New Information on Tataouinea hannibalis from the Early Cretaceous of Tunisia and Implications for the Tempo and Mode of Rebbachisaurid Sauropod Evolution.

Federico Fanti,Andrea Cau,Luigi Cantelli,Mohsen Hassine,Marco Auditore,Peter Dodson

doi:10.1371/journal.pone.0123475

Federico Fanti, Andrea Cau + Show 4 more

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https://doi.org/10.1371/journal.pone.0123475

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Abstract

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.

Highlights

The partial skeleton of a rebbachisaurid sauropod was discovered in the fall of 2011 by Mr A
Acquired skeletal elements of the type specimen of Tataouinea hannibalis shows that some pneumatic features previously considered exclusive of diplodocids among diplodocoids were present in some rebbachisaurids
In this paper we present a detailed description of the osteology of the type specimen of Tataouinea hannibalis, including newly acquired material

Summary

Introduction

The partial skeleton of a rebbachisaurid sauropod was discovered in the fall of 2011 by Mr A. A first excavation carried out in collaboration with the Office National des Mines (ONM) resulted in the acquisition of the sacrum and the first five caudal vertebrae, that were transported to the Musée de l’Office National des Mines in Tunis. These elements were severely vandalized after their transportation to the capital city: the unstable political situation of the recent years resulted in terrible damages at the cultural heritage of this country, including paleontological specimens. A new field expedition in the spring of 2013 led to the collection of the fully articulated rest of the tail (caudal vertebrae 6–17) as well as further sedimentological and paleontological investigations at the El Mra locality

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