Mahakala (dinosaur)

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Mahakala
Skeleton reconstruction by Mahakala omnogovae, above the known skeletal parts.

Skeleton reconstruction by Mahakala omnogovae , above the known skeletal parts.

Temporal occurrence
Upper Cretaceous ( Campanium )
80 million years
Locations
Systematics
Lizard dinosaur (Saurischia)
Theropoda
Maniraptora
Deinonychosauria
Dromaeosauridae
Mahakala
Scientific name
Mahakala
Turner et al. , 2007
Art
  • Mahakala omnogovae

Mahakala is a genus of theropod dinosaur from the group of Dromaeosauridae . So far only a fragmentary skeleton is known that was discovered in the Gobi desert in Mongolia and is around 80 million years old ( Upper Cretaceous , Campanium ). The only species, Mahakala omnogovae , was found by Turner et al. described . Mahakala was a very small and basal (original) representative of the Dromaeosauridae with a length of about 70 cm.

features

Mahakala was a very small theropod - the thigh bone (femur), which is particularly important for size estimates, is only 80 mm long. The animal's weight is estimated at around 700 g. Despite its small size, the specimen found died in young adulthood, which is indicated by the degree of fusion of the vertebrae, the ankle joint , and the skull, as well as histological analyzes. The tail was very long, similar to that of basal birds, basal troodontids, and other dromaeosaurids. Mahakala probably had proportionally large eyes - similar to troodontids but different from other dromaeosaurids. As a dromaeosaurid, Mahakala displayed the typical enlarged, sickle-shaped claw on the second toe.

There are three characteristics described at which the species can be clearly distinguished from other genera ( autapomorphies ): Thus was Elle (ulna) strongly compressed, wide along the body axis and tapered in a thin edge forward to. The femur showed an elongated lateral ridge in the posterodistal area. Furthermore, the posterior caudal vertebrae showed subhorizontal, laterally aligned prezygapophyses (connecting elements of the vertebrae).

Systematics

Phylogenetic studies by Turner et al. show that Mahakala was a basal (original) dromaeosaurid. This genus shows characteristics that are also found in early birds and troodontids, but are absent in other dromaeosaurids. Mahakala was as small as the basal bird Archeopteryx , the basal oviraptorosaur Caudipteryx or the basal troodontid Mei . From this, the researchers conclude that a small body size was not first developed by the birds, but that the common ancestors of the Deinonychosauria and the birds were small. The common ancestor of all Paraves (deinonychosauria and birds), according to the researchers, probably had a length of about 65 cm and a weight of 600 to 700 g. In the evolution of the Deinonychosauria, however, a radical increase in size of up to three orders of magnitude has occurred several times in various lineages. In the first description of Halszkaraptor published in December 2017 , Mahakala was placed together with this and Hulsanpes in the newly introduced subfamily Halszkaraptorinae .

Find and naming

The only find ( holotype , copy number IGM 100/1033) consists of a fragmentary skull with a postcranium and was discovered in Tugrugyin Shireh in the Mongolian Aimag Ömnö-Gobi . Today the remains are kept in the Mongolian Institute of Geology in the Mongolian capital Ulan Bator . Stratigraphically , the find comes from the Tugrugyin layer member of the Djadokhta Formation ( Campanium ).

The generic name comes from Sanskrit and is known after Mahakala , one of the eight protective deities of the teachings of the Buddha ( Dharmapala ) in Tibetan Buddhism . The specific epithet omnogovae refers to the site in the southern Gobi desert.

literature

Unless otherwise noted, all information comes from the following work:

Individual evidence

  1. ↑ Cau, A .; Beyrand, V .; Voeten, D .; Fernandez, V .; Tafforeau, P .; Stein, K .; Barsbold, R .; Tsogtbaatar, K .; Currie, P .; Godrfroit, P. (December 6, 2017). Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs . Nature . doi: 10.1038 / nature24679

Web links

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