page_title: Erlikosaurus
section_title: Classification
hierarchical_section_title: Erlikosaurus / Classification
caption_attribution_description: In-situ endocranial elements of the described therizinosaurian taxa displayed in their phylogenetic context. Bone rendered transparent to reveal endocranial anatomy. (Phylogeny modified from Zanno 2010)
context_page_description: Erlikosaurus is a genus of therizinosaurid theropod dinosaurs that lived in Asia during the Late Cretaceous period. The fossils, a skull and some post-cranial fragments, were found in the Bayan Shireh Formation of Mongolia in 1972, dating to around 96 million and 89 million years ago. These remains were later described by Altangerel Perle and Rinchen Barsbold in 1980, naming the new genus and species Erlikosaurus andrewsi. It represents the second therizinosaur taxon from this formation with the most complete skull among members of this peculiar family of dinosaurs.
context_section_description: Erlikosaurus was by Perle assigned to the Segnosauridae, a group today known as the Therizinosauridae, confirmed by later cladistic analyses. Therizinosaurs were a strange group of theropods that ate plants instead of meat, and had a backward-facing pubis, like ornithischians. Also like ornithischians, their jaws were tipped by a broad rounded bony beak useful for cropping off plants.
  The relationships of therizinosaurs were quite complicated when the first members were discovered. As an example, the first known therizinosaur taxon, Therizinosaurus, was interpreted to represent turtle-like animals that used the elongated claws to feed on seaweed.  However, in 1970, Rozhdestvensky proposed the idea that therizinosaurs (then known as segnosaurs) instead of being non-dinosaur creatures, they were in fact, theropods. Later, in 1980, segnosaurs were thought to be slow, semiaquatic animals, with this, Gregory S. Paul claimed that these controversial animals had no theropod characteristics and they were prosauropods with ornithischian adaptations, also, they shared evolutionary relationships. However, with the description of more genera such as Alxasaurus, Nanshiungosaurus, and the redescription of the skull of Erlikosaurus, more theropod evidence began to be supported. With the discovery and description of the feathered Beipiaosaurus, therizinosaurs were utterly recognized as theropods, and started to be reconstructed in an accurate, bipedal posture.
   
  Consequently, therizinosaurs are now classified as theropods, within the Coelurosauria. Lindsay Zanno was one of the first authors in examine with detail the relationships and affinites of therizinosaurs. Most of her work have been useful in many conducted phylogenetic analysis. The cladogram below is the result of the recently performed phylogenetic analysis of the Therizinosauria by Hartman et al. 2019 using the data provided by Zanno in 2010. Erlikosaurus occupied a very derived position in a clade formed with Nothronychus:
caption: Holotype skull of Erlikosaurus (below) and endocranial elements of other therizinosaurs
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