page_title: Sauropoda
section_title: Herding and parental care
hierarchical_section_title: Sauropoda / Palaeobiology / Herding and parental care
caption_attribution_description: Juvenile Sauropod (Toni, specimen SMA 0009) skeleton at Royal Ontario Museum, Toronto, Canada.
context_page_description: Sauropoda, or the sauropods, are a clade of saurischian dinosaurs. They had very long necks, long tails, small heads, and four thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land. Well-known genera include Brachiosaurus, Diplodocus, Apatosaurus, Brontosaurus, and Mamenchisaurus.
  The oldest known unequivocal sauropod dinosaurs are known from the Early Jurassic. Isanosaurus and Antetonitrus were originally described as Triassic sauropods, but their age, and in the case of Antetonitrus also its sauropod status, were subsequently questioned. Sauropod-like sauropodomorph tracks from the Fleming Fjord Formation might, however, indicate the occurrence of the group in the Late Triassic. By the Late Jurassic, sauropods had become widespread. By the Late Cretaceous, those groups had mainly been replaced by the titanosaurs, which had a near-global distribution. However, as with all other non-avian dinosaurs alive at the time, the titanosaurs died out in the Cretaceous–Paleogene extinction event. Fossilised remains of sauropods have been found on every continent, including Antarctica.
context_section_description: Many lines of fossil evidence, from both bone beds and trackways, indicate that sauropods were gregarious animals that formed herds. However, the makeup of the herds varied between species. Some bone beds, for example a site from the Middle Jurassic of Argentina, appear to show herds made up of individuals of various age groups, mixing juveniles and adults. However, a number of other fossil sites and trackways indicate that many sauropod species travelled in herds segregated by age, with juveniles forming herds separate from adults. Such segregated herding strategies have been found in species such as Alamosaurus, Bellusaurus and some diplodocids.
  In a review of the evidence for various herd types, Myers and Fiorillo attempted to explain why sauropods appear to have often formed segregated herds. Studies of microscopic tooth wear show that juvenile sauropods had diets that differed from their adult counterparts, so herding together would not have been as productive as herding separately, where individual herd members could forage in a coordinated way. The vast size difference between juveniles and adults may also have played a part in the different feeding and herding strategies.
  Since the segregation of juveniles and adults must have taken place soon after hatching, and combined with the fact that sauropod hatchlings were most likely precocial, Myers and Fiorillo concluded that species with age-segregated herds would not have exhibited much parental care. On the other hand, scientists who have studied age-mixed sauropod herds suggested that these species may have cared for their young for an extended period of time before the young reached adulthood. A 2014 study suggested that the time from laying the egg to the time of the hatching was likely to have been between 65 and 82 days. Exactly how segregated versus age-mixed herding varied across different groups of sauropods is unknown. Further examples of gregarious behavior will need to be discovered from more sauropod species to begin detecting possible patterns of distribution.
caption: Cast of Toni, a juvenile diplodocid
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