ARCTIC VOL. 67, NO. 1 (MARCH 2014) P. 1 – 9 A Hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous (Campanian) Kanguk Formation of Axel Heiberg Island, Nunavut, Canada, and Its Ecological and Geographical Implications MATTHEW J. VAVREK,1 LEN V. HILLS2 and PHILIP J. CURRIE3 (Received 1 October 2012; accepted in revised form 30 May 2013) ABSTRACT. A hadrosaurid vertebra was recovered during a palynological survey of the Upper Cretaceous Kanguk Formation in the eastern Canadian Arctic. This vertebra represents the farthest north record of any non-avian dinosaur to date. Although highly abraded, the fossil nonetheless represents an interesting biogeographic data point. During the Campanian, when this vertebra was deposited, the eastern Canadian Arctic was likely isolated both from western North America by the Western Interior Seaway and from more southern regions of eastern North America by the Hudson Seaway. This fossil suggests that large-bodied hadrosaurid dinosaurs may have inhabited a large polar insular landmass during the Late Cretaceous, where they would have lived year-round, unable to migrate to more southern regions during winters. It is possible that the resident herbivorous dinosaurs could have fed on non-deciduous conifers, as well as other woody twigs and stems, during the long, dark winter months when most deciduous plant species had lost their leaves. Key words: Appalachia, Arctic, Campanian, dinosaur, Laramidia, palaeobiogeography RÉSUMÉ. La vertèbre d’un hadrosauridé a été retrouvée pendant l’étude palynologique de la formation Kanguk remontant au Crétacé supérieur, dans l’est de l’Arctique canadien. Il s’agit de la vertèbre appartenant à un dinosaure non avien qui a été recueillie la plus au nord jusqu’à maintenant. Même si ce fossile est fortement abrasé, il n’en reste pas moins qu’il représente un point de donnée biogéographique intéressant. Pendant le Campanien, lorsque cette vertèbre a été déposée, l’est de l’Arctique canadien était vraisemblablement isolé de l’ouest de l’Amérique du Nord par la mer intérieure occidentale, et des régions plus au sud de l’est de l’Amérique du Nord par le bras de mer Hudson. Ce fossile suggère que de gros dinosaures hadrosauridés auraient pu habiter une grande masse terrestre insulaire polaire pendant le Crétacé tardif, où ils auraient évolué à l’année, étant incapables de migrer vers les régions plus au sud pendant l’hiver. Il est possible que les dinosaures herbivores résidents se soient nourris de conifères non décidus ainsi que d’autres tiges ou brindilles ligneuses pendant les longs mois sombres de l’hiver, lorsque la plupart des espèces végétales décidues avaient perdu leurs feuilles. Mots clés : Appalachia, Arctique, Campanien, dinosaure, Laramien, paléobiogéographie Traduit pour la revue Arctic par Nicole Giguère. INTRODUCTION et al., 2012), the Northwest Territories (Russell, 1984), and Nunavut (Russell, 1990; Núñez-Betelu et al., 2005). Addi- Since the first evidence of polar dinosaurs was discovered tional areas, such as northern Alberta (Currie et al., 2008; in Spitsbergen (Svalbard) in 1960 (de Lapparent, 1960, Fanti and Miyashita, 2009) and northern British Columbia 1962), Late Cretaceous dinosaurs have been found across (Rylaarsdam et al., 2006; Arbour and Graves, 2008), are not much of the Arctic (Rich et al., 2002; Weishampel et al., considered polar today, but would have been near or north 2004; Gangloff, 2012). These findings include remains of the Arctic Circle during the Cretaceous. from Russia (Nessov and Golovneva, 1990; Averianov and A hadrosaurid dinosaur vertebra was found on Axel Sues, 2007; Godefroit et al., 2009), Alaska (Brouwers et al., Heiberg Island, Nunavut (Fig. 1), in July 1992 during a 1987; Fiorillo and Gangloff, 2000; Gangloff et al., 2005; stratigraphic and palynological survey of the Kanguk Fiorillo, 2008; Brown and Druckenmiller, 2011), Yukon Formation in the northeastern Canadian Arctic (Núñez- (Rouse and Srivastava, 1972; Gangloff et al., 2004; Evans Betelu et al., 2005). This same expedition also recovered 1 Royal Ontario Museum, Department of Natural History, 100 Queen’s Park, Toronto, Ontario M5S 2C6, Canada; [email protected] 2 Deceased 3 Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada http://dx.doi.org/10.14430/arctic4362 © The Arctic Institute of North America 2 • M.J. VAVREK et al. capped by a rooted paleosol and is directly overlain by mud- stones of the Kanguk Formation. A similar situation exists at Strathcona Fiord (78.5472˚ N, 82.9153˚ W), but the coars- ening upward sequence is less well defined and is replaced by interbedded sandstones, which thin upwards and have interbeds of mudstone that thicken upwards. The coars- ening upward sequences gradational to the Eureka Sound Group are coarsest in the east and are thinner and finer- grained to the west. This pattern indicates that the source of the Kanguk Formation lay to the east of May Point along the axis of Ellesmere Island, and thus the dinosaur vertebra was sourced west of the axis of Ellesmere Island. Hills et al. (1994) described Scaphites depressus Reeside from the Kanguk Formation at the head of Glacier Fiord on southwestern Axel Heiberg Island, providing clear evidence of a connection with the Western Interior Seaway. Palyno- logical evidence indicates that the Kanguk Formation at Glacier Fiord is contiguous with the formation at May Point, although the sediments at May Point were deposited farther offshore. Since uplift on Axel Heiberg Island post- dates the Kanguk Formation, present-day Axel Heiberg Island was not yet above sea level when the dinosaur fossil FIG. 1. Location of Axel Heiberg Island, Nunavut, Canada. Star denotes was deposited. Therefore, the vertebra must have originated approximate discovery site of the dinosaur fossil at May Point. from a nearby terrestrial area. additional vertebrate remains of a hesperornithid bird and a large fish Xiphactinus( sp.) from nearby Ellesmere Island LOCAL GEOLOGY (Hills et al., 1999), although no non-avian dinosaurs were found on that island. This most northerly occurrence of a The hadrosaurid vertebra was found within the upper non-avian dinosaur has biologic, climatic, and geographic portion of the Kanguk Formation, at May Point on Axel implications for dinosaurs inhabiting this region during the Heiberg Island, Nunavut, Canada (Fig. 2). The local sedi- Late Cretaceous. ments also contained a large marine reptile fossil and abundant dinoflagellate cysts (Núñez-Betelu et al., 2005), indicating that the dinosaur bone was preserved in a marine GEOLOGICAL SETTING environment. The dinosaur fossil is abraded, suggesting it was likely worn in a fluvial or shoreline environment before The Sverdrup Basin is a major Carboniferous to Pale- being transported out to sea for burial. ogene depocentre within the Canadian Arctic Islands (Embry, 1991; Embry and Beauchamp, 2008), and the Cenomanian/Turonian to Campanian aged Kanguk Forma- PALYNOLOGY tion outcrops extensively within the basin (Núñez-Betelu et al., 1994). In general, the lower Kanguk Formation is com- Samples collected 8 m above the dinosaur-bearing hori- posed of dark, organic-rich mudstones that represent a low- zon yielded dinoflagellate cysts, acritarchs, spores, and pol- oxygen and low-energy environment (Núñez-Betelu et al., len (Appendix 1). In particular, the palynomorphs recovered 1994). The upper Kanguk Formation strata are composed were well preserved, and the assemblage was dominated of claystones, siltstones, and very fine-grained sandstones by the dinoflagellate Scrinodinium crystallinum (Núñez- (Núñez-Betelu et al., 1994). These upper beds record a shal- Betelu et al., 2005). The microfossil assemblage correlates low shelf and nearshore facies and contain an abundant well with Biozone 4 of Núñez-Betelu (1994), suggesting a marine and terrestrial microfossil record, as well as inocer- middle Campanian age (Núñez-Betelu et al., 2005). amids, ammonites, and indeterminate marine vertebrates (Núñez-Betelu et al., 1994; Hills et al., 1999). The Kanguk Formation gradationally overlies the Has- PALAEOCLIMATE AND PALAEOGEOGRAPHY sel Formation and is gradationally overlain by the Eureka Sound Group on Ellesmere Island. At Cañon Fiord, Elles- The climate during the Late Cretaceous was much mere Island (79.8758˚ N, 82.2378˚ W), the upper Hassel warmer than at present (Frakes, 1979; Barron, 1983; Hal- Formation consists of a series of coarsening upward cycles lam, 1985), and Arctic regions in particular had much higher separated by marine mudstones. The last of these cycles is temperatures, which produced a smaller equator-to-pole LATE CRETACEOUS HADROSAURID • 3 temperature gradient than exists today (Barron, 1983; Amiot et al., 2004). By the Campanian, global temperatures had declined somewhat from their high in the Turonian (Parrish and Spicer, 1988a; Jenkyns et al., 2004), and Arctic regions during the Campanian may have experienced frosts and some snowfall (Wolfe and Upchurch, 1987; Amiot et al., 2004). Sea levels during the Late Cretaceous were much higher than at present (Haq et al., 1987), and large portions of North America were flooded by inland seaways (Kauffman and Caldwell, 1993; Smith et al., 1994; Hay et al., 1999). In particular, the large Western Interior Seaway extended from the Arctic Ocean to the Gulf of Mexico for most of the Late Cretaceous, dividing North America into western and eastern sub-continents, sometimes referred to as Laramidia and Appalachia, respectively. During the Late Cretaceous, North America was at approximately the same latitude as it is today, although it was rotated clockwise relative to its present orientation (Smith et al., 1994; Scotese, 2002). This rotation meant that Alaska, Yukon, northern British Columbia, and Alberta would have been farther north than they are currently, while eastern Nunavut would have been somewhat farther south. The rotation of the continent would have placed sev- eral dinosaur-bearing localities in northern British Colum- bia and Alberta near or north of the Arctic Circle; however, Axel Heiberg Island would have been farther south (at approximately 75˚ N) than it is at present (Scotese, 2002).