Haplocanthosaurus
| Key | Value |
|---|---|
| Name Meaning | “simple-spined lizard” |
| Location | United States (Colorado, Utah, Wyoming) |
| Time Period | c. 155 million years ago (Late Jurassic) |
| Length | 47 ft (14.5 m) |
| Weight | 14 tons (12,700 kg) |
| Locomotion | Quadruped |
| Diet | Herbivore |
| Described | 1903 (Hatcher) |
| Geological Formation(s) | Morrison |
| Valid Species | Haplocanthosaurus priscus (type), Haplocanthosaurus delfsi |
Phylogeny: Dinosauria > Saurischia > Sauropodomorpha > Plateosauria > Massopoda > Sauropodiformes > Sauropoda > Gravisauria > Eusauropoda > Neosauropoda > Diplodocoidea > Haplocanthosauridae
Overview: Haplocanthosaurus was a medium-sized sauropod, growing to between fourteen and fifteen meters in length. Known fossils of the animal includes most of its neck vertebrae, most of its spine, the upper portion of the tail, pelvic bones, the shoulder, and some limb bones. No skull has been found. The first of these fossils were found in Colorado, in the late 1890’s, forming the basis for its 1903 description, published by fossil hunter John B. Hatcher. Hatcher originally gave it the name Haplocanthus, meaning “simple-spined”, referring to how its vertebral neural spines were less specialized than those of other sauropods Hatcher had studied (though we now know they were fairly typical). The name Haplocanthus would turn out to be occupied by a fish genus, so the similar name of Haplocanthosaurus was quickly selected as a replacement. Additional fossilized remains were found in the 1950’s, used in 1988 to describe a second species within the genus.
All recovered fossils of Haplocanthosaurus come from the famous Morrison Formation, formed in the Late Jurassic. Haplocanthosaurus is specifically known from its deeper layers, so it may’ve lived somewhat earlier than some other Morrison sauropods (of which there are many). It’s probably one of the more obscure sauropods from the formation. Contemporaries may’ve included an early Brontosaurus species, the stegosaur Hesperosaurus, and a species of Allosaurus. These animals are believed to have inhabited a semi-arid, seasonal river basin. Food sources for Haplocanthosaurus may’ve included ferns, cycads, and conifers. The classification of this dinosaur has been a matter of debate for some years. It was originally seen as a basal sauropod closely related to Cetiosaurus, or later as a relative of Brachiosaurus. Most modern studies place Haplocanthosaurus within the superfamily Diplodocoidea, as an early branching member, possibly within its own family.