Volkheimeria

• Chubut, Argentina ( Cañadón Asphalt Formation)

• Volkheimeria chubutensis

Volkheimeria is a genus of dinosaur from the group of sauropods. So far, a single, very fragmentary skeleton is only known from the Middle Jurassic ( Callovian ) of the Argentine province of Chubut comes. This is an original representative of the sauropods, the relationships within this group are uncertain. The only way is Volkheimeria chubutensis.

Fund and naming

The only skeleton comes from a locality near the village of Cerro Cóndor from the layers of Cañadón Asphalt lineup. Although known since 1949, the numerous fossils of this locality were recovered only in the years 1977, 1982 and 1983 by research teams under the direction of paleontologist José Bonaparte. In addition to the Volkheimeria - skeleton of the locality harbored five incomplete skeletons of sauropods Patagosaurus and two skeletons of theropods Piatnitzkysaurus.

The skeleton consists of some cervical, dorsal, and sacral vertebrae, pelvis, and the femur and tibia. It was established in 1979, first described scientifically by Joseph Bonaparte as a new species and genus, Volkheimeria chubutensis. The genus name honors the Argentine geologists and paleontologists Wolfgang Volkheimer, while the second part of the species name, chubutensis, has the province of Chubut.

Characteristics and systematics

The only copy of Volkheimeria was smaller than the contemporary and much better known Patagosaurus who could reach a length of up to 14 meters: So the ilium attaches Volkheimeria 45 centimeters in length, while at Patagosaurus it measures 95 centimeters in length.

In his first description José Bonaparte classified this species as original sauropod from the group of " Cetiosauridae ". John McIntosh (1990 ) noted that Volkheimeria has similarities with the dating from the Middle Jurassic of Madagascar Lapparentosaurus and provides both genera to the Brachiosauridae. Upchurch and colleagues ( 2004) noted, meanwhile, that no features are known to substantiate a classification within the Brachiosauridae and that Volkheimeria has been taken into account in any phylogenetic study - consistently these authors classify the genus therefore as Sauropoda incertae sedis ( sauropod with unknown relationships ). Fernando Novas (2009 ) argues that Volkheimeria can be classified within the Eusauropoda - a group that includes all sauropods except for some very original forms. To show Volkheimeria like other Eusauropoden opisthocoele - that is on the front convex and concave at the rear - caudal vertebrae; Also there is no anterior trochanter of the femur while the tibia Cnemialkamm side projecting out. At the same time Novas noticed that this genus shows a number of very original features, some of which are reminiscent of prosauropods; so the shaft of the ischium was slim and extended the pubis, also the spinous processes of the vertebrae were craniocaudal (along the midline of the body ) extended. Novas generally assumed, therefore, that it was an original representative of Eusauropoda.

From other genera to Volkheimeria be distinguished on the basis of the intervertebral foramen of the vertebrae, which is deeply incised into the vertebral bodies.