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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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Caudal vertebra 7 of Tataouinea hannibalis.Vertebra in right lateral (A), proximal (B) and distal (C) views. Scale bar: 10 cm. Abbreviations: col, collapsed area; fo, fossa; hr, hyposphenal ridge; nc, neural canal; pcdl, posterior centrodiapophyseal lamina; podl, postzygodiapophyseal lamina; pz, prezygapophysis; pzdl, prezygodiapophyseal lamina; ri, rib; spof, spinopostzygapophyseal fossa; sprl, spinoprezygapophyseal lamina.
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pone.0123475.g010: Caudal vertebra 7 of Tataouinea hannibalis.Vertebra in right lateral (A), proximal (B) and distal (C) views. Scale bar: 10 cm. Abbreviations: col, collapsed area; fo, fossa; hr, hyposphenal ridge; nc, neural canal; pcdl, posterior centrodiapophyseal lamina; podl, postzygodiapophyseal lamina; pz, prezygapophysis; pzdl, prezygodiapophyseal lamina; ri, rib; spof, spinopostzygapophyseal fossa; sprl, spinoprezygapophyseal lamina.

Mentions: This vertebra is well preserved, lacking only the dorsal half of the neural spine and the lateral end of both ribs (Fig 10). The anterior half of the vertebra has suffered a more intense transversal compression than the posterior part, producing a partial dislocation of the neural arch, that is shifted onto the proximolateral corner of the right side of the centrum. The centrum is slightly taller than long in lateral view, taller than wide proximal view (in part due to transversal compression) and approximately as tall and wide in distal view. The proximal intercentral facet is flat, whereas the distal facet is distinctly concave. The right lateral surface of the centrum is depressed by a large irregular fossa, the depth of which is probably exaggerated by the vertebra deformation. No lateral fossa in present in the left side of the centrum. The ventral surface of the centrum is transversely narrow, sub-rectangular in ventral view, with parallel lateral sides that are projected ventrally delimiting a midline sulcus. The neurocentral suture is obliterated. The neural arch extends above the proximal two thirds of the centrum. The bases of the ribs are placed at the level of the neurocentral suture, and are inclined laterodorsally. Prominent distal centrodiapophyseal laminae bound the depressed dorsodistal surface of the centrum, although this may be a taphonomic artefact. The prezygapophyses are projected proximodorsally well beyond the level of the proximal intercentral surface. The prezygapophyses are widely separated and are not joined by a ventral interprezygapophyseal lamina. The postzygapophyses are placed more dorsally than the prezygapophyses. A prominent hyposphenal ridge joins the ventral base of the postzygapophyses and the dorsodistal margin of the neural canal. The preserved base of the neural spine is placed in the distal end of the neural arch. The neural spine is moderately thick. Both spinoprezygapophyseal and spinopostzygapophyseal laminae are present and well developed. The spinoprezygapophyseal laminae form the sharp lateral margins of the prespinal lamina. The spinopostzygapophyseal laminae bound laterally a deep postspinal fossa, the latter bounded ventrally by the hyposphenal ridge. The prezygodiapophyseal lamina is sharp. The prezygospinodiapophyseal fossae are deep. In the right prezygospinodiapophyseal fossa, an accessory ridge links the middle of the medial margin of the spinodiapophyseal lamina with the floor of the fossa. The prominent postzygodiapophyseal laminae are posteriorly concave and bound the shallow hyposphenal postzygodiapophyseal fossae.


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)

Caudal vertebra 7 of Tataouinea hannibalis.Vertebra in right lateral (A), proximal (B) and distal (C) views. Scale bar: 10 cm. Abbreviations: col, collapsed area; fo, fossa; hr, hyposphenal ridge; nc, neural canal; pcdl, posterior centrodiapophyseal lamina; podl, postzygodiapophyseal lamina; pz, prezygapophysis; pzdl, prezygodiapophyseal lamina; ri, rib; spof, spinopostzygapophyseal fossa; sprl, spinoprezygapophyseal lamina.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123475.g010: Caudal vertebra 7 of Tataouinea hannibalis.Vertebra in right lateral (A), proximal (B) and distal (C) views. Scale bar: 10 cm. Abbreviations: col, collapsed area; fo, fossa; hr, hyposphenal ridge; nc, neural canal; pcdl, posterior centrodiapophyseal lamina; podl, postzygodiapophyseal lamina; pz, prezygapophysis; pzdl, prezygodiapophyseal lamina; ri, rib; spof, spinopostzygapophyseal fossa; sprl, spinoprezygapophyseal lamina.
Mentions: This vertebra is well preserved, lacking only the dorsal half of the neural spine and the lateral end of both ribs (Fig 10). The anterior half of the vertebra has suffered a more intense transversal compression than the posterior part, producing a partial dislocation of the neural arch, that is shifted onto the proximolateral corner of the right side of the centrum. The centrum is slightly taller than long in lateral view, taller than wide proximal view (in part due to transversal compression) and approximately as tall and wide in distal view. The proximal intercentral facet is flat, whereas the distal facet is distinctly concave. The right lateral surface of the centrum is depressed by a large irregular fossa, the depth of which is probably exaggerated by the vertebra deformation. No lateral fossa in present in the left side of the centrum. The ventral surface of the centrum is transversely narrow, sub-rectangular in ventral view, with parallel lateral sides that are projected ventrally delimiting a midline sulcus. The neurocentral suture is obliterated. The neural arch extends above the proximal two thirds of the centrum. The bases of the ribs are placed at the level of the neurocentral suture, and are inclined laterodorsally. Prominent distal centrodiapophyseal laminae bound the depressed dorsodistal surface of the centrum, although this may be a taphonomic artefact. The prezygapophyses are projected proximodorsally well beyond the level of the proximal intercentral surface. The prezygapophyses are widely separated and are not joined by a ventral interprezygapophyseal lamina. The postzygapophyses are placed more dorsally than the prezygapophyses. A prominent hyposphenal ridge joins the ventral base of the postzygapophyses and the dorsodistal margin of the neural canal. The preserved base of the neural spine is placed in the distal end of the neural arch. The neural spine is moderately thick. Both spinoprezygapophyseal and spinopostzygapophyseal laminae are present and well developed. The spinoprezygapophyseal laminae form the sharp lateral margins of the prespinal lamina. The spinopostzygapophyseal laminae bound laterally a deep postspinal fossa, the latter bounded ventrally by the hyposphenal ridge. The prezygodiapophyseal lamina is sharp. The prezygospinodiapophyseal fossae are deep. In the right prezygospinodiapophyseal fossa, an accessory ridge links the middle of the medial margin of the spinodiapophyseal lamina with the floor of the fossa. The prominent postzygodiapophyseal laminae are posteriorly concave and bound the shallow hyposphenal postzygodiapophyseal fossae.

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