page_title: List of dinosaurs of the Morrison Formation
section_title: Diplodocids
hierarchical_section_title: List of dinosaurs of the Morrison Formation / Sauropods / Diplodocids
caption_attribution_description: English: Illustration of the diplodocid Apatosaurus louisae, a species related to A. excelsus (formerly Brontosaurus). The spine placements are speculative based on evidence for small spikes along the backs of diplodocids.
context_page_description: The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock that is found in the western United States, which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone and limestone and is light grey, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
caption: Apatosaurus louisae
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