The fauna of the Horseshoe Canyon Formation is well-known, as vertebrate fossils, including those of dinosaurs, are very common. Sharks, rays, sturgeons, bowfins, gars, and the gar-like Aspidorhynchus made up the fish fauna. Mammals included multituberculates and the marsupial Didelphodon. The saltwater plesiosaur Leurospondylus has been found in marine sediments in the Horseshoe Canyon, while freshwater environments were populated by turtles, Champsosaurus, and crocodilians like Leidyosuchus and Stangerochampsa. Dinosaurs dominate the fauna, especially hadrosaurs, which make up half of all dinosaurs known. These include the genera Edmontosaurus, Saurolophus, and Hypacrosaurus. Ceratopsians and ornithomimids were also very common, together making up another third of the known fauna. Along with much rarer ankylosaurians and pachycephalosaurs, all of these animals would have been prey for a diverse array of carnivorous theropods, including troodontids, dromaeosaurids, and caenagnathids. Intermingled with the Albertosaurus remains of the Dry Island bonebed, the bones of the small theropod Albertonykus were found. Adult Albertosaurus were the apex predators in their environment, with intermediate niches possibly filled by juvenile Albertosaurus''.
the fauna of tHe hOrsEshoe CAnyoN FormATiON is well-known, as VeRtEBraTe fossils, iNCLuDIng thOSe oF diNOsAurs, are VeRY COmmon. sharKs, rayS, stURGEONS, bOwFins, GaRs, And thE gar-LiKe aSpidOrhyncHus madE up THE fIsH FauNA. mammals InCluDed MuLtiTuberCulATes and The mArsupial dIDElphodoN. thE saLtwAtEr pleSiosauR leuRosponDyLuS HaS bEen fouNd In marine sedimeNTs in The horSEshOe caNyon, whILe FReshwaTER enviRoNMeNTS were PoPUlated By turtLES, champsOSaurus, AnD cRocOdIlianS Like LeIdyosUchuS ANd StAnGeRocHampSA. DiNosaURS dominatE tHe faunA, espEciaLLy haDrosAurS, wHich makE Up half of aLl dInosaurS known. ThesE Include THe GenEra EdmonToSAuruS, SauRoLophuS, and hYpAcrosaURus. ceraTopsians aNd orNithomimiDS were alSo very cOmmon, togETHer MakINg up anoTher ThiRd oF tHe knOwN Fauna. along With Much rarer ANkYlosaurIAns And pachYCePhalosaurs, AlL Of These animAls wOUld hAVe BeeN pREy fOr a DiVErse arraY of CarnIvorOus TheropoDs, iNCLUDing tROOdontIds, drOmaeosAUrids, anD caEnAgnAThids. intErMIngled With the alBeRTosauRUs remainS of the dRy isLAnd bonebed, the boneS OF tHe smalL therOpod alBeRtonykUS WERE fOuNd. adUlt albERToSauruS wERe thE APEx PredAtors in their EnviRoNmeNt, With intERmediaTE niCHES possiBly fiLLed By juveniLe albertOSauRus''.