Alberta Palaeontology, a Summary
Alberta, more than any other part of Canada, is renowned for its dinosaur fossil record. In fact, it's one of the top places in the world to find dinosaur bones, a fact that too often escapes many citizens of the province who take it for granted.
When it comes to the science of vertebrate palaeontology in Alberta, there's so much to explore and appreciate. From The history of dinosaur hunting in the province, its prehistoric ecology, the biology and lives of the creatures preserved here, and the geological processes that not only fossilized them but exposed them to our eye today... All of this is worth learning more about, and as a lifelong fossil fanatic, I can't wait to begin.
To be clear up front, this is far from a totally complete overview of the vast science of palaeontology in Alberta. For starters, we'll be keeping to the province's Mesozoic fossil record, meaning the time of the dinosaurs, and will leave the 'Ice Age' stuff for, hopefully, its own entry. While I've done my best to keep this summary current and accurate, and to back up as many facts as possible with references, please leave a comment if you have anything to add.
Geology and Geography
To understand how fossils got here, what their environment in life was like, and where they fit into the history of life on Earth, we need to study the rocks they're found in. Fossils are generally found in sedimentary rock, which if you remember your grade 3 is formed by tiny mineral particles eroded from other rocks, deposited in layers by water or wind, and hardening into formations over millions of year. The remains of living things that become buried by these depositing sediments can become mineralized in one way or another, which turns them into a fossil.
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| Dry Island Buffalo Jump Provincial Park. By Nick Carter |
We divide units of sedimentary rock into distinct formations based on their physical characteristics like age, location, and types of sedimentary rock found within. Different formations generally represent distinct ecosystems, and the type of rocks and fossils present in a formation gives us clues as to what kind of environment the formation was laid down in. For example, sandstone and mudstone layers tend to indicate rivers flowing through the area, carrying and depositing sand and mud particles as they went. Coal seams and amber tell us the area was forested. Shales or chalk mean the environment was a marine one at the time. It gets more refined and complicated than this, but rest assured that folks with training in geology can tell a lot about a prehistoric environment by simply looking at a rock exposure.
Different parts of the world have rock exposures from different points in time in different places. This is due to many things, including the movement of landmasses and erosion affecting certain areas in particular ways. Even though Alberta has rocks going all the way back to way before the dinosaurs, such as Cambrian rocks exposed in the mountains, most of the really famous and productive rocks come from the late Cretaceous period, spanning the Campanian and Maastrichtian ages. This is around the end of the age of dinosaurs. Older rocks are further down, and younger rocks are higher up. That's one of the fundamental rules of geology. Rocks from slightly earlier in time are certainly found here, but their fossil assemblages are poorly understood. So, no offense to the Smoky Group or Dunvegan Formation, but we'll save things like that for later.
Many of the dinosaur-bearing late Cretaceous formations in Alberta were deposited along the western shore of the Western Interior Seaway, the great inland sea that run up and down much of central North America, connecting the Gulf of Mexico to the Arctic Ocean. Further west, the Cordillera mountain ranges were continuing to rise in towering uplands. The modern Canadian Rockies are part of that mountain chain. Rivers flowed from the western highlands eastward towards the sea, carrying eroded sediments with them that were deposited as sandstone and mudstone layers inland, and marine shales at and beyond the shore. All sorts of plants and animals thrived in the coastal lowlands as well as in the seaway itself, and when they died, many were washed away by moving water, buried within layers of sediment, and fossilized. Did dinosaurs also live further inland towards the western highlands? Certainly, but the relative scarcity of late Cretaceous exposures combined with the more complicated geology of the Rockies makes finding evidence of them more difficult.
One of the oldest rock formations with a good deal of vertebrate fossils known from Alberta is the Milk River Formation. This formation can be seen, naturally, along the Milk River where it bends northwards just inside the far southern edge of the province. Writing-on-Stone Provincial Park is a handy place to see it. The Milk River Formation's lowest section starts in the older Santonian age about 84.1 million years ago, and it ends at about 83.6 million years ago. While the Milk River Formation might be harder to find in Alberta than other rocks we'll touch on later, its important because it tells palaeontologists more about what sorts of animals were living here before the more well-known faunal assemblages from later on, filling in our understanding of how the environment and species of Cretaceous Alberta changed over time.
The next rocks of note to vertebrate palaeontologists are a group of formations together known as the Belly River Group. This group spans from about 78.5 million to 75.8 million years ago, and exposures of varying ages can be found throughout central and southern Alberta. The oldest formation in the Belly River Group is the Foremost Formation. Relatively scarce outcroppings can be seen along rivers in the deep southeastern part of the province, and although much of the material from this formation has been less than complete, palaeontologists over the last two decades or so have been working hard to study the fossils from this formation and have described several interesting species of dinosaur from these remains.
Overlying the Foremost Formation in southeastern Alberta is the Oldman Formation, named for Alberta's Oldman River. It spans from about 77.5 to 76.5 million years ago, and overlaps in time with the Two Medicine Formation further to the southwest, which is mostly found in Montana and just over the Alberta border, and is famous for its fossilized dinosaur nests. Many different dinosaur species have been found in the Oldman and, while they might not be at the top of most people's favourite dinosaur lists, Oldman Formation species can be seen on display at world-class museums like the Canadian Museum of Nature and Royall Tyrrell Museum.
In terms of geology and fossil record, the Oldman is superficially similar to the overlying Dinosaur Park Formation. This rock unit, which is about 76.5 to 75 million years ago is also exposed in places throughout southeastern Alberta, but the best location to explore it would have to be its namesake, Dinosaur Provincial Park. While other rocks listed here can be abundant in scientifically valuable fossils, the Dinosaur Park Formation exposures in Dinosaur Provincial Park are a staggering treasure trove of late Cretaceous fossils. Words really can't do it justice. I was once lucky enough to be driving the great Argentinian palaeontologist, Rudolfo Coria to the airport in Grande Prairie, after showing him the fossil collections of the Philip J. Currie Dinosaur Museum, and asked him what the best fieldwork location he's ever visited was. Without much difficulty he told me it was Dinosaur Provincial Park. A glance at the Dinosaur Park fossil record shows practically a greatest hits-list of late Cretaceous North American dinosaurs, minus only Triceratops and Tyrannosaurus. We'll touch on that more later on.
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| Dinosaur Park Formation badlands at, naturally, Dinosaur Provincial Park. By Nick Carter |
During this time, the water levels of the Western Interior Seaway continued to rise, until the sea covered nearly all of eastern and central Alberta. This is the time of the marine Bearpaw Formation, from about 75 to 72 million years ago. This created an environment where most dinosaurs, aside from ocean-going birds, couldn't continue living. Further inland at this time, though, dinosaurs from remaining terrestrial locations, represented in places like the upper part of Montana's Two Medicine Formation, would occasionally wash out to sea after dying, likely carried by rivers after bloating due to gas buildup from microorganisms within the carcass. Examples include a specimen of the duck-billed dinosaur Prosaurolophus which was already known from the Dinosaur Park Formation. All sorts of marine animals from ammonites to mosasaurs and more dwelt here as well. One notable Bearpaw exposure is south of Lethbridge where a commercial mine digs for ammolite, a gemstone that arises from fossilized ammonite shells. Many impressive marine reptile skeletons have been found in quarries like this.
Eventually the time of extra-high sea levels began to end, and from this time we find terrestrial deposits in the Alberta prairies again. Overlying the Bearpaw is the Horseshoe Canyon Formation, spanning till about 67 million years ago into the early Maastrichtian era, the final section of the Cretaceous period. The southwestern Alberta rocks of the St. Mary River Formation is of a similar age. The Horseshoe Canyon Formation is the rock that many Albertans probably think of when they envision the classic Alberta badlands. This is because the town of Drumheller, Canadas dinosaur capital, as well as the surrounding area sit in a valley along the Red Deer River that is bordered by iconic Horseshoe Canyon Formation exposures. Truth is, the other formations listed here are also found in badland-type landscapes, and I honestly must say the older Dinosaur Park Formation badlands further east along the Red Deer are more impressive. In addition to that, you can also see the Horseshoe Canyon Formation exposed in more than just badlands. Edmontonians only need to look at the south side of the North Saskatchewan River- the greyish-brown rock exposures that can be seen in places along the river's south bank are Horseshoe Canyon Formation. The Edmonton Group, which the Horseshoe Canyon Formation is the oldest member of, gets its name from this fact. In any case, this rock unit has also yielded no shortage of beautiful and iconic dinosaur fossils as well as all sorts of other Cretaceous animals. These fossil creatures are related to earlier forms found in the Dinosaur Park Formation, but represent different species in a different kind of assemblage. What happened between these two times?
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| Horseshoe Canyon Formation exposure outside the Royal Tyrrell Museum near Drumheller. By Nick Carter |
We need to look to the north. At this point we've covered a lot of well-studied rock formations ranging from the Edmonton area down to the far-flung grasslands of deep southern Alberta. But did you know that plenty of fossils are also now being found hundreds of kilometres to the northwest? It's true. Ranging from just over the border into northeastern B.C. and across parts of Alberta's Peace country, particularly the area around Grande Prairie, the Wapiti Formation can be found. Spanning from about 80 to 68 million years ago from the Campanian to the Maastrichtian eras, the Wapiti Formation overlaps in time with much of the rock we've already covered. Its northwesterly position means that this inland formation wasn't interrupted by the incursion of the Western Interior Seaway. This not only means that it allows palaeontologists to figure out what was living further inland and to the north in late Cretaceous Alberta, but some particularly important fossil sites were actually deposited while the rest of the province was under water during the Bearpaw times, meaning we can start to piece together what kind of land-based and freshwater animals lived in Alberta during the gap in the fossil record between the Dinosaur Park and Horseshoe Canyon Formations. The disadvantage is that, because of remote outcropping locations and extensive plant coverage, there's less Wapiti Formation exposures to explore for fossils in than we'd like. Vertebrate trackways, however, are interestingly abundant in this formation. You can see productive outcroppings in places like the Redwillow and Wapiti Rivers and the Kleskun Hills, Alberta's northernmost badlands.
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| Wapiti Formation exposure at the Kleskun Hills near Grande Prairie. By Nick Carter |
Skipping over the relatively unproductive Battle and Whitemud Formations, we come to the youngest member of the Edmonton Group and the end of the Age of Dinosaurs with the Scollard Formation. You can see this exposed in places along the Red Deer River near Trochu, and it's also present in patchy areas above the Wapiti. This rock actually crosses the Cretaceous-Palaeogene boundary, and you can actually see that transition point in the rock where a layer of iridium can be found. In southwestern Alberta, the Scollard grades into the Willow Creek Formation, and belongs to the same broader environment also seen in Saskatchewan's Frenchman Formation as well as the American Hell Creek, Denver, and Laramie Formations. Beyond that, the Paskapoo Formation can be found across swaths of southwestern Alberta, including around Calgary. The Paskapoo is from early in the Palaeogene period, a time when avian dinosaurs (birds) were beginning to really diversify, but by this time all other dinosaurs had gone extinct.
Palaeoenvironment
Much of what we know about the climate and environment of late Cretaceous Alberta comes from sites that were deposited in a low-lying plain where meandering rivers and braided streams flowed down from the Rocky Mountains and drained into the Western Interior Seaway, bringing down sediments that would eventually become rock. Back then the Rockies wouldn't look very familiar to us today. Instead of the sharp, snow-capped peaks and deep valleys, they were a tall, rolling highland region. As differential erosion caused different rocks to wear down at different speeds, the Rockies eventually changed into what we see today, a bit lower in elevation but a much more dramatic landscape with more dynamic altitude differences between peaks and valleys. It took millions of years and and Ice Age to get there, though.
The environment of Cretaceous Alberta would be both familiar and strange. Many folks tend to generalize the world of the Age of Dinosaurs as a sort of giant tropical terrarium, with palm trees swaying as the ground was gently rocked by earthquakes and volcanic eruptions. In truth, while global temperatures were on average higher than today, and temperature differences between the poles and equator were much less dramatic than they are now, there was still a great variety of habitats, climates, and landscapes back then. That said, we're far from understanding the whole picture at the moment. As it stands, much of Alberta in the Campanian was, climatically-speaking, not dissimilar from today's Mississippi delta in some ways. A flat, swampy land of rivers and bayous near the ocean's shore. Summers were hot and humid. Back then Alberta was actually further north than today, meaning summer days would've been even longer. Dramatic thunderstorms would've rolled in from the sea from time to time, bringing high winds and torrents of rain.
Coal, leaf impressions, fossilized pollen, and petrified wood tell us of the plant life at the time. Coniferous trees mostly included cypresses, podocarps, pines, and redwoods, plus some cycads. Ginkgoes lived here too, as did flowering trees such as figs and plane trees. The undergrowth was a variety of familiar shrubs and smaller flowers. Grass hasn't taken over the plant world at this time, and so much of the ground cover was taken up by ferns and mosses.
Winters would have been a slightly different matter. While nowhere as severe as modern Alberta winters can be, our latitude at the time meant very long, frosty winter nights, probably with the occasional snowfall. It might seem odd to picture dinosaurs going about their business in such conditions, but in manly places today modern reptiles deal with cool and even freezing conditions for part of the year. The environment of Cretaceous Alberta- a temperate to subtropical region that also experienced long, dark winter nights- doesn't really exist to the same degree today. It was once assumed that the more northwestern Wapiti Formation experienced more intense and perhaps even severe winters due to its geographical position, and what was seen as the near absence of fossil turtles and crocodiles was believed to have supported this. However, more recent findings of these reptiles might indicate the region was milder than we'd previously thought.
Despite this generalizing, our late Cretaceous formations show gradual environmental change closely tied with fluctuating sea levels and geographic position. Sandstones and mudstones tell us of rivers and coastal floodplains in the Belly River group and lower Horseshoe Canyon Formation, while the Wapiti indicates an inland environment with rivers and lakes and less marine influence.
Fossil Animals
Listing every fossil animal (and we'll stick to vertebrates here as I'm far less experienced with invert palaeontology) would take a long time, but there are some interesting trends we can see across Cretaceous Alberta. It wasn't all just dinosaurs of course. Plenty of different animals shared the environment at the time, and many of them wouldn't look out of place today.
Starting with fish, it's a well-known fact that cartilaginous or chondrichthyan fish, sharks and rays that is, are much older than the dinosaurs. A variety of sharks are known from Alberta, mostly from their teeth, since the dentine and enamel of teeth fossilize much better than comparatively soft cartilage. Sharks weren't restricted to the marine Bearpaw Formation either, as shark teeth found in nearshore formations indicate they probably swam up into estuaries or coastal bayous. One of the easiest chondrichthyan teeth to recognize is Myledaphus. This animal was a rhinobatid, or guitarfish- a type of ray known for their elongate bodies. Myledaphus teeth are like tiny hexagon-shaped blocks with two little roots at the bottom. The top of the tooth is flat and likely used for crushing the shells of clams and such nabbed from the sea floor. Thanks to a very well-preserved specimen at the Royal Tyrrell Museum in which part of the skeleton fossilized, we actually have a good idea as to what Myledaphus looked like.
Other fish included close relatives of modern sturgeons, bowfin, and gar that patrolled the swamps, as well as the needle-jawed fish Belonostomus out in the seaway which left no close relatives alive today (Neuman & Brinkman, 2005). While beautifully preserved skeletons of Cretaceous sturgeon and gar have been found in Alberta. the most common bits of them to find are things like their distinctive spines and scales.
Amphibians would have been a common site in wetlands at the time (Gardner, 2005). Several different types of salamanders are known, mostly from their thin little jaw bones lined with peg-shaped teeth. Frogs were around too. We also had creatures called albanerpetontids (good luck pronouncing it), part of the extinct Allocaudata order. They looked superficially like salamanders, but the anatomy of these animals tells us they seem to have split off long ago from the same common ancestor that also gave rise to the frogs and salamanders group (Batrachia) and the caecillians.
While the time after the big Cretaceous extinction is often nicknamed the 'Age of Mammals', in reality mammals go back a long way before. True mammals arose in the Jurassic period, and our earlier mammaliaform ancestors arose at about the same time as the dinosaurs. In general, Mesozoic mammals are known for being fairly small by modern standards, ranging from about the size of a shrew to the size of a small dog, give or take. Many folks assume that mammals didn't grow big at the time because dinosaurs would've just eaten them on sight, but it's not that simple. Dinosaurs were able to attain bigger sizes earlier in time than mammals were, and they quickly came to dominate the big land animal ecological roles, or niches. Larger mammals would have to compete with the already established dinosaurs for food and space. So, instead, they stayed on the small side. Many seem to have been gnawing herbivores or predators of insects and other small vertebrates, living under ground and coming out at night to feed and move around. The tricky thing, however, is that Cretaceous mammals from Alberta are mostly known from teeth attached to fragments of jaw bone. The reason for this is because the environment at the time with all that moving water and big animals stomping around favoured preservation of larger animals with hard, sturdy bones. That's why remains of small dinosaurs are fairly rare in Alberta, even though they were here. Since teeth are harder than bone, the delicate skeletons of mammals would get crushed or swept away, while their teeth stood a better chance of being preserved.
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| Fossil mammal jaw at the Royal Tyrrell Museum. By Nick Carter |
Mammals from Cretaceous Alberta include a now extinct group called the multituberculates. These were a diverse group at the time, ranging from the Jurassic to just after the dinosaurs in the Eocene. Species from Alberta include Cimolomys, Cimolodon, and Mesodma, among others (Fox, 2005). Multituberculates looked remarkably similar to modern rodents, and ranged in shape and size from little mouse-like creatures to marmot-like burrowers and squirrel-like climbers. They were sort of like Mammalia's earlier stab at a rodent-style life, but instead of the chiseling incisors of modern rodents, multituberculates had an enlarged lower premolar for slicing off pieces of food before it was ground up by the teeth further back.
Alberta was also home to metatherians, a group that includes modern marsupials (Fox, 2005). Species like Alphadon and Eodelphis were small carnivores/omnivores that may have looked and behaved not dissimilar to our modern opossums. We also had the slightly larger and more powerful carnivore Didelphodon (Fox & Naylor, 1986). Some early placental mammals, the same group that most mammals today belong to, would've also been around.
On to reptiles. One of the more common reptiles from Cretaceous Alberta were the choristoderes. They don't seem to have any close living relatives, but choristoderes somehow managed to survive the Cretaceous extinction before vanishing in the Miocene era. One of the better known choristoderes is Champsosaurus, several species of which are known from different formations from late Cretaceous Alberta. Perhaps the most commonly said thing about Champsosaurus is that it wasn't a type of crocodile, but that disclaimer is important because Champsosaurus looked, superficially at least, very much like a small crocodile or gharial. Okay, so what was it? Well, they were small aquatic predators that dwelt in wetlands, presumably feeding on fish, amphibians, and other freshwater animals (Erickson, 1985). This lifestyle, by necessity, led them to evolve their gharial-like appearance. Unlike crocodilians, however, Champsosaurus had palatal teeth, small pointy teeth on the roof of the mouth, that assisted in gripping prey while swallowing.
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| Champsosaurus at the University of Alberta. By Nick Carter |
Various types of plesiosaurs, those marine reptiles with flippers, long necks, and tiny heads (though some species were built rather differently) have been found in marine and nearshore deposits throughout Alberta. The most impressive is probably Albertonectes from the Bearpaw Formation, which had the longest neck of any known plesiosaur at 23 feet long (Kubo et al., 2012). Plesiosaurs swam the prehistoric seaways feeding on schools of small fish. Those long necks probably helped them get their long teeth and snapping jaws close to their prey without their large bodies betraying their presence.
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| Elasmosaurus, a type of plesiosaur, at the University of Alberta. By Nick Carter |
A variety of lizards inhabited Cretaceous Alberta (Caldwell, 2005). Prehistoric beaded lizards and whiptails were among them, as was the large varanid Palaeosaniwa, which could grow to the size of a modern Komodo dragon. There were even bigger lizards in the seaway, too. These were the mosasaurs- giant marine lizards that evolved fin-shaped limbs and tail flukes for a completely aquatic lifestyle. The best rock to find mosasaurs in is Bearpaw Formation rock, and many wonderfully complete mosasaurs have been found in ammonite mines near Lethbridge. Mosasaur species found in Alberta include Mosasaurus missouriensis (Konishi et al., 2014) and Prognathodon overtoni (Konishi et al., 2011). Mosasaurs were among the most dangerous predators of the Cretaceous oceans, and seem to have fed on just about whatever the felt like, from ammonites and turtles to sharks and plesiosaurs. Probably other mosasaurs, too.
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| Mosasaur display at the Royal Tyrrell Museum. By Nick Carter |
Several extinct turtle groups, such as the baenids, adocids, and nanhsiungchelyids inhabited the wetlands of Cretaceous Alberta, alongside relatives of modern trionychid softshell turtles (Brinkman, 2005). Many of these probably looked similar to the modern pond turtles we're used to. The huge Basilemys, however, was a big, flat-shelled species and probably lived on land like a modern tortoise (Mallon & Brinkman, 2018). There's also a sea turtle known from the Bearpaw called Nichollsemys.
The top wetland predators were crocodilians, true crocodilians this time. Well, more accurately they were more closely related to alligators. Species like Leidyosuchus, Albertochampsa, and Stangerochampsa inhabited the province (Wu et al., 1996) (Wu, 2005). These would have strongly resembled modern crocodilian species, presumably living a similar lifestyle, indicating the warm, swampy nature of southeastern Alberta at the time. Did they prey on dinosaurs? Probably smaller ones, along with turtles, mammals, and any other smaller animals that wandered close to the water's edge. Alberta's crocodilians grew to a fairly modest size- we haven't found any traces of Mesozoic giants like the southern Deinosuchus yet from the province.
Pterosaurs, the flying reptiles closely related to dinosaurs, were also present in Alberta, though they're comparatively rare due to their hollow, fragile bones. The best known and coolest Alberta pterosaur must be Cryodrakon, the giant stork-like predator from the Dinosaur Park Formation (Hone et al., 2019). Like its famous Texas relative Quetzalcoatlus, this long-necked animal likely hunted on the ground, stalking unwary prey before snatching them in its long toothless beak. Despite its size, it was likely still capable of flight.
Now we get to the dinosaurs. Different types of these magnificent creatures came and went throughout the late Cretaceous, and different formations had different assortments of dinosaur species. We can actually see trends in different groups becoming more or less common and diverse over time.
Some of the most common large plant-eating dinosaurs were the hadrosaurs, or 'duck-billed dinosaurs'. These were generalist herbivores that could travel around and feed at different levels, from the forest floor to the lower canopy. Their specialized tooth arrangement at the back of the jaws, known as a dental battery, kept a constant armament of chewing teeth at the ready, new ones always ready to replace worn-down ones. Bone beds indicate that at least some hadrosaur species travelled in herds. Hadrosaurs came in two subfamilies: the lambeosaurines, which sported hollow and often elaborate head crests, and the saurolophines, which either had solid flat or spike-shaped crests, or no bony crest at all. Lambeosaurines were more common and diverse in the older Campanian times, and included charismatic species like Corythosaurus, Lambeosaurus, and Parasaurolohpus. Hypacrosaurus from the Maastrichtian Horseshoe Canyon Formation appears to have been Alberta's last known lambeosaurine. Campanian saurolophines include Brachylophosaurus, Gryposaurus, and Prosaurolophus. The closely-related Saurolophus existed in the Horseshoe Canyon Formation, as did perhaps Alberta's most common hadrosaur, Edmontosaurus. This classic duckbill is found from the Drumheller badlands to Edmonton to west of Grande Prairie and beyond, making it widespread if nothing else (Bell et al., 2013). At least one possibly new lambeosaurine is known from Wapiti Formation sites, but without complete adult skulls so far, it's hard to tell exactly what we've got there (Holland et al., 2021).
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| Edmontosaurus with an Albertosaurus skull at the Royal Alberta Museum. Check out the mural of the environment at the time behind the display. By Nick Carter |
The other common large herbivores are the horned ceratopsians. Like the hadrosaurs, they were beaked plant-eaters with chewing dental batteries, but their narrow jaws were more suitable to browsing on rough foliage. They too come in two different families: the centrosaurines which tended to have smaller, rounded frills bearing more elaborate spikes and studs, and the chasmosaurines with their longer snouts and rectangular frills. There were also the pig-sized leptoceratopsids as well, a more basal group of smaller, hornless browsers. Some centrosaurines travelled in large to enormous herds, as evidenced by bone beds that seem to represent huge groups of these animals that were likely killed by the flooding effects of violent storms. Several bone beds of Centrosaurus and Styracosaurus are known from the Dinosaur Park Formation (Eberth & Getty, 2005) and at least two Pachyrhinosaurus bone beds, each probably representing a different species, have been found in the Wapiti Formation (Currie et al., 2008). The more productive of these two, a super dense bone bed containing the species Pachyrhinosaurus lakustai, holds a special place in my heart. It's remote and muddy, but it was the first place I ever got to help dig for dinosaur bones.
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| Centrosaurus at the University of Alberta. By Nick Carter |
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| Pachyrhinosaurus skulls at Pipestone Creek. By Nick Carter |
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| Chasmosaurus skull at the University of Alberta. By Nick Carter |
The remaining big herbivores, a group of low browsers, were the ankylosaurs. These dinosaurs had bony studs called osteoderms that grew in the skin, forming a protective suit of armour. These distinctive bits of bone are some of the most commonly found remains of these dinosaurs. In the nodosaurid ankylosaurus, these osteoderms could grow into large protective/display spines. Examples include Edmontonia and Panoplosaurus. The famously well-preserved Borealopelta is also a nodosaurid from older mid-Cretaceous rock far to the north. In their cousins the ankylosaurids, a defensive bony club formed at the end of the tail. Ankylosaurids include Scolosaurus, Anodontosaurus, Euoplocephalus, and the biggest of all, Ankylosaurus itself the the end of the Cretaceous.
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| Scolosaurus at the Royal Tyrrell Museum. By Nick Carter |
Smaller herbivores are less commonly found due to the preservation bias, but were probably abundant back in the day. These included the dome-headed pachycephalosaurs like the dog-sized Stegoceras (not the be confused with Stegosaurus) and the thescelosaurids- small, bipedal distant cousins of the hadrosaurs.
The biggest carnivores were the tyrannosaurids, and several different species inhabited Alberta. These powerful bone-crushers were Alberta's only large predators by the late Cretaceous, usurping previous ecological roles once filled by variety of different carnivores. Shed teeth from these dinosaurs, especially in herbivore bone beds, are relatively common as far as predator remains go, and I can say from experience they make for an exciting find. Tyrannosaurids came in two different varieties here: the bulkier tyrannosaurines, and the lithe, proportionally longer-legged albertosaurines. The oldest known species so far is the tyrannosaurine Thanatotheristes from the Foremost Formation (Voris et al., 2020). Its close relative Daspletosaurus torosus took over in the Oldman Formation. A second undescribed Daspletosaurus species also lived in the Dinosaur Park Formation where is coexisted alongside Alberta's most common tyrannosaur, the albertosaurine Gorgosaurus. The latter genus was a very successful predator, and multiple skeletons ranging from juveniles to adults have been found in Dinosaur Provincial Park. Its close relative Albertosaurus (some argue the two represent different species of the same genera) was the sole large predator of the Horseshoe Canyon Formation, and is known from the southern badlands as well as the Edmonton area and possibly beyond. It has the distinction of being the first predatory dinosaur from Alberta to be described and named.
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| A famously amazing Gorgosaurus at the Royal Tyrrell Museum. By Nick Carter |
While rarer here than in the United States, Alberta's Scollard and Willow Creek Formations have given us remains of the big daddy dino itself, Tyrannosaurus. Many of the best preserved Tyrannosaurus specimens get nicknames, like Stan, Sue, and Jane. Alberta has one too, the elegant Black Beauty which can be seen on display at the Royal Tyrrell Museum.
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| Black Beauty's skull at the Royal Alberta Museum. Alberta's best Tyrannosaurus. By Nick Carter |
Tyrannosaurids were part of the theropod group- the two legged, mostly carnivorous, sometimes feathered dinosaurs. Not all of them were predators, though. Matter of fact, Alberta was home to a few types of theropods that ate plants. There were the ornithomimids, the 'ostrich mimic' dinosaurs, which included species like Struthiomimus and Ornithomimus. They weren't the direct ancestors of modern ostriches and emus and such, but looked and probably behaved in a somewhat similar manner to them due to leading a comparable lifestyle. These sprinting specialists likely fed on soft plants, seeds, insects, and other such food. While it was suspected for a while that they were feathered, some important finds from Alberta have proven that ornithomimids did indeed have plumed, ostrich-like feathers (Zelenitsky et al., 2012) (Van Der Reest et al., 2016).
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| Struthiomimus skeleton at the Royal Tyrrell Museum. By Nick Carter |
Another interesting family were the caenagnathids. Members of the oviraptorosaur group, these feathered herbivores were amazingly birdlike with their beaks and cassowary-like crests. They're also tantalizingly uncommon, unlike in Mongolia where so many beautifully complete specimens of their oviraptorid relatives have been found. Albertan caenagnathids include Chirostenotes, Apatoraptor, and Caenagnathus.
Birdlike predators can also be found here. The smallest, Albertonykus, represents our sole known alverezsaurid (Longrich & Currie, 2009), which were a family of tiny insect-eating dinosaurs with enlarged claws that may have been useful for digging bugs out of dirt and wood. Speaking of enlarged claws, we also had our fair share of dromaeosaurids, the family that includes dino celebrity Velocriaptor. These were predators of small to mid-sized animals, catching and pinning down prey with their famous 'killing claws' before the teeth did the rest of the work. While Velociraptor itself was confined to Mongolia, Alberta's dromaeosaurids from this time deserve equal attention. The first to be described was the species that gave this group its name, Dromaeosaurus from the Dinosaur Park Formation. This dog-sized predator is relatively uncommon, and its shed teeth are found more often than identifiable bones. The skull of Dromaeosaurus was relatively short and deep, and it seems to have had a pretty powerful bite (Therrien et al., 2005). The most common Alberta dromaeosaurid is probably Saurornitholestes, a Dinosaur Park Formation species which has also given us the province's best-preserved specimen of this group- a nearly complete skeleton missing only most of the tail has shed a lot of light on this animal and dromaeosaurid diversity in the province in general (Currie & Evans, 2020). Other Alberta dromaeosaurids include the microraptorine Hesperonychus form the Dinosaur Park Formation, Atrociraptor from the Horseshoe Canyon Formation, and Boreonykus from the Wapiti.
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| Dromaeosaurus on display at the Royal Alberta Museum. By Nick Carter |
Troodontids, close cousins of the dromaeosaurids, are a bit more mysterious, and their taxonomy is still controversial. They had longer legs, bigger eyes, weaker jaws, and smaller 'killing claws' than dromaeosaurids did, indicating they might have been more specialized for sprinting after smaller, softer prey animals in lower light conditions. Species known from skeletal material include Stenonychosaurus (which was once lumped under the name Troodon) from the Dinosaur Park Formation and Albertavenator from the Horseshoe Canyon Formation. Troodontid teeth, with their large and distinct serrations, are known from these and other late Cretaceous formations across Alberta, as are dromaeosaur-like teeth of unknown origin and other more mysterious small theropod teeth like those of whatever Richardoestesia is.
Last but not least, we come to the birds, a group of feathered theropods that happen to still be around today. A few rare bird fossils are known from Alberta, including remains of hesperornithifoms, an extinct group of large flightless diving birds (Currie, 2005). A feather from a similar sort of bird was also reported from Wapiti Formation amber (Cockx et al., 2020). With their fragile hollow bones, late Cretaceous birds would've been more common than the fossil record suggests.
Conclusion
That brings us to the end of this long summary, but this is far from the last or definitive word on palaeontology in Alberta; there's still plenty out there for fossil enthusiasts to learn about, let alone for palaeontologists to discover. If you want to see and learn more about Alberta's fossil record, here's a shortlist of places where people study palaeontology in Alberta, and where you can see, learn about, and potentially get involved with fossils:
- Royal Tyrrell Museum of Palaeontology
- Royal Alberta Museum
- Dinosaur Provincial Park
- University of Alberta
- University of Calgary
- Philip J. Currie Dinosaur Museum
Catch you in the badlands~
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