A <i>Spinops sternbergorum</i> (Ornithsichia: Ceratopsia) parietal from the Dinosaur Park Formation (upper Campanian) of Muddy Lake, Saskatchewan

Late Campanian terrestrial communities of western Canada are best known from the fluvial–paralic deposits of the Dinosaur Park Formation (DPF) in Dinosaur Provincial Park (DPP), Alberta. However, a growing list of localities from isolated DPF outcrops, outside of the DPP area, offers a glimpse into palaeocommunities that evolved isochronously with DPP biotas in greater proximity to the Western Interior Seaway. Over the past decade, one such locality was explored along Lake Diefenbaker in Saskatchewan Landing Provincial Park. The initial palaeoecological analysis of this marginal marine community was based on palynomorph and vertebrate microfossil diversity and has laid a foundation for the current study of its monodominant ceratopsian bonebed. The latter has resulted in new occurrences of Centrosaurus apertus and of the elmisaurine Citipes elegans for Saskatchewan based on incomplete yet diagnostic specimens. Centrosaurus apertus is unequivocally identified by a parietal bar bearing two prominent P1 and P2 hooks, which expands the geographical and habitat range of this species to the most coastal environment known from the DPF. Furthermore, the presence of Centrosaurus apertus suggests that the DPF in this region of Saskatchewan is closer in age to the lower DPF than to the uppermost DPF in DPP, which is at odds with a previous palynostratigraphic interpretation. The faunal composition of this bonebed also supports the presence of a widely distributed metacommunity across these deposits. This contribution demonstrates how evidence from multiple localities in the DPF along a spatial gradient, beyond the temporal gradient available within DPP alone, expands the picture of this metacommunity as a potential model system for biotic turnover in response to sea level rise at a geological temporal scale.

The badlands of Dinosaur Provincial Park (Alberta, Canada) are renowned for the exceptional abundance and diversity of Campanian-aged vertebrate body fossils, especially dinosaurs. Due to the steep exposures and rapid erosion, dinosaur tracks and trackways are considered extremely rare but have been recorded from a small number of concretionary casts, which pertain to hadrosaurids and a single tyrannosaurid. Here, we document the first multitaxic dinosaur footprint assemblage from the Dinosaur Park Formation based on a new locality that contains multiple individual ceratopsids, two tyrannosaurids, a possible ankylosaurian, and a small theropod-like taxon. Ceratopsid tracks are globally rare but dominate the new tracksite, suggesting gregarious behaviour, which is also supported by their regular spacing and parallel arrangement. The possible ankylosaurian track is identified (in part) on account of having three distinct pedal digits, consistent with the pedal anatomy of several Dinosaur Park ankylosaurids (Euoplocephalus, Dyoplosaurus) and the newly erected ichnotaxon Ruopodosaurus clava but differentiating it from other ankylosaurian tracks (Tetrapodosaurus isp.). Importantly, the new tracks are the first natural moulds (concave epirelief) found in Dinosaur Provincial Park, which, due to the unique geomorphology of the area, can only be recognised in outcrops where there are prominent sediment displacement rims. The new search image outlined here has already resulted in several subsequent trackway discoveries, and has the potential to transform ichnological studies in the Dinosaur Park Formation and related formations where badlands prevail.

The badlands of Dinosaur Provincial Park (Alberta, Canada) are renowned for the exceptional abundance and diversity of Campanian-aged vertebrate body fossils, especially dinosaurs. Due to the steep exposures and rapid erosion, dinosaur tracks and trackways are considered extremely rare but have been recorded from a small number of concretionary casts, which pertain to hadrosaurids and a single tyrannosaurid. Here, we document the first multitaxic dinosaur footprint assemblage from the Dinosaur Park Formation based on a new locality that contains multiple individual ceratopsids, two tyrannosaurids, a possible ankylosaurian, and a small theropod-like taxon. Ceratopsid tracks are globally rare but dominate the new tracksite, suggesting gregarious behaviour, which is also supported by their regular spacing and parallel arrangement. The possible ankylosaurian track is identified (in part) on account of having three distinct pedal digits, consistent with the pedal anatomy of several Dinosaur Park ankylosaurids (Euoplocephalus, Dyoplosaurus) and the newly erected ichnotaxon Ruopodosaurus clava but differentiating it from other ankylosaurian tracks (Tetrapodosaurus isp.). Importantly, the new tracks are the first natural moulds (concave epirelief) found in Dinosaur Provincial Park, which, due to the unique geomorphology of the area, can only be recognised in outcrops where there are prominent sediment displacement rims. The new search image outlined here has already resulted in several subsequent trackway discoveries, and has the potential to transform ichnological studies in the Dinosaur Park Formation and related formations where badlands prevail.

Dinosaur Provincial Park (DPP) was designated as a UNESCO World Heritage Site in 1979, but in 1955 the exceptional quality and abundance of dinosaur fossils were already recognized with 80 km2 of the richest fossil beds being set aside as an Alberta, Canada, provincial park. DPP represents possibly the best window into the biology of the Late Campanian anywhere in the world. At present, more than 35 species of dinosaurs, 32 species of fish, 10 species of amphibians, 29 taxa of non-dinosaurian reptiles, 1 bird, and 20 taxa of mammals are known to have been discovered in DPP. The dinosaur fossils of DPP were first seriously collected in 1912, with many “trophy” specimens being sent to museums in Ottawa, Toronto, New York, Washington, and London among others. This initial rush of dinosaur fossil collecting persisted until the 1930s, but with declining effort and results. In the late 1960s and early 1970s, scientific study of the park resumed in earnest, and by the 1980s, the park was receiving the full attention of staff from the newly created Royal Tyrrell Museum of Palaeontology, based in Drumheller. With modern scientific thinking and techniques being applied to its dinosaurian, and especially non-dinosaurian, fossils, the park is as important a resource as ever. Hydrocarbon exploration in Alberta has contributed immensely to our knowledge of the geological history of the province during the Cretaceous, thus enabling a better understanding of the factors, both physical and biological, that contributed to the creation, preservation, and subsequent exposure of the extensive fossil resources contained within DPP.

A new dragonfly species, Cordualadensa acorni gen. et sp. nov ., assigned to Cordualadensidae fam. nov. (Odonata, Cavilabiata), is described from Dinosaur Provincial Park (DPP). The taxon represents the oldest known North American fossil taxon within Cavilabiata and the only Mesozoic dragonfly for Canada. This discovery provides a missing link in the evolutionary transition from the early Cretaceous Cavilabiata to extant families and introduces one of the few dragonflies known from the late Cretaceous fossil record. The specimen described herein also confirms that insect impression fossils can be preserved in the Dinosaur Park Formation (DPF) and suggests that the diversity of the entomofauna preserved in DPP's fossil assemblage is only beginning to be fully appreciated. The presence of dragonflies in the DPF also supports the hypothesis that Campanian Alberta had a sufficiently high insect biomass to support insect predators at higher trophic levels.

Composition, radioisotopic ages, and potential significance of an altered volcanic ash (bentonite) from the Upper Cretaceous Judith River Formation, Dinosaur Provincial Park, southern Alberta, Canada

Terrestrial strata of the Judith River−Belly River wedge, widely exposed in the plains of north-central Montana, southern Alberta, and southwestern Saskatchewan, were pivotal in early stratigraphic investigations of the Western Interior of North America and are renowned to this day for their spectacular preservation of Late Cretaceous fossils, most notably dinosaurs. Correlation of the Judith River Formation in Montana with the Foremost, Oldman, and Dinosaur Park Formations (= Belly River Group) in Canada has been challenging for a variety of reasons, including lithostratigraphic complexities, legacy bentonite ages of limited comparability, and distinctly different stratigraphic models on opposite sides of the international border. An updated model calibrated with U-Pb zircon ages provides an improved framework for stratigraphic analysis. New geochronology indicates that the Oldman−Dinosaur Park discontinuity in Dinosaur Provincial Park correlates in age with the mid-Judith discontinuity in the Judith River Formation in Montana, which is interpreted as an expansion surface linked to a major pulse of accommodation and onset of the Bearpaw transgression at ca. 76.3 Ma. The regionally expressed shift in alluvial facies marking the mid-Judith discontinuity can be traced in well logs from Montana to southern Canada, where it loses distinction and transitions to a subsurface signature typical of the Oldman−Dinosaur Park discontinuity, which in turn can be traced north to Dinosaur Provincial Park and beyond. Across this expanse, both discontinuities parallel the Eagle/Milk River shoulder at approximately the same stratigraphic height, confirming their chronostratigraphic significance. These findings have clear implications for regional correlation and the evolution of alluvial depositional systems in a foreland basin setting, and they afford an opportunity to evaluate existing interpretations and advance understanding of the stratigraphy and paleontology of the Judith River−Belly River wedge. The term “Judith River−Belly River discontinuity” should be used henceforth to refer to the chronostratigraphically significant stratal discontinuity that subdivides the Judith River−Belly River wedge throughout the plains of north-central Montana, southern Alberta, and southwestern Saskatchewan.

Some 353 isolated skulls and partial to complete skeletons with known locations have been collected in ∼100 years from the 80 km2 of badlands in Dinosaur Provincial Park (DPP), Alberta, Canada. We wanted to estimate how many skeletons were lost to erosion before collection began and how many await discovery. Within the boundaries of DPP, a volume of rock 145 m thick between the surface of the down-cutting Red Deer River and the capping prairie was subdivided into 5 m thick slabs using digital elevation data with an average horizontal spatial resolution of 19 m and a vertical resolution of 1 m. The exposed surface area of each slab was calculated. Dinosaur fossil localities were determined with high-precision GPS surveys. The number of dinosaurs collected from the surface of a 5 m slab was divided by the product of the exposed area and an estimated erosional thickness of 80 cm to give a volume density of dinosaur fossils. Multiplying the volumes of rock lost from each layer by the dinosaur densities for each layer, the numbers of skeletons lost was determined. Estimates of the numbers of raisins in two loaves of raisin bread were made using a limited number of slices as a test of the method. Of the original volume of DPP, 6.58 km3 (60%) has eroded away, taking with it a mean number of 6310 hadrosaurs, 1640 ceratopsians, 1030 ankylosaurs, and 1600 theropods. The 5.02 km3 (40%) of rock remaining in the park can be expected to produce more dinosaur fossils of similar quality, with mean values of 6700 hadrosaurs, 1700 ceratopsians, 1010 ankylosaurs, and 1720 theropods. These estimates are minima as the estimation process excluded bone beds, the plethora of isolated bones littering the land surface of DPP, and the 100+ skulls and skeletons from the region that lack locality information.

The holotype of the dromaeosaurid Saurornitholestes langstoni was described in 1978 on the basis of fewer than 30 associated cranial and postcranial bones of a single individual from Dinosaur Provincial Park. Four additional partial skeletons of Saurornitholestes were recovered from Campanian (Upper Cretaceous) beds of Alberta and Montana over the next 25 years, although reasonably complete skeletons remained elusive, and virtually nothing was known about the skull. The lack of truly diagnostic material has been problematic, and the relationships of Saurornitholestes to other dromaeosaurids have been difficult to resolve because of the incomplete knowledge of its anatomy. In 2014, an almost complete skeleton, including the skull, was collected less than a kilometer from where the holotype had been found. Although similar in body size to Velociraptor, the facial region of the skull is relatively shorter, taller, and wider. The nasals are pneumatic. The premaxillary teeth are distinctive, and teeth previously identified in the Dinosaur Park Formation as Zapsalis abradens can now be identified as the second premaxillary tooth of S. langstoni. Morphology and wear patterns suggest that these may have been specialized for preening feathers. Many traits define a Campanian North American clade, Saurornitholestinae, that is distinct from an Asian clade that includes Velociraptor (Velociraptorinae). This new information on the skull allows a more complete evaluation of its systematic position within the Dromaeosauridae and supports the suggestion of at least two major faunal interchanges between Asia and North America during the Cretaceous. Anat Rec, 303:691-715, 2020. © 2019 American Association for Anatomy.

Dinosaur Provincial Park (DPP; southern Alberta) yields a well-preserved and uniquely-diverse assemblage of late Campanian dinosaur fossils. Because the assemblage plays a central role in documenting Late Cretaceous peak-dinosaur-diversity, a chronostratigraphic framework for DPP’s fossils has evolutionary and paleoecological significance that extends beyond DPP’s boundaries. Here we employ high-precision CA-TIMS U-Pb zircon geochronology to constrain the ages of five bentonites that are semi-evenly spaced through the exposed bedrock section. Weighted mean 206Pb/238U dates for the bentonites range from 76.7 Ma to 74.3 Ma (with 2σ internal errors of ≤30 kyr), indicating that the section is younger than previously understood and that it encompasses a longer time span (2.4 Myr). Combined with biostratigraphic data, these results confirm a previous hypothesis that the Oldman–Dinosaur Park formation contact becomes younger toward southeastern Alberta. A significantly lower sediment accumulation rate near the Oldman-Dinosaur Park formation contact suggests the presence of a ~230 kyr hiatus (or stacked hiatuses) near the contact. Coincident first occurrences of five palynomorph taxa—that otherwise show stratigraphically staggered first occurrences in southeastern Alberta—support an interpretation that the hiatus is limited to the uppermost few meters of the Oldman Formation. Previously amassed sedimentological and stratigraphic data suggest that the hiatus may be a consequence of overall lower rates of sediment accumulation and interrupted sedimentation along the northern edge of the Oldman sedimentary lobe. Rates of sediment accumulation stay largely constant through the Dinosaur Park Formation, but may decline upwards into the Bearpaw Formation. Applying a currently accepted ammonite biochronology to DPP’s age-calibrated strata correlates the bottom of the section with the middle of the Baculites scotti Zone, and the top of the section with the approximate base of the Baculites compressus Zone. Four previously recognized dinosaur-assemblage zones at DPP are also calibrated and show durations of approximately 600–700 kyr, similar to those of ammonite biozones.

Stratigraphy and sedimentology of vertebrate microfossil sites in the uppermost Judith River Formation (Campanian), Dinosaur Provincial Park, Alberta, Canada

Paleoenvironmental reconstruction of Late Cretaceous rivers, Dinosaur Park Formation, Alberta, Canada

ABSTRACTAn articulated, 1.5 m long skeleton of a juvenile Chasmosaurus, lacking only the front limbs, pectoral girdles, and terminal caudal vertebrae, was collected from the Dinosaur Park Formation in Dinosaur Provincial Park, Alberta. The short, tall skull has a narrow frill that lacks a posterior embayment. Many of the cranial bones are co-ossified in spite of the small size of the specimen. The nasals form an incipient horncore, and the short, knob-like postorbital horncore lacks sinuses. The palpebral is not fused to the rest of the skull. The frontal fontanelle is keyhole-shaped. The triangular squamosal extends to the back of the parietals. Epiossifications are lacking, although the squamosal margin is thick and scalloped. The parietal has a pronounced midline sagittal crest. Parietal fenestrae, if present, would have been narrow and elongate. There are only 18 maxillary tooth positions. The syncervical comprises three co-ossified, but distinct vertebrae. Anterior caudal vertebrae support unfused caudal ribs. Ossified tendons in the neck, trunk, and sacrum do not extend into the tail. Hind limb proportions are comparable to those of adult ceratopsids. The pedal unguals are distally acute. Skin impressions are similar to those of mature chasmosaurines. Phylogenetic analysis, if all characters are coded as they are seen, suggests that the specimen is a basal chasmosaurine. When size or age dependent characters are recoded as ‘?,’ the specimen groups with other Chasmosaurus. These characters should only be used in phylogenetic analyses when all specimens are mature.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Currie, P. J., R. B. Holmes, M. J. Ryan, and C. Coy. 2016. A juvenile chasmosaurine ceratopsid (Dinosauria, Ornithischia) from the Dinosaur Park Formation, Alberta, Canada. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1048348.

Bone bed 43 is one of at least eight paucispecific Centrosaurus bone beds located in the Dinosaur Park Formation (Upper Campanian) in Dinosaur Provincial Park, Alberta, Canada. It long has been used as a case example for evidence of herding and social behavior in dinosaurs, but a detailed analysis of the site has not been presented until this study. The bone bed is dominated by the disarticulated, mostly fragmentary and slightly abraded remains of Centrosaurus apertus, with minor occurrences of other taxa, notably teeth from the large tyrannosaurid Albertosaurus libratus. Fossils occur in a stacked to amalgamated succession of lag deposits, deposited and reworked at the erosional base of a paleochannel. The most parsomonious scenerio suggests that Centrosaurus material represents part of a large aggregation of animals (possibly numbering in the thousands) that died by drowning on the alluvial plain. Disarticulation occurred at a point upriver from the bone-bed site. Scavenging by theropods, prima...

The lambeosaurine hadrosaurid Parasaurolophus is known from rare occurrences in Campanian deposits of western North America. A previously undescribed large hadrosaurid braincase from the Dinosaur Park Formation (Alberta, Canada) is assigned to the genus Parasaurolophus on the basis of several derived characters associated with the frontal–nasal articulation at the base of the crest. This identification is supported by two separate phylogenetic analyses, in which the specimen clusters with other more completely known Parasaurolophus exemplars. If correctly identified, the specimen represents the third and largest cranial specimen of the genus from the Late Cretaceous of Alberta. The specimen occurs in the same deposits as the holotype specimen of Parasaurolophus walkeri and may represent a late ontogenetic stage of this taxon. As opposed to a small frontal dome in the holotype of P. walkeri , the external contribution of the frontal to the skull roof is obliterated in the new specimen. If these hypothesized ontogenetic changes in the skull roof correlate with the size and posterodorsal development of the crest, as in other lambeosaurines, it suggests that the crest had not reached its full expression in the holotype. When placed into a detailed biostratigraphic context for the first time, the limited Parasaurolophus material from the Belly River Group is distributed in the lower half of the Dinosaur Park Formation at Dinosaur Provincial Park. This suggests that Parasaurolophus may be associated with the lower Centrosaurus – Corythosaurus assemblage zone and may have preferred more inland environments than other hadrosaurids, such as Lambeosaurus and Prosaurolophus .