Antarctosaurus

Femurs of Antarctosaurus wichmannianus exhibited in the Museo de la Plata ( Argentina)

• Argentina (Río Colorado Formation)

• Antarctosaurus wichmannianus (type )

Antarctosaurus is a genus of sauropod dinosaur from the group of Titanosauria.

So far, a fragmentary skeleton is known, which dates from the Upper Cretaceous ( Campanian early ) of Argentina and consists of parts of the skull and the rest of the skeleton. This skeleton was discovered in 1916 and 1929 described by German paleontologist Friedrich von Huene first time scientifically. As type species named by Huene Antarctosaurus wichmannianus. In the same year described by Huene another way, which he named because of the huge size of the bones Antarctosaurus giganteus.

Since then, three additional species from India, Kazakhstan and Brazil have been described, of which, however, showed as later studies, no actually belongs to Antarctosaurus.

The name Antarctosaurus ( gr ant - ( anti) - "opposite", arktos - "north ", saura - " lizard" ) means something like "lizard in front of the North" has the locality in South America, a continent in the southern hemisphere. Although the name has the same origin as the name Antarctica, however, does not refer to this continent.

System

The systematic position of Antarctosaurus wichmannianus has been controversial since the first description by von Huene. Von Huene this genus stopped for a Titanosaurier, but found that the skull and particularly the jaw bones and teeth strong similarities with diplodocids as Diplodocus had: So the teeth were like a pin and tilted forward, while the rows of teeth short and to the leading section jaws were limited. Werner Janensch (1929 ) suspected because of these findings that the Titanosauridae and Diplodocidae were closely related to each other - this hypothesis has been drawn until the late 1990s in doubt. After its first description Antarctosaurus wichmannianus was filed by several authors within either the Titanosauridae or due to the skull features within the Diplodocoidea. To make matters worse, it is not clear whether the Skulls and the rest of the skeleton actually belong to the same individual, as suggested by Huene, as the Fund position of the bone is not documented. Today is believed that the skulls of titanosaurs and Diplodocoideen independently developed a similar morphology ( convergent evolution ). So the Titanosaurier are now considered relatives of the Brachiosauridae and are classified within the Macronaria.

There is now consensus that Antarctosaurus is classified within the Titanosauria. Upchurch and colleagues ( 2004) suggest that it was a secondary (modern) Titanosaurier within the Lithostrotia. Wilson ( 2005) classified Antarctosaurus within the Nemegtosauridae, along with genres such as Nemegtosaurus, Quaesitosaurus and Rapetosaurus.

Research History and Types

Antarctosaurus wichmannianus

Antarctosaurus wichmannianus is the type species and the only Antarctosaurus - type, which is recognized as valid. The fragmentary skeleton was discovered in 1916 by Wichmann at General Roca in the Argentine province of Río Negro, the rocks of the discovery site belong stratigraphically to the Río Colorado Formation. Friedrich von Huene examined the remains of 1923-1926 in Buenos Aires and described it in 1929 as Antarctosaurus; the Artepitheth wichmannianus honors Wichmann, the finder of the skeleton.

The Fund covers the rear portion of the skull, including almost complete skull, isolated jaw fragments, and further isolated skull bones, including leg scales ( squamosal ), parietal ( parietal ), square leg (squares), and prefrontal ( frontal ). Remains of the rest of the skeleton include a neck vertebrae, caudal vertebrae, ribs, shoulder blade (scapula ), parts of the right foreleg, including a fragmentary upper arm bone (humerus ), parts of ulna ( ulna ) and radius (radius ) and a fragmentary skeleton of the hand, hip bones, including partial ilium ( ilium ), ischial ( ischium ) and partial pubis ( pubic ), and the left hind leg including the thigh bone (femur), shinbone ( tibia), talus ( astragalus ), heel bone ( calcaneus ) and metatarsals with a.

Antarctosaurus giganteus

After the description of the genus with the type species Antarctosaurus Antarctosaurus wichmannianus described by Huene in the same year another way, which he called because of their enormous size Antarctosaurus giganteus. This species is known only by very fragmentary remains and is considered by many researchers as a noun dubium ( dubious name). Finds come from the Río Neuquén - formation from the Argentine province of Neuquén and are dated to the late Coniacian to early Santonian.

The most famous bone of Antarctosaurus giganteus are two huge thigh bone ( femurs ), the longest of which measures 2.35 meters. This Antarctosaurus giganteus is one of the largest known sauropod ever. Researchers led by Gerardo Mazzetta (2004) estimate the weight of this type at 69 tons, the type species Antarctosaurus wichmannianus meanwhile, is estimated at 34 tons.

" Antarctosaurus " septentrionalis ( = Jainosaurus )

1933 described by Huene and Matley another Antarctosaurus species from the Lameta lineup of India - Antarctosaurus septentrionalis. Today, this remains a separate genus, Jainosaurus are attributed.

" Antarctosaurus " jaxartensis

This type named the Soviet paleontologist Anatoly Riabinin in 1939 on the basis of an isolated femur from Kazakhstan. Today out as a noun dubium, is one of these bones with high probability not to Antarctosaurus.

" Antarctosaurus " brasiliensis

" Antarctosaurus " brasiliensis based on two fragmentary leg bones and a partial vortex from the Bauru Formation of Brazil, which were described in 1971 by Arid and Vizzotto. This type applies dubium as a noun.