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OSTAFRIKASAURUS

a meat and fish-eating spinosaurid theropod dinosaur from the Late Jurassic of Tanzania.
Pronunciation: os-TAF-rih-kuh-SOR-us
Meaning: Ostafrika lizard (see etymology)
Author/s: Buffetaut (2012)
Synonyms: None known
First Discovery: Tendaguru, Tanzania
Chart Position: 649

Ostafrikasaurus crassiserratus

During the earliest part of the 1900s, Werner Janensch and his field crew amassed a collection of 230 theropod teeth from three "saurian beds" in the Late Jurassic dinosaur-bearing Tendaguru area of what we now know as Tanzania, but they weren't attached to jawbones, so classification was always going to be fraught with uncertainty.

By 1925, Janensch had eyeballed nine of the most grooved and largely-serrated teeth, grouped them into five "types" A to E, and tentatively coined Labrosaurus (?) stechowi to house them, based mainly on their similarity to a single tooth from North America's Morrison Formation that Marsh had named as a separate species of his Labrosaurus, Labrosaurus sulcatus, in 1896.

Since then, Marsh's Labrosaurus has been sunk as a synonym of Allosaurus, and Labrosaurus sulcatus and Labrosaurus stechowi were both assigned to Ceratosaurus sp. by Madsen and Welles in 2000. But one African tooth in particular has continued to drum up interest, with Denver Fowler (2008) suggesting it belonged to a critter somewhere between ceratosaurs and spinosaurids, and Azzurra Cillari (2010, unpublished Ph.D thesis) concluding it was closest to spinosaurids proper.

Ostafrikasaurus is based on this tooth, which Buffetaut confirmed as the property of a hitherto unknown species of spinosaurid in 2012 after comparing it to the teeth of baronychines such as Baryonyx. Being Jurassic in age it's by far the oldest known spinosaurid and illuminates the early history of these elusive, assumed fish hunters, particularly their dental evolution which seems to involve a reduction of serration coarseness (denticle size) from Ostafrikasaurus with denticles are as large as those on the teeth of "normal" theropods of similar size, to the much smaller denticles of Baryonyx, the indistinct serrations of Siamosaurus and finally the serration-lacking Spinosaurus, perhaps as an adaptation to changes in diet. That said, there's only so much info you can squeeze from a single tooth and until one turns up sprouting from a crocodile-like snout rumours will persist that Ostafrikasaurus is actually an African version of Ceratosaurus, perhaps Ceratosaurus (?) roechlingi which Janensch also coined in 1925 for remains from the same area.
(Ostafrika lizard with thickly-serrated teeth)Etymology
Ostafrikasaurus is derived from "Deutsch-Ostafrika" ("German East Africa", a German colony in East Africa where its remains were found) and the Greek "sauros" (lizard).
The species epithet, crassiserratus, is derived from the Latin "crassus" (thick) and "serratus" (serrated) in reference to the large serrations (denticles, 2-4 per mm) along the edge of the holotype tooth.
Discovery
The first remains of Ostafrikasaurus were discovered in the Upper Dinosaur Member of the Tendaguru Formation, southeastern Tanzania sometime between 1909 and 1913. The holotype (MB R 1084 — Janensch's "Typus A") is a single tooth. A second tooth (BM.R. 1091 — Janensch's "Typus D") was also assigned here but it was discovered in the Middle Dinosaur Member and may not actually belong.
Estimations
Timeline:
Era: Mesozoic
Epoch: Late Jurassic
Stage: Tithonian
Age range: 150-145 mya
Stats:
Est. max. length: ?
Est. max. hip height: ?
Est. max. weight: ?
Diet: Carnivore
Family Tree:
Dinosauria
Saurischia
Theropoda
Tetanurae
Megalosauroidea
Spinosauridae
Ostafrikasaurus
crassiserratus
References
• Janensch, W. (1925) "Die Coelurosaurier und Theropoden der Tendaguru-Schichten Deutsch-Ostafrikas [The coelurosaurs and theropods of the Tendaguru Formation of German East Africa]".
• Maier, G. (2003) "African Dinosaurs Unearthed: The Tendaguru Expeditions ". /uk.
• Cillari, A. (2010) "Teeth of Theropoda (Dinosauria, Saurischia): morphology, function and classification".
• Buffetaut, Eric (2012) "An early spinosaurid dinosaur from the Late Jurassic of Tendaguru (Tanzania) and the evolution of the spinosaurid dentition".
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To cite this page:
Atkinson, L. "OSTAFRIKASAURUS :: from DinoChecker's dinosaur archive".
›. Web access: 25th Sep 2017.
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