Editing Segnosaurus (section)

{{short description|Extinct genus of therizinosaurid dinosaur from late Cretaceous}}
{{Use American English|date=January 2020}}
{{Use mdy dates|date=January 2020}}
{{speciesbox
| fossil_range = [[Late Cretaceous]], {{fossilrange|90|earliest=102|latest=86}}
| image = Segnosaurus skeletal.png
| image_caption = Diagram showing known remains
| genus = Segnosaurus
| parent_authority = [[Altangerel Perle|Perle]], [[1979 in paleontology|1979]]
| species = galbinensis
| authority = Perle, 1979
}}

'''''Segnosaurus''''' is a [[genus]] of [[therizinosaurid]] [[dinosaur]] that lived in what is now southeastern Mongolia during the [[Late Cretaceous]], about 102–86&nbsp;million years ago. Multiple incomplete but well-preserved specimens were discovered in the [[Gobi Desert]] in the 1970s, and in 1979 the genus and species '''''Segnosaurus galbinensis''''' were named. The generic name ''Segnosaurus'' means "slow lizard" and the specific name ''galbinensis'' refers to the Galbin region. The known material of this dinosaur includes the lower jaw, neck and tail vertebrae, the pelvis, shoulder girdle, and limb bones. Parts of the specimens have gone missing or become damaged since they were collected.

''Segnosaurus'' was a large-bodied [[therizinosaur]] that is estimated to have been about {{convert|6–7|m|ft|abbr=on}} long and to have weighed about {{convert|1.3|MT|ST|abbr=on}}. It would have been bipedal, with the trunk of its body tilted upwards. The head was small with a beak at the tip of the jaws, and the neck was long and slender. The lower jaw was down-turned at the front and the teeth were distinct in having additional {{Dinogloss|denticles}} as well as third cutting edges in some of the hindmost teeth. The forelimbs were robust and had three fingers which bore large claws, and the feet had four toes supporting the foot—apart from therizinosaurs, all [[theropods]] had three-toed feet. The front of the pelvis was adapted to support the enlarged belly. The [[pubic bone]] was turned backwards, a feature that is only seen in birds and the dinosaurs most closely related to them.

The affinities of ''Segnosaurus'' were originally obscure and it received its own theropod family, Segnosauridae, and later when related genera were identified, an [[infraorder]], Segnosauria. Alternative classification schemes were proposed until more complete relatives were described in the 1990s, which confirmed them as theropods. The new fossils also showed Segnosauridae was a [[junior synonym]] of the earlier named family Therizinosauridae. ''Segnosaurus'' and its relatives are thought to have been slow-moving animals that, as indicated by their unusual features, were mainly herbivorous, whereas most other theropod groups were carnivorous. Therizinosaurs probably used their long forelimbs, long necks, and beaks when [[Browsing (herbivory)|browsing]], and large guts for processing food. ''Segnosaurus'' is known from the [[Bayan Shireh Formation]], where it lived alongside the fellow therizinosaurs ''[[Erlikosaurus]]'' and ''[[Enigmosaurus]]''; these related genera were probably [[niche partitioned]].