The paleoenvironment of Tyrannosaurus rex from ...antiquus Dawson or Ficus ceratops Knowlton are...

The paleoenvironment of Tyrannosaurus rex fromsouthwestern Saskatchewan, Canada

Elisabeth E. McIver�

Abstract: The recovery of identifiable plant remains intimately associated with a skeleton of Tyrannosaurus rex insouthwestern Saskatchewan, Canada, provides the basis for interpreting the latest Maastrichtian (65.5–65 Ma)paleoenvironment of the region. Fossil plants from the site are described, and fruits formerly known as Aesculusantiquus Dawson or Ficus ceratops Knowlton are transferred to a new taxon, Spinifructus antiquus (Dawson) comb.nov. Study of the sediments of the Frenchman Formation that host the bones and plants, in combination with analysisof the plants, indicates that the regional climate was mesothermal and without winter frost, but with seasonal drought.The T. rex is believed to have roamed a broad river valley abundantly vegetated by a largely deciduous flora. The de-ciduous nature of the Saskatchewan paleovegetation, interpreted as a response to low winter light levels at high lati-tude, contrasts strongly with the contemporaneous vegetation of a few degrees latitude further south and leads toquestions about how a dinosaur fauna survived in a region where the bulk of the vegetation entered an extended periodof dormancy.

Résumé : La collecte de restes de plantes identifiables intimement associées à un squelette de Tyrannosaurus rex dansle sud-ouest de la Saskatchewan, au Canada, constitue la base pour interpréter le paléoenvironnement du Maastrichtienterminal (65,5 à 65 Ma) de la région. Des plantes fossiles du site sont décrites et des fruits antérieurement connuscomme Aesculus antiquus Dawson ou Ficus ceratops Knowlton sont transférés à un nouveau taxon Spinifructus anti-quus (Dawson) comb. nov. L’étude des sédiments de la Formation de Frenchman qui contient les os et les plantes,combinée à l’analyse des plantes, indique que le climat régional était mésothermique et sans gelée hivernale mais avecdes sécheresses saisonnières. On croit que T. rex se déplaçait dans une large vallée de rivière où la végétation abon-dante était surtout à flore décidue. La nature décidue de la paléovégétation de la Saskatchewan, interprétée comme uneréponse aux faibles niveaux de lumière en hiver à haute latitude, contraste fortement avec la végétation contemporaineprésente à quelques degrés de latitude plus au sud et porte à remettre en question le fait qu’une faune de dinosaures aitsurvécu dans une région où la plus grande part de la végétation entrait dans une période de dormance étendue.

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Introduction

The remains of what is currently the most popular dinosaur,Tyrannosaurus rex, have been found in sediments of theFrenchman Formation (latest Maastrichtian) near Eastend,Saskatchewan, Canada. Recovery of the skeleton is continuing,and Tokaryk (1997b) has estimated that at least 65% of theskeleton was preserved. As few relatively complete skeletonsof T. rex have been discovered, the Eastend skeleton has thepotential to contribute new information about the species(Tokaryk 1997b).

This discovery, however, is remarkable for another reason,as the remains of this dinosaur were preserved in intimateassociation with numerous identifiable leaves, seeds, fruits,and other plant remains. This is a rare and improbable eventin itself, as the depositional environments required for pres-ervation of bones and plants are typically mutually exclusive

(Retallack 1997). Furthermore, other than the few fossil plantsdescribed by Berry (1935) and Dawson (1875), and plant cuticleremains from latest Maastrichtian coals of the Wood Mountainregion of Saskatchewan (McIver 1999), little has been knownabout the flora of the Frenchman Formation of Saskatchewan.Some of the fossil plants recovered appear new to science;others provide new information on previously describedtaxa. For example, well-preserved specimens of the fruitspreviously described as Ficus ceratops Knowlton providedinformation that allows taxonomic revision and assignmentof these fruits to a new genus, as a new combination,Spinifructus antiquus (Dawson) comb. nov.

Despite its popularity, little is written about thepaleoenvironments in which Tyrannosaurus rex existed.Retallack (1997, p. 353) reports that remains of T. rex “havebeen found in Sapakot, Maka, and Spatsiko paleosols, withno clear pattern of preference.” These soils are interpreted as

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Can. J. Earth Sci. 39: 207–221 (2002) DOI: 10.1139/E01-073 © 2002 NRC Canada

Received 28 April 2001. Accepted 26 September 2001. Published on the NRC Research Press Web site at http://cjes.nrc.ca on20 February 2001.

Paper handled by Associate Editor B. Chatterton.

E.E. McIver.1, 2 Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK S7N 5E2, Canada.

1�Author is deceased. Elisabeth McIver passed away on April 1, 2001.2Address correspondence to James Basinger. (e-mail: [email protected]).

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those of early successional communities of stream sides. Afew other reports discuss briefly the biogeography (Lehman1987), hunting behaviour (Currie 1997), and predator–preyrelationships (Chin 1997). It is well established that fossilplants provide the best evidence for ancient terrestrial envi-ronments and climate; therefore, the plants from the T. rexquarry, combined with sedimentological data, provide thebasis for interpreting the paleoenvironment of T. rex fromsouthwestern Saskatchewan. The nature of the vegetation,interpreted as fully deciduous, raises questions about the survivalof T. rex and of its prey in the region during months of winterdormancy.

Materials and methods

Stratigraphic contextSouthern Saskatchewan is primarily a land of flat, grass-

covered plains, or prairies. Beneath a thin veneer of Quaternaryglacial drift, the widely distributed, predominately marinedeposits of the Upper Cretaceous provide evidence of inundationof this part of the Western Interior by an epeiric seaway(Mossop and Shetsen 1994). Nonmarine sediments progradedin a northeasterly direction during regression of the sea inlatest Cretaceous time, although these deposits were to alarge extent removed by erosion before or during Pleistoceneglaciation. Nevertheless, some Maastrichtian and Tertiarydeposits form the hills, uplands, and buttes that characterizethe southwest corner of Saskatchewan (i.e., the CypressHills). These are primarily fluvial in origin, deposited bymeandering river systems.

Four late Maastrichtian formations overly the Campanianto Maastrichtian marine shales of the Bearpaw Formation:the mainly sandy Eastend Formation; the highly kaolinizedsands and refractory clays of the Whitemud Formation; thebentonitic Battle Formation; and the fluvial dinosaur-bearingFrenchman Formation (Fig. 1; Fraser et al. 1935; Furnival1946; Kupsch 1956). The Frenchman Formation is overlainby fluvial sediments deposited after the terminal Cretaceousextinction event that claimed the dinosaurs (Fig. 1). ThesePaleocene sediments of the Ravenscrag Formation arelignite-bearing, richly fossiliferous clays, silts, and sands,which are the source of abundant, well-preserved plantremains (McIver and Basinger 1993). In the Cypress Hillsregion, the Ravenscrag Formation may be overlain uncon-formably by the Eocene to Miocene Cypress Hills Formation,well known for its mammalian fauna (Lambe 1908; Fraser etal. 1935; Russell 1949; Storer and Bryant 1993; Storer1996). Elsewhere, the Ravenscrag Formation forms an erosionalsurface that may be covered by Quaternary drift (Fraser etal. 1935).

The remains of the Tyrannosaurus rex skeleton, called“Scotty” by the local residents, were recovered from sedimentsof the Frenchman Formation at Chambery Coulee, southeastof the town of Eastend. The Frenchman Formation commonlyconsists of two distinct facies types, one sand-dominated, theother clay-dominated. While these may appear to succeedone another locally, regionally these “units” are seen to belaterally discontinuous (Kupsch 1956; 1957).

The sandy facies of the Frenchman Formation are lightolive-grey to dark greenish-grey, in places yellowish-orangeto brown, with medium-scale cross stratification (Kupsch

1956). According to Kupsch (1956, p. 20), the sands are“medium to fine grained subgreywacke of the ‘salt-and-pepper’variety with locally some large indurated masses, wellcemented by calcium carbonate”. The sandy facies includesclay and silt lenses, macerated plant remains, fossil wood,and thin coal stringers. The skeleton of the Tyrannosaurusrex is preserved within sediments of the sandy facies, andthe plant remains described in this report were recoveredfrom sands and clay lenses associated with the skeleton.

The clay facies is predominately grey to green and blue topurple bentonitic clays, although fine-grained sands may beintercalated in places. Recognizable plant remains, otherthan rare beds of permineralized fruits and some organic debris,are unknown from the clay facies.

In places where a complete section has been preserved,the lower boundary of the Frenchman Formation appears torest conformably upon the Battle Formation (Fig. 2), but inmany places, including the study area of Chambery Coolee,an erosional unconformity exists beneath a thickened Frenchmanthat has removed a significant thickness of preexistingdeposits. In such areas, the existence of the Battle Formationis debatable, and in the absence of clearly distinguishingfeatures, the Frenchman and Battle are here lumped into asingle unit.

The contact between the Battle and the underlying WhitemudFormation is unconformable throughout the region, andrepresents a significant hiatus, during which the land surfacewas aerially exposed and subject to erosion, and the Frenchman–Battle may rest on Whitemud, Eastend, or Bearpaw deposits(Fraser et al. 1935; Kupsch 1957; Sweet et al. 1997;Catuneanu and Sweet 1999). Along the Frenchman River, inthe vicinity of Chambery Coulee, the Frenchman–Battle isabout 57 m thick, rests directly on Bearpaw shales, andappears to be infilling the deepest part of a broad erosionalchannel (Fraser et al. 1935; Fig. 2, section 3). To the northeast,along Swift Current Creek, the Frenchman–Battle is up to 55 mthick and also directly overlies the Bearpaw Formation,apparently representing continuation of this erosional valley(Kupsch 1957). Consistent with this interpretation, theFrenchman–Battle thins to the west and to the east, rests onprogressively younger deposits (Fig. 2), and is commonlythin to absent in the central and eastern parts of Saskatchewan(Fraser et al. 1935). Based on regional thicknesses of theFrenchman–Battle, a valley width of as much as 70 km issuggested.

Regional aerial exposure and erosion of the sub-Frenchmanunconformity apparently occurred during the earliest part ofthe late Maastrichtian. Catuneanu and Sweet (1999) attributethe change from erosional to aggradational regimes to adownward flexure of the lithosphere and subsidence in theregion associated with an orogenic pulse in the Cordilleraand compressional loading to the west.

The Frenchman–Ravenscrag contact is placed at the baseof the first coal seam and is typically conformable, so thatthe transition represents a regional environmental change. Ofconsiderable interest is the preservation in this region ofcontinuous Cretaceous–Tertiary boundary deposits, completewith an iridium-enriched boundary clay that is interpreted asrepresenting fallout from the Cretaceous–Tertiary boundaryimpact event (Lerbekmo et al. 1987; Lerbekmo et al. 1999;Kamo and Krogh 1995). In southwestern Saskatchewan, the

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Cretaceous–Tertiary boundary occurs immediately below orwithin the basal Ravenscrag coal seam, so that the chrono-stratigraphic and lithostratigraphic boundaries are more-or-lesscoincident.

Palynological data indicates that the Frenchman Formationwas deposited during the latest part of the Maastrichtian(Sweet et al. 1997; Braman and Sweet 1999). Magneto-stratigraphy places the entire formation within magnetocron29r, between 65.5 and 65 Ma (Fig. 1; Lerbekmo 1985, 1999).Thus, the time frame attributed to the deposition of theFrenchman sediments would be less than one-half millionyears (see Lerbekmo and Coulter 1985). The Tyrannosaurusrex remains were found 28.3 m below the Cretaceous–Tertiaryboundary, within sands of typical Frenchman lithology (Fig. 2;A.R. Sweet, personal communication, 2000), and can beconsidered to have lived perhaps a few hundred thousandyears before the end of the Cretaceous.

Fauna of the Frenchman FormationNon-mammalian vertebrate remains recovered from the

Frenchman Formation include crocodiles and other reptiles(lizards, snakes, turtles, champsosaurs), a few birds, andabout 14 dinosaur taxa (Tokaryk 1997a; also see Storer1989). Theropods include Tyrannosaurus rex,Sauronitholestes, Troodon, Richardoestes gilmorei, Chirostenotes,and Ornithomimus. Marginocephalians (represented byTriceratops horridus), ornithopods (Edmontosaurus and

Thescelosaurus), pachycephalosaurids, and ankylosauridswere also present.

Local depositional environmentPlant debris is common in the sands of the Frenchman

Formation, but until recently, few remains were identifiable;thus, the flora of the Frenchman has remained largelyunknown. The Tyrannosaurus rex skeleton, however, wasembedded in sediments rich in moderately well-preservedplant remains that represent a low-diversity flora of ferns,gymnosperms, and angiosperms (Appendix A). Also recoveredwere fish scales and shells of gastropods and clams. Asnoted previously, recovery of identifiable plants and bonesfrom the same bed is a rare event. Plants are best preservedunder reducing conditions with a low pH (Retallack 1997),where microbial activity is curtailed. Such conditions arecommonly associated with waterlogged habitats, such asswamps and marshes, that are rich in organic acids fromplant decay or with saturated soils low in calcium carbonate.Thus, the best preservation of plant remains occurs withinenvironments of low pH and low to negative Eh (oxidation–reduction potential; Retallack 1997). In contrast, bones andshells are best preserved in environments of high pH andhigh to positive Eh, or in other words, under alkaline andoxidizing conditions. These are commonly found in well-drained soils or sediments, or if in saturated sediments, thenwhere permeability is high and the sediments flushed with

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McIver 209

Fig. 1. Stratigraphic correlation in Central Alberta, Southwestern Saskatchewan, and Southwestern Manitoba. Adapted from Catuneanuand Sweet (1999).

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oxygen-rich water. Such deposits commonly appear yellow,brown, or red in color. Thus, conditions required for goodpreservation of plant remains and bones are typically mutuallyexclusive.

The depositional environment attributed to the Tyrannosaurusrex skeleton is that of a low-energy section of a broad,accretionary meandering river system, most probably a pointbar (see Fig. 3). In modern river systems, such a low energysite allows for accumulation of sands to very fine-grainedclays and silts, depending on flow regime. Shallow pools andstranded bars are typical of such sites. Delicate plant debrismay settle in these sites, and if soon buried and waterlogged,their integrity may be preserved. Clay-rich lenses or drapesmay create microenvironments more conducive to preservationof delicate plant remains than that which may generally existwithin the deposits. Lag deposits rich in more robust remainssuch as fruits, cones, and stems are also commonly associatedwith such depositional settings. That sediments were notgenerally exposed to acidic pore water is attested to byassociated bones and shells, which would have been rapidlyleached of carbonate. Indeed, in the case of the Tyrannosaurusrex skeleton, sediments associated with bones and plants arehighly calcareous, and the river water itself is interpreted ashaving been rich in calcium carbonate.

While the cause of death of the Tyrannosaurus rex isunknown, data from the site, including close association of asubstantial fraction of the skeleton, suggest that the beastdied at or very close to the site of preservation. It is unlikelythat the carcass was transported any appreciable distance, asthe sedimentary evidence is not consistent with the volumeand velocity of water required to move such a mass. Degradationof the bones indicates extensive exposure to aerial conditions,either continuously or intermittently, over a period of someyears prior to complete burial. Many other lines of evidencealso indicate that burial occurred over a protracted period oftime, including the intimate association of many plant-bearinghorizons with the skeleton, the complexity of interbeddedsediments, and the variability of both grain size and planttaxa in the beds (see Appendix A).

Plant fossils that form the basis of this study are curatedby the Royal Saskatchewan Museum, Regina, Saskatchewan,and are housed at the T. rex Discovery Centre, Eastend, Sas-katchewan. All plant fossils derived from the Tyrannosaurusrex quarry bear the locality numbers P2523 or P2683. Fossilsfrom a site nearby the T. rex quarry, informally called WestPoint, are approximately equivalent stratigraphically and bearthe locality number P2661. In addition, fossil fruits collectedfrom Frenchman sediments exposed in a clay pit near the

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Fig. 2. Stratigraphy of latest Cretaceous and Paleocene formations of southwestern Saskatchewan based on selected measured sectionsof Fraser et al. (1935). Section 1, Eastend area; Section 2, Anxiety Butte; Section 3, Frenchman River at Highway 37 (near ChamberyCoulee and the Tyrannosaurus rex skeleton); Section 4, Warholes valley; Section 5, Gwendella valley.

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211Fig. 3. Artistic reconstruction of river system ofTyrannosaurus rexfrom southwestern Saskatchewan, drawn by A. Tait. Plant taxa includeVitis stantonii (large tree on left);cycads, horsetails, cattails,Trochodendron flabellaseedlings (center and small tree lower right), ferns,Parataxodium, Ginkgo (tree on right).

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town of Ravenscrag, Saskatchewan, informally called theClay Alexander pit after the property owner, have beenincluded for comparative purposes and bear the localitynumber P2607. Type fossils on loan from the GeologicalSurvey of Canada (GSC) carry the GSC specimen number5451.

Discussion

Stratigraphic and sedimentary data indicate that theTyrannoasaurus rex from Chambery Coulee roamed ameandering river valley suggested to be up to 70 km inbreadth with erosional paired terraces up to 30 m deep (seeFigs. 2, 3). This environmental interpretation is consistentwith that of other T. rex from data on bone beds andpaleosols by Retallack (1997). At Bug Creek, Montana,T. rex was found in association with Triceratops in a greyclaystone paleosol with carbonaceous root traces. The topog-raphy was interpreted as “clayey swales of levee area oflarge meandering streams” (Retallack 1997, p. 1389).

Retallack (1997) interpreted the local paleovegetation ofthe Tyrannosaurus rex bone beds at Bug Creek as that of alowland colonizing forest. Many paleosols in the Hell CreekFormation that bear remains of T. rex and Triceratopshorridus are also interpreted by Retallack (1997) as earlysuccessional communities of stream sides. These sites arenot directly comparable to that of Chambery Coulee, becausethe T. rex at Chambery Coulee was buried by channel sandslacking rooted structures, and thus are not paleosols.Nevertheless, plant fossils from Chambery Coulee wouldappear to indicate colonizing vegetation nearby.

One of the most common fossil plants recovered fromChambery Coulee is the bald cypress-like conifer, ParataxodiumArnold and Lowther (Pl. 1, figs. 5–12). These remains werefound throughout the 3 m of sediment of the quarry, andalthough this may be due in part to greater resistance ofconifer twigs and seed cones to decomposition than thedeciduous leaves of angiosperms, it is apparent that trees (orforests) of Parataxodium were common and nearby. Theseconifer fossils appear to be the same as those assigned toSequoia dakotensis Brown (1939) from North Dakota, butthey are not Sequoia Endl. Nor are they Metasequoia Miki,for even though the phyllotaxy of both leaves and seed conescales may be decussate (Pl. 1, fig. 7), more commonlyappendages are helically arranged, as in Parataxodium (Pl. 1,

figs. 5, 6). Arnold and Lowther (1955), in their original de-scription of P. wigginsii Arnold and Lowther, interpret thetaxon as deciduous, occupying such environments as lowlandforests and back swamps. They also report that it was preservedin highly calcareous sediments. While the Frenchman sedimentsmay be calcareous, coal seams are absent from the FrenchmanFormation, so that there is no evidence to indicate that thiswas a conifer of widespread swamps in Saskatchewan,although it would seem likely that it was part of the riparianand floodplain vegetation (Fig. 3). Interestingly, two closerelatives, Metasequoia and Glyptostrobus Endl., did occupythe great coal swamp environments in the region during thePaleocene (McIver and Basinger 1993; McIver 1999), whenParataxodium appears to have gone extinct.

Another conifer recovered was Fokienia ravenscragenesisMcIver and Basinger, a member of the Cupressaceae sensustricto (Pl. 1, fig. 13). This appears to be the first report ofthe species from Cretaceous sediments, although it is knownfrom the early Tertiary of Saskatchewan and Alberta(McIver and Basinger 1990; McIver 1992).

Other gymnosperms include Ginkgo L and, from a sitenear the Tyrannosaurus rex quarry, a fossil that appears to bea cycad ovuliferous cone, cf. Zamia L (Pl. 1, fig. 4). Cuticleof latest Maastrichtian age, closely resembling that ofZamia, has previously been recovered from near WoodMountain, Saskatchewan (McIver 1999).

Stems of Equisetum were common in the sediments of thelower beds of the quarry, but most were poorly preserved.Less common were fragments of fern fronds.

The most common angiosperm leaf type found at the sitewas Trochodendroides flabella (Newberry) McIver and Basinger(Pl. 1, figs. 14, 18). About 134 leaves were collected, and ofthese 98 were elliptic to narrow ovate, 20 were broadlyovate, and 16 were obovate. All leaf shapes known for thetaxon were represented, but the majority of leaves weresmall and elliptical in shape. In fact, the skeleton itself wasin places embedded in sediments rich in small leaves of thisspecies (Pl. 1, fig. 18). Many of the small leaves fromChambery Coulee were less than 2 cm long and resemblethe seedling leaves of Joffrea speirsii Crane and Stockeyfrom the Paleocene of Alberta (Stockey and Crane 1983;Crane and Stockey 1985). I interpret these small ellipticalleaves as seedling leaves of plants colonizing point bars or asimilar site of accretion along the channel.

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Plate 1. Selected fossil plants recovered from the Frenchman Formation, southern Saskatchewan. fig. 4. cf. Zamia L. Seed cone.P2661.2. Scale bar = 1 cm. figs. 5–10. Scale bar = 5 mm. fig. 5. Parataxodium Arnold and Lowther. Leafy twig with helicalphyllotaxy. P2683.58. fig. 6. Parataxodium Arnold and Lowther. Leafy twig with helical phyllotaxy. P2683.20. fig. 7. ParataxodiumArnold and Lowther. Leafy twig with decussate phyllotaxy. P2683.10. fig. 8. Parataxodium Arnold and Lowther. Seed cone showingcone scales in section view and long, naked peduncle. P 2683.50. fig. 9. Parataxodium Arnold and Lowther. Seed cone with long, na-ked peduncle and cluster of bracts at base (arrow). P2683.30. fig. 10. Parataxodium Arnold and Lowther. Twig bearing pollen cones.P2523.265b. fig. 11. Parataxodium Arnold and Lowther. In situ pollen clump from a pollen cone of twig illustrated in Fig. 10. Scalebar = 10 µm. fig. 12. Parataxodium Arnold and Lowther. In situ pollen grain from pollen cone of twig illustrated in Fig. 10. Scale bar= 2 µm. figs. 13–16. Scale bar = 5 mm. fig. 13. Fokienia ravenscragensis McIver and Basinger. Two seed cones borne on peduncles.P2523.45. fig. 14. Trochodendroides flabella (Newberry) McIver and Basinger. Leaf with typical acute base and long petiole. P2683.40.fig. 15. Dryophyllum subfalcatum Lesquereux. Leaf from a block of sediment bearing pubis bone of skeleton. P2523.275. fig. 16. Un-identified leaf with dark spots (fungi?). P2683.24. fig. 17. Vitis stantonii (Knowlton) Brown. Base of leaf from block of sediment bear-ing pubis bone of skeleton. P2683.45. Scale bar = 1 cm. figs. 18–22. Scale bar = 2 mm. fig. 18. Trochodendroides flabella (Newberry)McIver and Basinger. Small leaf interpreted as seedling leaf. P2683.28. fig. 19. Unidentified fruit. P2683.2. fig. 20. Unidentifiedpermineralized fruit. P2607.17. fig. 21. Unidentified winged fruit. P2523.192. fig. 22. Unidentified syncarpous fruit. P2683.15.

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Leaves of Vitis stantonii (Knowlton) Brown (Pl. 1, fig.17), Dryophyllum subfalcatum Lesquereux (Pl. 1, fig. 15),and Dombeyopsis obtusa (Lesquereux) Dorf are interpretedas leaves of trees. Also present were small unidentifiedtoothed leaves that at least superficially look ulmoid. Oneunidentified leaf appears to have been infected by a fungus(Pl. 1, fig. 16). The small leaflets of the aquatic angiospermTrapago angulata (Newberry) McIver and Basinger were notcommon in the sediments, but they were well distributedthroughout sediments at the level of the Tyrannosaurus rex.Preservation of these leaflets further supports the conclusionthat the skeleton was deposited in low-energy waters of theriver system.

Numerous fruits and seeds were recovered (Pl. 1, figs. 19–22;Appendices A, B), including two distinct size classes ofNyssidium arcticum (Heer) Iljinskaja fruits and numerousfruits previously assigned to Ficus ceratops Knowlton. Newinformation from Chambery Coulee indicates clearly that thelatter are not figs, nor was Knowlton’s 1911 report the earliestvalid publication of the taxon. In 1875, Dawson describedand assigned such fruits to Aesculus antiquus Dawson.These are not Aesculus L either, and the fruits are assignedhere to the new taxon, Spinifructus antiquus (Dawson)comb. nov. (see Appendix B). The fruits of S. antiquus arevery common and well distributed throughout the sediments,including the beds at the same level as the dinosaur andthose immediately overlying the skeleton (see Appendix A,Fig. A1). Fruits of this type are well known from other plantlocalities in the uppermost Cretaceous of the Western Interior,including other beds of the Frenchman Formation inSaskatchewan, the Scollard Formation of Alberta, and theLance and Hell Creek formations of North Dakota, Montana,and Wyoming. Many of these remains are permineralized,but others, such as those from the Tyrannosaurus rex site,are preserved as compression–impression remains, and thesereveal an outer spiny exocarp not previously recorded for thespecies (Appendix B, Pl. B1, figs. B1–B16). It could not bedemonstrated that these fruits have affinity with a moderngenus, but they appear most like the fruits of a palm. A fragmentof what is believed to have been a palm frond has beenrecovered from a site nearby the Tyrannosaurus rex quarry,but apart from appearing to bear pinnate leaves, little elsecould be gleaned from the specimen. Palms are well knownfrom the Lance and Hell Creek formations (i.e., Knowlton1909; Dorf 1942; Johnson and Hickey 1990).

A few additional taxa of the Frenchman Formation areknown from cuticular remains reclaimed from coal samples ofthe Wood Mountain region of Saskatchewan (about 140 km eastof the Tyrannosaurus rex quarry). These included Glyptostrobus,Sphagnum L, Typha L, and water lilies (McIver 1999).

The vegetation in the vicinity of the Tyrannosaurus rex siteis interpreted as primarily riparian, but would have includedthat of forested lowlands and flood plains associated withthe river (see reconstruction of paleoenvironment Fig. 3).Forests of the region are interpreted as being mixed broadleafand coniferous, and almost entirely deciduous. Apart fromdisturbed sites, forests would have covered the land surface(see Tiffney 1997).

The climate of the region during the deposition of theFrenchman Formation is interpreted as mesothermal and

subhumid. The presence of palms, cycads, and crocodiles inthe Frenchman gives evidence that freezing temperatureswere rare or absent at that time. For example, palms aremainly tropical today, but inhabit a wide range of ecologicalniches including rainforests, deserts, and high altitudes withwinter snow. Nevertheless, all palms have a single bud, andif that is killed by frost, the stem dies (Heywood 1978). Thesediments of the Frenchman Formation do not indicate thatdrought was common, but rare beds of oxidized sands andthe presence locally of large indurated calcareous massessuggest that the climate was seasonally dry. Climates ofnorthern Florida today may be somewhat analogous to thosepresent in Saskatchewan during the deposition of theFrenchman Formation. Taxa such as palms, cycads, the baldcypress, and numerous angiosperms flourish in the seasonallydry climates of northern Florida, where winter frosts occuroccasionally.

Despite similarities in climates of the latest Maastrichtianof Saskatchewan and modern Florida, there must be a significantdifference that strongly influences vegetation. The flora ofthe Frenchman Formation is low in diversity and decidedlydeciduous. Floras of Florida are diverse and contain manybroadleaf evergreen taxa. Florida today is nearly subtropical,while southern Saskatchewan, in the latest Maastrichtian,was at a paleolatitude of approximately 58°N (McIver andBasinger 1993; Smith et. al 1994). Floristic difference isinterpreted as the consequence of dissimilar light regimes,such that low winter light levels in Saskatchewan wouldhave enforced a winter dormancy that is neither temperaturenor drought induced.

Contemporaneous floras of the Lance and Hell Creekformations of Montana and Wyoming, however, weredominated by evergreen angiosperms (Wolfe and Upchurch1986, 1987). This more southern vegetation (paleolatitudes46–56°N), is interpreted by Wolfe and Upchurch (1986) assubhumid, notophyllous, broad-leaved, evergreen forests.Floras of the southern part of Saskatchewan might beexpected to fall within the same climatic zone, as its climateis also interpreted as mesothermal and subhumid; however,the flora of the Frenchman Formation differs fundamentallyfrom those of the Lance and Hell Creek of Montana andWyoming in lacking a broad-leaved evergreen component(Knowlton 1909; Berry 1934; Brown 1939; Dorf 1942;Wolfe and Upchurch 1986; Johnson and Hickey 1990). Theangiosperm taxa interpreted as deciduous from the Frenchmanflora appear in these more southern floras as well, but thesouthern floras bear many members of the Lauraceae andMoraceae, for example, not known from the Frenchman.This suggests that a light-induced ecotone existed betweenthe Frenchman and Lance–Hell Creek floras, perhaps verynear 58°N latitude, where critically low winter light levelsexcluded most broadleaf evergreen angiosperm taxa. Vegetationinhabiting southern Saskatchewan immediately following theCretaceous–Tertiary Boundary Event was similarly highlydeciduous (McIver and Basinger 1993). Nevertheless, palmsand cycads were not excluded from these latitudes, for inaddition to their record in the Frenchman Formation, theyare represented in the Maastrichtian and early Paleocene ofAlberta, with most fossils from sites somewhat further norththan the Frenchman sites (Bell 1949; unpublished data).

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Winter dormancy and deciduousness of the vegetation ofthe Frenchman Formation leads to some intriguing questions.How did the Tyrannosaurus rex from southern Saskatchewan,and its prey, survive the winter? Two different strategies exist:(1) they endured a period of low or non-existent plantproductivity that would have lasted for months, or (2) theywould have migrated southward to occupy a winter rangewhere vegetation remained green and productive.

If large-bodied herbivores do not leave a deciduous envi-ronment, they must rely upon nutritious organs of dormantvegetation. Berry (1924) suggested that the herbivorousdinosaurs of this region ate the underground tubers ofEquisetum, which were plentiful. This may have been true,but it is unlikely that these tubers would support more than asmall select group. In addition, seeds or fruits, such asSpinifructus antiquus, would appear to have been highlynutritious (i.e., large fleshy seed), and could have beenconsumed by some dinosaurs. Evidently, discouragingherbivory was part of the evolutionary strategy of the species,given the evolution of the formidable spiny exocarp.Browsing on dormant twigs is a strategy successfullyadopted by modern herbivores such as moose and deer inboreal forests during the winter, and it is possible that evenlarge dinosaurs could find sufficient food to sustain themselvesin the much warmer winters of the Maastrichtian. It wouldseem likely that during winter, the swamps would havebecome more accessible to a large predator such asTyrannosaurus rex, and vegetation reduction may have madethe prey more accessible and susceptible.

It is also possible that the large-bodied dinosaurs weremigratory, as are many groups of large-bodied mammals oftoday. While the distance to the refuge of the Lance–HellCreek environments would have been no obstacle for a dinosaurfauna, there are some arguments against long-distancemigrations, as tyrannosaurid and hadrosaurid dinosaurs areknown from the North Slope of Alaska (Brouwers et al.1987), and according to Lehman (1987, p. 211), Tyrannosaurus“ranged into all environments though out the length of theWestern Interior region”. It seems unlikely that animals ofthe northernmost regions would ever escape high-latitudelight regimes by migration.

Whether large-bodied dinosaurs remained in situ, or migratedinto and out of the deciduous zone, there exist importantphysical constraints on the occupation of a deciduous landscapeby homeothermic (whether endothermic, inertial homeothermic,or some extinct equivalent) organisms. Important answers toquestions about physiology and behaviour of dinosaurs maylie in an understanding of their occupation of the high latitudes.

Summary

This study gives evidence that the Tyrannosaurus rexroamed through early successional communities of streamsides and thrived in a mesothermal climate without significantwinter frost, but with seasonal precipitation. Summer vegetationis interpreted as mixed broad-leaved and coniferous, andluxuriant; however, the deciduousness of these forests, whichsupported the presumed prey of the T. rex, including herbivoressuch as Triceratops, hadrosaurs, and others, suggests thatwinter food supplies may have been scarce. Whether herbivores

and carnivores remained in the region during the winter, ormigrated southward to a winter range, important questionsremain concerning dinosaurian physiology or behaviour.

Acknowledgments

Thanks are due to: staff of the Saskatchewan Museum ofNatural History (Regina and Eastend Divisions), H. Bryant,T. Tokaryk, D. Stoffregen, M. Vovchuk, J. Hodgins; and tosummer volunteers of the Eastend Research Station, A.Tait, L. Gagnon, H. Johnson, G. Rose, and J. Rose; to R.Tremaine, J. Basinger, G. Wakabayashi, and C. Wakabayashifor assistance in collecting specimens in 1998; to LiuYusheng for extracting and photographing the pollen; to K.Aulenback for providing specimens from the Royal TyrrellMuseum of Palaeontology (RTMP); to A.R. Sweet for infor-mation on the age and deposition of the sediments; to A. Taitfor undertaking artistic reconstruction of the environment; tothe University of Saskatchewan, Saskatoon, Saskatchewan,and the Natural Sciences and Engineering Research Councilof Canada for financial support (President’s award, PNSERC7–71685 to E. E. McIver); and to J.F. Basinger for criticallyreading and revising the manuscript.

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Berry, E.W. 1924. The food value of an Equisetum from the LanceFormation of Saskatchewan. Canadian Field Naturalist, 34: 131–132.

Berry, E.W. 1934. A Lower Lance florule from Harding County,South Dakota. U.S. Geological Survey, Professional Paper 185-F, pp. 127–132.

Berry, E.W. 1935. A preliminary contribution to the floras of theWhitemud and Ravenscrag formations. Geological Survey ofCanada, Memoir 182, pp. 1–107.

Braman, D.R., and Sweet, A.R. 1999. Terrestrial palynomorphbiostratigraphy of the Cypress Hills Wood Mountain, andTurtle Mountain areas (Upper Cretaceous – Paleocene) ofWestern Canada. Canadian Journal of Earth Sciences, 36:725–741.

Brouwers, E.M., Clemens, W.A., Spicer, R.A., Ager, T.A,Carter, L.D., and Sliter, W.V. 1987. Dinosaurs on the NorthSlope, Alaska: high latitude, latest Cretaceous environments.Science, 237: 1608–1610.

Brown, R.W. 1939. Fossil plants from the Colgate Member of theFox Hills Sandstone and adjacent strata. U.S. Geological Survey,Professional Paper 189-I, pp. 239–275.

Catuneanu, O., and Sweet, A.R. 1999. Maastrichtian–Paleoceneforeland-basin stratigraphies, western Canada: a reciprocalsequence architecture. Canadian Journal of Earth Sciences, 36:658–703.

Chin, K. 1997. What did Dinosaurs eat? Coprolites and other directevidence of dinosaur diets. In The complete dinosaur. Edited byJ. O. Farlow and M.K. Brett-Surman. Indiana University Press,Bloomington, Ind., pp. 371–382.

Crane, P.R., and Stockey, R.A. 1985. Growth and reproductivebiology of Joffrea speirsii gen. et sp. nov., a Cercidiphyllum-like

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plant from the Late Paleocene of Alberta. Canadian Journal ofBotany, 63: 340–364.

Currie, P.J. 1997. Theropods. In The complete dinosaur. Edited byJ.O. Farlow and M.K. Brett-Surman. Indiana University Press,Bloomington, Ind., pp. 216–233.

Dawson, J.W. 1875. Note on the plants, collected by G.M.Dawson, from the lignite tertiary deposits, near the forty-ninthparallel. In British North American Boundary Commission; re-port on the geology and resources in the vicinity of the forty-ninthparallel. Edited by G.M. Dawson. Dawson Brothers, Montreal,Que., pp. 237–331.

Dorf, E. 1942. Upper Cretaceous floras of the Rocky Mountainregion. Carnegie Institution of Washington, Contributions toPalaeontology, 508, pp. 1–168.

Fraser, F.J., McLearn, F.D., Russell, L.S., Warren, P.S., andWickenden, R.T.D. 1935. Geology of southern Saskatchewan.Geological Survey of Canada, Memoir 176, pp. 1–137.

Furnival, G.M. 1946. Cypress Lake map-area, Saskatchewan.Geological Survey of Canada, Memoir 242, pp. 1–161.

Heywood, V.H. 1978. Flowering plants of the world. MayfairPress, New York.

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McIver, E.E., and Basinger, J.F. 1993. Flora of the RavenscragFormation (Paleocene), southwestern Saskatchewan, Canada.Palaeontographica Canadiana, 10, pp. 1–167.

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Stockey, R.A., and Crane, P.R. 1983. In situ Cercidiphyllum-likeseedlings from the Paleocene of Alberta, Canada. AmericanJournal of Botany, 70: 1564–1568.

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Tokaryk, T.T. 1997b. A rex with a new home. Geology Today,September–October: 190–193.

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Appendices A and B on following pages.

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Appendix A. Sedimentary beds, flora, andfauna

Plant-bearing sediments of the Frenchman Formation ofthe Tyrannosaurus rexquarry site were separated into twosuites: a lower bed bearing the dinosaur remains and mostplant fossils; and an upper, immediately overlying the skeleton(see Fig. A1).

Lower bedThe lower bed is about 2 m thick, composed predominately

of sand with silts and clays intercalated as either thin beds orlenses. Woody twigs and plant debris are common throughoutthis bed, and some lenses were black with organic matter.The uppermost sediments are silty clays with someconglomerates; this layer produced fruits and seeds andsome leaf remains. The basal part of the bed was composedof fine, cross-bedded sands overlain by silts and silty clays;this contained the best preserved leaf remains.

Flora and fauna of the lower bedEquisetumsp.Fern (cf.Dryopteris carbonensisKnowlton)Ginkgo sp.Parataxodiumsp.Fokienia ravenscragensisMcIver and BasingerTrochodendroides flabella (Newberry) McIver and

BasingerTrochodendroides speciosa(Ward) Berry

cf. Juglans denverianaKnowltonTrapago angulata(Newberry) McIver and BasingerVitis stantonii(Knowlton) BrownDombeyopsis obtusa(Lesquereux) DorfDryophyllum subfalcatum(Knowlton) Dorfcf. Ulmaceae leavesSpinifructus antiquus(Dawson) comb. nov.Carpites ulmiformisDorfNyssidium arcticum(Heer) Iljinskajacf. Nyssidium arcticum (small) = Leguminosites

arachioides-minorBerryCarpolithes kneehillensisBellcf. Carpites lakesiiKnowltonNumerous small nut-like fruitsOther unidentified fruits and seedsMonocotyledon stemsMedium to large sized logscf. water lily rootsTyrannosaurus rexHadrosaur (teeth)Small theropod remainsTurtle (leg bone)Fish (head plate, scales, gar scales)Mammal (toothless jaw fragment)ClamsGastropods

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Fig. A1. Tyrannosaurus rexand plant fossil quarry at Chambery Coulee.

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Upper bedThe upper bed was about 1 m thick and composed of

concoidally fracturing mudstones with abrupt lateral transi-tion to sands and silts. The mudstones bore an assortment offruits and seeds, some permineralized. Leaf fossils were rare,but fish scales were abundant. The sand and silt beds alsocontained large fruits similar to those of the mudstones, andrarely included ironstone concretions.

Flora and fauna of the upper bedParataxodium sp.Unidentified angiosperm leavesSpinifructus antiquusSmall nut-like fruitsLarge logsFish (scales)

Appendix B. Systematics of Spinifructusantiquus (Dawson) comb. nov.

Family and order: Incertae sedis

Genus: Spinifructus gen. nov.

Generic diagnosis: Fruit ovate; exocarp fibrous, spiny;mesocarp composed of fibres; endocarp stony, groovedlongitudinally, pear-shaped with elongated base; seed smooth.

Type: Spinifructus antiquus

Species: Spinifructus antiquus (Dawson) comb. nov.Aesculus antiquus Dawson 1875, North American Boundary

Commission, p. 330, figs. 8,9.Palmocarpon sp. Stanton and Knowlton 1897, p. 136.Ficus ceratops Knowlton 1911, p. 389, figs. 1–4; Brown

1939, p. 248, figs. 1–14; Dorf 1942, p. 153.Guarea ceratops Graham 1962, p. 523, pl. 90, figs. 1, 2,

5, 6, 8, 9.

Original diagnosis: “Pericarp 1½ inches in length and 1inch in breadth; obovate, truncate at base, regularly roundedabove, with several strong woody spines on the upper half.Seed of similar form but smooth or with a few tortuousimpressions” (Dawson 1875, p. 330).

Emended diagnosis: Fruit up to 75 mm long, 55 mmwide; exocarp fibrous, with woody spines; mesocarp composedof longitudinal fibres; endocarp stony, grooved longitudinally,pear-shaped, basal portion elongate, tip rounded; seed ovate,apiculate at base, testa smooth.

Holotype: GSC 5451-1 (Pl. B1, fig. B1); Paratype:GSC 5451-2 (Pl. B1, figs. B2, B3).

Type locality and geological ageFrenchman Formation from badlands south of Wood

Mountain, Saskatchewan, Canada; Maastrichtian. Referredto as “Lower Ravenscrag” by Dawson (1875), GSC localityNo. 4095. These beds were later named the FrenchmanFormation (Furnival 1946).

Material examined for this study: About 60 fruits ofSpinifructus antiquus were collected from the Tyrannosaurusrex quarry of the Frenchman Formation; 16 of these show

the spiny exocarp. Additional permineralized specimensfrom the Clay Alexander pit, near Ravenscrag, Saskatchewan,were examined, as were specimens from the Scollard Formationof Alberta.

DescriptionThese fruits from the Tyrannosaurus rex quarry range from

about 16 mm long by 14 mm wide to 75 mm by 55 mm. Theexocarp is only preserved on compression–impressionspecimens, and it appears to have been fibrous with woodyspur-shaped to apiculate spines, although rarely the projectionsappear as short flanges (Pl. B1, figs. B1, B2, B6, B11, B13,B15, B16). The inner surface of the exocarp is relativelysmooth, and fossil molds of the outer surface are punctuatedwith carbon-filled projections of various sizes, which are thebases of the spines (Pl. B1, figs. B2, B6, B11). Commonly,the base of the spine is circular in cross-section, but someare elliptic and may be more than 5 mm wide. Exocarpshave not been identified on permineralized specimens.

The mesocarp is composed of fibres that may be up to2.0 mm in diameter at the base of the fruit (Pl. B1, figs. B4,B7, B8). These dichotomize and become narrower as theyspread out over the body of the endocarp (Pl. B1, fig. B7).Fibres of permineralized specimens examined ranged from2.0 to 5.0 mm in diameter (Pl. B1, fig. B7). Most fruits nolonger retain the base, and there appears to be a naturalabscission or fracture zone near the base (compare Pl. B1,figs. B1, B2). Although rarely preserved, both permineralizedand compressions–impression fossils show intact fibres runningthe full length of the endocarp, including the neck portion(Pl. B1, fig. B4). Compressed specimens may show a thickrim of carbonaceous material (Pl. B1, figs. B5, B10, B14)that encircles the endocarp on the plain of compression (Pl.B1, figs. B12, B16); these are interpreted as compressedfibres of the mesocarp, and a consequence of the fossilizationprocess.

The endocarp is stony and bears ribs and grooves. Ribbingof the endocarp is more coarse in the basal part (neck of thepear-shaped body) than in the rest of the endocarp (Pl. B1,figs. B7, B8). These ribs may be up to 2.0 mm wide near thebase, and the grooves between are about as broad and arefilled with fibres. These fibres dichotomize, becoming smalleras they cover the body of the endocarp. In some instances,one or two shallow grooves are found to run from base toapex of the endocarp and are filled with permineralized materialof a different colour than that of the fibres (Pl. B1, fig. B7).The inner surface of the endocarp appears to have beensmooth (Pl. B1, figs. B7, B12, B14).

Vascularization of the apex of the fruit is preserved in oneof the specimens from Alberta. This revealed a single veinabout 0.75 mm in diameter surrounded closely by sevenveins that were about 0.5 mm in diameter; this is interpretedas the point of convergence of the vascular traces of the fruitat the apex.

All seeds were preserved as casts, but the seeds appear tohave had a smooth testa and to have filled the space withinthe endocarp (Pl. B1, figs. B7, B12, B14). They are ovate inshape, and the base has a short, narrow, accuminate tip.Seeds were not obvious in permineralized specimens, and

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the interior is completely filled with fine-grained, homogenoussediment or crystalline mineral matter.

RemarksThese fossil fruits from the Frenchman Formation are

clearly the same as those assigned to Ficus ceratops byKnowlton (1911) and Guarea by Graham (1962), but theyare neither Ficus nor Guarea. It appears that both Knowltonand Graham assigned the fruits on the basis of superficialsimilarity of the shape of the bony endocarp of the fossil toexocarps of selected extant genera. The nature of the exocarpof the fossil was apparently unknown at the time, althoughfruits of this type, revealing a spiny exocarp, had been describedpreviously by Dawson (1875).

Dawson (1875) assigned his fruits to Aesculus L on thebasis of their spiny outer wall, but again this similarity toAesculus is superficial. Dawson’s fruits were examined (seePl. B1, figs. B1–B3) and clearly show the characteristics typi-cal of the fruits from the Tyrannosaurus rex quarry and ofthose assigned to Ficus ceratops.

I believe these to be the fruits of an angiosperm. I couldnot find any extant family of dicotyledons that wouldaccommodate them, but that would not exclude them fromthe subclass. I believe them more likely to be fruits of amonocotyledon — a palm, as Stanton and Knowlton (1897)originally suggested. As with many palms, they are largefruits, and appear to have been part of a large, denseinfructescence. There is no evidence of a peduncle, but theredoes appears to have been a basal point of abscision that isconsistent with such an infructescence. Also, when the fossilfruits are found, they typically occur closely associated andmay be abundant. One bed of the Scollard Formation of Albertaproduced more than 200 fruits in a small area (K. Aulenback,personal communication, 2000; A.R. Sweet, personalcommunication, 2001).

The fruits of Spinifructus antiquus also have a complexstructure resembling that found in many palm fruits, withfeatures of all three fruit layers occurring in closely relatedpalms. For example: Astrocaryum Meyer has a spinyexocarp; Asterogyne Wendland ex Hooker has a groovedmesocarp, which is similar to that of the fossil; and Barcella(Trail) Trail ex Drude has a thick, fibrous mesocarp, thefibres running parallel to the long axis of the fruit, as in thefossil (see Uhl and Dransfield 1987). These extant generaare all members of the Cocoeae, all have distributions in

Central or Southern America, and all have single-seededfruits. Investigation of the Arecaceae Schultz-Schultzenstein,however, failed to reveal any single genus that could accom-modate them, so that the fossil fruits appear to belong mostlikely to an extinct genus of arecoid palm.

Palms are known from the Frenchman Formation, andwere therefore present in the region at the time the fossilfruits were preserved; a fragment of what appears to be apinnate palm leaf was recovered from a site very near theTyrannosaurus rex quarry. Unfortunately, the fragment wasnot well enough preserved, nor complete enough, to beassigned to a taxonomic level below family.

References

Brown, R.W. 1939. Fossil plants from the Colgate Member of theFox Hills Sandstone and adjacent strata. U.S. Geological Survey,Professional Paper 189-I, pp. 239–275.

Dawson, J.W. 1875. Note on the plants, collected by G.M.Dawson, from the lignite tertiary deposits, near the forty-ninthparallel. In British North American Boundary Commission; reporton the geology and resources in the vicinity of the forty-ninthparallel. Edited by G.M. Dawson. Dawson Brothers, Montreal,Que., pp. 237–331.

Dorf, E. 1942. Upper Cretaceous floras of the Rocky Mountain region.Carnegie Institution of Washington, Contributions to Palaeontology,508, pp. 1–168.

Furnival, G.M. 1946. Cypress Lake map-area, Saskatchewan.Geological Survey of Canada, Memoir 242, pp. 1–161.

Graham, A. 1962. Ficus ceratops Knowlton and its affinities withthe living genus Guarea. Journal of Paleontology, 36: 521–523.

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© 2002 NRC Canada

McIver 221

Plate B1. Spinifructus antiquus (Dawson) comb. nov. figs. B1–B3. Scale bar = 5 mm. fig. B1. Fruit showing spiny exocarp. Holotype.GSC 5451-1. fig. B2. Cast of internal surface of endocarp (seed) with outer rim composed of compressed mesocarp and endocarp wall(arrow). Paratype. GSC 5451-2. fig. B3. Counterpart of specimen illustrated in Fig. 2, showing residual carbon of mesocarp. Paratype.GSC 5451-2. fig. B4. Permineralized specimen showing outer surface of endocarp including base with its ribs and channels. Notecrystallization (white material) and what appears to be a natural fracture point (arrow). P2607.15 Scale bar = 1 cm. fig. B5. Fruitshowing exocarp with carbonaceous mesocarp and endocarp intact, except at base. Note spines (arrow). P2683.53ab. Scale bar = 5 mm. fig. B6.Fruit illustrated in Fig. 5 after removal of mesocarp and endocarp. Note base of spines on inner surface of exocarp (arrow). P2683.53b.Scale bar = 5 mm. fig. B7. Permineralized endocarp showing ribs and channels at neck towards base (incomplete) and dichotomizingfibers of endocarp body. Note flange running from base to apex (arrow). P2607.15. Scale bar = 1 cm. fig. B8. View of apex of endocarpof fruit illustrated in Fig. 7. Scale bar = 1 cm. figs. B9–B16. Scale bar = 5 mm. fig. B9. Cast of inner surface of endocarp (seed) overlyingcarbonaceous remains of fruit parts. P2683.52ab. fig. B10. Inner mold of exocarp of fruit illustrated in Fig. 9 with seed removed. P2683.52b.fig. B11. Fruit showing impression of spines (arrows) of exocarp. All three layers of fruit wall are preserved. P2683.56. fig. B12. Fruitwith inner mold of endocarp and outer rim composed of endocarp wall and mesocarp (arrow). P2683.55. fig. B13. Fruit with endocarpand remnants of mesocarp (large arrow), partially separated from exocarp with spines (small arrow). P2683.8a. fig. B14. Small fruit showingseed and attached fragments of endocarp and mesocarp at base. Note the thickness of the endocarp and mesocarp (arrow). P2683.14.fig. B15. Spines of exocarp. P2683.7. fig. B16. Endocarp of fruit with attached mesocarp and exocarp (arrow) with spines. P2683.54.

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