a–b), from southeast England. The present specimen, however, has a more slender whorl compared with the neotype.
GSC No. 21239 (Fig. 2.1, 2.2), figured by McLearn (Reference McLearn1972, pl. 10, figs. 3a–c) as a specimen of D. spiniferum, has eight rows of tubercles on the outer whorl in middle growth stage, including an additional row on each side of the venter that is not seen in typical examples of the species, and fine and delicate tuberculation and fine ribbing on the outer whorl; consequently, this specimen appears to fall outside of the range of morphological variation for D. spiniferum. It is closely similar to a specimen illustrated by Casey (Reference Casey1962, p. 272, text-figs. 94–d, e) as D. mammillatum var. praecox, and we herein include it within material assigned to D. mammillatum.
Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876)
Figure 4 Lectotype of Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876), GSC No. 5014b, Skidegate Inlet, west of Alliford Bay, exact locality not recorded (Coll. J. Richardson, 1872). (1) ventral, and (2) left lateral views of plaster cast of lectotype, coated with ammonium chloride.
Figure 5 (1) Shell ornamentation of Douvilleiceras spiniferum (Whiteaves) in early growth stage. GSC No. 10708, GSC Loc. C-300855. NC=primary constriction. (2, 3) Ontogenetic changes in the whorl section of Douvilleiceras spiniferum (Whiteaves) in (2) early growth stage (GSC No. 10708, GSC Loc. C-300855), and (3) early to middle growth stage (GSC No. 10711, GSC Loc. 48572).
Figure 6 Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876). (1, 2) GSC No. 10700, GSC Loc. C-300855, ventral and right lateral views. (3, 4) GSC No. 10702, GSC Loc. C-300855, right lateral and dorsal views. (5-7) GSC No. 10693, GSC Loc. C-300855, left lateral, ventral, and dorsal views. (8, 9) GSC No. 10670, GSC Loc. C-300855, right lateral and ventral views. (10, 11) GSC No. 10677, GSC Loc. C-300855, left lateral and right lateral views. (12-14) GSC No. 10662, GSC Loc. C-300855, left lateral, ventral, and dorsal views. All specimens coated with ammonium chloride.
Figure 7 Suture line of Douvilleiceras spiniferum (Whiteaves) from Haida Gwaii. (1) Ontogenetic changes in suture line in early growth stage, GSC No. 10711, GSC Loc. 48572. (2) Suture line at middle growth stage, shell diameter approximately 40 mm, GSC No. 10708, GSC Loc. C-300855. Sutural nomenclature after Wedekind (Reference Wedekind1916), as augmented by Korn et al. (Reference Korn, Ebbighausen, Bockwinkel and Klug2003).
Figure 8 Whorl sections of Douvilleiceras spiniferum (Whiteaves) in middle growth stage. (1) GSC No. 10747, GSC Loc. 7591a. (2) GSC No. 10711, GSC Loc. 48572. (3) GSC No. 21240, collected from talus at Bush Island, Skidegate Inlet (unassigned locality). (4) GSC No. 5014b, Skidegate Inlet, west of Alliford Bay, exact locality not recorded (Coll. J. Richardson, 1872). (5) GSC No. 10746, GSC Loc. C-196887. (6) GSC No. 5014a, Skidegate Inlet, west of Alliford Bay, exact locality not recorded (Coll. J. Richardson, 1872).
Figure 9 Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876). (1, 2) GSC No. 10706, GSC Loc. C-300855, left lateral and ventral views. (3, 4) GSC No. 10660, GSC Loc. C-300855, ventral and right lateral views. Both specimens coated with ammonium chloride.
Figure 10 (1, 2)Douvilleiceras scabrosum Casey, Reference Casey1962, GSC No. 21241, GSC Loc. 7594, left lateral and ventral views. (3–5) Douvilleiceras offarcinatum (White, Reference White1887), GSC No. 10709, GSC Loc. C-304101, left lateral and ventral views, and whorl section. Both specimens coated with ammonium chloride.
1876Ammonites stoliczkanus var. spiniferus; Whiteaves, p. 24, pl. 3, fig. 3, pl. 4, fig.1.
1900Acanthoceras spiniferum; Whiteaves, p. 273, pl. 35, figs. 2, 3, 3a, text-fig. 14.
?1938Douvilleiceras restitutum; Anderson, p. 175, pl. 54, fig. 2.
1962Douvilleiceras leightonense var. pringlei; Casey, p. 277, pl. 41, figs. 3a–b, text-fig. 102j.
1967Douvilleiceras charshangense; Mirzoyev, p. 54, pl. 7, figs. 1–5.
1972Douvilleiceras spiniferum; McLearn, p. 62, pl. 10, figs. 1–3, pl. 11, figs. 1–2.
1972Douvilleiceras sp. b; McLearn, p. 67, pl. 13, figs. 1A–B, pl. 26, fig. 1.
1979Douvilleiceras tarapacaense; Etayo-Serna, p. 54, pl. 7, fig. 5, pl. 8, figs. 2, 6.
Types
GSC No. 5014b, the lectotype selected by McLearn (Reference McLearn1972) and illustrated by Whiteaves (Reference Whiteaves1876, pl. 3, fig. 3; McLearn, Reference McLearn1972, pl. 11, figs. 1A–C; illustrated herein in Fig. 4), from Skidegate Inlet, west of Alliford Bay, exact locality not recorded (Coll. J. Richardson, 1872). GSC No. 5014a, a paralectotype also figured by Whiteaves (Reference Whiteaves1876, pl. 4, fig. 1; McLearn, Reference McLearn1972, pl. 10, figs. 1A–C), was collected from the same locality.
Ontogenetic description
The ontogenetic development in the relatively early stage of D. spiniferum (less than 35 mm in shell diameter) has been studied on selected specimens (GSC No. 10708 and GSC No. 10711) from Maude Island. The protoconch appears roughly ellipsoidal in shape. A clear primary constriction exists at approximately 0.9 mm diameter. The shell surface before the primary constriction is smooth, without any trace of ribs or tubercles on the whorl. After the primary constriction, a faint lateral tubercle, or possible spine, begins to appear on the mid-flanks. These tubercles number eight per whorl at approximately 2.5 mm of shell diameter (Fig. 5.1). The whorl at this stage is greatly depressed, the height being much smaller than the width, and the whorl section is trapezoidal in form. The ontogenetic changes in the whorl section after about 1.5 mm in shell diameter are shown in Figure 5.2.
At approximately 4.2 mm in diameter, faint and numerous ribs appear on the venter, lacking tubercles. They appear to be irregular in strength. The first ventrolateral tubercle appears at about 6.2 mm in diameter as a faint conical elevation on the ventrolateral part of the ribs. At the same stage, the lateral tubercles are represented by a long spine. With further growth, the ventrolateral elevation becomes gradually higher, and then forms a distinct tubercle at approximately 7.5 mm in diameter, although it is not yet clavate. At approximately 11.5 mm in diameter, the third row of tubercles appears ventrolaterally to the second row of tubercles, and the ribs between the first ventrolateral tubercles have disappeared or become quite faint. In this stage, the first ventrolateral tubercles appear to be clavate. The first umbilical tubercles, forming the fourth row, develop along the umbilical margin at approximately 14.5 mm in diameter. At 22 mm in diameter, the third ventrolateral tubercle forms ventrolaterally to the second ventral tubercle (Fig. 6.1). Finally, at approximately 43 mm in diameter, a faint spinose tubercle appears between the lateral tubercle and the umbilical one. Regarding such ontogenetic changes as appearance or disappearance of tubercles and ribs, the present species shows great variation between individuals (Fig. 5.2, 5.3).
The sutural elements of D. spiniferum at middle growth stage are of typical Douvilleiceras form, characterized by fairly deep and narrow external and lateral lobes, and a broad and somewhat rounded first lateral saddle (E/A) (Fig. 7.2). The suture line of the extremely early growth stage is, unfortunately, not observed. At D ≈ 1–2 mm, however, the suture is expressed as EAUI, while at D >2.5 mm it is expressed as EAU2U1I, as shown in Figure 7.1. The suture of the later growth stage is given as EAU2U1I (Korn et al., Reference Korn, Ebbighausen, Bockwinkel and Klug2003). The pattern of ontogenetic change of the suture line of D. spiniferum is closely similar to that of D. “charshangense” figured by Mirzoyev (Reference Mirzoyev1967, p. 56, fig. 2).
Occurrence
This species is common in the lower part of the Haida Formation, particularly in the Brewericeras hulenense Zone (= mammillatum Zone) on Maude Island, and particularly in the Leymeriella (L.) tardefurcata and D. mammillatum zones, the lower Albian of the Lower Greensand of southern England.
Material
A large number of additional GSC specimens were obtained from calcareous concretions collected at GSC Loc. C-300855, whereas a few other specimens were collected from GSC localities 7591a, C-304101, C-304102, and GSC C-304103. All of these latter four localities are in the lower part of the Haida Formation.
Dimensions
See Table 2.
Table 2 Dimensions of specimens of Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876) from Haida Gwaii, British Columbia
All measurements in millimeters.
Measurements in parentheses are approximate.
* Indicating an additional row on each side of the venter.
Variation
Douvilleiceras spiniferum from Maude Island exhibits a very wide range of morphological variation, particularly in the number and mode of tubercles, and the shape of the whorl section. The species is generally characterized by six rows of tubercles on each flank, and occasionally seven at diameters greater than approximately 60 mm (Fig. 8). As pointed out by McLearn (Reference McLearn1972, p. 65), the appearance of an additional row of tubercles immediately adjacent to the first ventrolateral tubercles on either side, or rarely both sides, of the venter is rare, but noted. If this additional row becomes as large as the first ventrolateral tubercles, it becomes difficult to distinguish D. spiniferum from some European species, such as D. mammillatum (Schlotheim) and D. leightonense Casey. A rare example from Maude Island, GSC No. 10706 (Fig. 9.1, 9.2), shows nine rows of tubercles on each rib at 110 mm diameter; these rows are composed of fairly faint, node-like tubercles, and are not clavate on the ventrolateral part. This specimen shows typical features of D. spiniferum on the inner whorl, however: it has three rows of tubercles in the ventrolateral region at about 55 mm diameter. The specimen GSC No. 10704 has six rows of tubercles at 26.3 mm diameter and is the smallest example in our material showing six rows of tubercles. GSC No. 5014b, the lectotype of D. spiniferum figured by McLearn (Reference McLearn1972, pl. 11, figs. 1A–C; Fig. 4 herein), is unique in his material. This specimen shows different extent of tuberculation on each side: there are seven rows of tubercles on the right side of the shell, but only six rows on the left side (Fig. 8.4). This specimen appears to represent an intermediate morphological form between American D. spiniferum and European D. leightonense. Such difference in ornamentation between the right and left sides of the shell, seen as a rare example in D. spiniferum, is noted occasionally in other ornate ammonites, for example Lyelliceras ulrichi Knechtel from the middle Albian (Obata et al., Reference Obata, Shibata and Ogawa1975).
Regarding the mode of tuberculation, the present species is characterized by strong tubercles on each rib, compared with D. mammillatum discussed above. Several interesting specimens in our material, including GSC No. 10662 and GSC No. 10747, have extremely strong ventrolateral tubercles and coarse ribs in the middle growth stage (D ≈ 40–50 mm) (Figs. 6.12–6.14, 8.1). These ventrolateral tubercles are massive and form spiral ridges. In addition, the ventral sulcus is wide and deep, but not U-shaped in outline. These specimens appear to resemble a specimen of D. orbignyi Hyatt figured by Casey (Reference Casey1962, pl. 40, fig. 6), which has the weakest ornamentation among specimens referred to D. orbignyi. The Canadian specimens differ distinctly from others of D. orbignyi, however, in having three clavate tubercles in their ventrolateral region. Therefore, they are probably extreme variants of D. spiniferum.
Remarks
The morphological characters of this species have been described by Whiteaves (Reference Whiteaves1900, p. 273), and also re-examined by McLearn (Reference McLearn1972, p. 62). McLearn described the morphology of several specimens of D. spiniferum, including the lectotypes of the species, and also discussed its variation and affinities. Based on the large amount of material available, McLearn (Reference McLearn1972, p. 63) recognized one broad species-group of Douvilleiceras from the Haida Formation, viz. D. spiniferum, and two extreme variants or possible new species within this group, viz. Douvilleiceras sp. a and Douvilleiceras sp. b. Many of these specimens are poorly preserved, however, and consist of less than half a whorl.
As pointed out by McLearn (Reference McLearn1972, p. 66), Douvilleiceras restitutum Anderson (Reference Anderson1938, p. 175, pl. 54, fig. 2), from Shasta County in northern California, is closely similar to the present species, particularly in the numbers of ribs and rows of tubercles. The holotype of D. restitutum has a large shell being 153 mm in diameter, and non-tuberculate ribs above a diameter of 90 mm. Although the extent of variation in Anderson’s species has not been described, it appears to fall readily within the range of D. spiniferum in having similar morphological features on the outer whorl of the full-grown shell. A number of the specimens of Douvilleiceras charshangense from the D. mammillatum Zone of the Gissar Range in central Asia figured by Mirzoyev (Reference Mirzoyev1967, pl. 7, figs. 1–5) are considered here to fall closely within the range of variation shown by D. spiniferum, as described above. The holotype of D. charshangense, No. 116/300 (Mirzoyev, Reference Mirzoyev1967, p. 54, fig. 1, pl. 7, figs. 1–4), is quite similar to D. spiniferum in the shape of its whorl section and in showing six distinct rows of tubercles with three ventrolateral clavi. D. spiniferum also resembles D. leightonense var. pringlei Casey (Reference Casey1962, p. 277, pl. 41, figs. 3a-b, text-fig. 102j) from the Leymeriella (L.) tardefurcata and D. mammillatum zones of the Lower Greensand, particularly in having six rows of tubercles, coarser ribs, and similar whorl section. D. leightonense var. pringlei appears to fall readily within the range of variation of the present species.
Douvilleiceras offarcinatum (White, Reference White1887)
1887Ammonites offarcinatus; White, p. 219, pl. 23, figs. 3–4.
1938Douvilleiceras aurarium; Anderson, p. 175, pl. 53, fig. 1.
?1940Douvilleiceras offarcinatum; Scott, p. 1011, pl. 58, figs. 4–5.
?1974Douvilleiceras sp. cf. D. offarcinatum; Young, p. 188, pl. 1, fig. 2, pl. 4, figs. 5, 10, pl. 5, figs. 5, 6, pl. 7, fig. 3.
?1979Douvilleiceras abozagloi; Etayo-Serna, p. 55, pl. 8, fig. 7.
Types
White (Reference White1887, p. 219, pl. 23, figs. 3–4) illustrated two original specimens from the old wharf (Trapiche das Pedras Velho), Bom Jardim, Sergipe Province. They were probably obtained from the Riachuelo Formation, Sergipe Group, in Brazil.
Description
The specimen GSC No. 10709 is approximately 57 mm in diameter. The specimen has rectiradiate to very gently rursiradiate ribs and lacks intercalated ribs on the outer whorl. Ribs number 21 per whorl. On the outer whorl there are five rows of tubercles on each rib, consisting of three clavate tubercles in the ventrolateral region, a bullate or spinose lateral tubercle, and an umbilical tubercle, as shown in Figure 10.5. The medial ventral sulcus is wide.
Dimensions
See Table 3.
Table 3 Dimensions of specimens of Douvilleiceras offarcinatum (White, Reference White1887) from Haida Gwaii, British Columbia
All measurements in millimeters.
Material
A single specimen, GSC No. 10709, obtained from a sandy calcareous concretion at GSC Loc. C-304101, Haida Formation.
Occurrence
This species is known from the upper lower Albian, the mammillatum Zone of the lower part of the Haida Formation in Canada, the Cuchillo Formation in Texas, and Sergipe Province in Brazil.
Remarks
The morphological characters of this specimen are closely similar to those of the holotype of D. aurarium Anderson (Reference Anderson1938, p. 175, pl. 53, fig. 1) from Shasta County, northern California. It is difficult to distinguish D. aurarium from D. offarcinatum (White, Reference White1887) from Brazil, particularly in the mode and number of tubercles on both examples. Our specimen is somewhat similar to D. spiniferum; a distinct difference between them, however, is that our example of D. offarcinatum shows no intermediate tubercle between the lateral and umbilical tubercles, even in the middle growth stage at 57 mm in diameter. Because the intermediate tubercles in D. spiniferum are already present on the flanks at this growth stage, the characteristic tuberculation of this specimen thus appears to fall outside the range of variation of D. spiniferum.
Douvilleiceras scabrosum Casey, Reference Casey1962
Figures 10.1, 10.2, 11
Figure 11 Whorl sections of Douvilleiceras scabrosum Casey from Haida Gwaii. GSC No. 21241, GSC Loc. 7594, at approximately 75 mm in shell diameter (1) and at approximately 127 mm in shell diameter (2).
?1841Ammonites mammillaris; d’Orbigny, p. 249, pl. 72, fig. 5.
1962Douvilleiceras scabrosum; Casey, p. 278, pl. 40, figs. 1–3, pl. 42, figs. 2a-b, text-figs. 102f, 103i.
1972Douvilleiceras sp. a; McLearn, p. 67, pl. 12, figs. 1A, B.
Types
The holotype, BM C69861, illustrated by Casey (Reference Casey1962, pl. 40, figs. 1a-b, text-fig. 102f), from Folkstone Beds, mammillatum Zone Bed, Chrismill Bridge (M20 Motorway), Eyhorne Street, Kent (Coll. H. G. Owen); paratypes GSM 107909 (Casey, Reference Casey1962, pl. 40, figs. 2a-b), GSM 70424 (Casey, Reference Casey1962, pl. 40, figs. 3a-b, text-fig. 103i), GSM 107913 (Casey, Reference Casey1962, pl. 42, figs. 2a-b), Folkestone Beds, main mammillatum bed, Copt Point, Folkestone, Kent (Coll. R. Casey), GSM Zn940 from the Folkestone Beds, the puzosianus Subzone, Sandling Junction, and BM C54304 from Machéroménil, Ardennes.
Dimensions
See Table 4.
Table 4 Dimensions of specimens of Douvilleiceras scabrosum Casey, Reference Casey1962 from Haida Gwaii, British Columbia
Notes
All measurements in millimeters.
* Measurements taken from plaster cast.
** Indicating an additional row on each side of the venter.
Material
A single specimen, GSC No. 21241, described and illustrated by McLearn (Reference McLearn1972, p. 67, pl. 12, figs. 1A-B; illustrated herein in Fig. 10.1, 2) as Douvilleiceras sp. a, is from GSC Loc. 7594.
Occurrence
This species is known from the mammillatum Zone of the lower part of the Haida Formation in Canada and the Lower Greensand of southern England and France.
Remarks
This specimen was identified by McLearn (Reference McLearn1972, p. 67, pl. 12, figs. 1A-B) as Douvilleiceras sp. a. McLearn described the features of this specimen, giving comparisons with two other species of Douvilleiceras, D. spiniferum and D. scabrosum. McLearn concluded that the specimen either represents an extreme variant of D. spiniferum or a new species. We re-examined the specimen GSC No. 21241. The ribs are unequal in strength and rarely intercalated on the outer whorl. The tuberculation is represented by four distinct clavate tubercles in the ventrolateral region, a strong lateral spinose tubercle, a faint intermediate node-like tubercle, and a bullate umbilical one (Fig. 11.1). Based on the composition of these tubercles, this specimen falls distinctly outside of the range of variation of D. spiniferum.
The morphological features of this specimen, particularly the mode of tuberculation, the number of rows of tubercles on each side, and the mode of ribbing, are closely similar to those of the paratype of D. scabrosum Casey, GSM 107909 (Casey, Reference Casey1962, p. 278, pl. 40, figs. 2a-b), from the mammillatum Zone of England. The Canadian specimen has somewhat weaker ribs than the paratype of D. scabrosum, and the initial appearance of the intermediate tubercles in this specimen is somewhat later than in the holotype and paratypes of D. scabrosum. It does appear, however, to fall within the relatively wide variation of D. scabrosum. According to Casey (Reference Casey1962, p. 278), D. scabrosum differs from D. mammillatum in having irregular and coarse ribbing and a wide ventral sulcus. In addition, the number of rows of tubercles on each side is seven, although the holotype specimen exhibits an additional row of tubercles on each side of the venter (Casey, Reference Casey1962, p. 285, text-fig. 102f).
Douvilleiceras aff. spiniferum (Whiteaves, Reference Whiteaves1876)
Figure 12 Douvilleiceras aff. spiniferum (Whiteaves, Reference Whiteaves1876) from Haida Gwaii, GSC No. 10710, GSC Loc. C-300855. (1, 2) Dorsal and left lateral views, coated with ammonium chloride. (3) Whorl section. (4) Suture line. Scale bar=3 mm. Small dashed ellipses denote nodes; larger irregular dashed features denote ribs.
Description
Although the specimen has a secondarily deformed body-chamber shell, the ornamentation on the septate part of the whorl is well-preserved. The shell is of the middle growth stage, ca. 67.8 mm in diameter, evolute and widely umbilicate. The whorl is depressed (B/H =1.34). The whorl section is polygonal along the costa, with maximum thickness at the mid-flank. Ribs on the outer whorl are rectiradiate across the middle and outer parts of the flank, but rursiradiate on the umbilical margin; they number twenty-two on the outer whorl, and are coarse and separated by interspaces wider than the ribs themselves. There are six rows of tubercles on the body chamber at about 67 mm diameter. Three ventral tubercles are clavate, forming somewhat distinct spiral ridges. On the septate part of the whorl greater than 40 mm diameter, the lateral and umbilical tubercles are faint or lacking, and the ribs on the inner half-whorl are fused to form a wing-like feature, rather than distinct tubercles (Fig. 12.3). The ventral sulcus is wide and deep, but not U-shaped in outline. The suture line is well-preserved on the septate portion of the whorl (Fig. 12.4). The external (E) and lateral (A) lobes are relatively narrow and deep, and the first lateral (E/A) and umbilical (A/U1) saddles are broad. The character of the suture is a typical douvilleiceratid.
Dimensions
See Table 5.
Table 5 Dimensions of specimens of Douvilleiceras aff. spiniferum (Whiteaves) from Haida Gwaii, British Columbia
All measurements in millimeters.
Measurements in parentheses are approximate.
Material
A single specimen, GSC No. 10710, was collected by M. Futakami from a calcareous concretion at GSC Loc. C-300855.
Occurrence
The specimen was obtained from the lower member of the Haida Formation. Its stratigraphic position is assigned to the upper part of the lower Albian, the mammillatum zone.
Remarks
The specimen is characterized by an extended rib which forms a wing-like feature on the inner half-whorl of the middle growth stage. Due to the presence of this extended rib on the flanks, the umbilical tubercle has disappeared, and the lateral tubercle becomes faint or disappears altogether. The specimen is unique, particularly in the shape of its costal section, and differs from all other species of Douvilleiceras in this feature. The specimen is similar to D. spiniferum (Whiteaves) in the mode of the ventrolateral clavate tubercles, which exhibit the great range of variation described above. The specimen differs from typical D. spiniferum, however, in having the unique, extended rib on the inner half-whorl on the middle growth stage. In addition, the ribs on this species are sharper than those of D. spiniferum. This specimen may represent an extreme variant of D. spiniferum, possibly a malformed shell of that species, or possibly a new species altogether.
Discussion
Ammonites assigned to the genus Douvilleiceras are characterized by the presence of a ventral sulcus and multituberculate ribs in the early and middle growth stages. The tuberculation consists of five to ten rows of tubercles on each rib in the middle growth stage, about 50 or 60 mm to 100 mm in shell diameter. The tubercles are variable in morphology and position; typically they consist of umbilical bullae or spinose nodes, lateral spinose nodes, and ventrolateral clavi, often with numerous intermediate tubercles. The umbilical and lateral tubercles form the bases of spines, which were probably broken off from the shell during post-mortem processes. The rather depressed whorl is polygonal in cross-section.
In late growth stage, generally over 100 to ~150 mm in shell diameter, the ventral sulcus and ventrolateral tubercles become gradually fainter with growth and finally disappear altogether. The non-tuberculate ribs on the outer whorl of the full-grown shell are more numerous than the tuberculate ones in the middle growth stage. The whorl has a nearly circular cross-section, and maintains faint tubercles on the umbilical margin. The largest shells of the genus known to us include an example assigned to Douvilleiceras sp. cf. leightonense (Casey, Reference Casey1962, p. 276, text-fig. 97) from southeast England, which is about 440 mm in diameter (approximately 650 mm in estimated shell diameter), and also another example assigned to D. clementinum (Courville and Lebrun, Reference Courville and Lebrun2010, p. 27, fig. 12) from Troyes (Aube) in the Paris basin which is over 800 mm in diameter. These specimens exhibit weak tuberculation only in the umbilical region and the ribs are also faint, weakening on the latest preserved part of the whorl to the extent the flanks are almost smooth. The simplified suture line is characterized by fairly deep and narrow external and lateral lobes, and a broad and somewhat rounded first lateral saddle.
Previously-described species of Douvilleiceras exhibit various morphological features in the middle growth stage of their ontogenetic sequences. We consider the mode of tuberculation and ribbing in the middle growth stage, as well as the general shell proportions, as the key morphological criteria to be used in differentiating species of Douvilleiceras. The ventrolateral ornamentation that characterizes the middle growth stage is particularly diagnostic, as Casey (Reference Casey1962) has noted. The morphological features in early and late growth stages of this genus are similar to those of the late Aptian genus Cheloniceras. For this reason, identification of a species or a genus of Douvilleiceras based on the morphological features of the early or late growth stage alone is often problematic.
Conclusions
The rich Cretaceous faunas of the Haida Gwaii archipelago of British Columbia contain an abundance of ammonite taxa and serve as a reference for Albian faunas of the northeast Pacific region. Specimens of the cosmopolitan genus Douvilleiceras form a significant component of the late early Albian faunas of Haida Gwaii and have traditionally been assigned to a single species, Douvilleiceras spiniferum (Whiteaves, Reference Whiteaves1876). We recognize five from the Albian strata of Haida Gwaii, which are Douvilleiceras mammillatum (Schlotheim), D. offarcinatum (White), D. scabrosum Casey, D. spiniferum (Whiteaves), and D. aff. spiniferum (Whiteaves). Among these, D. spiniferum is particularly abundant, with many specimens exhibiting well-preserved shell. This population thus provides a comprehensive understanding of the ontogenetic development of the early growth-stage of D. spiniferum, as well as the successive ontogenetic changes in the species’ whorl shape, its ornamentation and suture line, and its overall morphological variation, which is substantial. The stratigraphic position of Douvilleiceras faunas on Haida Gwaii are within the Brewericeras hulenense Zone (=mammillatum Zone) of the upper lower Albian in Canada, equivalent with the Leymeriella (L.) tardefurcata and D. mammillatum zones of the lower to upper lower Albian in England.
Douvilleiceras populations of Haida Gwaii demonstrate that species of the genus are characterized by appreciable morphological variation, particularly with respect to the shape of the whorl and the pattern of ribbing and tuberculation. Morphological variation is most accentuated in the middle growth stage, approximately 50 or 60 mm to 100 mm in shell diameter, with earlier and later growth-stages showing less distinctive features. The most useful criteria for differentiating species within the genus Douvilleiceras are the mode of tuberculation and ribbing, as well as overall shell proportions, of the middle growth stage.
Acknowledgments
We thank the late Mr. Yoshitaro Kawashita, who helped us collect specimens on Haida Gwaii, and Mr. Rod Bartlett (Vancouver), who provided expert specimen preparation. Hillary Taylor and Peter Krauss provided help with graphics and photo production and Fontaine Hwang and Diane Thompson provided assistance in obtaining critical literature. We are much indebted to the late Emeritus Prof. Tatsuro Matsumoto (Kyushu University), as well as Drs. Ikuwo Obata (National Science Museum, Tokyo; deceased), Hugh G. Owen (Natural History Museum, London), and Terry P. Poulton (Geological Survey of Canada, Calgary) for their critical readings of early drafts of the manuscript and for providing valuable comments on systematics. The manuscript was also improved significantly through the contributions of Dr. Hugh Owen and we extend our sincere thanks for his effort. This study was carried out with the financial support of Kawamura Gakuen Woman’s University (Abiko) and the Geological Survey of Canada (Project 880038). This paper is a contribution of IGCP Project 362 and also Geological Survey of Canada Contribution 2005312.
Appendix A. Fossil Locality Data
GSC Loc. 7591a. 103F/01 map-area, UTM Zone 8, 697125E, 5900850N. Skidegate Inlet, Maude Island, north shore, east section, east side of Contact Bay; small cave separates agglomerates from base of Haida Formation; float. Coll. F. H. McLearn, 1921, Field # Q.H.D.8. Haida Formation.
GSC Loc. 7594. 103F/01 map-area, UTM Zone 8, 697925E, 5900900N. Skidegate Inlet, Maude Island, north shore, east section; in place. Coll. F. H. McLearn, 1921, Field # Q.H.D.14. Haida Formation.
GSC Loc. 7598. 103F/01 map-area, UTM Zone 8, 693775E, 5901350N. Skidegate Inlet, Lina Island, south shore, a large ledge along shore below McLellan house, west; in place. Coll. F. H. McLearn, 07/08/1921, Field # Q.H.E.3. Haida Formation.
GSC Loc. 7613a. 103F/01 map-area, UTM Zone 8, 700125E, 5900100N. Skidegate Inlet, northerly [Bush Island] of two islets in Alliford Bay between Transit Island and Kwuna Point; float. Coll. F. H. McLearn, 08/09/1921, Field # Q.H.P.2. Haida Formation.
GSC Loc. 48572. 103F/01 map-area, 53° 13.25’N, 132° 2.00’W. Skidegate Inlet, Maude Island. Coll. A. Sutherland Brown, 1961, Field # ASB-61-295. Haida Formation.
GSC Loc. C-196887. 103G/04 map-area, Zone 9, 300900E, 5897850N. Northern Moresby Island, along logging road; in place. Coll. J. W. Haggart, 07/17/1991, Field # HFB-91-273. Haida Formation.
GSC Loc. C-300855. 103F/01 map-area, UTM Zone 8, 697900E, 5900775N. Skidegate Inlet, northeast shore of Maude Island; in place. Coll. J. W. Haggart, 07/21/1993, Field # HFB-93-631 and M. Futakami, 09/11/1997. Haida Formation.
GSC Loc. C-303724. 103G/04 map-area, UTM Zone 9, 300650E, 5897850N. Northern Moresby Island, small cliff along north side of logging road; in place. Coll. J.W. Haggart, 07/17/1991, Field # HFB-91-271. Haida Formation.
GSC Loc. C-304101. 103G/04 map-area, UTM Zone 9, 300650E, 5897850N. Northern Moresby Island, small cliff along north side of logging road; in place. Coll. M. Futakami, 05/16/1997. Haida Formation.
GSC Loc. C-304102. 103F/01 map-area, UTM Zone 8, 697950E, 5900725N. Skidegate Inlet, Robber Point, northeast shore of Maude Island; in place. Coll. M. Futakami, 09/11/1997. Haida Formation.
GSC Loc. C-304103. 103F/01 map area, UTM Zone 8, 697640E, 5900800N. Skidegate Inlet, Maude Island, north shore; in place. Coll. M. Futakami, 10/04/1997. Haida Formation.
