Tanystropheidae, Gervais, 1859
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publication ID |
https://doi.org/ 10.4202/app.00489.2018 |
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persistent identifier |
https://treatment.plazi.org/id/03F4EA51-EE70-2013-FCC2-F8FCFBAEF92E |
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treatment provided by |
Felipe |
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scientific name |
Tanystropheidae |
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? Tanystropheidae indet.
Material.—UNIPAMPA 733, UFRGS-PV-492- T, UFRGS- PV-647- T: isolated cervical vertebrae from Sanga do Cabral Formation (Induan–early Olenekian).
Description.—UNIPAMPA 733 ( Fig. 1 View Fig ) presents an elongated and amphicoelous centrum. The parapophyses and diapophyses are poorly developed and situated in different processes and near each other in the centrum. In lateral view, the anterior articular surface of UNIPAMPA 733 is raised dorsally relative to the posterior surface. The neural spine is dorsoventrally low and laminar, lacking a transverse expansion (spine-table) and presenting a post-spinal fossa. The neural spine is abraded in its anterior and posterior extremities, preventing the recognition of a possible overhang” (sensu Ezcurra 2016). A faint longitudinal keel runs the length of the centrum. In ventral view, UNIPAMPA 733 shows a thin anteroposterior keel extending through the whole centrum. The specimen has a total length of 18.45 mm.
Among the vertebrae, UFRGS-PV-492- T ( Fig. 2 View Fig ) is better preserved. However, this specimen has a broken neural spine, making it impossible to analyze the shape of this structure. The preserved portion of the neural spine, however, is reminiscent of a thin and low longitudinal lamina, possibly extending for almost the entire anteroposterior length of the centrum. With a total length of 20.26 mm, UFRGS-PV-492- T shows an elongated amphicoelous centrum and a higher anterior articular surface with relation to the posterior one. The diapophyses and parapophyses are close to each other on the anterior surface of the centrum. Notably, this specimen displays a clear longitudinal keel that extends laterally on the centrum. The ventral surface of the centrum shows a keel that extends along its entire length. Although a ventral keel is also present in specimens UNIPAMPA 733 and UFRGS-PV-647- T, they are not as well preserved as in UFRGS-PV-492- T. The ventral surface of the centrum (excluding the keel) is slightly rounded. In lateral view, the postzygapophysis of UFRGS-PV-492- T is slightly elevated dorsally above the level of the prezygapophysis, with short and spaced articular surfaces. Due to the preservation, it is not possible to evaluate the presence of epipophyses or the transpostzygapophyseal lamina.
The preserved portion of the neural spine of UFRGS- PV-647- T ( Fig. 3 View Fig ) indicates a dorsoventrally deep lamina. The vertebral body is elongated, and the centrum is amphicoelous. Due to poor preservation, the parapophyses and diapophyses are not readily distinguishable. However, these structures seem to be poorly developed. It is also not possible to determine if the postzygapophyses are separated or connected to each other. In lateral view, UFRGS-PV-647- T shows the anterior articular surface of the centrum raised dorsally relative to the posterior one. The centrum also possesses a lateral transverse keel. This specimen shows a ventral keel that does not reach the anterior articular margin. Specimen UFRGS-PV-647- T has a total length of 15.40 mm.
In all the vertebrae, it is not possible to determine whether the neural spine ends anteriorly or posteriorly to the postzygapophyses.
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Tavera, Department of Geology and Geophysics |
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