The Dinosaur Park Formation is the uppermost member of the Belly River Group (also known as the Judith River Group), a major geologic unit in southern Alberta. It was deposited during the Campanian stage of the Late Cretaceous, between about 76.5 and 74.4 million years ago. It was deposited in alluvial and coastal plain environments, and it is bounded by the nonmarine Oldman Formation below it and the marine Bearpaw Formation above it.Eberth, D.A. 2005. The geology. In: Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis, p.54-82. .
The Dinosaur Park Formation contains dense concentrations of dinosaur skeletons, both articulated and disarticulated, which are often found with preserved remains of soft tissues. Remains of other animals such as fish, turtles, and crocodilians, as well as plant remains, are also abundant.Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis, p. 277-291. . The formation has been named after Dinosaur Provincial Park, a UNESCO World Heritage Site where the formation is well exposed in the badlands that flank the Red Deer River.
Research history The Dinosaur Park Formation has been a significant source of terrestrial vertebrate fossils for over a century. The first recorded account of fossils was in 1871 by the priest Jean-Baptiste L'Heureux who was shown bones of the "grandfather of the buffalo" by the Blackfoot Confederacy he was living with, though these notes were never published. Official reports of dinosaur bones in western Canada were reported by George Mercer Dawson in 1874 from southern Saskatchewan and Alberta along the Milk River. Further discoveries by Dawson and his colleagues of the Geological Survey of Canada continued in the 1880s, including the 1884 discovery by Joseph Burr Tyrrell of the skull of a theropod identified as Laelaps by American palaeontologist Edward Drinker Cope but named in 1905 as Albertosaurus by American palaeontologist Henry Fairfield Osborn. In 1889 rich fossil beds in the areas of Deadlodge Canyon and Berry Creek were found by Thomas Chesmer Weston along the Red Deer River. The areas along the Red Deer River would be more completely surveyed by Canadian palaeontologist Lawrence Lambe from 1897 until 1901, when he, along with Osborn, described the fossils found in what was then considered to be the Belly River Formation of mid-Cretaceous age.
Geological setting
The Dinosaur Park Formation is composed of sediments that were derived from the erosion of the mountains to the west. It was deposited on an alluvial to coastal plain by river systems that flowed eastward and southeastward to the Bearpaw Sea, a large inland sea that was part of the Western Interior Seaway. That sea gradually inundated the adjacent coastal plain, depositing the marine shales of the Bearpaw Formation on top of the Dinosaur Park Formation.
The Dinosaur Park Formation is about thick at Dinosaur Park. The lower portion of the formation was laid down in fluvial channel environments and consists primarily of fine- to medium-grained, crossbedded sandstones. The upper portion, which was deposited in overbank and floodplain environments, consists primarily of massive to laminated, organic-rich mudstones with abundant root traces, and thin beds of bentonite. The Lethbridge Coal Zone, which consists of several seams of low-rank coal interbedded with mudstones and siltstones, marks the top of the formation.
The sediments of the Dinosaur Park Formation are similar to those of the underlying Oldman Formation and they were originally included in that formation. The two formations are separated by a regional disconformity, however, and are distinguished by petrographic and sedimentologic differences. In addition, articulated skeletal remains and bonebeds are rare in the Oldman Formation but abundant in the Dinosaur Park Formation.
Biostratigraphy The Dinosaur Park Formation can be divided into at least two distinct faunas. The lower part of the formation is characterized by the abundance of Corythosaurus and Centrosaurus. This group of species is replaced higher in the formation by a different ornithischian fauna characterized by the presence of Lambeosaurus and Styracosaurus. The appearance of several new, rare species of ornithischian at the very top of the formation may indicate that a third distinct fauna had replaced the second during the transition into younger, non-Dinosaur Park sediments, at the same time an inland sea transgresses onto land, but there are fewer remains here. An unnamed pachyrhinosaur, Vagaceratops irvinensis, and Lambeosaurus magnicristatus may be more common in this third fauna.
Paleofauna Dinosaurs
Remains of the following dinosaurs have been found in the formation:Currie, P.J. 2005. Theropods, including birds. In: Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis, p. 367-397. .
Ornithischians Remains of the following ornithischians have been found in the formation:Ryan, M.J., and Evans, D.C. 2005. Ornithischian dinosaurs. In: Currie, P.J., and Koppelhus, E.B. (eds), Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed. Indiana University Press: Bloomington and Indianapolis, p. 312-348. .
Ankylosaurs Numerous specimens that cannot be definitively assigned to ankylosaurs are known from the formation, including fragmentary cranial, dental, postcranial, and armour material. As all ankylosaurids from the Campanian of Alberta and Montana were historically referred to Euoplocephalus sensu lato, the taxonomy is variable between studies and ranges from one to seven valid genera between the Dinosaur Park, Judith River, Two Medicine, and Horseshoe Canyon Formations.
Ankylosaurs from the Dinosaur Park Formation Genus Species Location Stratigraphic position Material Notes Images Anodontosaurus A. inceptus Hilda, Alberta Middle DPF Two skulls, one with partial skeleton Previously considered specimens of Euoplocephalus but then referred to Anodontosaurus lambei, otherwise only known from the Horseshoe Canyon Formation, before being given the new species A. inceptus. Dyoplosaurus D. acutosquameus Q002 Lower DPF Partial skull and skeleton, two tail clubs Thought to be a synonym of Euoplocephalus for a time but separated as a distinct taxon. Edmontonia E. rugosidens Q009, Q043, Q101, Q201, Q229, Q230 Lower DPF At least six partial skulls and skeletons A nodosaurid also known from the Two Medicine Formation Euoplocephalus E. tutus Q059, Q198 Lower to middle DPF Partial skulls and skeletons An ankylosaurid historically including all material from the formation. While some studies include up to 11 specimens even with Anodontosaurus, Dyoplosaurus and Scolosaurus separated, others limit it to 5 specimens and also separate Platypelta. Panoplosaurus P. mirus Q008, Q228 Middle DPF Skulls and skeleton A nodosaurid 1/3 less common than Edmontonia. Platypelta P. coombsi Q052 Lowermost DPF Skulls and skeletons Considered specimens of Euoplocephalus by some studies, but separated as a distinct genus by others. Scolosaurus S. cutleri Q080, Q089 Base of DPF Skull(s?) and skeletons Thought to be a synonym of Euoplocephalus for a time but separated as a distinct taxon. Has been suggested to include Oohkotokia from the Two Medicine Formation, and also to be from the top of the Oldman Formation if the quarry is incorrectly mapped. S. thronus Quarry No. 112 Upper DPF Skull and partial skeletons Considered indeterminate ankylosaurids or specimens of Euoplocephalus by some studies, but separated as a distinct species by others.
Ceratopsians An unnamed Pachyrhinosaurus-like taxon has been recovered from the formation.
Ceratopsians from the Dinosaur Park Formation Genus Species Location Stratigraphic position Material Notes Images Centrosaurus C. apertus Middle, 76.2-75.5Ma ago "[Fifteen] skulls, several skeletons, all adult; abundant bone-bed material with rare juveniles and subadults." C. nasicornis may be a synonym. A centrosaurine ceratopsid Chasmosaurus C. belli Middle, 76–75.5Ma ago "[Twelve] skulls, several skeletons."A chasmosaurine ceratopsidC. sp.Lower, ~76.5MaAn unnamed chasmosaurine ceratopsid formally attributed to Chasmosaurus russeliCryptarcus C. russelli Upper, 75-75.6Ma A nearly complete skull.A chasmosaurine ceratopsid. Formerly assigned to Chasmosaurus. Mercuriceratops M. gemini Lower, ~77Ma ago "one apomorphic squamosal" A chasmosaurine ceratopsid Monoclonius M. lowei A dubious centrosaurine ceratopsid. Synonymous with Centrosaurus. Pentaceratops P. aquilonius Uppermost, 74.8 MA two frill fragments A dubious chasmosaurine ceratopsid that may be the same species as Spiclypeus shipporum. Spinops S. sternbergorum Lower, 76.5Ma "partial parietal bone, partial dentary, unidentifiable limb fragments, partial skull, and partial right squamosal." A centrosaurine ceratopsid. The holotype's locality is uncertain and may be from the upper Oldman Formation. A parietal from Muddy Lake, Saskatchewan suggests they were present in the lower Dinosaur Park. Styracosaurus S. albertensis Upper, 75.5-75.2Ma ago "[Two] skulls, [three] skeletons, additional material in bone beds." A centrosaurine ceratopsid Unescoceratops U. koppelhusae Partial lower jaw A leptoceratopsid thought to have been between one and two meters long and less than 91 kilograms. Its teeth were the roundest of all leptoceratopsids. Vagaceratops V. irvinensis Upper, 75Ma ago "[Three] skulls, skeleton lacking tail." A chasmosaurine ceratopsid species previously classified as a species of Chasmosaurus.
Ornithopods At least one indeterminate thescelosaurid specimen has been recovered from the formation.
In a 2001 review of hadrosaur eggshell and hatchling material from the Dinosaur Park Formation, Darren H. Tanke and M. K. Brett-Surman concluded that hadrosaurs nested in both the ancient upland and lowlands of the formation's depositional environment. The upland nesting grounds may have been preferred by the less common hadrosaurs, like Brachylophosaurus or Parasaurolophus. However, the authors were unable to determine what specific factors shaped nesting ground choice in the formation's hadrosaurs. They suggested that behavior, diet, soil condition, and competition between dinosaur species all potentially influenced where hadrosaurs nested.
Sub-centimeter fragments of pebbly-textured hadrosaur eggshell have been reported from the Dinosaur Park Formation. This eggshell is similar to the hadrosaur eggshell of Devil's Coulee in southern Alberta as well as that of the Two Medicine and Judith River Formations in Montana, United States. While present, dinosaur eggshell is very rare in the Dinosaur Park Formation and is only found in two different microfossil sites. These sites are distinguished by large numbers of pisidiid clams and other less common shelled invertebrates like unionid clams and snails. This association is not a coincidence as the invertebrate shells would have slowly dissolved and released enough basic calcium carbonate to protect the eggshells from naturally occurring acids that otherwise would have dissolved them and prevented fossilization.