Dicraeosaurus

Dicraeosaurus Temporal range: Late Jurassic, 155–150 Ma PreЄ Є O S D C P T J K Pg N ↓
Dicraeosaurus skeleton
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Sauropodomorpha
Family:	Dicraeosauridae
Subfamily:	Dicraeosaurinae Janensch, 1929
Genus:	Dicraeosaurus Janensch, 1914
Species
D. hansemanni Janensch, 1914 (type) D. sattleri Janensch, 1914

Dicraeosaurus (Gr. δικραιος, dikraios "bifurcated, double-headed" + Gr. σαυρος, sauros "lizard") is a genus of small diplodocoid sauropod dinosaur. It was named for the spines on the back of the neck. The first fossil was described by paleontologist Werner Janensch in 1914.

Description

Restoration of D. hansemanni

Unlike most diplodocoids, Dicraeosaurus had a large head with a relatively short and wide neck. The neck contained 12 unusually short vertebrae, so it could probably browse vegetation only from ground level to a height of about 3 metres (9.8 ft). It also lacked the whiplash tail that other diplodocids had. It was smaller, at only reached 12 metres (39 ft) in length. It gets its name, which means two-forked lizard, from the spines that came from the vertebrae. They were not straight as in some members of the family. Each one was “Y” shaped, like a fork. These spines also provided muscle attachment points.

Palaeoecology

Dicraeosaurus lived in the Late Jurassic. It was herbivorous; however, it didn’t compete with other dinosaurs for vegetation. Fossils have been discovered in the rocks of Tendaguru Hill in Tanzania. The rocks also yield fossils of Giraffatitan and Kentrosaurus. As there was a distinct difference in size between these animals, they would probably have browsed for vegetation at different levels, allowing them to co-exist without significant competition.

Classification

Dicreosaurids shown to scale

Restoration of the head

The following cladogram follows an analysis by Sereno et al. in 2007.

Diplodocoidea	Diplodocidae Apatosaurus Diplodocus Suuwassea Dicraeosauridae Amargasaurus Brachytrachelopan Dicraeosaurus Rebbachisauridae Histriasaurus Rebbachisaurus Cathartesaura Limaysaurus Zapalasaurus Demandasaurus Nigersaurus

External links

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