vertebrae and they may have been caused by environmental factors, such as the way in which these hadrosaurs interacted with their environments, making them more susceptible to get cancer, or, through genetic inheritance. Meaning that they carried cancer-promoting genes. In 2007, Rothschild and Tanke reported the increased presence of osteochondrosis in hadrosaurs. Though they examined several other dinosaur groups, this disease appears to be particularly common in hadrosaurs, which were rapidly growing animals. The analysis was focused in pedal bones since osteochondrosis has not been reported from manual elements. Specimens of Edmontosaurus and Hypacrosaurus were more affected by osteochondrosis (5% and 2% of occurrence, respectively) but in hadrosauroids like Gilmoreosaurus and Bactrosaurus the disease was rather absent, likely due to the relatively low sample and therefore the presence of osteochondrosis in all hadrosaurs can not be discarded. These findings indicate that the skeleton of dinosaurs was primarily formed by cartilage. Paleoenvironment Gilmoreosaurus is known from the Late Cretaceous Iren Dabasu Formation, which has been dated back to the Cenomanian stage around 95.8 ± 6.2 million years ago. During its times, the formation was dominated by braided floodplains and large meanders with some connections to the oceans. Extensive vegetation that maintained a great variety of herbivorous dinosaurs was also present on the formation as seen on the multiple skeletons of hadrosauroids, the prominent paleosol and the numerous palynological occurrences. Hadrosauroid remains are very common across the formation, which reflect these animals as wide-ranging in both time and space. Bactrosaurus is another hadrosauroid from the formation, known from multiple specimens like Gilmoreosaurus. Ponderous herbivorous animals like Gilmoreosaurus and Bactrosaurus may have been medium to low-level browsers. Fellow herbivores include the therizinosaurids Erliansaurus and Neimongosaurus. Gigantoraptor, a large oviraptorosaur from the formation, may have been an omnivore as suggested by the mandibular morphology or at least, a partial high-browser. The geographic range of Gilmoreosaurus overlapped with the fast-running tyrannosauroid Alectrosaurus, likely being the prey item for this theropod. See also Timeline of hadrosaur research References Hadrosaurs Cenomanian life Late Cretaceous dinosaurs of Asia Cretaceous Mongolia Fossils of Mongolia Fossil taxa described in 1979 Ornithischian genera