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

Fanti F, Cau A, Cantelli L, Hassine M, Auditore M - PLoS ONE (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, Università di Bologna, Bologna, Italy; Museo Geologico Giovanni Capellini, Alma Mater Studiorum, Università di Bologna, Bologna, Italy.

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.

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BBM palaeogeographyc analysis of Rebbachisauridae.Time-calibrated palaeobiogeography of eusauropods focusing on rebbachisaurids (above) and result of the time-event algorithm test on Rebbachisauridae (below), based on the BBM analysis of the MCCT recovered by Bayesian inference. Values at nodes indicate posterior probability values >0.5. Abbreviations: A, Asia; B, Europe; C, North America; D, Africa; E, South America. Black circles indicate uncertain optimization.
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pone.0123475.g022: BBM palaeogeographyc analysis of Rebbachisauridae.Time-calibrated palaeobiogeography of eusauropods focusing on rebbachisaurids (above) and result of the time-event algorithm test on Rebbachisauridae (below), based on the BBM analysis of the MCCT recovered by Bayesian inference. Values at nodes indicate posterior probability values >0.5. Abbreviations: A, Asia; B, Europe; C, North America; D, Africa; E, South America. Black circles indicate uncertain optimization.

Mentions: The MCCT found shows a topology overall comparable to the results of parsimony analyses (topology shown in Figs 22 and 23). Among non-rebbachisaurid OTUs, the most relevant difference from the parsimony-based analysis was the placement of turiasaurians and Haplocanthosaurus among macronarian neosauropods instead of, respectively, as a basal eusauropod branch and the basalmost diplodocimorphs. Nevertheless, the basal macronarian nodes including the above-mentioned taxa showed low posterior probability values, and should be considered as tentative. Since an evaluation of non-diplodocoid relationships was beyond the aims of our analysis, and given the small sample among non-diplodocoids, these conflicting interpretations between parsimony and Bayesian analyses are not further discussed here (see [65] for a discussion of turiasaurian placement among Eusauropoda). The monophyly of both rebbachisaurid-flagellicaudatan node and Rebbachisauridae was well supported by the model (posterior probability values, pp, of, respectively, 0.84 and 0.96). Although most of the recovered rebbachisaurid nodes show relatively low pp, the topology agrees with the results of the parsimony analysis in placing Histriasaurus and Zapalasaurus as basal rebbachisaurids not members of Khebbashia, in placing Cathartesaura as sister taxon of Limaysaurus, in recovering Rebbachisaurinae with the same inclusiveness found in the implied weighting parsimony analyses (above), with Katepensaurus as basalmost rebbachisaurine, and Nigersaurus as sister taxon of the clade including Demandasaurus, Rebbachisaurus and Tataouinea. The Bayesian and parsimony analyses differ in the placements of Amazonsaurus and Comahuesaurus as basal members of Limaysaurinae in the Bayesian topology. It is noteworthy that the results of a parsimony analysis enforcing Amazonsaurus and Comahuesaurus as basal limaysaurines (as resulted in the Bayesian analysis) produced shortest topologies only four steps longer than the unforced topologies, a step difference not statistically significant (p = 0.12, n = 8) [66], suggesting that these taxa act as “wildcard” OTUs with placement biased by the analytical method followed.


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

Fanti F, Cau A, Cantelli L, Hassine M, Auditore M - PLoS ONE (2015)

BBM palaeogeographyc analysis of Rebbachisauridae.Time-calibrated palaeobiogeography of eusauropods focusing on rebbachisaurids (above) and result of the time-event algorithm test on Rebbachisauridae (below), based on the BBM analysis of the MCCT recovered by Bayesian inference. Values at nodes indicate posterior probability values >0.5. Abbreviations: A, Asia; B, Europe; C, North America; D, Africa; E, South America. Black circles indicate uncertain optimization.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414570&req=5

pone.0123475.g022: BBM palaeogeographyc analysis of Rebbachisauridae.Time-calibrated palaeobiogeography of eusauropods focusing on rebbachisaurids (above) and result of the time-event algorithm test on Rebbachisauridae (below), based on the BBM analysis of the MCCT recovered by Bayesian inference. Values at nodes indicate posterior probability values >0.5. Abbreviations: A, Asia; B, Europe; C, North America; D, Africa; E, South America. Black circles indicate uncertain optimization.
Mentions: The MCCT found shows a topology overall comparable to the results of parsimony analyses (topology shown in Figs 22 and 23). Among non-rebbachisaurid OTUs, the most relevant difference from the parsimony-based analysis was the placement of turiasaurians and Haplocanthosaurus among macronarian neosauropods instead of, respectively, as a basal eusauropod branch and the basalmost diplodocimorphs. Nevertheless, the basal macronarian nodes including the above-mentioned taxa showed low posterior probability values, and should be considered as tentative. Since an evaluation of non-diplodocoid relationships was beyond the aims of our analysis, and given the small sample among non-diplodocoids, these conflicting interpretations between parsimony and Bayesian analyses are not further discussed here (see [65] for a discussion of turiasaurian placement among Eusauropoda). The monophyly of both rebbachisaurid-flagellicaudatan node and Rebbachisauridae was well supported by the model (posterior probability values, pp, of, respectively, 0.84 and 0.96). Although most of the recovered rebbachisaurid nodes show relatively low pp, the topology agrees with the results of the parsimony analysis in placing Histriasaurus and Zapalasaurus as basal rebbachisaurids not members of Khebbashia, in placing Cathartesaura as sister taxon of Limaysaurus, in recovering Rebbachisaurinae with the same inclusiveness found in the implied weighting parsimony analyses (above), with Katepensaurus as basalmost rebbachisaurine, and Nigersaurus as sister taxon of the clade including Demandasaurus, Rebbachisaurus and Tataouinea. The Bayesian and parsimony analyses differ in the placements of Amazonsaurus and Comahuesaurus as basal members of Limaysaurinae in the Bayesian topology. It is noteworthy that the results of a parsimony analysis enforcing Amazonsaurus and Comahuesaurus as basal limaysaurines (as resulted in the Bayesian analysis) produced shortest topologies only four steps longer than the unforced topologies, a step difference not statistically significant (p = 0.12, n = 8) [66], suggesting that these taxa act as “wildcard” OTUs with placement biased by the analytical method followed.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Alma Mater Studiorum, Università di Bologna, Bologna, Italy; Museo Geologico Giovanni Capellini, Alma Mater Studiorum, Università di Bologna, Bologna, Italy.

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.

Show MeSH
Related in: MedlinePlus