Maleev originally classified "Therizinosaurus" as to have been a giant marine turtle and the genus was assigned by Maleev to a separate Therizinosauridae given how enigmatic the specimen was. The fossils remained with uncertainty among the scientific community, however, in 1970 Rozhdestvensky was one of the first paleontologists suggesting that "Therizinosaurus" was actually a theropod dinosaur instead of some turtle. Also, the supposed ribs of the holotype were likely from a different dinosaur, possibly some sauropodomorph. With the discovery and description of "Segnosaurus", in 1979 Perle named a new family of dinosaurs, the "Segnosauridae". He tentatively placed the family within Theropoda given the similarities of the mandible and dentition to other members. A year later, the new genus "Erlikosaurus" was named by Barsbold and Perle in 1980. They named a new infraorder called the Segnosauria, composed by "Erlikosaurus" and "Segnosaurus". They also noted that while aberrant and having ornithischian-like pelves, segnosaurs featured similar traits to other theropods. With the discovery of the referred hindlimb to "Therizinosaurus" in 1982 by Perle, he concluded that "Segnosaurus" was very similar to the latter based on the pes morphology and they possibly belonged to a single, if not the same group. In 1983, Barsbold named a new genus of segnosaur "Enigmosaurus". He analysed the pelvis of this new genus and pointed out that segnosaurids were so different from other theropods that they could be outside the group or represent a different lineage of theropod dinosaurs. Later on the same year, he intensified the exclusion of segnosaurs from being theropods by noting that their pelves resembled those of sauropod dinosaurs.