Model of a feathered Therizinosaurus cheloniformis
|Upper Cretaceous (late Campanium to early Maastrichtian )|
|76.4 to 69.9 million years|
|Maleev , 1954|
Therizinosaurus lived during the late Upper Cretaceous (Upper Campanium to Lower Maastrichtian ) and was one of the last and largest representatives of the unique group of Therizinosauridae. Few fossilized bones of this species are known, including huge claws of the hands, which led to the naming. Its total length is estimated to be 9 meters.
Discovery and species
The first fossil remains of Therizinosaurus were discovered in 1948 by a joint Russian-Mongolian expedition in the Nemegt Formation in southwest Mongolia. The researchers excavated several huge claws up to one meter in length. In 1954, Evgeni Alexandrovich Maleev (international: EA Maleev) described this find, based on a specimen from Mongolia, as what he believed at the time, a large turtle-like reptile, since he believed the claws were the ribs of such an animal. (The species name T. cheloniformis - "turtle- shaped ") is based on this . It was not until further expeditions excavated more fossils, including further claws, but also front and rear limbs, in the early 1950s that it became clear to which creature these belonged. Later discoveries in northern China finally allowed the paleontologists to reconstruct the basic structure of the skeleton. It became clear that it was not a turtle, but a dinosaur.
The discovery that the enigmatic Segnosauridae , such as Erlikosaurus and Segnosaurus, were theropods , also made it possible to assign the Therizinosaurus. There have been various theories about the ancestry of the Segnosauridae. Some researchers thought they were descendants of the Sauropodomorpha . But well-preserved recent finds, such as that of Alxasaurus in 1993 and Beipiaosaurus in 1996, revealed important details such as the feet and skulls and the bird-like pelvis of these primitive members of the dinosaur family. This confirmed that the Segnosauridae, including Therizinosaurus, were members of a group of theropods, which was now referred to as Therizinosauridae. Therizinosauridae were therefore highly developed herbivorous theropods from the group of Maniraptora .
Although only incompletely preserved fossil remains of Therizinosaurus have been preserved, it is possible to draw conclusions about the shape of the Therizinosaurus from other species of the Therizinosauridae family . Like the rest of the family, he probably had a small skull and a long neck. He walked on two legs and the width of the basin of other Therizinosauridae suggests a large, thick trunk. His arms reached a length of 2.5 m. Its rear extremities ended in four supporting, strong toes, in which they differ from the feet of other theropods, and the first toe was designed as a dewclaw .
The most noticeable feature of Therizinosaurus was the huge claws on the three fingers of its hands. The largest claws found so far are incomplete, but they probably reached a length of less than a meter.
The feeding habits of Therizinosaurus are unknown, as no skull finds have been made that could provide clues about nutrition. Like other Therizinosauridae, however, it was likely primarily herbivorous. The claws of the Therizinosaurus may have served various purposes, such as the defense against predatory dinosaurs such as the Tarbosaurus living at the same time , territorial or courtship fights among each other or to pull leafy branches to the mouth to eat. Or maybe the claws served all of these purposes. This way of life was assumed by the Therizinosaurus in the documentation In the Empire of the Giants with Nigel Marven .
- Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , pp. 160-161, online .
- Ринченгийн Барсболд : Хищные динозавры мела Монголии. Совместная Советско-Монгольская палеонтологическая экспедиция (= Труды. 19). Наука, Москва 1983, pp. 1–120 (In English: Rinchen Barsbold: Carnivorous dinosaurs from the Cretaceous of Mongolia. The Joint Soviet-Mongolian Paleontological Expedition (= Transaction of the Joint Soviet-Mongolian Paleontological Expedition. Vol. 19). Self-published by the author, Berkeley CA 1983, online ).
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- Thomas E. Svarney, Patricia Barnes-Svarney: The Handy Dinosaur Answer Book. Visible Ink Press, Canton MI 2003, ISBN 0-7808-0724-3 .