page_title: Haplocanthosaurus
section_title: Description
hierarchical_section_title: Haplocanthosaurus / Description
caption_attribution_description: Haplocanthosaurus delfsi
context_page_description: Haplocanthosaurus is a genus of intermediate sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period, 155 to 152 million years ago. The type species is H. priscus, and the referred species H. delfsi was discovered by a young college student named Edwin Delfs in Colorado, USA. Haplocanthosaurus specimens have been found in the very lowest layer of the Morrison Formation, along with Hesperosaurus, Brontosaurus yahnahpin, and Allosaurus jimmadseni.
context_section_description: Haplocanthosaurus was one of the smallest sauropods of the Morrison. While some Morrison sauropods could reach lengths of over 20 meters (or over 66 feet), Haplocanthosaurus was smaller, reaching a total length of 14.8 meters (49 feet) and an estimated weight of 12.8 metric tons.
  Haplocanthosaurus is known from many elements, mostly of vertebra. In the middle and cervical caudals of Apatosaurus, Camarasaurus, Cetiosaurus and Haplocanthosaurus, the intraprezygapophyseal lamina is separate from the root of the neural canal by a vertical midline lamina. In the last few caudals and the most cranial dorsals, the lateral edge of the prezygapophyseal lamina becomes widened and roughened. Hatcher (1901) interpreted this as forming the attachment area for the muscles from which the scapular blade was suspended.
  The dorsoventrally elongate oval outlines are characteristic of Haplocanthosaurus with only Camarasaurus also possessing them. The parapophyses remaining as oval facets on the craniolateral margin, and the sacral spines 1-3 fused are also found in both Haplocanthosaurus and Camarasaurus.
  The Cetiosaurus specimen OUMNH J13695 has a low horizontal ridge on each of its lateral surfaces, creating a slightly subhexagonal transverse cross-section, and that feature is also seen on Cetiosauriscus, the anterior caudals of Haplocanthosaurus, and caudals 15-30 of Omeisaurus. Also, the area around the periphery of each articullar face is flattened, creating a ‘bevelled’ appearance, and also occurs in Haplocanthosaurus and Cetiosauriscus.
caption: Restoration of H. delfsi
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