page_title: Apatosaurus
section_title: Lifestyle
hierarchical_section_title: Apatosaurus / Lifestyle
caption_attribution_description: Infant Apatosaurus dinosaur tracks from the Jurassic of Colorado, USA (public display, Morrison Natural History Museum, Morrison, Colorado, USA). This rock is a channel sandstone, deposited in an ancient river or stream. The sandstone block has dinosaur bones in it, plus some remarkable dinosaur tracks on its top surface. The large depression at the top left part of the block (below the head of the model) is an adult sauropod dinosaur footprint, attributed to Apatosaurus. The row of shadowed depressions below the adult track is a set of infant Apatosaurus footprints. Claw impressions are present. No tail drag marks are present (dinosaur tail traces are very rare everywhere on Earth - dinosaurs didn't want to drag their tails, because friction would slow them down, plus it would cause pain). Stratigraphy: Morrison Formation, Upper Jurassic Locality: Quarry 5, Dinosaur Ridge, west of Denver, north-central Colorado, USA Trace fossils are any indirect evidence of ancient life. They refer to features in rocks that do not represent parts of the body of a once-living organism. Traces include footprints, tracks, trails, burrows, borings, and bitemarks. Body fossils provide information about the morphology of ancient organisms, while trace fossils provide information about the behavior of ancient life forms. Interpreting trace fossils and determination of the identity of a trace maker can be straightforward (for example, a dinosaur footprint represents walking behavior) or not. Sediments that have trace fossils are said to be bioturbated. Burrowed textures in sedimentary rocks are referred to as bioturbation. Trace fossils have scientific names assigned to them, in the same style &amp; manner as living organisms or body fossils.
context_page_description: Apatosaurus is a sauropod dinosaur which lived in the Upper Jurassic period. It is in the same family as Diplodocus. Brontosaurus was once thought a later name for Apatosaurus, but is now proved to be a separate genus.
  Apatosaurus grew as big as 21 meters long, 4.5 meters tall at the hip, and weighed up to 23 metric tons. It ate plants. Its bones have been found in Wyoming, Colorado, Oklahoma, and Utah.
  When it was first found, scientists thought that Apatosaurus lived partly under water, since it could not hold its own weight on dry land. Now they think it lived on dry land, probably in herds.
  The cervical vertebrae were less elongated and more solid than those of Diplodocus. The bones of the leg were much stockier, implying a more robust animal. The tail was held above the ground during normal locomotion. Like most sauropods, Apatosaurus had only a single large claw on each forelimb, with the first three toes on the hind limb possessing claws.
  There are at least two species of Apatosaurus:
  A. ajax was discovered by Othniel Charles Marsh in 1877.
  A. louisae was discovered by William Holland in 1915.
context_section_description: It was believed throughout the 19th and early 20th centuries that sauropods like Apatosaurus were too massive to support their own weight on dry land. It was theorized that they lived partly submerged in water, perhaps in swamps. Recent findings do not support this. Sauropods are now thought to have been fully terrestrial animals. A study of diplodocid snouts showed that the square snout, large proportion of pits, and fine, subparallel scratches of the teeth of Apatosaurus suggests it was a ground-height, nonselective browser. It may have eaten ferns, cycads, seed ferns, horsetails, and algae.
  Important issues like heat control, metabolic rate and respiration are still unclear. Some scientists state that the heart would have had trouble sustaining sufficient blood pressure to oxygenate the brain. Others suggest that the near-horizontal posture of the head and neck would have eliminated the problem of supplying blood to the brain because it would not have been elevated.
  James Farlow calculates that an Apatosaurus-sized dinosaur about 35 t (34 long tons; 39 short tons) would have had 5.7 t (5.6 long tons; 6.3 short tons) of fermentation contents (food being digested). "The heat of fermentation may have been a significant source of thermoregulatory heat for these reptiles".
caption: Tracks of a juvenile.
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