Tapuiasaurus
| Tapuiasaurus | ||||||||||
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![Skull of the type specimen. Photography and drawing from Zaher et al., 2011. [1]](https://de.wikipedia.org/wiki/Datei:Tapuiasaurus.png)
Skull of the type specimen . Photography and drawing from Zaher et al. , 2011. |
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| Temporal occurrence | ||||||||||
| Lower Cretaceous ( Aptium ) | ||||||||||
| 126.3 to 112.9 million years | ||||||||||
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| Systematics | ||||||||||
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| Scientific name | ||||||||||
| Tapuiasaurus | ||||||||||
| Zaher et al., 2011 | ||||||||||
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Tapuiasaurus is a genus of sauropod dinosaur from the group of titanosaur that in Lower Cretaceous Brazil lived. So far, a single fragmentary skeleton is known, which consists of an almost complete skull, some vertebrae and bones of the limbs and is dated to the Aptium (126.3 to 112.9 million years ago). Tapuiasaurus wasscientifically described in 2011 with the only species Tapuiasaurus macedoi .
Features and meaning
So far, only a few skulls of titanosaurs have been found - almost complete skulls are only known from the late Cretaceous, highly derived (advanced) genera Nemegtosaurus and Rapetosaurus . The fairly complete skull of Tapuiasaurus fills an important gap in the fossil record and shows that the skull shape typical of the late Cretaceous Titanosauria was already common in the early Cretaceous. It is the only known Titanosauria skull from South America to date.
As with other derived titanosaurs such as Nemegtosaurus and Rapetosaurus , the skull is characterized by an elongated snout and nostrils that were located at the level of the eye sockets . The teeth were thin and cylindrical - the row of teeth reached back to the front edge of the anterior orbital window . A similar skull morphology can be found in the Diplodocoids - these similarities are probably due to convergent evolution .
The genus can be distinguished from other Titanosauria by unique features ( autapomorphies ) on the skull bones: The posteroventral (ventrally directed backwards) extension of the quadratojugale was hook-shaped. The anterior (front) process of the zygomatic bone (jugale) was pointed and forms a large part of the lower edge of the anterior orbital window . The anterolateral (anterior lateral) tip of the wing bone (pterygoid) is in contact with the medial (middle) area of the wing bone process, the ectopterygoid .
Systematics
Tapuiasaurus is one of the derived (advanced) Titanosauria, as can be seen, for example, in the procoelen (concave on the front) front and middle caudal vertebrae. It is tapuiasaurus probably the closest with rapetosaurus used and which forms Schwestertaxon of this type, such as a phylogenetic analysis shows. Rapetosaurus and Tapuiasaurus show various anatomical similarities that are not found in the also closely related Nemegtosaurus - for example, in both genera the antorbital window was the same size or larger than the eye sockets. The grouping Tapuiasaurus , Rapetosaurus and Nemegtosaurus is also summarized under the name Nemegtosauridae .
Although Tapuiasaurus was a relatively inferred titanosaur, its fossils are about 30 million years older than those of other inferred titanosaurs. This discovery shows that there must be various "spirit lineages" in the development of derived titanosaurs that are not fossilized.
Find and naming
The only skeleton comes from northern Minas Gerais near the city of Coração de Jesus . This skeleton was discovered and excavated along with the skeleton of an abelisauroid theropod . The rocks of the site belong to the Quiricó Formation , a formation within the Sanfranciscan Basin. This approximately 1,100 kilometer long basin is interpreted as a rift valley and was created by the same tensile forces that led to the opening of the Atlantic Ocean .
The skeleton (copy number MZSP-PV 807) consists of an almost complete skull with jawbone and hyoid bone (hyoid), various vertebrae ( atlas , axis , five further cervical vertebrae and five dorsal vertebrae with ribs), sternum (sternum), coracoid (raven bone), parts of the front legs ( femur (humerus), spoke (radius), Elle (ulna), metacarpal bone (metacarpal)), and parts of the rear legs (thigh bone (femur), fibula (fibula) and an almost complete foot skeleton). Most of the bones were found in their original anatomical position.
This genus was scientifically described for the first time in February 2011 by researchers working with Hussam Zaher . The name Tapuiasaurus is derived from Tapuia , a word from the Ge languages used for Indian tribes that are native to the interior of Brazil. The second part of the species name, macedoi , honors Ubirajara Alves Macedo, who discovered the fossil-bearing layers near Coração de Jesus.
Individual evidence
- ↑ a b c d e f g h i j k Hussam Zaher, Diego Pol, Alberto B. Carvalho, Paulo M. Nascimento, Claudio Riccomini, Peter Larson, Rubén Juarez-Valieri, Ricardo Pires-Domingues, Nelson Jorge da Silva Jr. , Diógenes de Almeida Campos: A Complete Skull of an Early Cretaceous Sauropod and the Evolution of Advanced Titanosaurians. In: PLoS ONE . Vol. 6, No. 2, 2011, e16663, doi : 10.1371 / journal.pone.0016663 .
- ↑ Jeffrey A. Wilson: An Overview of Titanosaur Evolution and Phylogeny. In: Fidel Torcida Fernández-Baldor, Pedro Huerta Hurtado (eds.): Actas de las III Jornadas Internacionales sobre Paleontología de Dinosaurios y Su Entorno. = Proceedings of the 3rd International Symposium about Paleontology of Dinosaurs and their Environment Paleontología de dinosaurios y su entorno. Salas de los Infantes (Burgos, España), 16 al 18 de septiembre de 2004. Colectivo arqueológico-paleontológico de Salas, Salas de los Infantes (Burgos, España) 2006, ISBN 84-8181-227-7 , pp. 169-190 .
