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First basal neoceratopsian from the Oldman Formation (Belly River Group), Southern Alberta

Preface xiii
Acknowledgments xv
List of Contributors xvii
List of Reviewers xxi
1. Forty Years of Ceratophilia / PETER DODSON 3
2. Taxonomy, Cranial Morphology, and Relationships of Parrot-Beaked Dinosaurs
(Ceratopsia: Psittacosaurus) / PAUL C. SERENO 21
3. A New Species of Archaeoceratops (Dinosauria: Neoceratopsia) from the Early Cretaceous of the
Mazongshan Area, Northwestern China / HAI-LU YOU, KYO TANOUE, AND PETER DODSON 59
4. A Redescription of the Montanoceratops cerorhynchus Holotype with a Review of
Referred Material / PETER J. MAKOVICKY 68
5. First Basal Neoceratopsian from the Oldman Formation (Belly River Group), Southern
6. Zuniceratops christopheri: The North American Ceratopsid Sister Taxon Reconstructed on the
7. Horned Dinosaurs (Ornithischia: Ceratopsidae) from the Upper Cretaceous (Campanian)
Cerro del Pueblo Formation, Coahuila, Mexico / MARK A. LOEWEN, SCOTT D. SAMPSON,
8. New Basal Centrosaurine Ceratopsian Skulls from the Wahweap Formation (Middle Campanian),
Grand Staircase–Escalante National Monument, Southern Utah / JAMES I. KIRKLAND AND
9. A New Pachyrhinosaurus-Like Ceratopsid from the Upper Dinosaur Park Formation
(Late Campanian) of Southern Alberta, Canada / MICHAEL J. RYAN, DAVID A. EBERTH,
10. New Material of ‘‘Styracosaurus’’ ovatus from the Two Medicine Formation of Montana /
11. A New Chasmosaurine (Ceratopsidae, Dinosauria) from the Upper Cretaceous Ojo
Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico / ROBERT M. SULLIVAN
First Basal Neoceratopsian from the Oldman Formation
(Belly River Group), Southern Alberta
an isolated frontal (TMP 87.89.8) referred to Pre-
noceratops sp. from the Oldman Formation of southern
Alberta is a recent addition to the scarce record of North
American basal neoceratopsians. TMP 87.89.9 shares the
diagnostic characters of Prenoceratops, such as the trans-
verse postorbital ridge and the deep frontal depression.
The crista cranii coinciding with the interfrontal suture is
identified as a new autapomorphy for the genus Pre-
noceratops. A unique combination of characters in TMP
87.89.8 includes the absence of the olfactory bulb im-
pression, presence of the cerebral fossa, and a fossa that
probably represents part of the nasal cavity. Although
this suggests that TMP 87.89.8 may represent a distinct
species of Prenoceratops, the possibility of ontogenetic
variation cannot be ruled out. There were at least three
distinct basal neoceratopsian taxa in the Campanian of
southern Alberta and northwestern Montana: Cerasinops,
Leptoceratops, and Prenoceratops. Prenoceratops is the sec-
ond ornithischian genus exclusively occurring in the up-
per Oldman and upper Two Medicine formations,
suggesting a faunal link due to the similar inland, rela-
tively dry environments.
Despite our understanding of the richness of Late Cretaceous
dinosaur faunas, the North American record of basal neo-
ceratopsians (non-ceratopsid neoceratopsians) is surprisingly
poor (Ryan and Currie 1998; You and Dodson 2004). This con-
trasts with the remarkable diversity of Asian basal neocera-
topsians during this time (You and Dodson 2004; Makovicky
and Norell 2006). Recent discoveries (Ryan and Currie 1998;
Chinnery 2004; Chinnery and Horner 2007) strongly suggest
that the diversity of North American basal neoceratopsians is
greater than previously thought. Basal neoceratopsians have
been identified from the Milk River, Dinosaur Park, Horseshoe
Canyon, St. Mary River, and Scollard formations in southern
Alberta, Canada, and from the Two Medicine and St. Mary
River formations in northwestern Montana, in the United
States (Brown 1914; Sternberg 1951; Chinnery and Weisham-
pel 1998; Ryan and Currie 1998; Makovicky 2001; Chinnery
2004; Chinnery and Horner 2007). The chronological range of
the basal neoceratopsians in Alberta thus spans from the latest
Santonian to latest Maastrichtian (Ryan and Currie 1998), al-
though there are several long gaps within this range where
basal neoceratopsian material has not been recovered. The
longest of these gaps occurs between the Milk River and Dino-
saur Park formations. Although cf. Montanoceratops (TMP
82.11.1) was reportedly collected from the Belly River Group
and could have potentially filled this gap, the specimen is
likely to have been recovered from the Willow Creek For-
mation (a rationale for this interpretation in ‘‘Discussion’’).
Except for excellent skeletons of Leptoceratops (Brown 1914;
Sternberg 1951) from the Scollard Formation and that of cf.
miyashita, currie, & chinnery-allgeier
Geologic correlation chart
for Upper Cretaceous strata
in southern Alberta and
northwestern Montana. The
grey shade indicates formations
from which basal neoceratopsian
material has been collected
(sources cited in the text).
Marine units are shaded black.
Radiometric dates and
nomenclature from Brinkman
(2003), Eberth (2005), Eberth et
al. (2001), Horner et al. (2001),
Rogers (1997, 1998), and Rogers
et al. (1993).
First Basal Neoceratopsian from the Oldman Formation 85
Locality map showing Devil’s Coulee, where TMP
87.89.8 was collected. The map is modified after Horner and
Currie (1994).
Montanoceratops (TMP 82.11.1; Ryan and Currie 1998) from
the Willow Creek Formation, the basal neoceratopsian speci-
mens from Alberta are mostly fragmentary and often repre-
sented only by teeth from microvertebrate localities.
A basal neoceratopsian frontal (TMP 87.89.8) represents the
first record of this group from the Oldman Formation of Al-
berta, and provides new information on the cranial anatomy
of basal neoceratopsians.
Institutional Abbreviations. CMN: Canadian Museum of Na-
ture, Ottawa; ICM: Children’s Museum of Indianapolis, Indi-
anapolis; MNHCM: Mokpo Natural History and Culture Mu-
seum, Mokpo; TMP: Royal Tyrrell Museum of Palaeontology,
Drumheller; UWGM: University of Wisconsin Geology Mu-
seum, Madison.
Anatomical Abbreviations. cc: crista cranii; ci: impression of
cerebrum; fd: frontal depression; if: interfrontal suture; ls:
laterosphenoid suture; na: nasal contact; nc: nasal cavity; ob:
olfactory bulb impression; or: orbital rim; os: orbitosphenoid
suture; pa: parietal suture; po: postorbital contact; pr: post-
orbital ridge; sr: sagittal ridge.
Systematic Paleontology
Ornithischia Seeley 1888
Ceratopsia Marsh 1890
Neoceratopsia Sereno 1986
Prenoceratops Chinnery 2004
Prenoceratops sp.
Referred Specimen. TMP 87.89.8, an isolated right frontal.
Locality. TMP 87.89.8 was surface collected from the upper
Oldman Formation (Fig. 5.1) at Devil’s Coulee, southern Al-
berta (Fig. 5.2), close to the nesting site of Hypacrosaurus
stebingeri (Horner and Currie 1994). The upper Oldman For-
mation exposed at Devil’s Coulee is dated at 75.05 Ma (Eberth
and Deino 1992). The Devil’s Coulee locality is approximately
correlated with the Lethbridge Coal Zone in the uppermost
part of the Dinosaur Park Formation in Dinosaur Provincial
Park, which marks an early westward transgression of the
Bearpaw Sea in the southern plains of Alberta.
Comments. The basal neoceratopsian affinity of TMP 87.89.9
is supported by the combination of the following characters:
medially emarginated orbital rim of thick frontal; prefrontal
separated by nasal from protruding anterior process of frontal;
wide and flat orbital depression; and unfused frontal suture.
TMP 87.89.8 is referred to Prenoceratops Chinnery 2004 based
on the following diagnostic characters: crista cranii coalesced
to the interfrontal suture; straight, transverse postorbital ridge;
and frontal depression excavated deeper than one-third the
thickness of frontal (Chinnery 2004).
TMP 87.89.8 (Fig. 5.3) is an isolated right frontal. The anterior
portion and much of the lateral margin were lost due to ero-
sion. As preserved, the specimen measures 98.4 mm in length.
The bone is deep medially, but becomes shallower anteriorly,
laterally, and posteriorly. The frontal of TMP 87.89.8, Lepto-
ceratops CMN 8889, and UWGM 3992.05 (Fig. 5.4C, D) is
thicker and wider than it is in Prenoceratops (Fig. 5.4A, B).
Leptoceratops and the animal represented by TMP 87.89.8 are
larger than Prenoceratops (ICM 2003.1.1; MNHCM field num-
ber 61, Fig. 5.4A). This is consistent with an allometric trend in
dinosaurs that the skull roof generally becomes wider and
thicker as body size increases. As in most ceratopsians (Dod-
son et al. 2004), the frontal is not fused to its counterpart but
the medial frontal sutural surface is sculpted by numerous
grooves. A mid-height longitudinal groove separates this sur-
face into upper and lower parts (Fig. 5.3D).
In dorsal view (Fig. 5.3A), a sutural surface at the anterior
edge represents the posterior end of the nasal contact, suggest-
ing that the nasal excluded the prefrontals from contacting
each other. Most basal neoceratopsians share this character,
whereas in at least some ceratopsids (e.g., Centrosaurus and
Styracosaurus; Sampson et al. 1997), the prefrontals meet each
other at the midline and prevent frontal-nasals contact. The
orbital rim is gently emarginated as in other basal cera-
topsians. The deeply sculpted grooves associated with vascu-
lar pits on the dorsal surface are similar to cranial ornamenta-
tion present on most ceratopsids. Leptoceratops (UWGM
31992.05; Fig. 5.4C) and Prenoceratops (MNHCM field num-
miyashita, currie, & chinnery-allgeier
TMP 87.89.8 in (A) dorsal, (B) ventral, (C) right lateral, and (D) medial views. Scale bars are 5 cm.
First Basal Neoceratopsian from the Oldman Formation 87
Prenoceratops frontals in (A) dorsal view (MNHCM
field number 65 on left, MNHCM field number 61 on right)
based on Chinnery (2004); (B) ventral view (field number 65).
Leptoceratops frontals (UWGM 3992.05) in (C) dorsal and
(D) ventral views based on Ott (2003). Scale bars are 2 cm.
bers 61 [Fig. 5.4A] and 65 [Fig. 5.4A]) have less conspicuous
pitting, with shallow parallel grooves occurring on the dorsal
surface of the frontals. The postorbital contact is partially pre-
served in TMP 87.89.8, and indicates that the postorbital over-
lapped the frontal posteriorly as it does in other basal cera-
topsians including Leptoceratops, Liaoceratops, Psittacosaurus,
and Yamaceratops (Makovicky and Norell 2006).
The posterior one-third of the bone is marked by the deep
frontal depression (Fig. 5.3A). As in Prenoceratops (Chinnery
2004) and Cerasinops (Chinnery and Horner 2007), the frontal
depression is deeper than one-third of the total frontal thick-
ness. A sharply defined, straight transverse postorbital ridge
separates the frontal depression from the rest of the bone. This
is diagnostic for Prenoceratops (Chinnery 2004), but is more
dorsally pronounced in TMP 87.89.8. In other basal cera-
topsians, this postorbital ridge is gently curved. A low, narrow
sagittal ridge separates the frontal depression from the mid-
line at least anteriorly in TMP 87.89.8. Leptoceratops (CMN
8889; UWGM 31992.05) shares with TMP 87.89.8 the mor-
phology of the sagittal ridge, but the ridge is absent on Pre-
noceratops frontals (MNCHM field numbers 61, 65). The par-
tially preserved parietal sutural surface indicates that the
frontals were wedged between the parietals on the midline.
The frontal-parietal suture is roughly transverse in other basal
ceratopsians such as Protoceratops (Gregory and Mook 1925).
In ventral view (Fig. 5.3B), the crista cranii delineates the
wide orbital space medially and coalesces with the interfrontal
suture. The right and left cristae would have met at the mid-
line, constricting the dorsal sulcus for passage of the olfactory
tract. The olfactory tract then would have exited anteriorly
below this constriction. Prenoceratops frontals (MNHCM field
numbers 61 and 65) show the same condition, but Leptocera-
tops (UWGM 31992.05; Fig. 5.4D) retains separation between
the right and left cristae as in other dinosaurs. Ceratopsids
have a transverse ridge connecting the cristae cranii at about
the same position (Lehman 1989). A similar transverse ridge is
also observed in hadrosaurids (Horner 1992; Evans 2006) and
in basal euornithopods (Weishampel et al. 2003), in which the
sphenethmoid suture extends onto the ridge. Such a ridge is
absent in basal ornithopods (Sues 1980; Galton 1989, 1997)
and pachycephalosaurs (TM pers. obs.). The connection be-
tween the crista cranii and the orbitosphenoid is substantial,
occurring from the constriction between the cristae postero-
laterally and extending to the laterosphenoid suture. Based on
the position of this suture, the laterosphenoid of TMP 87.89.8
would have had an exceptionally long lateral process to con-
tact the postorbital. There is no clear indication of the sphe-
nethmoid contact, which has been observed on the transverse
ridge between cristae cranii in euornithopods (Horner 1992;
Weishampel et al. 2003; Evans 2006). The crista cranii of Lepto-
ceratops have a rough texture along the anteromedial margin
of the orbital depression that probably marks the spheneth-
moid suture (UWGM 31992.05; Fig. 5.4D).
A deep, wide depression occurs near the interfrontal suture
on the ventral surface at the broken anterior end (Fig. 5.3B)
that most likely marks the posterior end of the nasal cavity.
Leptoceratops has a shallow, wide trough for the nasal that ex-
tends to the ventral surface of the frontal (Ott 2003). The de-
pression may be absent in Prenoceratops, although the corre-
sponding area seems to be slightly depressed in two of the
three Prenoceratops frontal specimens (MNHCM field numbers
48 and 61 [Fig. 5.4B]). The presumed nasal cavity depression is
much deeper in TMP 87.89.8 than it is in either Prenoceratops
or Leptoceratops. One of the frontals of Prenoceratops (MNHCM
field number 65, Fig. 5.4A) preserves a clear olfactory bulb
impression behind the nasal cavity (TM pers. obs.), but TMP
87.89.8 has no recognizable feature in the same position. In
TMP 87.89.8, there is a shallow, small depression near the
interfrontal suture on the ventral surface at the posterior end
of the specimen, which represents the cerebral fossa (Fig.
5.3B). Since size and depth is much smaller than that expected
miyashita, currie, & chinnery-allgeier
for a cerebrum from a basal neoceratopsian of this size, the
cerebrum must have been only in a partial contact with the
frontal. Prenoceratops frontals do not form a distinct depres-
sion for the cerebrum.
TMP 87.89.8 shares with Prenoceratops the autapomorphies of
(1) transversely straight postorbital ridge, (2) frontal depres-
sion that is deeper than one-third the thickness of the frontal,
and (3) crista cranii that coincides with the interfrontal suture
(Chinnery 2004). TMP 87.89.8 has four possible autapomor-
phic characters: a deeply sculpted dorsal surface of the frontal;
a deep nasal cavity depression; an interfrontal suture that is
divided into upper and lower parts; and an unequivocal sagit-
tal ridge along the interfrontal suture that would have sepa-
rated right and left frontal depressions at least anteriorly. Un-
fortunately, these characters are not consistently present on
the remaining North American neoceratopsians (Cerasinops,
Leptoceratops, Montanoceratops, and Zuniceratops) to facilitate a
robust phylogenetic analysis. It is possible that these dif-
ferences, in addition to the width and the thickness of the
frontals, are the result of individual variation, or are size-
related. The frontal of TMP 87.89.8 would have been at least
approximately 30% longer than the frontals of Prenoceratops
(MNHCM field numbers 61 and 65; Fig. 5.4A, B) suggesting
that it may represent a large adult of Prenoceratops pieganensis.
Alternatively, TMP 87.89.8 may have come from a new species
of Prenoceratops. Until more material can be recovered from
the Oldman Formation of Alberta, we conservatively refer
TMP 87.89.8 to Prenoceratops sp.
Comparison of TMP 87.89.8 to other basal neoceratopsians
from North America indicates that there is significant mor-
phological variation in skull roof characters (e.g., shape of
the crista cranii, depth of frontal depressions, and presence
or absence of nasal cavity, impression of olfactory bulb, and
cerebral fossa) within these taxa. These characters are candi-
dates for a refined phylogenetic analysis of ceratopsians in
the future.
Finally, it must be noted that the sculpturing on the dorsal
frontal surface of Leptoceratops (UWGM 31992.05; Fig. 5.4C),
Prenoceratops (MNCHM field number 61), and TMP 87.89.8
implies the presence of a thick keratinous covering (Horner
and Marshall 2002) over at least this portion of the skull.
TMP 87.89.8 is the first basal neoceratopsian material from
the Oldman Formation, helping to fill in one of the longest
gaps in the basal neoceratopsian record in Alberta. In addition
to Prenoceratops, Leptoceratops sp. is known from the Dinosaur
Park Formation (Ryan and Currie 1998) and Cerasinops from
the Two Medicine Formation below the interval that pro-
duced Prenoceratops (Chinnery and Horner 2007).
Ryan and Currie (1998) also reported a basal neoceratopsian
tentatively identified as Montanoceratops sp. (TMP 82.11.1) re-
covered from a massive yellow sandstone block located on the
Oldman River (Tanke 2007). Examination of the specimen
suggests that the preserved matrix is more consistent with
sediments from the Maastrichtian-aged portion of the Willow
Creek Formation (Fig. 5.1) that predominantly crops out
along the Oldman River, rather than from the Belly River
Group that is not widely exposed along the river (Wall and
Rosene 1977). Grain size of the matrix associated with TMP
82.11.1 is finer than the typical medium-to-fine sands in the
Belly River Group, and the matrix contains more cement than
typical sandstone from the Belly River Group (TM unpub-
lished data). Therefore, we propose that TMP 82.11.1 most
likely came from the Maastrichtian-aged Willow Creek Forma-
tion and, therefore, can no longer be included in consider-
ation of the diversity of North American basal neoceratop-
sians from the Campanian.
Prenoceratops and the lambeosaurine Hypacrosaurus stebin-
geri (Horner and Currie 1994) are the only two ornithischians
shared between the upper Oldman Formation (OF) of Alberta
and the upper Two Medicine Formation (TMF) of Montana.
These formations represent similarly well-drained, seasonally
dry floodplain environments (OF, D. A. Eberth pers. com.
2007; TMF, Rogers 1997). The type material of Prenoceratops
(ICM 2003.1.1) was recovered from a bonebed 50 m below the
Bearpaw Formation (Chinnery 2004), which places its strati-
graphic position close to the bentonite dated at 74.3 Ma in the
upper Two Medicine Formation (Horner et al. 1992). With the
radiometric dating of the Devil’s Coulee locality at 75.05 Ma
(Eberth and Deino 1992), the type material of Prenoceratops is
less than 1.0 Ma younger than TMP 87.89.8. Presence of Preno-
ceratops and Hypacrosaurus stebingeri in the upper Two Medi-
cine formations suggests persistence of the Oldman Forma-
tion ornithischian fauna from Alberta in the inland setting of
Montana up to the maximum westward transgression of the
Bearpaw Sea. It is also possible that the younger occurrences of
Prenoceratops and Hypacrosaurus stebingeri in the Two Medicine
Formation are a result of inland migration in response to the
westward Bearpaw transgression, a hypothesis supported by
the suggestions of a number of authors (e.g., Sternberg 1951;
Ryan and Currie 1998; Ott 2006; You and Dodson 2004) who
have attributed the rarity of basal neoceratopsians in western
North America to their preference for an inland, drier habitat.
The seasonally dry floodplain depositional setting of the
strata at Devil’s Coulee (D.A. Eberth pers. comm. 2007) also
supports this hypothesis.
First Basal Neoceratopsian from the Oldman Formation 89
James Gardner and Brandon Strilisky (TMP) provided access to
collections. We acknowledge that Nick Longrich (University
of Calgary) independently came up with the identification
of TMP 87.89.8. We also thank Lisa Buckley (Tumbler Ridge
Dinosaur Center), Peter Dodson (University of Pennsylvania),
Takuya Konishi (University of Alberta), Hans Larsson (McGill
University), Michael Ryan (Cleveland Museum of Natural His-
tory), Darren Tanke (TMP), and François Therrien (TMP) for
discussions. François Therrien and David Eberth (TMP) shared
unpublished information on Devil’s Coulee. Don Henderson
(TMP) and Don and Lorraine Woodruff (Drumheller) provided
accommodations for TM. Reviews by David Evans (Royal On-
tario Museum) and Michael Ryan improved clarity of the
manuscript and led to refined assessment of the basal neo-
ceratopsian diversity. T. Miyashita also acknowledges Federico
Fanti (University of Bologna), Eva Koppelhus (University of
Alberta), Kaoru Kitahara, Kazuhiro Magome, Jun-ichi and
Kanae Miyashita, Hisao Nakagawa, Miyuki Tajima, and Mar-
iko Takahashi (Tokyo) for their long-standing support.
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... Chinnery (2004) and Chinnery and Horner (2007) described Prenoceratops pieganensis and Cerasinops hogkissi, respectively, from the Campanian portion of the Two Medicine Formation of Montana. Miyashita et al. (2010) referred a frontal from the Devil's Coulee locality of the Oldman Formation of southern Alberta to Prenoceratops sp. Makovicky (2001) identified a braincase (AMNH 5244) of Montanoceratops from the Maastrichtian beds of the upper Horseshoe Canyon Formation of Alberta; however, the exact locality for the quarry of this specimen is unknown and it may have been collected from the Scollard Formation, which also has extensive exposure in the area. ...
... A review of Montanoceratops by Makovicky (2010), building on work by Chinnery and Weishampel (1998), highlighted important information about the skeleton of Montanoceratops including the fact that the nasal is unknown for the taxon. Miyashita et al. (2010) clarified that the provenance of TMP 82.11.1, a partial neoceratopsian skeleton referred to Montanoceratops, is derived from the Willow Creek Formation (Maastrichtian), rather than the Campanian Belly River Group of Alberta as suggested by Ryan and Currie (1998). Makovicky (2010) suggested that TMP 82.11.1 represents an indeterminate leptoceratopsid that cannot be referred to Cerasinops, Montanoceratops or Leptoceratops, but which may have affinities with Prenoceratops. ...
... DMT ¼ Drumheller marine tongue. Modified fromBrinkman (2003),Miyashita et al. (2010) andSampson and Loewen (2010). ...
... These morphological differences are reinforced by the stratigraphic position of Ferrisaurus relative to Cerasinops and Prenoceratops (latest Maastrichtian, vs. middle to Upper Campanian; Chinnery & Horner, 2007;Chinnery, 2004), given that no other dinosaur species with temporally well-resolved specimens spans the middle Campanian to latest Maastrichtian elsewhere in Laramidia (Eberth et al., 2013;Fowler, 2017). An enigmatic specimen, TMP 1982.11.1, from the Maastrichtian Willow Creek Formation (Miyashita, Currie & Chinnery-Allgeier, 2010) has been referred to Montanoceratops by several authors (Ryan & Currie, 1998), but was considered neither a representative of Montanoceratops, Leptoceratops, or Cerasinops by Makovicky (2010). Several additional as-yet undescribed specimens in the collections of the TMP (Tanke, 2007) may represent examples of either Montanoceratops, Leptoceratops, or Ferrisaurus and their description may help clarify the differences between these three taxa or provide new anatomical information for Ferrisaurus. ...
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A partial dinosaur skeleton from the Sustut Basin of northern British Columbia, Canada, previously described as an indeterminate neornithischian, is here reinterpreted as a leptoceratopsid ceratopsian, Ferrisaurus sustutensis , gen. et. sp. nov. The skeleton includes parts of the pectoral girdles, left forelimb, left hindlimb, and right pes. It can be distinguished from other named leptoceratopsids based on the proportions of the ulna and pedal phalanges. This is the first unique dinosaur species reported from British Columbia, and can be placed within a reasonably resolved phylogenetic context, with Ferrisaurus recovered as more closely related to Leptoceratops than Montanoceratops . At 68.2–67.2 Ma in age, Ferrisaurus falls between, and slightly overlaps with, both Montanoceratops and Leptoceratops , and represents a western range extension for Laramidian leptoceratopsids.
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An associated incomplete skeleton of a ceratopsid dinosaur from the Campanian deposits of the Allison Member of the Menefee Formation in New Mexico, USA is described. Although it was originally described over two decades ago, newly prepared portions of the Menefee Formation skeleton and reinterpretations of previously known morphology, in addition to newly described specimens have provided new information on ceratopsids, and centrosaurines in particular. These new data allow for a thorough reassessment of the specimen and the erection of a new taxon: Menefeeceratops sealeyi gen. et sp. nov., potentially the oldest recognized member of Centrosaurinae. Menefeeceratops sealeyi is represented by diagnostic cranial and postcranial skeletal elements. The cranial elements include a portion of the left premaxilla, a nearly complete left postorbital horncore, a parietal fragment, the right and left squamosals, the left jugal, the predentary, and the left dentary. Postcranial material consists of two cervical vertebrae, eight dorsal vertebrae, a partial sacrum with six sacral vertebrae, 11 dorsal ribs, the distal left radius, proximal and distal portions of the left ulna, the left femur, and a left metatarsal II. The taxonomic validity of Menefeeceratops sealeyi is supported by a combination of several morphological characters. These include a lack of epiossifications on the lateroposterior edge of the parietal (shared with Machairoceratops), three epiossifications on the squamosal, and three smaller, secondary undulations as part of episquamosal locus S1. There are also two subequal embayments on the posterior free margin of the squamosal with the more dorsal embayment (between episquamosal loci 1 and 2) distinctly larger than the ventral (= lateroventral) one (between episquamosal loci 2 and 3), three ridges on the lateral (dorsolateral) surface of the squamosal, an elongate posterior portion of the squamosal, the presence of a shallow but distinct groove on the medial surface of the squamosal nearly paralleling the ventrolateral and ventroposterior edges, elongate postorbital (= supraorbital) horns that are anteriorly curved distally, and two elongate ridges on the lateral surface of the dentary that diverge anteriorly, creating a distinct anterior triangular fossa. Phylogenetic analysis of Menefeeceratops sealeyi places this new species as a basal centrosaurine, most closely related to Crittendenceratops krzyzanowskii, thus adding to the growing record of centrosaurines discovered in western North America. It thus provides new information about the diversity of morphologies throughout different species and the temporal and paleobiogeographic distribution of these animals throughout Laramidia during the Late Cretaceous. Its presence as one of the, if not the, oldest members of the Centrosaurinae also suggests centrosaurines originated in the southern portions of western North America and the southern Rocky Mountain region, and subsequently radiated north during the upper middle to late Campanian.
The Upper Cretaceous in the southern Alberta Foothills is represented almost entirely by clastic sediments with a maximum thickness of about 14,000 ft (4270 m). This essentially uninterrupted sequence, in which all stages from the late Cenomanian through the Maestrichtian are represented, consists of alternating phases of marine, littoral or deltaic, and continental deposition. A succession of 11 microfaunas is recognized in the Alberta Group and Bearpaw Formation.
Ceratopsia consists of Psittacosauridae and Neoceratopsia. Psittacosauridae is a monogeneric (Psittacosaurus) clade consisting of ten species, while basal Neoceratopsia is formed by eleven genera, with twelve species of basal Neoceratopsia being recognized. This chapter discusses the anatomy, phylogeny, and paleobiology of basal ceratopsians. Basal ceratopsians are small (1–3 m long), bipedal or quadrupedal herbivores. The best preserved and described specimens representing the major subgroups among basal ceratopsians are Psittacosaurus mongoliensis, Archaeoceratops oshimai, Protoceratops andrewsi, and Leptoceratops gracilis.
Approximately half of existing dinosaur species belonging to the Order Ornithischia, or the 'bird-hipped' dinosaurs, which include such familiar forms as the stegosaurs, ankylosaurs, hadrosaurs, and ceratopsids. Although ornithischians are generally conceded to have descended from a common ancestor, little is known about the pattern of descent. Comparison of more recently discovered ornithischian fossils from China and Mongolia to better-known North American forms has shed light on the pattern of evolutionary diversification among ornithischians, a pattern that began approximately 200 My ago and ended abruptly nearly 140 My later at the end of the Cretaceous.-from Author
The cranial anatomy is described for the basal hypsilophodontid dinosaur Thescelosaurus neglectus GILMORE (1913), the only valid species. Two characters that have been used to separate the other hypsilophodontids from Thescelosaurus, the midorbital width of the frontals and the steepness of the braincase, probably had a more complicated evolutionary history within the Ornithischia than previously thought. Autapomorphic characters of Thescelosaurus include: frontals wide at midorbital level, supraoccipital almost excluded from dorsal margin of foramen magnum, surangular with prominent lateral process; low angle to ventral margin of braincase, buccal surface of maxillary teeth (lingual on dentary teeth) have two converging crescentic patterns formed by numerous secondary ridges; femur longer than tibia.