| Dicraeosaurus | |
|---|---|
 | |
| Dicraeosaurus skeleton | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Superfamily: | †Diplodocoidea |
| Family: | †Dicraeosauridae |
| Subfamily: | †Dicraeosaurinae Janensch, 1929 |
| Genus: | †Dicraeosaurus |
| Type species | |
| †Dicraeosaurus hansemanni | |
| Species | |
| |
Dicraeosaurus (Gr.δικραιος,dikraios "bifurcated, double-headed" + Gr.σαυρος,sauros "lizard") is agenus ofdiplodocoidsauropoddinosaur that lived in what is nowLindi Region,Tanzania during the lateJurassic period. The genus was named for the neural spines on the back of its neck. The first fossil was described by paleontologistWerner Janensch in 1914.
Unlike most diplodocoids,Dicraeosaurus had a comparatively large head with a relatively short and wide neck. The neck contained 12 unusually shortvertebrae, likely indicating a low-level browser of vegetation no more than 3 metres (9.8 ft) off the ground.[2]Dicraeosaurus also lacked the "whiplash" tail tip typical of diplodocoids. It was smaller than many other diplodocoids, at only 14–15 metres (46–49 ft) in length and 5–6 metric tons (5.5–6.6 short tons), though this still makes it among the larger known members of the family Dicraeosauridae.[3][4] The genus is notable for the rather tall neural spines protruding from its vertebrae, which it is named for. They were not straight as in some members of the family, instead forming a rough "Y" shape. These spines likely provided muscle attachment points.[5]
In 2008, Lehman and Woodward estimated the minimum and maximum ages of a mature adultDicraeosaurus at 11 to 22 years, and the average growth rate to be 227–455 kg (500–1,003 lb) per year.[6]
Dicraeosaurus was a mid-sized herbivore for its ecosystem, found in theTendaguru Formation ofTanzania, which dates to the Late Jurassic. The rocks also yield fossils ofGiraffatitan andKentrosaurus. As there was a distinct difference in size between these dinosaurs, they would probably have browsed on vegetation at different levels and therefore competition between them was likely rare.[5]
