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Tataouinea (rebbachisaurid sauropod from Tunisia) osteological description and environment

Ben Creisler

New in PLoS ONE:

Federico Fanti, Andrea Cau, Luigi Cantelli, Mohsen Hassine & Marco
Auditore  (2015)
New Information on Tataouinea hannibalis from the Early Cretaceous of
Tunisia and Implications for the Tempo and Mode of Rebbachisaurid
Sauropod Evolution.
PLoS ONE 10(4): e0123475.

The rebbachisaurid sauropod Tataouinea hannibalis represents the first
articulated dinosaur skeleton from Tunisia and one of the best
preserved in northern Africa. The type specimen was collected from the
lower Albian, fluvio-estuarine deposits of the Ain el Guettar
Formation (southern Tunisia). We present detailed analyses on the
sedimentology and facies distribution at the main quarry and a
revision of the vertebrate fauna associated with the skeleton. Data
provide information on a complex ecosystem dominated by crocodilian
and other brackish water taxa. Taphonomic interpretations indicate a
multi-event, pre-burial history with a combination of rapid
segregation in high sediment supply conditions and partial subaerial
exposure of the carcass. After the collection in 2011 of the
articulated sacrum and proximalmost caudal vertebrae, all showing a
complex pattern of pneumatization, newly discovered material of the
type specimen allows a detailed osteological description of
Tataouinea. The sacrum, the complete and articulated caudal vertebrae
1–17, both ilia and ischia display asymmetrical pneumatization, with
the left side of vertebrae and the left ischium showing a more
extensive invasion by pneumatic features than their right
counterparts. A pneumatic hiatus is present in caudal centra 7 to 13,
whereas caudal centra 14–16 are pneumatised by shallow fossae.
Bayesian inference analyses integrating morphological, stratigraphic
and paleogeographic data support a flagellicaudatan-rebbachisaurid
divergence at about 163 Ma and a South American ancestral range for
rebbachisaurids. Results presented here suggest an exclusively South
American Limaysaurinae and a more widely distributed Rebbachisaurinae
lineage, the latter including the South American taxon Katepensaurus
and a clade including African and European taxa, with Tataouinea as
sister taxon of Rebbachisaurus. This scenario would indicate that
South America was not affected by the end-Jurassic extinction of
diplodocoids, and was most likely the centre of the rapid radiation of
rebbachisaurids to Africa and Europe between 135 and 130 Ma.