Pronunciation: die-KREE-oh-SOR-us
Meaning: Bifurcated lizard
Author/s: Janensch (1914)
Synonyms: None known
First Discovery: Lindi, Tanzania
Discovery Chart Position: #111
Dicraeosaurus hansemanni
Dicraeosaurus is a diplodocoid, but not your run-of-the-mill diplodocoid. It was modestly sized, with a short neck, short whip-less tail and relatively large head, which set it apart from fellow diplodocoids like Diplodocus and Apatosaurus. But its most outstanding features are the forked or Y-shaped spines on its neck vertebrae, all of which slope forwards away from the body, apart from the four closest to the skull, which, weirdly, slope backwards.
The reason for such a design is uncertain but those forked spines, once suspected of supporting a short sail or fatty ridge, most probably anchored pure muscle which would have resulted in an incredibly deep, wide and strong neck. Living alongside the much larger, tree top-hogging Giraffatitan (with its long neck and spatulate teeth) and the much smaller, ground-grazing Kentrosaurus (with its short neck and scallop-edged roughly triangular teeth), the peg-toothed Dicraeosaurus was seemingly built to take advantage of mid-height vegetation so the three could co-exist without eating each other into extinction.
In a monumental instance of foresight, Werner Janensch used Dicraeosaurus to anchor its own family group (Dicraeosauridae) in 1929, which was a brave shout bearing in mind no other members were known at the time. However, the smaller Amargasaurus from Neuquen and the smaller still Brachytrachelopan from Chubut were later assigned here because they both exhibit similar features. Given their Argentine provenance, it may seem strange that the latter pair are the closest relatives of Africa's Dicraeosaurus. But South America was still joined to Africa (along with Antarctica, Madagascar and Australia) as a continent known as Gondwana until the turn of the Early Cretaceous.
The reason for such a design is uncertain but those forked spines, once suspected of supporting a short sail or fatty ridge, most probably anchored pure muscle which would have resulted in an incredibly deep, wide and strong neck. Living alongside the much larger, tree top-hogging Giraffatitan (with its long neck and spatulate teeth) and the much smaller, ground-grazing Kentrosaurus (with its short neck and scallop-edged roughly triangular teeth), the peg-toothed Dicraeosaurus was seemingly built to take advantage of mid-height vegetation so the three could co-exist without eating each other into extinction.
In a monumental instance of foresight, Werner Janensch used Dicraeosaurus to anchor its own family group (Dicraeosauridae) in 1929, which was a brave shout bearing in mind no other members were known at the time. However, the smaller Amargasaurus from Neuquen and the smaller still Brachytrachelopan from Chubut were later assigned here because they both exhibit similar features. Given their Argentine provenance, it may seem strange that the latter pair are the closest relatives of Africa's Dicraeosaurus. But South America was still joined to Africa (along with Antarctica, Madagascar and Australia) as a continent known as Gondwana until the turn of the Early Cretaceous.
Etymology
Dicraeosaurus is derived from the Greek "dikraios" (bifurcated, forked, split) and "sauros" (lizard), which refers to the forked or 'Y'-shaped spines on its vertebrae.
The species epithet, hansemanni, honors expedition sponsor Dr. David von Hansemann.
Discovery
The first fossils of Dicraeosaurus hansemanni were discovered in Tendaguru Quarry M in the "Middle Saurian Bed" of the Tendaguru Formation, Kindope, Lindi Town, 105 km north of Mtara City, Tanzania, by Werner Janensch and Edwin Hennig between 1909 and 1912. The holotype (HMN) is a partial skeleton.
