page_title: Spinophorosaurus
section_title: Skull
hierarchical_section_title: Spinophorosaurus / Description / Skull
caption_attribution_description: Spinophorosaurus nigerensis GCP-CV-4229 (holotype). (A–C)— Braincase in dorsal (A), caudal (B), and left lateral (C) views. (D, E)— Right quadrate and pterygoid in lateral (D) and medial (E) views. (F, G)— Dorsal end of right quadrate in lateral (F) and caudal (G) views. Scale bars  = 10 cm (A–C), 5 cm (D, E), and 2 cm (F, G).
context_page_description: Spinophorosaurus is a genus of sauropod dinosaur that lived in what is now Niger during the Middle Jurassic period. The first two specimens were excavated in the 2000s by German and Spanish teams under difficult conditions. The skeletons were brought to Europe and digitally replicated, making Spinophorosaurus the first sauropod to have its skeleton 3D printed, and were to be returned to Niger in the future. Together, the two specimens represented most of the skeleton of the genus, and one of the most completely known basal sauropods of its time and place. The first skeleton was made the holotype specimen of the new genus and species Spinophorosaurus nigerensis in 2009; the generic name refers to what was initially thought to be spiked osteoderms, and the specific name refers to where it was found. A juvenile sauropod from the same area was later assigned to the genus.
  The subadult holotype specimen is estimated to have been around 13 m in length, whereas the paratype was about 14 m long. The shoulder height reached by these individuals was estimated at around 4 m, and the weight at about 7 metric tons.
context_section_description: The frontal bones of the skull roof were fused in the midline, unlike the other sutures of the skull. Between the frontals was a small pineal foramen, about 10 mm (0.4 in) in front of the suture between the frontal and the parietal bones. The rear margin of the skull had an open postparietal notch, a feature otherwise only known in dicraeosaurids and Abrosaurus. A notch following the midline at the front of the conjoined frontal bones indicates there might have been a prong extending from each nasal bone to between the frontals, as may have been the case for Nigersaurus but is unusual among sauropods in general. The upper temporal fenestrae, a pair of major openings on the skull roof, were four times broader than long; such broadened fenestrae were typical for Shunosaurus and more derived (or "advanced") sauropods. The occipital condyle at the back of the skull was concave on the sides, like in Shunosaurus. The basal tubera (a pair of extensions on the underside of the skull base that served as muscle attachments) were enlarged and were directed to the sides, unique among known sauropods. The quadrate did not have a concavity on the hind-side, an ancestral condition otherwise only known in Tazoudasaurus among sauropods. The spatulate (spoon shaped) teeth were unique in possessing enlarged, spaced denticles around the top of the crown, with a higher count of denticles on the front edge of the crown.
  The braincase of Spinophorosaurus was broad and short from front to back, moderately deep, and of relatively large size overall. It differed significantly from those of other Jurassic sauropods, possibly except Atlasaurus. They shared a basipterygoid process on their basisphenoids that were similar in being directed strongly backwards. A CT endocast of the holotype's brain cavity showed it was similar to most sauropods in having pontine and cerebral flexures that were well marked, a pituitary fossa that was large and oblong, and in that the structure of the brain was obscured by spaces that housed relatively thick meninges as well as by dural venous sinuses. The labyrinth of the inner ear was characteristic in having long and slender semicircular canals, similar to those of Massospondylus and Giraffatitan. Its neuroanatomy was in some ways intermediate between that of basal (or "primitive") sauropodomorphs and the more derived neosauropods.
caption: Skull elements of the holotype: braincase (A–C), right quadrate and pterygoid bones (D, E), and upper end of the right quadrate (F, G)
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