Erketu
- Boron Guve, Dorno Gobi Aimag, Mongolia
- Erketu ellisoni
Erketu is a genus of sauropod dinosaur from the group of Titanosauriformes, who lived during the late Cretaceous in what is now Mongolia.
This genus is characterized by a self- sauropods for extremely long neck. Erketu was a medium-sized sauropod, but since so far only known a fragmentary skeleton, no exact size information can be given. Erketu was scientifically described with the only known type ( type species ) Erketu ellisoni in 2006 by Daniel and Mark Norell Ksepka.
The genus name Erketu plays on Erketü to Tengri, a god of Tengriasm while the Artepitheth ellisoni Mick Ellison honors due to his contributions to dinosaur research at the American Museum of Natural History.
Fund and Fund Location
The so far only find this animal was from an expedition of the American Museum of Natural History and the Mongolian Academy of Sciences in Dorno Gobi Aimag, an aimag (administrative unit ) in the southeast of Mongolia made in 2002. The expedition found some turbulence at the surface of the ground immediately in front of it hid the front of the neck portion in the anatomical network ( articulated ). Next was the lower portion of the right leg - shin (tibia), the fibula ( fibula ) and talus ( astragalus ) - to be recovered articulated. In addition, a heel bone ( calcaneus ) and the right breastbone ( sternum) were found. However, the nationwide search was unsuccessful after the skull, although the Atlas, the first cervical vertebra, is completely preserved. The discovery of a Sauropodenschädels is generally a great rarity, as the skull was only weakly connected to the neck and because only small in size, not often stayed with the rest of the body.
When the research team visited again the reference in the subsequent time, it discovered another three cervical vertebrae in anatomical composite that belonged to the same instance. These vortices were described in 2010 by Ksepka and Norell.
The of the 2002 expedition newly discovered treasure location boron Guve was a flood zone probably during the time of deposition. Among the other finds a location where the remains of sauropods and turtles, as well as theropods - it is a large predator the size of a Allosaurus and a representative of Maniraptora known, was slightly larger than Deinonychus. Furthermore, were discovered fossil fruits. The age of the layer is estimated to be the late Cretaceous - but a more accurate time stamp is not possible because a suitable material for radiometric dating is missing.
From Mongolia originating Sauropodenfossilien are rare and usually very fragmentary. The discovery of Erketu forms - together with the discovery of Opisthocoelicaudia, a skull of Nemegtosaurus and of Quaesitosaurus - the only exception.
Description
Compared with other sauropods Erketu overall was indeed long, but not very heavy. Whether by greatly prolonged cervical vertebrae very long neck in proportion to body size, however, was longer than the other extremely long-necked genera such Mamenchisaurus, can not be said, since the total number of vertebrae is unknown.
The cervical vertebrae are higher than wide and to reduce weight significantly opisthocoel, ie the vortex centers are concave on the front straight and on the back. Another big dump is located laterally at the centers. A CT scan of the vortex shows that large parts of the center were filled with any air-filled chambers, remained little more than a vortex backbone left. From the fourth cervical vertebrae were found upward forked spinous processes.
However, the most striking feature of the cervical vertebrae is its strong extension. The so-called elongation index (Ei, Wedel et al., 2000), the ratio of the length of the vortex base and the height of the condyle, which is used to compare the eddy length with other sauropods is in Erketu is greater than any other sauropods known from the corresponding material. However, a direct comparison with the long-necked sauropods very Omeisaurus and Sauroposeidon, which also have very long cervical vertebrae is difficult because good stuff is missing.
Significantly longer cervical vertebrae or an increased number of cervical vertebrae on the extension of the neck can be found in many sauropods. Brachiosaurus for example, had only 13 cervical vertebrae, which, however, were significantly prolonged while Euhelopus had 17 cervical vertebrae, but these were not extended.
System
Erketu is of Ksepka and Norell (2006) within the Somphospondyli ( Wilson and Sereno, 1998), but arranged outside the Titanosauria because some specific for Titanosauria features are missing. He forms a sister taxon to Euhelopus and Titanosauria. In a recent cladistic analysis Ksepka and Norell (2010) Erketu see as a sister genus of Qiaowanlong, a sauropod recently described from China. Both genera show bifurcated spinous processes of the cervical vertebrae, a feature that in other species not findet.Qiaowanlong and Erketu were more closely related according to this analysis with the Titanosauria as Euhelopus.
The possible relationships are shown in the following cladogram (simplified after Ksepka and Norell, 2010):
Euhelopus
Erketu
Qiaowanlong
Titanosauria