Eomamenchisaurus

• Yunnan, People's Republic of China ( Zhanghe Formation)

• Eomamenchisaurus yuanmouensis

Eomamenchisaurus is a genus of sauropod dinosaur from the Middle Jurassic of China. So far, a single, very fragmentary skeleton is only known, which consists of parts of the back spine, sacrum, pelvis and hind limbs. This genus was first described scientifically in 2008 with the only kind Eomamenchisaurus yuanmouensis of Chinese researchers led by Lü Junchang. These researchers Eomamenchisaurus to Mamenchisauridae, a previously detected only from China group of sauropods, which was characterized in particular by a very long neck. Eomamenchisaurus dates from the Middle Jurassic and is thus geologically older than most other representatives of Mamenchisauridae - this circumstance also has the generic name (Greek eos - "early", ch Mǎménxī马 门 溪;. Sauros gr - "lizard "). The second part of the species name, yuanmouensis, has the Yuanmou county in the Chinese province of Yunnan, where the fossils were discovered.

Locality

The only previous Fund comes from Jiangyi in Yuanmou county in Yunnan Province; he was rescued from the same quarry from which the remains of the genus previously Yuanmousaurus were recovered. Today, the fossils are in the local Lufeng Dinosaur Museum.

Systematics and Features

In its first description Junchang Lü and colleagues presented Eomamenchisaurus to Mamenchisauridae. This group is one of the Eusauropoda, which all sauropods belong to some very original forms, but is classified outside the Neosauropoda, of which all advanced sauropods. The validity of the Mamenchisauridae is controversial, so it could be in fact a paraphyletic collection of related Eusauropoden not act closer. According to Lu and colleagues, looking at the Mamenchisauridae as a monophyletic group, provides Eomamenchisaurus an original member of this group; a closer examination of the relationships ( phylogenetic analysis) is still pending.

The assignment to the Mamenchisauridae was based on various features of the sacrum, which consisted, as with other Mamenchisauriden of four sacral vertebrae: for example, made ​​the vertebral body more than a third of the total height of the vertebrae from, also were the first and second vertebrae of the sacrum, not each other merged. As with Mamenchisaurus hochuanensis, Mamenchisaurus youngi and Chuanjiesaurus were the ninth and tenth dorsal vertebrae fused together.

From other genera can be Eomamenchisaurus by a number of features differ: For example, the vertebral bodies of the vertebrae showed no Pleurocoele ( lateral openings ), while their front ends to slightly convex were flat. The length ratio between the tibia and femur was 0.64. The ischium was a long, straight rod-like stem which was longer than that of the pubic bone.