Latirhinus (no confundir con el iguanodonte Altirhinus) fue un dinosaurio pico de pato cuyos restos fueron hallados en México. Su principal característica era su nariz arqueada similar a la de Kritosaurus. La verdad es que nunca he visto una imágen de Latirhinus y no sé mucho de el, asi que este dibujo es completamente hipotético. Ahora a esperar a ver alguna imagen oficial y ver que tanto me acerqué a la realidad Mientras tanto, primer Latirhinus en DA mwahaha
Latirhinus (not to be confused with the iguanodont Altirhinus) was a duckbilled dinosaur whose remains were found in Mexico. Its main trait was an arched nose similar to Kritosaurus. Truth is I have never seen a Latirhinus reconstruction so this drawing is completely hypothetical. Now, I can only wait for an official picture of the dino to see how close I got to reality. Meanwhile, first Latirhinus in DA
Aqui esta la version completa de "Stalking Trucidocynodon" :> El Trucidocynodon, un cinodonte depredador similar en tamaño y "diseño básico" al leopardo moderno, acecha a dos Staurikosaurus que a su vez persiguen a varios cinodontes mas pequeños.
Here's the full version of "Stalking Trucidocynodon" :> A Trucidocynodon, a predatory cynodont similar in size and "basic design" to the modern leopard, stalking two Staurikosaurus which chase after some smaller cynodonts themselves.
Coelurus is a well known,small, bipedal carnivore from the jurassic and belong to the family coeluridae, which consists of coelrus itself and the larger Tanycolagreus. Coelurus is now considered to be ancestral to the later tyrannosaurs and therefore belongs to the superfamily of tyrannosauroidea, just like tanycolagreus does. Coelurus was a very gracile predator, barely 2 and a half metres long, it had slender ,long legs, ideal for running, and a long tail that was used as balance. Its head isnt known, only the lower jaw is partially known from this animal. This is the replacement pic in the tyrannpsaur project for this: fav.me/d55oz68 Coelurus is probably THE classic small theropod, 3 fingers, 2 legs, a long slender body and the typical theropod like feet.
Alamosaurus sanjuanensis is the biggest north American sauropod found so far. Newer fossils found indicate that this animal approached the size of Argentinosaurus and Puertasaurus ,both from south america, which means that alamosaurus was one of the biggest dinosaurs ever to walk the eart. Alamosaurus is one of the last titanosaurs and the last big sauropod of North america. Alamosaurus was a plant eater with a long neck and a long tail. My alamosaurus is based on scott hartmans skeletal reconstruction of alamosaurus[link] although I think my one turned out a bit too compact..
Liliensternus is the biggest theropod of the triassic, and guess what, itcomes from Germany !
Liliensternus was first described as aspecies of halticosaurus in 1934 by Friedrich von Huene. !984 it was redescribed by Welles as a seperate genus, with the name L. liliensterni, honouring the german amateur palaeontologist Hugo Rhüle von Lilienstern who found the fossils.
As the biggest predatory dinsaur of its time, liliensternus was an apex predator. It hunted smaller dinosaurs probably as well as equaly big "prosauropods" like rhuleia and plateosaurus. The animal was very fast and agile
Liliensternus belongs to the coelophysoids and is thought to be the ancestor of the dilophosaurids. It is often depicted with a narrow crest on its head, similar to that of Dilophosaurus itself. As a coelophysoid,the animal was very lean and surprisingly light for its size, it is thought to have reached a weight of only 150 kg!
And now the largest inhabitant of the Bahariya ecosystem, Paralitian stromeri, a maybe 23 m long titanosaur, heavy enough to crush the tank of Arnold Schwarzenegger, big enough to impress... everyone, and maybe defensive looking enough to let even a few Aegyptosaurus peacefully graze in its shadow.
This old bull with many scars and a healed fracture in the tail could be the specimen which Smith ET AL. published 2001
For this picture I used mostly 's skeletal drawing/description as a reference:
Edit: oh and maybe this is a bit more pleasing for your eyes than the "knightian" apatosaurs from JW
Finally, after weeks, I'm able to present you the next picture of the Jurassic Germany series.
I'm not a specialist for sauropods and it's long ago that I draw a primitve sauropod/sauropodomorph like Ohmdenosaurus, so please excuse anatomical errors which could occur. In addition it was very difficult to reconstruct this species. Ohmdenosaurus is only known from a tibia and two bones of the tarsus (and maybe ossified tendons, but that's controversial). With between 3 and 4 meters in lenght it could be a example of island dwarfism It's the only known dinosaur of the Posidonienschiefer and traces at the bones indicate that the specimen, or parts of it, were washed into the ocean. I show the animal here in an coastal forest which consists of coniferous, thujas, ginkgo, ferns and fern trees (as always data about the paleoflora is very poor).
In an bavarian lagoon, 150 mio years ago, a Cricosaurus suevicus female and it's Babys rest for a moment. It's not known if metriorhynchids were ovipar or already ovivivipar, so I don't show here the act of birth as I formally planed it (sorry for all All Yesterdays fans). I choose this marine crocodile as my first Jurassic Germany subject because these animals are underrated in paleoart and because they show some fascinating adaptation for their habitat. A hypocerk tail, flipper like limbs, sald Glands and no armor.
This is obviously not the original coloration but because the real color lost so much during scanning I colored it, more monochrome, again. The adult is normally dirty yellow with gray blue stripes on it's back.
Illustration to scale of 18 species of basal ceratopsians. They are almost all here. I've avoided the more obscure genera such as Xuanhuaceratops, Lamaceratops, the dubious ones such as Asiaceratops, Breviceratops and Kulceratops, those that are known by very fragmentary materials such as Turanoceratops, and of course the tooth taxa such as Craspedodon. I also put down only two of the ~12 species of Psittacosaurus. The coronosauria next...
A sampling of 12 dinosaurs drawn to scale... Can you guess what they are? To give a bit more incentive, the winner will get to choose one prehistoric animal of his/her choice for me to illustrate...
update was the first to guess them all correctly, was close second. Good work! The dinosaurs are: Prenocephale, Lambeosaurus, Sauropeleta, Spinosaurus, Spinops, Argentinosaurus, Stegosaurus, Ornithomimus, Velociraptor, Cryolophosaurus, Dicraeosaurus, Muttaburrasaurus.
This is my second entry for "All Your Yesterdays" paleoart contest. While the concept may not be pretty original, some of the details and interpretations of the fossil material actually are. Below is description of the artwork. If you're interested to know which parts of this artwork are speculative, please take time and read it.
Unusual interpretation of one of the typical paleoart memes – big herbivore stuck in specific substance, surrounded by bunch of predators waiting for easy meal. The scene takes place in what’s now Zimbabwe (Africa) some 190 million years ago, near a desert oasis where an adult individual of Massospondylus carinatus is stuck in a dry quicksand. Hours later, when the dark fell, the sounds of the trapped animal attracted some small theropods – Megapnosaurus rhodesiensis. Because of the much greater size of the prosauropod they just waiting for time to do its job and weaken the stuck dinosaur. All that Massospondylus got left is to use its inflatable dewlap in attempt to scare off the little carnivores.
Environment – both of the depicted species of dinosaurs are know to have (at least partially) inhabited desert regions with sand dunes and oasisaes.
Dry quicksand – unlike normal quicksand, the dry quicksand doesn’t contain water. It forms when fine sands reduce their density by blowing air trough it. For more information on the dry quicksand, take a look here - [link] . Given the mechanism of forming dry quicksand what’s better place to get stuck in it than a sand desert, where constant winds change the landscape by moving sand particles.
Why during the night? – While during the day the temperatures in deserts are usually too high for (big) animals to wander trough the sandy landscape, during the night the weather is colder, sometimes even cold. This change in the temperatures probably forced dinosaurs living in such region to be more active at sunset or during the night. A study of the skleral ring and orbit morphology of various dinosaurs indicated that some prosauropods and a species of Megapnosaurus were probably nocturnal animals, and this was used to back up their depictions here.
Massospondylus – although this ‘prosauropod’ is known from complete remains, its appearance here is quite speculative. I restored it with very big inflatable dewlap used for intraspecific and interspecific visual display functions. Many modern birds pose such structure, and maybe the same applied to variety of non-avian dinosaurs. The keratinous spikes along the dorsal part of the body are based on fossil evidence from Diplodocus, and the scaly integument is reconstructed after what’s known for Sauropodomorpha’s integumentary structures. Recently published paper describing tail amputation in possibly specimen of Massospondylus directly inspired this reconstruction. Here, the animal lost the distal part of its tail probably after attack of the theropod Dracovenator, which lived in the same time and place. The “coloration” pattern of the animal is similar to sand’s ripple-marks, and it is supposed to help the ‘prosauropod’ to blend better with the environment (sand dunes).
Megapnosaurus – reconstructed with pair of hypothetical low keratinous crests. Protofeathers are also speculative at the moment, only because there is no direct evidence for their presence in so basal theropods. As one of those people who support the idea of some kind of dorsally located keratinous integumentary structures being basal trait of Dinosauria, I think the presence of protofeathers (to some degree) in primitive theropods is not that far-fetched. Also, dino-fuzz could have been of benefit for the animal, increasing its termoregulatory efficiency during the cold desert nights. Of course, the visual display functions of protofeathers, especially in intraspecific interactions such as mating rituals, is beyond a doubt here. Megapnosaurus’ “color” pattern is based on the bird Oenanthe deserti.
Butler, R. J., A. M. Yates, O. W. M. Rauhut, C. Foth. 2013. A pathological tail in basal sauropodomorh dinosaur from South Africa: evidence for traumatic amputation?- Journal of Vertebrate Paleontology, 33, 224-228.
Chiappe, L. M., R. A. Coria, L. Dingus, F. Jackson, A. Chinsamy, M. Fox. 1998. Sauropod dinosaur embryos from the Late Cretaceous of Patagonia.- Nature, 396, 258-261.
Czerkas, S. A. 1992. Discovery of dermal spines reveal a new look for sauropod dinosaurs.- Geology, 20, 1068-1070.
Paul, G. S. 2010. The Princeton field guide to dinosaurs.- Princeton University Press. (referenced for skeletal drawing of Megapnosaurus)
Schmitz, L., R. Motani. 2011. Nocturnality in dinosaurs inferred from scleral ring and orbit morphology.- Science, 332, 705-708.
Skeletal drawing of Massospondylus by Scott Hartman - [link]
Unfortunatelly the lowermost part of the artwork was cut off by the scanned, and this is the reason why part of the foot of the right Megapnosaurus is not visible, which greatly affects composition. Tried to scan the image again but got the same result, dunno why.
Medium: Pencil (2B and 5B) on yellow paper (+ digital editing with Photoshop CS3). Done: 2013. Time spend on this artwork - 20+ hours.
Reconstruction of Miragaia longicollum, the "sauropod-mimic" stegosaur from the Late Jurassic of Portugal. The arrangement of plates and spikes, as well as the shape of the dorsal plates, is speculative due to the incompleteness of the fossil material from this dinosaur. Here, I have depicted the plates as covered by more extensive keratinous sheet which changes their shape.
References: Mateus, O., S. C. R. Maidment, N. A. Christiansen. 2009. A new long-necked "sauropod-mimic" stegosaur and the evolution of the plated dinosaurs.- Proceeding of the Royal Society B: Biological Sciences, 276, 1815-1821.
Gorgosaurus, meaning "fierce lizard") is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period, between about 76.5 and 75 million years ago. Fossil remains have been found in the Canadian province of Alberta and possibly the U.S. state of Montana. Paleontologists recognize only the type species, G. libratus, although other species have been erroneously referred to the genus.
Like most known tyrannosaurids, Gorgosaurus was a bipedal predator weighing more than a metric ton as an adult; dozens of large, sharp teeth lined its jaws, while its two-fingered forelimbs were comparatively small. Gorgosaurus was most closely related to Albertosaurus, and more distantly related to the larger Tyrannosaurus. Gorgosaurus and Albertosaurus are extremely similar, distinguished mainly by subtle differences in the teeth and skull bones. Some experts consider G. libratus to be a species of Albertosaurus; this would make Gorgosaurus a junior synonym of that genus.
Gorgosaurus lived in a lush floodplain environment along the edge of an inland sea. An apex predator, it was at the top of the food chain, preying upon abundant ceratopsids and hadrosaurs. In some areas, Gorgosaurus coexisted with another tyrannosaurid, Daspletosaurus. Though these animals were roughly the same size, there is some evidence of niche differentiation between the two. Gorgosaurus is the best-represented tyrannosaurid in the fossil record, known from dozens of specimens. These plentiful remains have allowed scientists to investigate its ontogeny, life history and other aspects of its biology.
Gorgosaurus was smaller than Tyrannosaurus or Tarbosaurus, closer in size to Albertosaurus and Daspletosaurus. Adults reached 8 or 9 meters (26 to 30 ft) from snout to tail. Paleontologists have estimated full-grown adults to weigh more than 2.4 tonnes (2.7 short tons). The largest known skull measures 99 centimeters (39 in) long, just slightly smaller than that of Daspletosaurus] As in other tyrannosaurids, the skull was large compared to its body size, although chambers within the skull bones and large openings (fenestrae) between bones reduced its weight. Albertosaurus and Gorgosaurus share proportionally longer and lower skulls than Daspletosaurus and other tyrannosaurids. The end of the snout was blunt, and the nasal and parietal bones were fused along the midline of the skull, as in all other members of the family. The eye socket was circular rather than oval or keyhole-shaped as in other tyrannosaurid genera. A tall crest rose from the lacrimal bone in front of each eye, similar to Albertosaurus and Daspletosaurus. Differences in the shape of bones surrounding the brain set Gorgosaurus apart from Albertosaurus.
Gorgosaurus teeth were typical of all known tyrannosaurids. The eight premaxillary teeth at the front of the snout were smaller than the rest, closely packed and D-shaped in cross section. In Gorgosaurus, the first tooth in the maxilla was also shaped like the premaxillary teeth. The rest of the teeth were oval in cross section, rather than blade-like as in most other theropods. Along with the eight premaxillary teeth, Gorgosaurus had 26 to 30 maxillary teeth and 30 to 34 teeth in the dentary bones of the lower jaw. This number of teeth is similar to Albertosaurus and Daspletosaurus but is fewer than those of Tarbosaurus or Tyrannosaurus.
Gorgosaurus shared its general body plan with all other tyrannosaurids. Its massive head was perched on the end of an S-shaped neck. In contrast to its large head, its forelimbs were very small. The forelimbs had only two digits, although a third metacarpal is known in some specimens, the vestigial remains of the third digit seen in other theropods. Gorgosaurus had four digits on each hindlimb, including a small first toe (hallux) which did not contact the ground. Tyrannosaurid hindlimbs were long relative to overall body size compared with other theropods. The largest known Gorgosaurus femur measured 105 centimeters (41 in) long. In several smaller specimens of Gorgosaurus, the tibia was longer than the femur, a proportion typical of fast-running animals. The two bones were of equal length in the largest specimens. The long, heavy tail served as a counterweight to the head and torso and placed the center of gravity over the hips.
*Note: Carr et al. regard Gorgosaurus libratus as a species of Albertosaurus and Tarbosaurus bataar as a species of Tyrannosaurus rex
Gorgosaurus is classified in the theropod subfamily Albertosaurinae within the family Tyrannosauridae. It is most closely related to the slightly younger Albertosaurus. These are the only two definite albertosaurine genera that have been described, although other undescribed species may exist. Appalachiosaurus was described as a basal tyrannosauroid just outside Tyrannosauridae, although American paleontologist Thomas Holtz published a phylogenetic analysis in 2004 which indicated it was an albertosaurine. More recent, unpublished work by Holtz agrees with the original assessment. All other tyrannosaurid genera, including Daspletosaurus, Tarbosaurus and Tyrannosaurus, are classified in the subfamily Tyrannosaurinae. Compared to the tyrannosaurines, albertosaurines had slender builds, with proportionately smaller, lower skulls and longer bones of the lower leg (tibia) and feet (metatarsals and phalanges).
The close similarities between Gorgosaurus libratus and Albertosaurus sarcophagus have led many experts to combine them into one genus over the years. Albertosaurus was named first, so by convention it is given priority over the name Gorgosaurus, which is sometimes considered its junior synonym. William Diller Matthew and Barnum Brown doubted the distinction of the two genera as early as 1922. Gorgosaurus libratus was formally reassigned to Albertosaurus (as Albertosaurus libratus) by Dale Russell in 1970, and many subsequent authors followed his lead. Combining the two greatly expands the geographical and chronological range of the genus Albertosaurus. Other experts maintain the two genera as separate. Canadian paleontologist Phil Currie claims there are as many anatomical differences between Albertosaurus and Gorgosaurus as there are between Daspletosaurus and Tyrannosaurus, which are almost always kept separate. He also notes that undescribed tyrannosaurids discovered in Alaska, New Mexico and elsewhere in North America may help clarify the situation.
Gorgosaurus libratus was first described by Lawrence Lambe in 1914. Its name is derived from the Greek γοργος/gorgos ("fierce" or "terrible") and σαυρος/saurus ("lizard"). The type species is G. libratus; the specific epithet "balanced" is the past participle of the Latin verb librare, meaning "to balance".
The holotype of Gorgosaurus libratus (NMC 2120) is a nearly complete skeleton associated with a skull, discovered in 1913 by Charles M. Sternberg. This specimen was the first tyrannosaurid found with a complete hand. It was found in the Dinosaur Park Formation of Alberta and is housed in the Canadian Museum of Nature in Ottawa. Prospectors from the American Museum of Natural History in New York City were active along the Red Deer River in Alberta at the same time, collecting hundreds of spectacular dinosaur specimens, including four complete G. libratus skulls, three of which were associated with skeletons. Matthew and Brown described four of these specimens in 1923.
Matthew and Brown also described a fifth skeleton (AMNH 5664), which Charles H. Sternberg had collected in 1917 and sold to their museum. It was smaller than other Gorgosaurus specimens, with a lower, lighter skull and more elongate limb proportions. Many sutures between bones were unfused in this specimen as well. Matthew and Brown noted that these features were characteristic of juvenile tyrannosaurids, but still described it as the holotype of a new species, G. sternbergi. Today's paleontologists regard this specimen as a juvenile G. libratus. Dozens of other specimens have been excavated from the Dinosaur Park Formation and are housed in museums across the United States and Canada. G. libratus is the best-represented tyrannosaurid in the fossil record, known from a virtually complete growth series.
In 1856, Joseph Leidy described two tyrannosaurid premaxillary teeth from Montana. Although there was no indication of what the animal looked like, the teeth were large and robust, and Leidy gave them the name Deinodon. Matthew and Brown commented in 1922 that these teeth were indistinguishable from those of Gorgosaurus, but in the absence of skeletal remains of Deinodon, opted not to synonymize the two genera. Although Deinodon teeth are very similar to those of Gorgosaurus, tyrannosaurid teeth are extremely uniform, so it cannot be said for certain which animal they belonged to. Deinodon is regarded as a nomen dubium today. Several tyrannosaurid skeletons from the Judith River Formation of Montana probably belong to Gorgosaurus, although it remains uncertain whether they belong to G. libratus or a new species. One specimen from Montana (TCMI 2001.89.1), housed in the Children's Museum of Indianapolis, shows evidence of severe pathologies, including healed leg, rib, and vertebral fractures, osteomyelitis (infection) at the tip of the lower jaw resulting in permanent tooth loss, and possibly a brain tumor.
Several species were incorrectly assigned to Gorgosaurus in the twentieth century. A complete skull of a small tyrannosaurid (CMNH 7541), found in the younger, late Maastrichtian-age Hell Creek Formation of Montana, was named Gorgosaurus lancensis by Charles Whitney Gilmore in 1946. This specimen was renamed Nanotyrannus by Bob Bakker and colleagues in 1988. Today, most paleontologists recognize Nanotyrannus as a juvenile Tyrannosaurus rex.Similarly, Evgeny Maleev created the names Gorgosaurus lancinator and Gorgosaurus novojilovi for two small tyrannosaurid specimens (PIN 553-1 and PIN 552-2) from the Nemegt Formation of Mongolia in 1955. Ken Carpenter renamed the smaller specimen Maleevosaurus novojilovi in 1992, but both are now considered juveniles of Tarbosaurus bataar.
In the Dinosaur Park Formation, Gorgosaurus lived alongside a rarer species of the tyrannosaurine Daspletosaurus. This is one of the few examples of two tyrannosaur genera coexisting. Similar-sized predators in modern predator guilds are separated into different ecological niches by anatomical, behavioral or geographical differences that limit competition. Niche differentiation between the Dinosaur Park tyrannosaurids is not well-understood. In 1970, Dale Russell hypothesized the more common Gorgosaurus actively hunted fleet-footed hadrosaurs, while the rarer and more troublesome ceratopsians and ankylosaurians (horned and heavily armoured dinosaurs) were left to the more heavy-built Daspletosaurus. However, a specimen of Daspletosaurus (OTM 200) from the contemporaneous Two Medicine Formation of Montana preserves the digested remains of a juvenile hadrosaur in its gut region, and another bonebed contains the remains of three Daspletosaurus along with the remains of at least five hadrosaurs.
Unlike some other groups of dinosaurs, neither genus was more common at higher or lower elevations than the other. However, Gorgosaurus appears more common in northern formations like the Dinosaur Park, with species of Daspletosaurus more abundant to the south. The same pattern is seen in other groups of dinosaurs. Chasmosaurine ceratopsians and hadrosaurine hadrosaurs are also more common in the Two Medicine Formation of Montana and in southwestern North America during the Campanian, while centrosaurine and lambeosaurines dominate in northern latitudes. Holtz has suggested this pattern indicates shared ecological preferences between tyrannosaurines, chasmosaurines and hadrosaurines. At the end of the later Maastrichtian stage, tyrannosaurines like Tyrannosaurus rex, hadrosaurines like Edmontosaurus and chasmosaurines like Triceratops were widespread throughout western North America, while albertosaurines and centrosaurines went extinct, and lambeosaurines were rare.
Based on Erickson et al. 2004.Gregory Erickson and colleagues have studied the growth and life history of tyrannosaurids using bone histology, which can determine the age of a specimen when it died. A growth curve can be developed when the ages of various individuals are plotted against their sizes on a graph. Tyrannosaurids grew throughout their lives, but underwent tremendous growth spurts for about four years, after an extended juvenile phase. Sexual maturity may have ended this rapid growth phase, after which growth slowed down considerably in adult animals. Examining five Gorgosaurus specimens of various sizes, Erickson calculated a maximum growth rate of about 110 kilograms (50 lb) during the rapid growth phase, slower than in tyrannosaurines like Daspletosaurus and Tyrannosaurus, but comparable to Albertosaurus.
Gorgosaurus spent as much as half its life in the juvenile phase before ballooning up to near-maximum size in only a few years. This, along with the complete lack of predators intermediate in size between huge adult tyrannosaurids and other small theropods, suggests these niches may have been filled by juvenile tyrannosaurids. This is seen in modern Komodo dragons, where hatchlings start off as tree-dwelling insectivores and slowly mature into massive apex predators capable of taking down large vertebrates. Other tyrannosaurids, including Albertosaurus, have been found in aggregations that some have suggested to represent mixed-age packs, but there is no evidence of gregarious behavior in Gorgosaurus.
All known specimens of Gorgosaurus libratus have been recovered from the Dinosaur Park Formation in Alberta. This formation dates to the middle of the Campanian, between 76.5 and 74.8 million years ago. At this time, the area was a coastal plain along the western edge of the Western Interior Seaway, which divided North America in half. The Laramide Orogeny had begun uplifting the Rocky Mountains to the west, from which flowed great rivers that deposited eroded sediment in vast floodplains along the coast. The climate was subtropical with marked seasonality, and periodic droughts sometimes resulted in massive mortality among the great herds of dinosaurs, as represented in the numerous bonebed deposits preserved in the Dinosaur Park Formation. Conifers formed the forest canopy, while the understory plants consisted of ferns, tree ferns and angiosperms.Around 73 million years ago, the seaway began to expand, transgressing into areas formerly above sea level and drowning the Dinosaur Park ecosystem. This transgression, called the Bearpaw Sea, is recorded by the marine sediments of the massive Bearpaw Shale.
The Dinosaur Park Formation preserves a great wealth of vertebrate fossils. A wide variety of fish swam the rivers and estuaries, including gars, sturgeons, sharks and rays, among others. Frogs, salamanders, turtles, crocodilians and champsosaurs also dwelled in the aquatic habitats. Azhdarchid pterosaurs and neornithine birds like Apatornis flew overhead, while the enantiornithine bird Avisaurus lived on the ground alongside multituberculate, marsupial and placental mammals. A number of species of terrestrial lizards were also present, including whiptails, skinks, monitors and alligator lizards. Dinosaur fossils in particular are found with unrivaled abundance and diversity. Huge herds of ceratopsids roamed the floodplains alongside equally large groups of hadrosaurine and lambeosaurine hadrosaurs. Other herbivorous groups like ornithomimids, therizinosaurs, pachycephalosaurs, small ornithopods, nodosaurids and ankylosaurids were also represented. Small predatory dinosaurs like oviraptorosaurs, troodonts and dromaeosaurs hunted smaller prey than the huge tyrannosaurids, Daspletosaurus and Gorgosaurus, which were two orders of magnitude larger in mass. Intervening predatory niches may have been filled by young tyrannosaurids.