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A high latitude vertebrate fossil assemblage from the Late Cretaceous of west-central Alberta, Canada: evidence for dinosaur nesting and vertebrate latitudinal gradient


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This study reports on a new microvertebrate locality from the Campanian (c 74 My) fluvial beds of the Wapiti Formation in the Grande Prairie area (west-central Alberta, Canada). This locality represents deposition on a low-gradient, waterlogged alluvial plain approximately 300 km to the north west of the Bearpaw Sea. Detailed sedimentological analyses suggest an environment characterized by a high-sinuosity channel system responsible for widespread oxbow lakes, bogs and marshes. A total of 260 identifiable elements were recovered from three distinct sites at the Kleskun Hill Park, documenting a diverse terrestrial and fresh-water palaeocommunity. The recovered fossils include those from hatchling- to nestling-sized hadrosaurid dinosaurs, indicating the presence of a nesting ground in the area. This is the first evidence for dinosaur nesting site in the Wapiti Formation and simultaneously an extremely rare evidence of high-latitude dinosaur nesting, the northernmost in North America to date. A large number of teeth of the small theropod Troodon are associated with baby hadrosaurids in the site supporting a northern affinity of this taxon as well as a previously proposed predator–prey association. Other dinosaurs are less common at the locality and include large and small theropods (i.e. tyrannosaurid, Saurornitholestes, Richardoestesia, Paronychodon, and dromaeosaurid) and five ornithischian taxa. Fish, squamate, turtle, and mammal elements were also identified. Collectively, the vertebrate fossil assemblage from the locality allows palaeocommunity reconstruction in the Wapiti Formation. The importance of the data collected from the new locality is twofold: first, they represent the first comprehensive report from a geographically significant area located between the well-sampled fossil localities of southern Alberta and the high-latitude localities of Alaska. Furthermore, the reconstructed vertebrate fauna support latitudinal gradient of vertebrate distribution along the Western Interior region during the Late Cretaceous.
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A high latitude vertebrate fossil assemblage from the Late Cretaceous of
west-central Alberta, Canada: evidence for dinosaur nesting and
vertebrate latitudinal gradient
Federico Fanti
, Tetsuto Miyashita
Dipartimento di Scienze della Terra e Geologico-Ambientali, Alma Mater Università di Bologna, Via Zamboni 67, 40126 Bologna, Italy
Department of Earth and Atmospheric Sciences, University of Alberta, 126 Earth Science Building, Edmonton, Alberta, Canada T6G 2E3
abstractarticle info
Article history:
Received 18 October 2008
Received in revised form 4 February 2009
Accepted 6 February 2009
Wapiti Formation
Microvertebrate fossil
Dinosaur nesting
This study reports on a new microvertebrate locality from the Campanian (c74 My) uvial beds of the Wapiti
Formation in the Grande Prairie area (west-central Alberta, Canada). This locality represents deposition on a
low-gradient, waterlogged alluvial plain approximately 300 km to the north west of the Bearpaw Sea.
Detailed sedimentological analyses suggest an environment characterized by a high-sinuosity channel
system responsible for widespread oxbow lakes, bogs and marshes. A total of 260 identiable elements were
recovered from three distinct sites at the Kleskun Hill Park, documenting a diverse terrestrial and fresh-water
palaeocommunity. The recovered fossils include those from hatchling- to nestling-sized hadrosaurid
dinosaurs, indicating the presence of a nesting ground in the area. This is the rst evidence for dinosaur
nesting site in the Wapiti Formation and simultaneously an extremely rare evidence of high-latitude
dinosaur nesting, the northernmost in North America to date. A large number of teeth of the small theropod
Troodon are associated with baby hadrosaurids in the site supporting a northern afnity of this taxon as well
as a previously proposed predatorprey association. Other dinosaurs are less common at the locality and
include large and small theropods (i.e. tyrannosaurid, Saurornitholestes,Richardoestesia,Paronychodon, and
dromaeosaurid) and ve ornithischian taxa. Fish, squamate, turtle, and mammal elements were also
identied. Collectively, the vertebrate fossil assemblage from the locality allows palaeocommunity
reconstruction in the Wapiti Formation. The importance of the data collected from the new locality is
twofold: rst, they represent the rst comprehensive report from a geographically signicant area located
between the well-sampled fossil localities of southern Alberta and the high-latitude localities of Alaska.
Furthermore, the reconstructed vertebrate fauna support latitudinal gradient of vertebrate distribution along
the Western Interior region during the Late Cretaceous.
© 2009 Elsevier B.V. All rights reserved.
1. Introduction
Microvertebrate localities from both marine and non-marine deposits
are a powerful tool for the study of palaeoecology and palaeobiogeo-
graphy. They represent a rich source of information on local biota and are
useful in addressing a variety of questions in palaeoecology (Sankey,
2008a). This study is a preliminary report on a new Campanian micro-
fossil locality from the Wapiti Formation beds exposed at the Kleskun Hill
Park (Grande Prairie area, west-central Alberta, Canada), and the rst
attempt to document the terrestrial taxa in the formation during the
maximum transgression of the Bearpaw Seaway in the Late Cretaceous.
High-resolution sedimentological data and an analysis of the hetero-
geneous fauna were combined to estimate the local biodiversity and the
relative abundance of selected groups of vertebrates. In so doing, we
focused primarily on faunal composition and comparison, and address
implications on environmental factors that characterized the fauna also
on the light of the proposed northsouth biozonation of vertebrate taxa
during the Campanian in western North America (Brinkman, 1990;
Eberth, 1990; Eberth and Brinkman, 1997; Ryan et al., 1998; Fiorillo and
Gangloff, 2000; Lehman, 2001; Sankey, 2001; Brinkman et al., 2004,
2007; Baszio, 2008; Sankey, 2008a; Wilson, 2008).
This paper consists of three parts: 1) a detailed description of
stratigraphic, sedimentological, and palaeocological signatures at the
Kleskun Hill; 2) a statement of the diversity of the vertebrate
assemblage recovered; and 3) a discussion on the implication of this
locality on latitudinal gradient of vertebrate distribution in the
Western Interior during the Late Cretaceous.
2. Geographical and geological setting
The Kleskun Hill Park area is located approximately 25 km
northeast of Grande Prairie (west-central Alberta) on the left side of
Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
Corresponding author. Tel.: +39 051 2094565; fax: +39 051 2094522.
E-mail address: (F. Fanti).
0031-0182/$ see front matter © 2009 Elsevier B.V. All rights reserved.
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the Smoky River (Fig. 1). Discontinuous badlands exposures, the most
northern occurrence of this peculiar geomorphology in Alberta
(Byrne, 1955), rise up to 100 m above surrounding plains over an
area of 16 km
. The Kleskun Hill badlands have been considered for
years as the richest fossil locality in the Grande Prairie area: hundreds
of disarticulated hadrosaur bones and other dinosaur remains
collected in the 1940s were referred to an unknown locality within
the area (Tanke, 2004). However, to date the locality has been neither
mapped nor documented and a description of squamate jaws by
Sternberg (1951) is the sole published work on the Kleskun Hill fossils.
The rst geological report on the Kleskun Hill was made by Allan
and Carr (1946) who tentatively correlated the exposures to the lower
Edmonton Formation southeast to the area. However, data from
geophysical well logs of exploration boreholes indicate that strata
exposed at Kleskun Hill Park lie approximately 340 m above the base
of the Wapiti Formation, within a lithostratigraphic unit characterized
by medium to high accommodation conditions, decimetre-to-metre
thick bentonitic layers, and well developed, tabular coal seams (Fanti,
2007). This unit is considered an inland equivalent of the Bearpaw
shale of central and southern Alberta, rather than that of the lower
Edmonton Group (i.e. Horseshoe Formation). Supporting this correla-
tion is a 20 cm thick, olive volcanic ash layer located in the lowermost
section of strata exposed in the park (Fig. 2) which yielded a
age of 73.77± 1.46 My (Eberth, in Fanti, 2007). This age is roughly
equivalent to the maximum transgression of the Bearpaw Seaway in
central and southern Alberta (Baculites compressus zone, 73.4 My;
Obradovich, 1993). Therefore, the Kleskun Hill palaeofauna is a rare
terrestrial fossil assemblage from a stratigraphic interval represented
by marine deposition elsewhere in western Canada and north-
western United States. Furthermore, the Wapiti fossil record is
geographically important, as the locality is between the deposits of
southern Alberta and the high-latitude fossil localities of Alaska (the
present day distance is in the range of 400 km north and 3200 km
south respectively; Parrish et al., 1987; Fiorillo et al., 2007).
Palaeogeographic reconstruction for the late Campanian of North
America place the southern Alberta localities (Belly River Group) at
about 58°N palaeolatitude, the Grande Prairie localities at approxi-
mately 65°N palaeolatitude (Scotese, 1991; Brinkman, 20 03), and the
Fig. 1. A, reference map of Alberta (Canada) showing the extension of the CampanianMaastrichtian Wapiti Formation. B, location of the study area northeast of Grande Prairie. Sites
A, B, and C are located within the Kleskun Hill Park area. Contour lines elevation data are expressed in metres. SS, cross section shown in Fig. 2.
38 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
Alaskan localities between 75° and 85°N latitude (Smith and Briden,
1977; Ziegler et al., 1983; Witte et al., 1987). Therefore, in this study
the Kleskun Hill Park assemblage is referred to as high latitude.
3. Materials, methods, and institutional abbreviations
For this study, the Kleskun outcrops were prospected from 2004 to
2008. This led to the identication of three restricted areas where
erosive processesand surface hydraulic transportationhad concentrated
vertebrate remains. Thesespots will be referred to in the text and gures
as Sites A, B, and C. Detailed outcrop analyses resulted in a composite
cross-section of the study area (SS,Fig. 2) that permitted to document
reciprocal stratigraphic occurrence of fossiliferous sites. Colours used for
sedimentological descriptions follow the Munsell Soil Colour Chart.
Following discovery of fossils fromthe surface of theoutcrop, a 4 m
area was excavated in 2004 at Site B by the eld crew of Royal Tyrrell
Museum of Palaeontology (Drumheller, Alberta, Canada). Sandy and
silty sediments to the depth of 40 cm werecollected for screen washing
(sieves of 1 mm). With about 90% of the collected matrix screened and
sorted, 29 specimens have been identied. In addition to this, surface
collection at Sites A, B, and C yielded 231 identiable specimens (for a
total amount of 260 specimens), primarily theropod teeth and hadro-
saurid postcranial and teeth fragments.
The collected specimens were primarily identied and compared
with those from the well-described CampanianMaastrichtian verte-
brate fossil assemblages in southern Alberta (Brinkman, 1990; Currie
et al., 1990; Brinkman and Neuman, 2002; Eberth et al., 2001; Sankey
et al., 2002). Identication of hadrosaurid elements, particularly of
juvenile and baby-sized individuals, is based on comparisons with
Hypacrosaurus stebingeri (Horner and Currie, 1994), Maiasaura
peeblesorum (Horner, 1999), and hadrosauridae indet. from the
Horseshoe Canyon (Ryan et al., 1998) and Dinosaur Park formations
(Tanke and Brett-Surman, 2001) of Alberta, and the Fruitland
Formation (Hall, 1993) of New Mexico. Identication and terminology
of the theropod teeth follow Currie et al. (1990),Baszio (1997a), and
Fanti and Therrien (2007).
3.1. Institutional abbreviation
UALVP, University of Alberta Laboratory of Vertebrate Palaeontology,
Edmonton, Alberta, Canada; TMP, Royal Tyrrell Museum of Palaeontol-
ogy, Drumheller, Alberta, Canada.
Fig. 2. Composite stratigraphic section showing the stratigraphic occurrence of Sites A, B, and C as well as the only dated bentonite from the Kleskun Hill locality. Paleocurrent
directions are represented by rose diagrams close to the beds in which the sedimentary structures were observed.
39F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
3.2. Other abbreviations
BW, tooth basal width; FABL, foreaft basal length; TCH, tooth
crown height.
4. Sedimentology
Fluvial deposits exposed at the Kleskun Hill represent a medium-
to-high sinuosity channel system within an alluvial plain and
comprise predominantly interbedded mudstone, siltstone, and
minor sandstone. Sedimentological analyses and facies associations
indicate that, overall, the depositional environment was a low-energy,
swampy alluvial area where a series of light coloured bentonitic
sandstones, organic rich-mudstones, coal seams, thin bentonite, and
ironstone beds accumulated under medium to high accommodation
conditions (Fig. 2).
The presence of three discrete and laterally persistent coal beds
permitted to reliably refer different outcrops and fossiliferous sites to
a composite stratigraphic column; signicant variations in geome-
tries, lithology, and palaeocurrents within observed inclined hetero-
litic strata (IHS, sensu Thomas et al., 1987) allowed to identify two
overlapping intervals in the exposed strata.
The lower interval (zone 1) is characterized by b14 metre thick
ning-upward sequences of silt and mud with minor ne grained
sandstone. Trenches through twelve outcrops show dips of bedding
planes between 20° and 35° suggesting a signicant component
of lateral accretion. IHS consist of brownish silt and grey, organic
rich mud forming a graded rhythms within individual inclined units
(Fig. 3A). Vertical accretion on top of IHS is documented by oxbowand
back swamp deposits that include brown and green mudstones
interbedded with wet and immature paleosols, bentonitic horizons,
and thin ironstone lenses (Fig. 3B). Gypsy, sideritic, and carbonaceous
concretions and nodules are recurrently associated with light coloured
sediments of this interval. Lastly, channel ll deposits of zone 1 are
capped by reddish peat horizons, 40 cm thick on average, that
gradually change into tabular coal seams up to a metre thick that deep
gently westward with an angle of 1011°. Such layers have been traced
at the Kleskun Hill Park over an area of approximately 40 km
as well
as in several well logs in the Grande Prairie region, thus supporting the
presence of high-water table and swampy environments over a vast
area. Vertebrate remains described herein were primarily recovered
from ne, organic-rich deposits of zone 1.
The overlying interval (zone 2) consists of up-to 7 metre thick
ning-upward sequences of low angle (510°) interbedded sand and
silt. Sporadic pebbles and ironstone nodules occur at the base of
inclined beds (Fig. 3C). Sandstones are light grey in colour, ne
grained, and characterized by a pervasive carbonate cement. Mud
component is nearly absent and restricted to discontinuous lenses.
Fining-upward deposits are often cut by channel-base ne sands
and locally topped by 1015 cm thick, discontinuous ironstone lay-
ers. In spite the fact that silicied plant and wood remains are
ubiquitous within this interval, zone 2 lacks organic-rich beds, paleo-
sols, as well as peat and coal, suggesting higher drainage conditions
and minor distance from the active channel belt. To date, few and
poorly preserved vertebrate remains have been recovered from this
The transition from zone 1 to zone 2 is interpreted as a shift from
highly vegetated, swampy and bog-rich environments characterized
by permanent high-water table conditions to the active channel belt
within the alluvial plain. Differences in lithology and clinoform
geometries observed in zones 1 and 2 may also reect local variations
in size, sinuosity, and pattern of the channel system and consequent
extension of oxbows and back swamp areas. Palaeocurrent measure-
ments (n=25) taken either parallel or perpendicular to that of
clinoforms from both zones 1 and 2 indicate predominant ows
direction toward the northeast (average on 25 measurements N60°E).
However, a certain degree of variability observed is consistent with a
high-sinuosity uvial system.
Fig. 3. Exposures of the Campanian uvial deposits of the Wapiti Formation at the Kleskun Hill Park. A, interbedded light coloured silt and organic-rich mudstones (IHS) capped by a
couplet of tabular reddish peat and coal. B, heavily rooted paleosol formed by interbedded dark grey, organic-rich mudstone and whitish, carbonaceous mudstone overlying a 45 cm
thick coal bed. C, the transition from muddy, organic-rich deposits of zone 1 to overlying silty and sandy channel facies of zone 2 (see text for discussion). D, site A. E, site B. F, site C
(see also Fig. 1). (For interpretation of the references to colour in this gure legend, the reader is referred to the web version of this article.)
40 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
Lastly, the top of the exposed interval at the Kleskun Hill is marked
by a 35 cm thick, laminated, carbonate cemented sandstone that also
denotes the present day prairie level morphology. The subaerial,
strongly erosive nature of its basal contact and the coarser grain size of
the sandstone suggest a crevasse splay origin.
5. Palaeopedology
The presence in the study area of distinctive paleosol related
features provides useful information on soil acidity, precipitations,
and water saturation. Pedotype are associated with specic environ-
ments (Fastovsky and McSweeney, 1987; Retallack et al., 1987;
Retallack, 1994, 2001; Schaetzl and Anderson, 2005) and therefore
may provide a reliable way to investigate local environmental and
climatic conditions preserved within the Kleskun Hill deposits.
Pedotype features observed in the study area include well developed
peat deposits, tabular coal seams, ironstone layers, bentonitic heavily
rooted soils, as well as sideritic, calcitic, and gypsic concretions, and
discontinuous siliceous/tuffaceous horizons.
The presence of several decimetre-thick peat levels within zone 1
indicate a water-saturated environment with persistent high moisture
content, such as bog or fen, characterized by acidic conditions. Peat
results from decomposition of signicant amount of organic matter
(usually plant remains) that accumulated under swamp, marsh, or
other kinds of vegetation that can tolerate permanent waterlogged
ground (Histosol,Retallack, 2001). The presence of extensive vegeta-
tion and still water is also indicated by abundant plant remains within
the peat layers (including coalied roots, seeds, leaves, and amber),
overlaying well developed coal seams, and laminar calcitic concre-
tions generated by occulation processes. Tabular, decimetre-thick
ironstone deposits, also support the presence of widespread bogs in
the area and signicant amounts of percolating water under tropical
or sub-tropical climatic regimes. Acid soil conditions are also
responsible for higher Fe concentrations and therefore for the
formation of observed sideridic nodules and ironstone layers. The
presence of siliceous nodules and tuffaceous concretions within the
uppermost portion of channel ll deposits of zone 1, probably reects
intense lisciviation processes of volcanic ash soils over a period of
weathering under humid climatic conditions (Podzols,Schaetzl and
Anderson, 2005). In support of this hypothesis, similar processes
observed today are typical of environments characterized by very
humid to temperate moist climate, high water table, and associated
with coniferous or mixed forests. However, such processes result in
light grey coloured horizons deep in the ground, whereas at the
Kleskun Hill chert accumulated primarily in concretions that
represent casts of roots and cavities. Large, bidimensional (35 cm)
gypsum crystals and concretions are fairly common within the silty
intervals of zones 1 and 2; their abundance suggests paleosol
development with possible wetdry cycles, strongly connected with
periods of prolonged subaerial exposure (Retallack, 2001; Schaetzl
and Anderson, 2005). However, such crystals are most likely related to
digenetic processes inuenced by sulphur-rich percolating water and
by intense bacterial activity within organic rich bogs (Phillips and
Bustin, 1996), as also documented by high sulfur contents within the
sediments (more than 600 ppm on average).
6. Vertebrate palaeontology
Dinosaur elements represent nearly 87% (n= 225) of the 260
fossils collected from the Kleskun Hill Park and consist predominantly
of hadrosaur and theropod teeth (including Troodon, tyrannosaurids,
Saurornitholestes,Richardoestesia,Paronychodon, dromaeosaurids, and
a bird), and hadrosaur postcranial elements (Fig. 4). The remaining
specimens include elements from shes, squamates, turtles, ankylo-
saurids, ceratopsids, pachycephalosaurids, and mammals, all char-
acteristic components of Campanian terrestrial assemblages in
western North America (Ryan et al., 1998; Brinkman, 2008; DeMar
and Breithaupt, 2008, and references therein).
6.1. Fish
Three different taxa of sh have been collected from Site B, each
represented by a single type of element: an esocoid dentary (TMP
2004.23.7), three holostean A scales (TMP 2004.23.6), and a holostean
B scale (TMP 2004.23.8; Fig. 8). The esocoid dentary has C-shaped
tooth bases as in those collected from the Campanian of southern
Alberta, and is most similar to Oldmanesox sp. in that there are only
one or two rows of teeth (Brinkman, 1990; Wilson et al., 1992). As in
Oldmanesox, the tooth row is single in the posterior part of the dentary
(Fig. 8AD). The scales of holostean A are identied on the basis of a
peg-and-socket joint, thin enamel cover, and absence of tab-like ex-
tension (Brinkman, 1990)(Fig. 8EG). The holostean B scale (Fig. 8H)
differs from those of a holostean A in that it has multiple tubercles
on the enamelled surface (Brinkman, 1990). The sh elements are
virtually indistinguishable from those described from the Campanian
of southern Alberta (Brinkman, 1990; Wilson et al., 1992; Brinkman
and Neuman, 2002)(Fig. 8AM).
6.2. Non-dinosaurian reptiles
A possibleturtle carapace fragment was collected from SiteA (Fig. 8),
but the weathering on thesurface precludespossibility of identifying the
element to further taxonomic level.
Squamate remains are relatively abundant and well-preserved in
Site A, consisting of articulated skulls and several isolated cranial and
postcranial elements. Specimens were recovered exclusively from a
discrete bentonitic paleosoil that occurs in the organic-rich deposits of
zone 1. Interestingly, squamate remains from the Cretaceous of North
America are more commonly found in signicantly dryer environ-
ments (Gao and Fox, 1991, 1996; Nydam, 2000; Nydam et al., 2007).
These noteworthy squamate materials merit detailed systematic
description elsewhere and are currently under study.
6.3. Theropoda
6.3.1. Troodontidae
The most abundant theropod teeth recovered from Site A are
identied as Troodon for having relatively large, strongly-hooked
denticles, and recurved crowns (Fig. 5AF). A few specimens have
wear facets (Schubert and Ungar, 2005) and spalled surfaces that
extend from the apexof the teeth. The Troodon teeth from the Kleskun
Hill Park are indistinguishable from other Troodon teeth described
from deposits of Wyoming (Lance Formation), Montana (Judith River
Formation), Alberta (Belly River Group, and Horseshoe Canyon
Formation), and Alaska (Prince Creek Formation) (Russell, 1948;
Brouwers et al., 1987; Currie, 1987; Currie et al., 1990; Fiorillo and
Currie, 1994; Baszio,1997a; Holtz et al.,1998; Ryan et al.,1998; Sankey
et al., 2002; Fiorillo, 2008a; Sankey, 2008b). Based on variation in
dental morphology along the dental series in Troodon (Currie, 1987),
the Kleskun Hill specimens encompass the entire tooth series,
including premaxillary, posterior maxillary, and posterior dentary
teeth. Troodon has been reported from other stratigraphic levels and
fossil localities of the Wapiti Formation in the Grande Prairie region
(Tanke, 2004; Currie et al., 2008) supporting a wide distribution of
this taxon; however, the relative abundance of Troodon teeth is
remarkably high at the Kleskun Hill microsites (11.9%).
6.3.2. Dromaeosauridae
Three teeth are identied as Saurornitholestes sp. (Fig. 5HL) based
on elongate and hooked shaped denticles, size differences between
anterior and posterior serrations and strong labio-lingual compres-
sion (Currie et al., 1990; Baszio, 1997a; Sankey et al., 2002).
41F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
6.3.3. Dromaeosauridae indet
Although only the anterior carina has been preserved, UALVP
50640.01 is distinctive in that denticles vary greatly in size along the
crown, from 2.5 to 5 per millimetre, curve slightly distally toward the
tip of the tooth, and have sharp ridges of enamel along the midline
(Fig. 5G). Blood grooves (sensu Fanti and Therrien, 2007,Fig. 3B) are
Fig. 5. Miscellaneous theropod and bird teeth from Kleskun Hill Park, Grande Prairie, Alberta. AB, Troodon posterior premaxillary or anterior maxillary tooth (TMP 2004.23.3):
A, detail of posterior denticles; B, entire specimen (lingual and labial). C, Troodon posterior dentary tooth, UALVP 48750 (labial and lingual); DE, Troodon premaxillary tooth, UALVP
48755 (labial): D, detail of denticles; C entire specimen. F, Troodon, UALVP 48753, anterior maxillary tooth (lingual and labial). G, Dromaeosauridae indet. tooth, detail of the
posterior carina, UALVP 50640.01. HL, Saurornitholestes tooth, TMP 2004.23.4: H, detail of posterior denticles; I, entire specimen (labial and lingual); L, detail of anterior denticles.
MO, Richardoestesia tooth, TMP 2004.93.3: M, detail of posterior denticles; N, entire specimen; O, detail of anterior denticles. P, Paronychodon tooth, UALVP 48815 (labial and
lingual). Q, Tyrannosauroid tooth, UALVP 50641.01 (anterior). R, Tyrannosauroid tooth, UALVP 48760, detail of denticles. S, Tyrannosauroid premaxillary tooth, UALVP 50641.02
(lingual). T, Tyrannosauroid tooth, (?dentary), UALVP 48773 (labial and lingual). UZ, bird tooth, TMP 2004.93.4: U, basal section; VZ, entire specimen (lingual and labial).
Fig. 4. Microvertebrate specimens (n=260) from the Kleskun Hill locality, Wapiti Formation. Dinosaur elements comprise the 86.5% of recovered elements (particularly hadrosaurid
and theropod elements), and squamates and shes are largely represented.
42 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
43F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
absent or restricted to the base of the denticles, being shallow and
poorly dened. Both denticles and blood grooves are oriented
perpendicular to the longitudinal axis of the tooth. Therefore,
specimen UALVP 50640.01 is assigned the taxonomic status Dro-
maeosauridae indet.
6.3.4. Family unknown
One incomplete tooth (UALVP 48815) is identied as Paronychodon
sp. (Fig. 5P). This specimen is the rst unequivocal record of this taxon
from the Wapiti Formation and is the most northern occurrence to
date. The non-serrated tooth has three characteristic longitudinal
ridges on both lingual and labial sides, and an elongated and slightly
apically curved overall shape (FABL, 2.3 mm; BW, 1.1 mm; TCH,
3.9 mm). The attened and ridged lingual surface becomes broader
anteriorly toward the base of the tooth.
6.3.5. Tyrannosauridae
Fragments of tyrannosaurid teeth are commonly encountered in all
the Kleskun Hill microvertebrate fossil sites as well as in other fossil
sites in the Grande Prairie area. Denticles are wider labially-lingually
than they are long proximodistally and occur 22.5 per millimetre
in the posterior carina and 33.5 per millimetre in the anterior one
(Fig. 5QS). Blood grooves are small and restricted to the base of
denticles. The most complete tooth (UALVP 48773.2007.6) lacks the
basal-most portion and would have exceeded 10 cm in height when
complete (FABL, 34.5 mm; BW, 30 mm; TCH 95 mm). The number of
denticles per millimetre on the anterior and posterior carinae is 2.5
and 2 respectively. In cross section, the tooth is compressed labio-
lingually. It is similar in size and overall morphological characteristics
to those of tyrannosaurids from the Campanian and Maastrichtian
successions of southern Alberta (Fig. 5T).
6.3.6. Theropoda incertae sedis
A single small theropod tooth from the Site B (TMP 2004.93.3) is
assigned to Richardoestesia gilmorei based on the minute denticles on
the anterior carina and the small denticles on the posterior carina
(Currie et al., 1990; Sankey et al., 2002). The tooth lacks the top of the
crown, but the morphology is identical to those found in the
Campanian deposits of southern Alberta in that it is labio-lingually
compressed with a moderately recurved posterior carina, and it is
relatively small compared to other theropod teeth (Fig. 5MO).
6.4. Bird
A small, unserrated tooth from the Site B (TMP 2004.93.4) is
identied as that of a bird (Fig. 5UZ). The tooth is short and lacks
denticles, but its posterior margin is blade-like and shows anincipient
carina. The crown is more compressed labio-lingually than in other
theropod teeth from the same locality. It has a few wrinkles on the
lingual surface parallel to the anterior margin of the tooth. It also differs
from the bird teeth from the Belly River Group (Campanian), southern
Alberta described by Sankey et al. (2002) in that the tooth crown
recurves slightly posteriorly (Hope, 2002). However, the crown tip is
still anterior to the posterior margin of the tooth and the crown base
expands anteroposteriorly as in other bird teeth (Sankey et al., 2002).
6.5. Hadrosauridae
More than half of hadrosaurid elements collected at the Kleskun
Hill consist of adult-sized teeth and teeth fragments, tendons, and
poorly preserved postcranial bones. Teeth are worn on the occlusal
surfaces and have a medial carina on the lingual surface.
Other hadrosaurid specimens include three dentary fragments,
well preserved teeth, dorsal and caudal centra, a partially preserved
pedal phalanx, and an ungual and are all referable to hatchling- to
nestling-sized hadrosaurs (Fig. 6). The dentary fragments (Fig. 6LQ)
have pitted surfaces on both sides, and the alveoli (45 mm in width)
correspond with size of the teeth. The better preserved baby tooth
(UALVP 48748) has a crown height and width of 7 and 4.5 mm
respectively, which roughly compares to the largest tooth of an
embryonic Hypacrosaurus stebingeri (4 mm in width; Horner and
Currie, 1994). As in other juvenile hadrosaurid teeth, the tooth is
compressed labio-lingually relatively to those of a typical hadrosaurid
adult. It has the crownroot angle greater than 145° as in
lambeosaurines (Horner et al., 2004). The tooth has a straight median
carina as in hadrosaurines and some lambeosaurines, and an
accessory ridge independent from the median carina on the enameled
side as in some lambeosaurine teeth (Horner et al., 2004). Teeth of
embryonic or hatchling individuals of Hypacrosaurus stebingeri
(Horner and Currie, 1994) and Hadrosauridae indet. (Ryan et al.,
1998) lack the accessory lingual ridge observed in the Kleskun
Hill specimens. Furthermore, the enamel edges have irregular and
tiny denticles (papillae, after Horner, 1992) toward the apex of the
tooth. Other teeth are roughly comparable to UALVP 48748 in size
(Fig. 6AC).
The baby-sized hadrosaurid vertebrae consist of a single dorsal
centrum (UALVP 48816) and four caudal centra (UALVP 48751.01,
48751.02, 50636.03 and 50636.09) (Fig. 6). UALVP 48816 reaches
10 mm in transverse central width, UALVP 48751.01 is 7 mm wide, and
UALVP 50636.09 is a distal caudal centrum with 4 mm in width, as
wide as the teeth are. All the specimens have smooth sutural surfaces
on the dorsal side for the neural arch. The neural canal is relatively
broad, being about two thirds of the centrum width. As in other
hadrosaurids, immature or mature individuals, the dorsal centrum
(UALVP 48816) is hexagonal when viewed anteriorly or posteriorly,
and bears ventral keels. The caudal centra (UALVP 48751.01 and
48751.02) are vertically low and transversely wide relative to those of
adult hadrosaurids. Ventrally, contact with a haemal arch is not clear.
UALVP 48751.01 retains a notochordal pit which has previously been
observed for baby hadrosaurid vertebrae from the Horseshoe Canyon
Formation (Ryan et al., 1998). The pedal ungual (UALVP 48817; 9 mm
in length) is relatively narrowand elongate compared to those in adult
hadrosaurids, and is less constricted at the base (Fig. 6TU).
The baby hadrosaurid materials from the Kleskun Hill compare
well with those of Hypacrosaurus stebingeri from the Oldman and Two
Medicine formations (Horner and Currie, 1994) and Hadrosauridae
indet. from the Horseshoe Canyon Formation (Ryan et al., 1998). The
baby-sized hadrosaurid materials are either not worn or with minor
abrasion, whereas wear is evident in the adult hadrosaurid elements.
The simples assumption is to associate the specimens to a single
hadrosaurid taxon. The accessory ridge parallel to the median carina
and the relatively large crownroot angle (Horner et al., 2004) further
suggest that these are from a lambeosaurine hadrosaur.
6.6. Ceratopsidae
Four ceratopsian teeth were recovered from microsites at the
Kleskun Hill Park. Three of them (UALVP 50636.08, 50636.10, and
50636.11) are referred to adult individuals based on size, overall
shape, and denticulate ridge (Fig. 7A). Specimen UALVP 50636.08
Fig. 6. Baby and juvenile hadrosaurid elements from Kleskun Hill Park, Grande Prairie, Alberta. AC, baby teeth (lingual): A, UALVP 50636.01, B, UALVP 48748, C, UALVP 50636.02.
D, dorsal centrum, UALVP 48816. E, caudal centrum, UALVP 50636.03. FH, caudal centrum, UALVP 48751.01, in anterior (F), dorsal (G) and ventral (H) views. I, caudal centrum,
UALVP 48751.02 (anterior). J, caudal centrum, UALVP 50636.09 (anterior). LM, maxillary fragment, UALVP 50636.04 (lingual and lateral). NO, jaw fragment, UALVP 50636.05
(lingual and lateral). PQ, jaw fragment, UALVP 50636.06 (lingual and ventral). RS, UALVP 50636.09. TU, pedal ungula, UALVP 50636.07 (lateral and anterior). V, distal end of ulna,
UALVP 50636.08. Z, caudal vertebra, UALVP 50637 (anterior).
44 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
45F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
represents a tooth from ajuvenile. It is signicantly smaller than other
ceratopsian teeth from the locality (FABL, 2 mm; TCH, 3 mm) and is
convex in both dorsoventral and mesiodistal views. It contains a sharp,
unserrated central ridge as well as less developed secondary ridges
and denticles (Fig. 7B). Ceratopsian remains are often recovered
within the uvial deposits of the Wapiti Formation, usually preserved
in large-scale bonebeds. Currently, all identiable ceratopsian speci-
mens from the formation are referred to two species of Pachyrhino-
saurus (Tanke, 2004; Currie et al., 2007; Fanti and Currie, 2007; Currie
et al., 2008). Therefore the teeth from the Kleskun Hill Park are
tentatively referred to Pachyrhinosaurus sp.
6.7. Ankylosauridae
Two ankylosaurid teeth (UALVP 48747 and TMP 2004.23.9) were
recovered from Sites A and B respectively. The teeth are weathered to
the extent that the enamel surface is almost entirely gone (Fig. 7C).
6.8. Hypsilophodontidae
A pachycephalosaur tooth (TMP 2004.93.1) were collected from
Site B. The base is thickened, and a robust median ridge supports the
spade-shape crown with multiple denticles and ridges (Fig. 7DG).
Tentatively identied as a hypsilophodont, an ornithischian isolated
tooth from the Site B (TMP 2004.93.5) is heavily worn and weathered.
Even though identication of such an incomplete element is difcult,
the labio-lingually attened tooth with multiple ridges extending to
the base of the crown is most likely a non-hadrosaurid ornithopod.
Size of the tooth assumes an animal similar in size with Parksosaurus
and immature Thescelosaurus (Fig. 7HL).
6.9. Mammals
Two isolated mammal teeth were collected from Site B. One is a
multituberculate P
(TMP 2004.23.2; Fig. 8ST). As in Chulsanbataar
and others (Clemens and Kielan-Jaworowska, 1978), the premolar is
plesiomorphic in having two roots. Its posterolingual part is reduced
by anterolingual expansion of the P
. The four cusps are largely conical
and weakly ridged on their anterior and posterior slopes long-
itudinally. Of the three cusps on the labial side, the anteriormost is the
smallest and more lingual than the posterior two. A transversely wide,
anteroposteriorly narrow basin sits between the anteriormost labial
cusp and the lingual cusp. The second labial cusp is highest, followed
by the posteriormost labial cusp and then by the lingual cusp. Based
on these characteristics, the premolar most closely resembles that of
Cimolodon, but the specimen lacks the posterior lingual cusp. In
addition, the only lingual cusp is displaced relatively more posteriorly,
the anteriormost labial cusp is the smallest, and the posteriormost
labial cusp is relatively larger and higher than in previously known
species of Cimolodon. The tooth is tentatively assigned here to Cimo-
lodon sp.
The second specimen is a double-rooted right lower molar of a
marsupial, presumably RM
(TMP 2004.23.1; Fig. 8UZ). The molar is
relatively shorter anteroposteriorly than in typical marsupial molars
such as that of Herpeotherium, and characterized by the trigonid twice
as tall as the talonid as in M
of Didelphodon coyi (Fox and Naylor,
1986). The roots are approximately 1.5 times deeper than height of the
trigonid. The molar has styler shelves around its anterior and posterior
margins. The metaconid is more anterior than the protoconid, and
reduced in size to the shortest cusp in the trigonid. Both the
protoconid and paraconid are oriented slightly posteriorly than the
Fig. 7. Miscellaneous ornithischian elements from Sites B and C. A, Pachyrhinosaurus sp. tooth, UALVP 48752 (lingual). B, baby ceratopsian tooth, UALVP 50636.10 (lingual).
C, ankylosaurid tooth, UALVP 48747 (labial). DG, Pachycephalosaurid teeth: DE, TMP 2004.93.1A (lingual and labial); FG, TMP 2004.93.1B (lingual and labial). HL,
hypsilophodont tooth, TMP 2004.23.5 (lateral, labial, and lingual).
46 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
metaconid. The triangle formed by the protoconid, metaconid, and
paraconid has an acute angle at the protoconid, comparable to Di-
delphodon sp., more acute than Eodelphis, and wider than D. coyi (Fox
and Naylor, 1986). The talonid basin is slightly narrower transversely
than the trigonid, and approximately as long anteroposteriorly as the
trigonid. The styler cups A, B, and C are nearly equal in size and form
the labial margin of the talonid basin. The styler cusp D is larger, at the
posterolabial corner of the talonid. It has two cristae extending toward
the hypoconid, and also connects to the posterior styler shelf. The
hypoconid is transversely wide, and the prehypoconid crista extends
anterolabially, separating a pocket on the lingual side between the
protoconid and the hypoconid from the talonid basin. Unlike Alpha-
don, the molar is less than twice anteroposteriorly long as wide across
the protoconid (Lillegraven, 1969). Unlike Pediomys, the styler cusps
sit closer to the trigonid, forming an anteroposteriorly limited talonid
basin as in Didelphodon (Lillegraven, 1969; Fox and Naylor, 1986). The
molar morphology most closely resembles that of Didelphodon, and
thus it is tentatively referred to Didelphodon sp. The molar is about
half the size of the previously described Didelphodon molars.
7. Discussion
The vertebrate diversity recovered from the Kleskun Hill sites
indicates that the locality is a multidominant, high diversity microsite
(following the classication and nomenclature proposed by Eberth
et al., 2007). The site originated in a channel/overbank-wetland
palaeoenvironment characterized by wet and humid climatic condi-
tions. The twelve dinosaur taxa identied outnumber other verte-
brates and represent 54.6% of the overall diversity. Hadrosaurid bones
and teeth are 46.9% of all the recovered elements and together with
theropod teeth (35.4%) constitute the bulk of the collection, with eight
taxa represented. Of paramount importance, elements identied as
baby and hatchling individuals represent the 18.9% of all hadrosaurian
material. These well preserved fossils were subject to negligible pre-
burial transportation, strongly supporting the presence of a nesting
ground nearby. In addition, the pattern of distribution of different taxa
appears to be intimately linked to different depositional environments
observed in the Kleskun Hill outcrops. For instance, Site A is
characterized by organic-rich clay and mud, and bentonitic paleosols
deposited under high- and still-water table conditions suggesting
permanent swampy and bogs-like environments. Multidominant
microsites are often interpreted as post-deposition reworked assem-
blages (Brinkman et al., 2007; Eberth et al., 2007; Rogers and Kidwell,
2007). However, sedimentological and palaeontological features
observed at Site A suggest accumulation in low-sedimentation-rate
palaeoenvironments unaffected by relevant hydraulic transportation
or reworking processes (Bown and Kraus, 1981; Eberth et al., 2007).
Thus, in terms of depositional system the site is referred to a wetland/
bog/marginal-pond palaeoenvironment.
Using the same classication criteria adopted for Site A, Sites B
and C can be referred to high-diversity multidominant and mono-
dominant microsites respectively (Fig. 9). Site B is dominated by sh
remains (37.9%), with frequent theropod (13.8%) and hadrosaur
(13.8%) elements, whereas Site C is characterized by abundant tyran-
nosaurs teeth (78.9%). Depositional setting distinguishes Sites B and
C from Site A. Both Sites B and C occur within sandy, well-drained,
channel-lag and overbank deposits characterized by high-energy and
signicant pre-burial reworking and abrasion, as indicated by the
poor preservation of vertebrate remains. In addition, elements col-
lected within this interval are: 1) generally larger than those
recovered at Site A; and 2) mainly come from large-sized animals
(i.e. full grown tyrannosaurs, ceratopsian, and hadrosaurs). Conse-
quently, the taxa represented in those sites are not necessarily
representative of the Kleskun Hill Park area and may include
elements mobilized by hydraulic processes within the active channel
belt of the alluvial plain.
7.1. Possible explanation for abundance of Troodon
Hadrosaurids and small theropods (Troodon,Saurornitholestes,
Paronychodon, and Dromaeosauridae indet.) represent 76.4% of all the
specimens from Site A. Particularly, hatchling- to nestling-sized
hadrosaurids occur at 10.9% (baby hadrosaurids account for 17.4% of
all hadrosaurian elements), and Troodon occupies 16.7%. Ryan et al.
(1998) suggested a non-random association between baby hadro-
saurids and Troodon in a microvertebrate fossil locality in the
Horseshoe Canyon Formation of southern Alberta (latest Campa-
nianearly Maastrichtian), where other dinosaur taxa are uncommon.
Barring the small sample size of Troodon and baby hadrosaurs, their
relative abundance may be congruent with Ryan et al.'s nding and
possibly expands this distribution of the baby hadrosaurid-Troodon
association northwards. Ryan et al. (1998) explained the association
with the hypothesis that Troodon hunted on either young or small
sized dinosaurs, at least as a part of their diet. However, the high
abundance of both baby hadrosaurids and Troodon in Site A alone does
not constitute evidence of the predatorprey association in the
locality. Whether or not feeding on hatchling and young hadrosaurs,
the abundance of small theropods at Site A is probably reection of
relatively large number of small-bodied predators in the area. The
small and agile carnivores would have been more successful in a
swampy, palustrine, and highly vegetated environment inaccessible to
larger carnivores such as tyrannosaurids.
Beside feeding strategy of Troodon, the genus seems to show
latitudinal gradient in its relative abundance within local theropod
faunas. Troodon is increasingly more common northward, with 6%
occurrence rate in the Judith River Formation of Montana (Currie and
Fiorillo, 1994), 31.2% in the northern section of the Wapiti Formation
(Fanti, 2007; this paper) and 65% in the Prince Creek Formation of
Alaska (Fiorillo and Gangloff, 2000; Fiorillo, 2006). Sankey (2001)
rejected the previous assignment of the theropod teeth to Troodon sp.
from the Aguja Formation of Texas, and suggested that Troodon was a
member of the northern dinosaur assemblages. The unusual abun-
dance of Troodon in the Kleskun Hill locality may not accurately reect
its real abundance in the region because it may assume local
environmental factors, such as food source, that favoured assembling
Troodon. Another confounding problem is that compared localities are
not necessarily contemporaneous to each other. Although these
caveats suggest that the high Troodon occurrence in the north may
be partly exaggerated, it is plausible that Troodon was more common
in northern regions (Baszio, 1997a,b; Fiorillo and Gangloff, 2000).
8. Faunal comparison
In spite of the taxonomical diversity preserved at the Kleskun Hill,
the limited sample size precludes a detailed and extensive statistic
comparison between the local fauna and fossil association reported
elsewhere in western Canada and the United States. However, the
microvertebrate fossil assemblage at the Kleskun Hill locality
represents 92% of the total vertebrate diversity recovered from the
Wapiti Formation to date. For this reason, specimens described in this
paper allow a preliminary reconstruction of the palaeocommunity in
such an important temporal and geographical context (Fig. 10).
Three sh taxa are recognized from the Kleskun Hill: an esocoid
(Oldmanesox sp.) and holosteans A and B. They are virtually indis-
tinguishable from their counterparts in the Belly River Group (Campa-
nian) of southern Alberta (Brinkman, 1990; Wilson et al., 1992;
Brinkman and Neuman, 2002) and represent the northernmost record
of this association. Holostean A continued to occur into Maastrichtian
deposits in southern Alberta (Horseshoe Canyon and Scollard forma-
tions, Edmonton Group), althoughOldmanesox and holostean B seem to
be absent in the Group (Eberth et al., 2001).
Discovery of squamates and a possible turtle from the Kleskun Hill is
geographically signicant because there has been no report of their
47F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
48 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
occurrence in the high-latitude and polar Late Cretaceous terrestrial
localities, including the Prince Creek Formation of Alaska (Buffetaut,
2004; Godefroit et al., 2008). Squamates are also interesting stratigra-
phically since their post-Bearpaw to early Maastrichtian record is scarce
in North America (Gao and Fox, 1996). Sternberg (1951) also reported a
teiid squamate jaw from thevicinity of the Kleskun Hill Park. In addition,
Tanke (2004) mentions occurrences of salamander and choristoderan
reptiles. However, such specimenswere not relocated in the collections
and therefore the presence of salamander and choristoderan from the
locality are yet to be conrmed.
All the dinosaur taxa are known from the CampanianMaastrich-
tian units of southern Alberta (the Belly River Group and Edmonton
Group: Brinkman, 1990; Currie et al., 1990)and,exceptforParony-
chodon,Richardoestesia, and the bird, also from the Prince Creek
Formation of Alaska (Rich et al., 1997; Fiorillo and Gangloff, 2000;
Gangloff et al., 2005). Notably, the occurrence of Paronychodon and
Richardoestesia are the northernmost records of these enigmatic
genera. Fiorillo (2008b) reported unusual teeth of Troodon from the
Prince Creek Formation of Alaska which are twice the size of those
known from southern Alberta and Montana; consequently Fiorillo
suggests that Troodon increases in body size northward, possibly
because of its dominance and competitive edge (e.g., increased orbit
diameter) over other theropods in higher latitudes.
On the contrary, the teeth of Troodon from the Kleskun Hill
Park are comparable in size to those from southern Alberta and
Montana. Therefore, our results are consistent with Fiorillo's hypo-
thesis that Troodon increases in body size as a function of its
dominance over multiple carnivorous niches, but not as a function
of high latitude as predicted by Bergman's rule. Because most taxa
are only identied to the higher taxonomic levels (i.e. Tyran-
nosauridae, Verociraptorinae, Ankylosauridae, Hypsilophodontidae,
Lambeosaurinae, Pachycephalosauridae, Paronychodon,Sauror-
nitholestes,andTroodon), it would not be surprising if the dinosaur
assemblages in Alaska, northern Alberta, and southern Alberta
differed at species or generic level, as predicted by the hypothesis
of dinosaur provincialism in western North America during the
Campanian and Maastrichtian (Lehman, 1987, 1997, 2001; Sampson
and Lowen, 2007). The current data from the Wapiti Formation
support a wide distribution of all dinosaur families and subfamilies
discussed in this paper along the Western Interior during the
Campanian and Maastrichtian, although this does not necessarily
refute the hypothesis of provincialism.
The mammals are tentatively identied as Cimolodon sp. and Di-
delphodon sp. respectively and are the northernmost occurrence for
the genera. In particular, Didelphodon sp. from the Kleskun Hill is most
similar to Didelphodon sp. from the Scabby Bute of southern Alberta
(St. Mary River Formation, Edmonton Group: Fox and Naylor, 1986)
based on the acute triangle formed by the trigonid cusps, suggesting a
close phylogenetic relationship. Discovery of both a multituberculate
and a marsupial is not surprising, because these mammals were
already reported from Alberta (Lillegraven,1969; Fox, 2005) and from
the Prince Creek Formation (SantonianMaastrichtian) of Alaska
(Clemens and Nelms, 1993; Fiorillo and Gangloff, 2000). Pending
taxonomic assignment of the Alaskan fossils, the Kleskun Hill
specimens are potentially important for mammal palaeobiogeography
during the Late Cretaceous of North America.
According to the most recently compiled dinosaur and other
vertebrate faunal lists (Tanke, 1988; Currie, 1989a; Ryan and Russell,
2001; Weishampel et al., 2004; Tanke, 2004) and in the light of recent
dinosaur discoveries in the Grande Prairie area (Fanti and Currie,
2007; Currie et al., 2008; this paper) more than thirty-ve species are
currently known from the Wapiti Formation. Amongst these taxa, the
ceratopsian dinosaur Pachyrhinosaurus lakustai (Currie et al., 2008)is
the only diagnostic vertebrate taxon described from the formation.
Currie et al. (2008) also conrmed that a second ceratopsian bonebed
above the CampanianMaastrichtian boundary in the Wapiti
Fig. 9. Relative distribution of Kleskun Hill taxa at the three fossiliferous sites. See the text for discussion.
Fig. 8. Miscellaneous elements from Sites A and B. AD, esocoid dentary, TMP 2004.23.7, in medial (A), lateral (B), dorsal (C), and ventral views (D). EG, Holostean A scales: E, TMP
2004.93.2 (dorsal and ventral), F, TMP 2004.23.8 (dorsal and ventral), G, TMP 2004.93.5 (dorsal and ventral), H, Holostean B scale, TMP 2004.23.8 (dorsal and ventral). IJ, amiid
centrum UALVP 50638.01, (anterior and dorsal). LM, amiid centrum UALVP 50638.02 (anterior and dorsal). N, possible turtle shell fragment, UALVP 48754. OP, Cimolodon sp. tooth
TMP 2004.23.2 (occlusal and labial views). QS, Didelphodon sp. tooth, TMP 20 04.23.1 (lingual, labial, and occlusal views).
49F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
Formation yielded a chelydrid turtle neural plate, a varanid squamate
vertebra, and crocodile scutes.
9. Nesting of hadrosaurids
Hatchling- to nestling-sized hadrosaurid elements from the
Kleskun Hill Park indicate that hadrosaurids nested in the area in
the late Campanian (74 My). A high-latitude record of dinosaur
nesting is extremely rare. Recently, Godefroit et al. (20 08) reported
eggshell fragments and juvenile hadrosaur elements from a latest
Cretaceous locality in northern Siberia. In North America, G. Nelms,
in Carpenter (1999) mentions Edmontosaurus sp. bonesfrom the
Prince Creek Formation of Ocean Point, Alaska, in the global survey
of baby dinosaur records. However, the supposed Alaskan baby
Edmontosaurus has neither been described nor illustrated since
Nelm's personal communication to Carpenter (1999). In addition,
thepresenceofEdmontosaurus is yet to be conrmed from Alaska
(Bell and Snively, 2008). Therefore, the report on the Alaskan baby
dinosaur material is considered not reliable in this study. The
Kleskun Hill locality is currently the northernmost published record
of a dinosaur nesting ground in North America, pending proper
assessment of the Alaskan material. Fiorillo (2008a) emphasized the
argument in Fiorillo and Gangloff (2001) that the juvenile
hadrosaur materials from the Prince Creek Formation represent
individuals younger than 1 year old. Therefore, it is likely that the
hadrosaurs were year-round residents of the region, inferring that
they also nested in the Arctic.
The hypothesized hadrosaurid nesting site at the Kleskun Hill is
also important in a palaeoecological perspective. Previously, hadro-
saurid nesting sites (referring to localities where eggshells or
embryonic elements have been reported) seemed to preferentially
occur in dry, upland regions (Horner, 1982; Horner and Currie, 1994).
Carpenter (1982, 1992), and Fiorillo (1987, 1989) reported eggshells
and baby or juvenile hadrosaurid specimens from the low-land
settings (the Lance and Hell Creek formations and the Judith River
Formation, respectively). In Alberta, Nadon (1993) noted common
occurrence of eggshells from the anastomosed uvial deposits of the
St. Mary River Formation, Ryan et al. (1998) described hatchiling- to
nestling-sized hadrosaurid elements from the Horseshoe Canyon
Formation, and Tanke and Brett-Surman (2001) also reported
hatchling- to nestling-sized hadrosaurid elements and eggshells
from the low-land Dinosaur Park Formation of southern Alberta.
Coupled with these previous ndings, the Kleskun Hill hadrosaurid
materials provide further evidences that hadrosaurids also nested in
low-land settings. Nadon (1993) proposed that ornithopods prefer-
entially selected wetland habitats as ideal reproductive site where a
soft substrate and ooded conditions would have deterred large
carnivores. The implications are that hadrosaurids seem to have had
various strategies in nesting site selection, and that the fossil record of
nesting sites is taphonomically biased against wet, lowland environ-
ment as weak acidity in groundwater would have generally enhanced
dissolution of eggshells and poorly ossied elements unless buffered.
In addition to hadrosaurids, small ceratopsian elements imply that
ceratopsians either nested in the region or had not migrated over long
distance from the nesting site (Currie, 1989b). Interestingly, post-
cranial elements ascribed to juvenile and subadult hadrosaurs have
been collected from nearly coeval strata cropping out along the Wapiti
River south of Grande Prairie (see also Tanke, 2004). Furthermore,
Currie et al. (2008) report of an almost complete ontogenetic series of
Pachyrhinosaurus lakustai (including juvenile, subadult, and adult
individual) from the densely packed Pipestone Creek bone bed which
has been dated 73.27± 0.25 My. Palaeogegraphic reconstruction for
the Bearpaw time (Dawson et al., 1994) place the Grande Prairie area
in the order of 250300 km from the shoreline, located approximately
Fig. 10. Reconstruction of the late Campanian vertebrate fauna of the Wapiti Formation near Grande Prairie, Alberta, based on the taxa from the Kleskun Hill locality and correlative
beds discussed in the text. Drawing by Lukas Panzarin.
50 F. Fanti, T. Miyashita / Palaeogeography, Palaeoclimatology, Palaeoecology 275 (2009) 3753
to the north and to the west of Edmonton. Sedimentological data and
palaeoenvironmental reconstruction presented in this study support
an extensive low-land environment (referring to the low and
relatively level ground of the region, in contrast with adjacent higher
country), genetically related to the maximum transgressive phase of
the Bearpaw Sea.
10. Conclusion
The Kleskun Hill Park vertebrate fauna represents the rst high-
diversity multidominant assemblage from the Late Cretaceous of
north western Canada. The fauna is also stratigraphically important
being the only locality that provides a glimpse of a diverse terrestrial
vertebrate fauna in western North America during the Bearpaw Sea
transgressive event about 74 My. At the Kleskun Hill Park, Site A best
represents the vertebrate diversity of the formation because of the
larger sample size. The site is characterized by relative abundance of
Troodon teeth and hatchling- to nestling-sized hadrosaur elements.
The latter suggests the presence of a hadrosaurid nesting ground
in the nearby lowland area within the alluvial plain. In contrast
Sites B and C, both with a smaller sample size, preserve a reworked
assemblage dominated by pre-burial uvial transportation. The
Kleskun Hill vertebrate fauna preserves many taxa that are common
in Campanian terrestrial vertebrate faunas in southern Alberta. The
locality marks the northernmost distribution of Paronychodon and
Richardoestesia. Additionally, three sh taxa (holosteans A and B, and
an escoid Oldmanesox sp.), squamates, and bird have not been re-
ported from Alaska to date (Fiorillo and Parrish, 2004; Fiorillo et al.,
2007). Multituberculates and marsupials have been reported from the
Prince Creek Formation of Alaska (Clemens and Nelms, 1993), but it is
not clear if the Kleskun Hill Park taxa (Cimolodon sp. and Didelphodon
sp.) are identical to their counterparts in the Campanian of southern
Alberta and Alaska. An impeding task is more sampling at the Kleskun
Hill and assessment of new material from the Alaskan localities which
may further result in testing the hypothesis of dinosaur provinciality
(Lehman, 2001). Although the sample size remains small, the
preliminary account of the vertebrate diversity demonstrates that
the Grande Prairie region promise to be a key area in both
stratigraphic and palaeobiogeographic contexts during the Late
Cretaceous of North America.
We thank the Palaeontological Society of Peace, especially Sheldon
Graber, Robert Hunt, Katalin Ormay, Desh Mittra, and their families,
the Grande Prairie Regional College, Philip Currie and Eva Koppelhus
(University of Alberta, Edmonton) for logistic supports in eld. Many
thanks are also extended to Nick Ormay and Walter Paszkowski for
their contribution to eldwork. Don Brinkman (TMP) and Patty Ralrick
did initial sorting and identication of the specimens stored in TMP. F.F.
is also indebted to Dennis Braman, Donald Brinkman, and David Eberth
(TMP) for sharing unpublished data and for stimulating discussions.
Don Brinkman, James Gardner, Brandon Strilisky (TMP) and Philip
Currie (U. of A.) provided access to the collections in their care.
Comments from Julia Sankey (California State University Stanislaus,
Turlock, USA), Finn Surlyk (University of Copenhagen, Denmark), and
an anonymous reviewer greatly improved this manuscript. The rst
draft beneted from discussion with Paul McNeil (Grande Prairie
Regional College) and Darren Tanke (TMP). We also acknowledge
Philip Currie, Eva Koppelhus, Rich Palmer (University of Alberta),
Don Henderson (TMP), and Kesia Andressen for their support at
various stages of the project. The specimens were illustrated by Lukas
Panzarin. T.M. extends thanks to students and staffs at Ohwada
Primary School of Hachioji (19921998) for continuing encourage-
ments. This work was supported by the University of Bologna, Museum
of Geology and Palaeontology Giovanni Capellini (Bologna, Italy),
Jurassic Foundation, Dinosaur Research Institute, and Grande Prairie
Regional College to F.F., and by personal funds from Junichi and Kanae
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... However, the current literature contains few well-constrained studies of the interplay between latitudinal and depositional gradients during the Late Cretaceous and how such interactions could have shaped the vertebrate communities of the time. Furthermore, the dynamics and ecological consequences of complex, large-scale Earth system events (e.g., major transgressions and regressions), capable of reshaping the geography and environment of entire depositional basins, have been addressed only at a conceptual level (Weishampel and Horner, 1987;Horner et al., 1992;Upchurch et al., 2002;Brinkman, 2003;Bell and Snively, 2008;Butler and Barrett, 2008;Fanti and Miyashita, 2009;Mannion et al., 2012Mannion et al., , 2014Lucas et al., 2016;Chiarenza et al., 2019). This dearth of information is primarily due to the lack of geographic and temporal continuity among fossil-bearing localities, combined with difficulties in tracing timerepresentative surfaces across multiple terrestrial sedimentary units (Sullivan and Lucas, 2006;Holland and Loughney, 2021). ...
... Second, the Wapiti Formation in the study area around Grande Prairie was deposited at a palaeolatitude close to 60 • N (Matthews et al., 2016), so its fossil assemblages are unusual in representing multiple highlatitude Late Cretaceous communities that succeeded one another across the 8 Ma timespan. Over the last decade, an increasing number of papers have described the diverse vertebrate fossil record of the Wapiti Formation, documenting some of the richest Cretaceous fossil sites in North America (Currie et al., 2008;Fanti and Miyashita, 2009;Bell et al., 2014;Fanti et al., 2015;Bell and Currie, 2016;, remarkably preserved individual specimens Bell et al., 2013aBell et al., , 2014Barbi et al., 2019), and diverse ichnofossil assemblages (Bell et al., 2013b;Fanti et al., 2013;Enriquez et al., 2020Enriquez et al., , 2021Enriquez et al., , 2022. ...
... However, integrated subsurface, outcrop and palaeontological data indicate that the fine-grained deposits of WU3 are correlative with the Bearpaw Formation of central Alberta (Fanti and Catuneanu, 2010;Zubalich et al., 2021). Sedimentological and palaeontological data also indicate that WU3 was deposited in extensive lowland environments located near (i.e., within tens of kilometres of) the palaeo-shoreline (Fanti andMiyashita, 2009, Fanti andCatuneanu, 2010;Schröder-Adams, 2014;Koppelhus andFanti, 2019, Chiarenza et al., 2019;Zubalich et al., 2021; this study). ...
Patterns of Late Cretaceous terrestrial vertebrate diversity across North America have been interpreted primarily in terms of biogeographic provincialism driven by latitude or coastal-inland habitat gradients. A major difficulty in determining the influence of these two gradients is the existence of some large gaps in the terrestrial fossil record, notably the ‘Bearpaw gap’ caused by a transgression of the inland Bearpaw Seaway during the latter part of the Campanian. In this context, the terrestrial fauna preserved in the Campanian deposits of the Wapiti Formation (west-central Alberta, Canada) is crucial for addressing the information deficit. Deposited at the edge of the palaeo-circumpolar region, Unit 3 of the strictly terrestrial Wapiti Formation (WU3) is coeval with the ‘Bearpaw gap’, a period when the terrestrial record from better-sampled areas elsewhere in Canada and the U.S.A. gives way to marine sediments. Here we show, based largely on evidence from the recently discovered DC (Dinosaur-Chelonian) Bonebed locality, that the diverse WU3 vertebrate fauna shares similarities with lowland to marginal marine ecosystems in the Oldman and Dinosaur Park formations which were deposited in southern Alberta prior to the Bearpaw gap. In addition, a major change in faunal composition demarcates the upper boundary of WU3, related to the disappearance of the Bearpaw Sea in Canada. Data presented here help, first and foremost, to bridge an ~1.2-million-year gap in the North American record of Campanian terrestrial vertebrates. Resemblances between the WU3 vertebrate fauna and slightly older assemblages from southern Alberta underscore the importance of determining the spatiotemporal changes in environmental factors (e.g., coastal proximity). The occurrence of one seemingly endemic lizard, together with differences in relative taxon abundance, suggest additional latitude-correlated factors, implicating both latitudinal and coastal-inland habitat gradients in driving the taxonomic composition of Late Cretaceous terrestrial faunas.
... All tracks were identified to the lowest possible taxonomic level, using their overall morphological characters and contextual (i.e., chronostratigraphic) relevance. Based on skeletal material recovered within Late Cretaceous terrestrial strata of both the Wapiti Formation and more broadly in western Canada [8,12,15,16,54,55], tridactyl prints from Tyrants Aisle can be confidently regarded as belonging to either hadrosaurid, theropod or, possibly, thescelosaurid dinosaurs; tracks that possess broad, rounded digits with blunt terminations and relatively broad heels were treated as hadrosaurid tracks, while prints with relatively slender digits, sharp claw marks, and more narrow heels were regarded as theropod-like tracks [7,56]. The term "theropod-like" is used herein to accommodate the theoretical possibility that some of these tracks may pertain to thescelosaurids, which arguably produced similar track morphologies to those of theropods, making them difficult to distinguish. ...
... The term "theropod-like" is used herein to accommodate the theoretical possibility that some of these tracks may pertain to thescelosaurids, which arguably produced similar track morphologies to those of theropods, making them difficult to distinguish. While thescelosaurids are presently unknown within Unit 4 of the Wapiti Formation, possible fragmentary remains of these dinosaurs have been recovered from Unit 3 [12]. ...
... Tridactyl theropod-like tracks were sorted into tyrannosaurid or indeterminate theropodlike morphotypes, primarily according to size. As tyrannosauroids are the only known largebodied functionally-tridactyl theropods within post-Cenomanian strata from North America [57,58], and given the presence of indeterminate tyrannosaurid body fossils and tracks within the Wapiti Formation [10,12,14,17], it was assumed that any tridactyl theropod-like track �45 cm in length-that does not show evidence of being a deep undertrack [59]-must belong to a tyrannosaurid maker. Deep undertracks may be considerably larger than the corresponding surface track and shallow undertracks, but can be recognised by their poorly defined, flattened track margins, and by the absence of such features as sharp claw marks, digital pad impressions, and skin impressions [60][61][62][63][64]. ...
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The Wapiti Formation of northwest Alberta and northeast British Columbia, Canada, preserves an Upper Cretaceous terrestrial vertebrate fauna that is latitudinally situated between those documented further north in Alaska and those from southern Alberta and the contiguous U.S.A. Therefore, the Wapiti Formation is important for identifying broad patterns in vertebrate ecology, diversity, and distribution across Laramidia during the latest Cretaceous. Tracksites are especially useful as they provide a range of palaeoecological, palaeoenvironmental, and behavioural data that are complementary to the skeletal record. Here, we describe the Tyrants Aisle locality, the largest in-situ tracksite known from the Wapiti Formation. The site occurs in the lower part of Unit 4 of the formation (~72.5 Ma, upper Campanian), exposed along the southern bank of the Redwillow River. More than 100 tracks are documented across at least three distinct track-bearing layers, which were deposited on an alluvial floodplain. Hadrosaurid tracks are most abundant, and are referable to Hadrosauropodus based on track width exceeding track length, broad digits, and rounded or bilobed heel margins. We suggest the hadrosaurid trackmaker was Edmontosaurus regalis based on stratigraphic context. Tyrannosaurids, probable troodontids, possible ornithomimids, and possible azhdarchid pterosaurs represent minor but notable elements of the ichnofauna, as the latter is unknown from skeletal remains within the Wapiti Formation, and all others are poorly represented. Possible social behaviour is inferred for some of the hadrosaurid and small theropod-like trackmakers based on trackway alignment, suitable spacing and consistent preservation. On a broad taxonomic level (i.e., family or above), ichnofaunal compositions indicate that hadrosaurids were palaeoecologically dominant across Laramidia during the late Campanian within both high-and low-latitude deposits, although the role of depositional environment requires further testing.
... Hadrosaurid specimens from bonebeds in these formations were among the first dinosaurs to be histologically sampled, which allowed for the reconstruction of their growth rates (Horner & Currie, 1994;Horner, Ricqles & Padian, 1999;Horner, De Ricqles & Padian, 2000) and provided the first evidence for parental care in dinosaurs (Horner & Makela, 1979;Horner, De Ricqles & Padian, 2000). Despite their frequency and importance, large numbers of North American hadrosaurid bonebeds have not been described in detail, particularly in northern rock units such as the Wapiti Formation (Fanti & Catuneanu, 2009;Fanti & Miyashita, 2009). These offer the opportunity to explore the diversity and preservation of hadrosaurids outside the traditionally sampled North American strata. ...
... Unlike its more famous southern counterparts, which are interrupted by marine transgressions of the Bearpaw Formation, the Wapiti Formation is a continuous package of terrestrial sediments (Eberth & Getty, 2005;Fanti & Catuneanu, 2009;Eberth & Braman, 2012). Although the Wapiti Formation was originally only for a single ceratopsian site, the Pipestone Creek Bonebed (Currie, Langston & Tanke, 2008b), fieldwork over the past 10-15 years has uncovered abundant vertebrate ichnofossils , articulated skeletons with skin impressions (Bell et al., 2014a;Bell et al., 2014b;Enriquez et al., 2021;Enriquez et al. in press), microfossil sites (Fanti & Miyashita, 2009), and macrofossil bonebeds (Tanke, 2004;Currie, Langston & Tanke, 2008b;Fanti, Currie & Burns, 2015) (Fig. 1). ...
... As such, the development of bone textural switches in Edmontosaurus sp. from Alaska could be the result of polar overwintering, with harsher seasons leading to growth interruption (Chinsamy et al., 2012), although distinct LAGs have also been noted in some hadrosaurids from temperate latitudes (Horner, Ricqles & Padian, 1999). Nevertheless, the lack of LAGs at the SCBB suggests that Unit 3 of the Wapiti Formation was deposited under relatively equable climatic conditions (Fanti & Miyashita, 2009). In any case, the use of LAGs to determine absolute age is evidently ambiguous, especially for humeri (Horner, Ricqles & Padian, 1999;Horner, De Ricqles & Padian, 2000;Vanderven, Burns & Currie, 2014;Woodward et al., 2015). ...
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Hadrosaurid (duck-billed) dinosaur bonebeds are exceedingly prevalent in upper Cretaceous (Campanian–Maastrichtian) strata from the Midwest of North America (especially Alberta, Canada, and Montana, U.S.A) but are less frequently documented from more northern regions. The Wapiti Formation (Campanian–Maastrichtian) of northwestern Alberta is a largely untapped resource of terrestrial palaeontological information missing from southern Alberta due to the deposition of the marine Bearpaw Formation. In 2018, the Boreal Alberta Dinosaur Project rediscovered the Spring Creek Bonebed, which had been lost since 2002, along the northern bank of the Wapiti River, southwest of Grande Prairie. Earlier excavations and observations of the Spring Creek Bonebed suggested that the site yielded young hadrosaurines. Continued work in 2018 and 2019 recovered ~300 specimens that included a minimum of eight individuals, based on the number of right humeri. The morphology of several recovered cranial elements unequivocally supports lambeosaurine affinities, making the Spring Creek sample the first documented occurrence of lambeosaurines in the Wapiti Formation. The overall size range and histology of the bones found at the site indicate that these animals were uniformly late juveniles, suggesting that age segregation was a life history strategy among hadrosaurids. Given the considerable size attained by the Spring Creek lambeosaurines, they were probably segregated from the breeding population during nesting or caring for young, rather than due to different diet and locomotory requirements. Dynamic aspects of life history, such as age segregation, may well have contributed to the highly diverse and cosmopolitan nature of Late Cretaceous hadrosaurids.
... (2) small supraorbital bones; and (3) a supracleithrum without a concave articular facet for articulation with the posttemporal. Holostean A scales have been reported from the upper Campanian Wapiti Formation of northern Alberta (Fanti and Miyashita, 2009), lower Maastrichtian portion of the Horseshoe Canyon Formation of Alberta (Larson et al., 2010), and the upper Maastrichtian Hell Creek Formation of Montana (Brinkman et al., 2014) but have not previously been reported from the Paleocene. ...
... In addition to those from the Dinosaur Park Formation, scales of Holostean B are present in the Campanian Wapiti Formation of Alberta (Fanti and Miyashita, 2009), Turonian-Coniacian Bissekty Formation of Uzbekistan (Fig. 3K), and the upper Turonian Kangut Formation of Axel Heiberg Island (Fig. 3L), but have not been found in upper Maastrichtian formations (Brinkman et al., 2014). The presence of scales of Holostean B in the Roche Percée sites is a significant range extension for this taxon and shows that this fish survived the K/Pg boundary event. ...
The diversity of fishes represented in upper Paleocene microfossil localities in the Ravenscrag Formation near Roche Percée, Saskatchewan, is documented. Thirteen kinds of fishes are recognized. Two chondrosteans are present, a sturgeon and a paddlefish, both represented by small, irregularly shaped, ornamented bony plates. Four kinds of basal neopterygians are identified. Two of these, Atractosteus and Cyclurus, are widely distributed in both Paleocene and Upper Cretaceous localities. The remaining two are unnamed taxa designated Holostean A and Holostean B that were known previously from Upper Cretaceous localities but have not been reported from the Paleocene prior to this report. The presence of these taxa in the late Paleocene further supports the conclusion that basal neopterygians were little affected by the K/Pg mass extinction event. Seven teleosts are present in the assemblage. This assemblage of teleosts is similar to assemblages of upper Paleocene fishes from the Paskapoo Formation of Alberta in the presence of osteoglossomorphs, a gonorhynchiform, the esocid Esox, a percopsiform, and at least one other acanthomorph. It differs in the presence of a generically indeterminate protacanthopterygian designated here as morphotype ES-1 and a teleost of uncertain relationships designated morphotype PT-1. Neither of these taxa is present in the Late Cretaceous, suggesting that they first appeared in the area during the early or middle Paleocene. Comparison of the fish assemblages of the late Paleocene and early Eocene suggests that a major faunal transition occurred at the Paleocene/Eocene boundary, and that this involved a decrease in diversity of basal neopterygians.
... Assignment of the trackmakers of Ty.I.8C and the BADP2019 pes track natural cast to Tyrannosauridae, rather than another theropod clade, relies on the observed absence of other large theropods from western North America during the latest Cretaceous (Weishampel et al., 2004;Eberth et al., 2013;Brown et al., 2015). While the theropod skeletal record from the Wapiti Formation is poor and taxonomically ambiguous (Fanti and Miyashita, 2009;Fanti et al., 2013;Brown et al., 2015), the Horseshoe Canyon Formation in southern Alberta provides a comparable, proximate, better sampled/studied, and partly contemporaneous rock unit (Eberth and Braman, 2012;Eberth et al., 2013). For instance, the discovery of Edmontosaurus regalis (Bell et al., 2014a) within Unit 4 of the Wapiti Formation, a hadrosaurid otherwise known exclusively from the lower members of the Horseshoe Canyon Formation (Campione and Evans, 2011;Eberth et al. 2013), supports the latter's use to evaluate taxa potentially present in parts of the Wapiti Formation. ...
... In any case, similar pedal morphology (Farlow et al., 2013) and growth rates (Erickson et al., 2004) indicate that tracks made by species of Gorgosaurus, Daspletosaurus, and Albertosaurus would likely be comparable in their growth trajectories. (Fig. 8C, D) The taxonomic affinity of small-to-medium tridactyl theropod footprints (such as Th.Tw1.4.6B) is complicated by the presence of at least one indeterminate ornithomimid within the Wapiti Formation (Ryan and Russell, 2001;Weishampel et al., 2004;Fanti and Miyashita, 2009) and at least three ornithomimid genera identified from the Horseshoe Canyon Formation (Ryan and Russell, 2001;Cullen et al., 2013;Claessens and Loewen, 2015;Macdonald and Currie, 2018). Based on North American ornithomimid pedes that are reasonably complete (e.g., Osborn, 1916;Cullen et al., 2013) and using these to scale more fragmentary, but larger specimens (see Longrich, 2008: fig. ...
Fossil tracks should theoretically capture differences in pedal anatomy between growth stages of the same taxon, particularly those related to the soft tissue of the foot, providing a more realistic view of pedal ontogeny than skeletal material alone. However, recognizing these ontogenetic trajectories is complicated by the influence of preservation and kinematics on track morphology, as well as the inherent difficulty of referring different tracks to a single taxon. Here, we explore differences in track morphology from a collection of tracks attributed to tyrannosaurids from Unit 4 of the Wapiti Formation (upper Campanian) in western Canada. Along with morphology, close geographic and stratigraphic associations suggest that the tracks pertain to similar tyrannosaurid trackmakers. A geometric morphometric analysis of the track outlines reveals size-dependent increase in relative track robusticity, driven primarily by an increase in 'heel' breadth and surface area. This relationship is lost when the dataset is expanded to include tyrannosaurid tracks globally, which we attribute to increased stratigraphic and taxonomic 'noise' within the global dataset that masks the tightly constrained patterns obtained from the Wapiti Formation tracks. Although there is some substrate and kinematic influence on certain aspects of track morphology, we hypothesize that the observed size-dependent relationship reflects genuine expansion in the breadth of the heel soft tissues and probably their overall surface area associated with growth. Increased pedal robusticity likely assisted with weight bearing and locomotor stability as body mass increased over ontogeny, supporting previous hypotheses that some tyrannosaurids underwent a growth-related reduction in relative agility and/or cursorial performance.
... Nevertheless, the issues of dinosaurian adaptations to polar Mesozoic environments remain debatable despite significant progress in this field. According to recent studies, dinosaurs reproduced in the polar regions and were year-round non-migratory high-latitude residents, as indicated by finds of eggshell fragments and bones of perinatal/neonatal and very young individuals (Godefroit et al., 2009;Fanti and Miyashita, 2009). Dinosaurs had reproductive cycles adapted for life in the polar regions and polar-specific life-history strategies, including endothermy (Druckenmiller et al., 2021). ...
... For example, Brinkman (1990) did not recognize pachycephalosaurid teeth as distinct from thescelosaurid ones, and Sahni (1972) assigned isolated thescelosaurid teeth to Thescelosaurus, a genus not present in the Judithian strata. Accurately identifying isolated pachycephalosaurid and thescelosaurid teeth from microsites should be considered a priority, and a prerequisite for J o u r n a l P r e -p r o o f accurate interpretations of these group's biogeography (Brown and Druckenmiller, 2011;Hudgins et al., 2020;Druckenmiller et al., 2021), paleoecology (Lyson and Longrich, 2011; Mallon and Anderson, 2014; Mallon and Evans, 2014; Wyenberg-Henzler, 2020), and distribution in fossil communities (Brinkman, 1990;Brinkman et al., 1998;Fanti and Miyashita, 2009;Larson et al., 2010;Oreska et al., 2013Oreska et al., , 2019. The sympatric coexistence of similarly sized herbivorous dinosaur groups (Ankylosauria, Ceratopsidae, Hadrosauridae, Leptoceratopsidae, Pachycephalosauridae, and Thescelosauridae) in the Late Cretaceous has been explained by niche partitioning reflected in differences in craniodental morphology (Mallon and Anderson, 2013). ...
Small herbivorous dinosaurs of the clades Pachycephalosauridae and Thescelosauridae occur in multiple Cretaceous formations in North America, their coexistence likely made possible by differences in feeding style. Fossils of these taxa are generally rare, but isolated pachycephalosaurid and thescelosaurid teeth are common at microfossil sites, and easily confused with one another in field and museum settings. Using qualitative features and a set of 12 measurements, the dentitions of the pachycephalosaurid Stegoceras validum and the thescelosaurid Thescelosaurus neglectus were compared, based on teeth preserved in identified skeletons. S. validum and T. neglectus possess heterodont dentitions, and their teeth differ in size, denticulation, crown symmetry, root and crown cross-sectional shapes, apical geometry, crown ornamentation, and wear facet patterns. Principal components analysis of the measurements shows that T. neglectus premaxillary, maxillary, and dentary crowns are readily morphologically distinguishable from one another, whereas all S. validum crowns cluster close to each other and to dentary crowns of T. neglectus. Linear discriminant analysis shows little overlap between S. validum and T. neglectus. The results indicate strong heterodonty in T. neglectus, whereas S. validum teeth are more uniform. Dental differences between the two species may imply that they differed in feeding function. The teeth of T. neglectus, combined with the narrow rostrum, suggest a selective feeding strategy. By contrast, S. validum has a wide rostrum and may have engaged in indiscriminate bulk-feeding behavior. This analysis of dental differences between S. validum and T. neglectus should facilitate identification of isolated pachycephalosaurid and thescelosaurid teeth from microfossil sites.
A treasure trove of dinosaur bones and teeth from Northern Alaska — many from juveniles and yearlings — reveals that dinosaurs lived year-round in the cold and dark environment of the high Arctic.
The unexpected discovery of non-avian dinosaurs from Arctic and Antarctic settings has generated considerable debate about whether they had the capacity to reproduce at high latitudes—especially the larger-bodied, hypothetically migratory taxa. Evidence for dinosaurian polar reproduction remains very rare, particularly for species that lived at the highest paleolatitudes (>75°). Here we report the discovery of perinatal and very young dinosaurs from the highest known paleolatitude for the clade—the Cretaceous Prince Creek Formation (PCF) of northern Alaska. These data demonstrate Arctic reproduction in a diverse assemblage of large- and small-bodied ornithischian and theropod species. In terms of overall diversity, 70% of the known dinosaurian families, as well as avialans (birds), in the PCF are represented by perinatal individuals, the highest percentage for any North American Cretaceous formation. These findings, coupled with prolonged incubation periods, small neonate sizes, and short reproductive windows suggest most, if not all, PCF dinosaurs were nonmigratory year-round Arctic residents. Notably, we reconstruct an annual chronology of reproductive events for the ornithischian dinosaurs using refined paleoenvironmental/plant phenology data and new insights into dinosaur incubation periods. Seasonal resource limitations due to extended periods of winter darkness and freezing temperatures placed severe constraints on dinosaurian reproduction, development, and maintenance, suggesting these taxa showed polar-specific life history strategies, including endothermy.
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Earth's changing climates, landscapes, and atmospheres are recorded in paleosols, which form in the Earth's critical zone by interactions between the lithosphere/pedosphere, biosphere, atmosphere and hydrosphere. Weathering during much of the Precambrian Eon was dominated by very high pCO2 (10x to >20x present atmospheric level, PAL) leading to acidic chemical weathering, with additional and very poorly constrained weathering influences of primitive biota. The Great Oxidation Event at 2.0–2.2 Ga was marked by a major increase in pO2, which was still very low compared to modern conditions. Towards the end of the Precambrian (Neoproterozoic) at least two major Snowball Earth glaciations occurred, punctuated by rapid warming, which intensified weathering processes, leading to releases of nutrients to oceans and the Cambrian Explosion and diversification of life. By the early Paleozoic the first nonvascular land plants evolved; these were small in stature, lacked deep root systems, were spore‐reproducing, and were limited to wet soil environments. They were followed by the arrival of invertebrate terrestrial soil organisms. By the Middle to Late Devonian, trees with deep‐penetrating root systems evolved that accelerated weathering and soil formation through the release of organic acids, which enhanced clay production. Coincident with afforestation, a significant drop in pCO2 (at or below PAL) and concomitant rise in pO2 (for a time exceeding PAL) culminated at the end of the Paleozoic Era with widespread Carboniferous coal swamps. Paleosols record the end‐Permian mass extinction and the Cretaceous‐Paleogene mass extinction and complement the marine records of these events. The Paleocene‐Eocene Thermal Maximum (PETM), a transient 200 kyr warming spike attributed to release of methane hydrates, is considered the closest ancient analog to modern climate change. Evolution of angiosperms (flowering plants) in the Cretaceous, and C4 grasses in the Miocene, record increasing diversification of land plant strategies and ability to occupy all known major terrestrial ecological niches.
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The diversity and distribution of teleosts in the Dinosaur Park Formation of Alberta, Canada, is evaluated on the basis of precaudal centra. In order to avoid the erection of redundant taxa, and to include all teleost precaudal centra in a single system, a parataxonomic system is erected. Fifteen distinct basal groups, termed morphoseries, are described. Growth-related changes and serial variation along the column are taken into account in defining these groups, so each morphoseries is interpreted as representing a distinct, low-level taxon of teleost. One of the morphoseries could be identified as hiodontid and two as acanthomorph on the basis of derived character-states. This is the first Cretaceous record of hiodontids in North America. In addition, elopomorphs, clupeomorphs, salmoniforms, and osteoglossoforms are recognized on the basis of general similarity with the precaudal centra in extant members of these groups. Two teleosts of intermediate level of evolution, but of uncertain relationships, are also present. Differences in the stratigraphic distributions of the morphoseries allow two distinct assemblages of teleosts to be recognized in the formation. One is present in fluvial-dominated localities of the Dinosaur Park Formation, the second in a complex of mud-filled channels in the Lethbridge Coal Zone. The paleoecological complexity present in the formation, and the high level of diversity of teleosts in these beds, emphasizes the importance of including disarticulated remains in studies of the diversity and distribution of teleosts in the Cretaceous.
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The record of dinosaurs from Alaska extends from the Late Jurassic through the Cretaceous. The record for the Late Jurassic is based on two photographed occurrences of dinosaurs, one a series of theropod tracks and the other a dinosaurian bone fragment. Both records occur in the southwestern part of the state. Similarly dinosaur records for the Early Cretaceous are represented but in very sparse numbers, consisting of a few footprint localities and a dinosaur skin impression locality that is also likely from this interval in time. Younger records of dinosaurs for Alaska also occur in the early Late Cretaceous (Cenomanian and Turonian). Such localities are growing in number and most are footprint localities. Generally these localities are confined to the northern part of the state. One exception to the footprint localities is that of a locality yielding a partial hadrosaur skeleton found in marine rocks in the south-central part of the state. By far the richest record of dinosaurs for the state is from the Campanian-Maastrichtian sequences of non-marine rocks. Whereas most of these localities are from northern Alaska, additional new localities have been found in the southwestern part of the state as well as in the central Alaska Range, near Mt. McKinley. This latest Cretaceous record consists of numerous fossil bone and footprint localities. The fossil vertebrate fauna recovered from Cretaceous rocks in Alaska include specimens of osteichthyan fishes, a chelonian, large and small theropods, birds, a hypsilophodontid, a pachycephalosaur, an ankylosaur, ceratopsians and hadrosaurians, as well as multituberculate, marsupial, and placental mammals. These specimens have been acquired through quarry and site excavations, and accumulated river bar and river bank float. The Cretaceous Gyeongsang Supergroup of Korea contains a comparably rich fossil vertebrate record. Whereas the Gyeongsang Supergroup is more prolific in the Early Cretaceous than the coeval Alaskan record it also contains fossil vertebrates that are correlative with the Campanian record of Alaska. Based on paleomagnetic reconstructions, both the Alaskan Cretaceous vertebrate fauna and the Korean vertebrate fauna represent ancient high-latitude faunas and should be examined in that light. In the modern Arctic, animals and plants demonstrate suites of unique features for life in extreme environments. Even though global climate in the Cretaceous in the high latitudes was milder than today some physical parameters, such as the quantity and angle of light, likely remained constant through time. Therefore, these Cretaceous vertebrate faunas hold valuable insights into adaptations for life in an ancient high-latitude environment.
This chapter, which presents and reviews a database of 383 citations that refer to more than 1,000 bonebeds, offers additional insight into how bonebeds formed in the past and what they can tell us about the ancient environments within which they formed. Its goals are to: identify, characterize, and document different types of bonebed; identify historical and scientific biases in the treatment of bonebeds; demonstrate the relative frequency of different types of bonebed in the database; identify and quantify patterns of occurrence for the different types of bonebed; and identify and quantify patterns of association between bonebed type and paleoenvironment. Most bonebeds in the database are easily classified using one or more of the following three measures: element size, taxonomic diversity, and relative taxonomic abundance. In addition, patterns of occurrence are identified in relation to the relative abundance of different types of bonebed, inferred mechanisms of origin, and recurrent associations of bonebed type and paleoenvironment.
Bonebeds are of interest to paleobiologists because they yield large numbers of fossils and, thus, provide important morphologic and taxonomic data sets that are the primary basis for integrative studies of paleobehavior, paleoecology, and paleocommunity structure. This chapter reviews paleobiological inferences that can be drawn from bonebed data sets, and explores the pertinent issues and biases that relate to framing testable paleobiological hypotheses. It first reviews the data gathered from bonebeds that are often used to characterize species (morphology and variation) and to describe patterns of ontogenetic growth and sexual dimorphism, and then explores various characteristics of bonebed assemblages that provide information leading to reconstructions of inter- and intraspecific paleobehaviors. The chapter concludes by analyzing the more synthetic paleobiological issues that relate to faunal analyses and paleocommunity reconstructions. It considers the ways in which taphonomic and geological biases affect the paleobiological signals recorded in bonebeds, and how understanding these biases allows for a reasonable reconstruction of the paleobiology of extinct species. Ultimately, the paleobiological inferences drawn from bonebeds relate to fundamental questions in evolution and ecology.
One of the southernmost North American late Campanian microvertebrate assemblages was collected from the upper Aguja Formation, Big Bend National Park, Texas. The dinosaurs provide additional evidence that distinct southern and northern terrestrial vertebrate provinces occurred contemporaneously during this time due to latitudinal differences in temperature and rainfall. Southern areas, such as west Texas, were warm dry, with non-seasonal climates, and with open-canopy woodlands; they appear to be less fossil-rich and less diverse than northern areas. Nine dinosaurs are present, based on isolated teeth: pachycephalosaurid; hadrosaurid; ceratopsian; tyrannosaurid; Saurornitholestes cf. langstoni (Sues, 1978); Richardoestesia cf. gilmorei (Currie et al., 1990); a new species of Richardoestesia , which is named here; and a undetermined theropod unlike any previously described. Previous reports of Troodon sp. from the Talley Mt. and Terlingua microsites are mistaken; they are a pachycephalosaurid. Many of the dinosaur teeth are small, and are probably from juveniles or younger individuals, evidence that dinosaurs nested in the area. Paleoecologically, the upper Aguja was probably more similar to the lower and more inland faunas of the Scollard Formation (~66 Ma) of Alberta than to contemporaneous northern faunas: both had drier, open environments and lower dinosaur abundance. This connection between climate and dinosaur abundance suggests that climatic factors were important in the Late Cretaceous dinosaur extinctions.