Editing Segnosaurus (section)

==History of discovery==
[[File:Cretaceous-aged dinosaur fossil localities of Mongolia.PNG|thumb|left|upright=1.4|[[Cretaceous]]-aged dinosaur fossil localities of Mongolia; ''Segnosaurus'' was found by areas C and D (right, Amtgay and Khara-Khutul localities).]]

In 1973, a joint [[Soviet]]–Mongolian expedition investigating the [[Bayan Shireh Formation]] at the Amtgay locality in the [[Gobi Desert]] of southeastern Mongolia discovered fossils that included the partial skeleton of an unknown [[dinosaur]]. Through 1974 and 1975, more remains were uncovered at the Amtgay and Khara-Khutul localities; though the skeletons were incomplete, the recovered bones were well-preserved. Other localities listed in the literature include Bayshin-Tsav and Urilbe-Khuduk. These fossils were scientifically [[species description|described]] in 1979 by the paleontologist [[Altangerel Perle]], who named the new [[genus]] and species ''Segnosaurus galbiensis''. The generic name is derived from the Latin word ''segnis'' ("slow") and the [[Ancient Greek]] ''sauros'' ("lizard"). The [[specific name (zoology)|specific name]] refers to the Galbin region of the Gobi Desert.<ref name="Perle1979">{{Cite journal |last=Perle |first=A. |author-link=Altangerel Perle |year=1979 |title=Segnosauridae – novoe semeistvo teropod is posdnego mela Mongolii |trans-title=Segnosauridae – a new family of Theropoda from the Lower Cretaceous of Mongolia |url=http://paleoglot.org/files/Perle%2079.pdf |url-status=live |journal=Trudy – Sovmestnaya Sovetsko-Mongol'skaya Paleontologicheskaya Ekspeditsiya |language=Russian |volume=8 |pages=45–55 |archive-url=https://web.archive.org/web/20121128221548/http://paleoglot.org/files/Perle%2079.pdf |archive-date=2012-11-28 |translator-last=Siskron |translator-first=C. |translator2-last=Welles |translator2-first=S. P.}}</ref><ref name="DFG97b">{{Cite book |title=Dinosaurs: The Encyclopedia |last=Glut |first=D. F. |publisher=McFarland & Co |year=1997 |isbn=978-0-89950-917-4 |location=Jefferson |pages=806–807}}</ref><ref name="barsbold1983"/>

The [[holotype specimen]] from the Amtgay locality is housed at the [[Mongolian Academy of Sciences]] under the specimen number IGM 100/80 (Mongolian Institute of Geology, formerly GIN). It includes the {{Dinogloss|mandible}} (lower jaws), an incomplete {{Dinogloss|humerus}}, a complete {{Dinogloss|radius}} and {{Dinogloss|ulna}} (lower arm bones), {{Dinogloss|phalanges}} of the fingers, a forelimb {{Dinogloss|ungual}} (claw bone), an almost-complete {{Dinogloss|pelvis}}, an incomplete right {{Dinogloss|femur}}, six {{Dinogloss|sacral vertebrae}}, ten {{Dinogloss|caudal vertebrae}} from the front of the tail, fifteen from the hindmost part of the tail, the first {{Dinogloss|gastral rib}}, and fragments of the dorsal ribs. Two more specimens were designated as [[paratype specimens]]; specimen IGM 100/82 from the Khara Khutul locality includes a femur, {{Dinogloss|tibia}} and {{Dinogloss|fibula}} (leg bones), {{Dinogloss|tarsals}} and {{Dinogloss|metatarsals}}, five toe phalanges including a foot ungual, rib fragments, complete {{Dinogloss|ilia}}, the upper portion of an {{Dinogloss|ischium}}, and the lower portion of a {{Dinogloss|pubis}}. Specimen IGM 100/83 includes a left {{Dinogloss|scapulocoracoid}} (shoulder girdle), a radius, an ulna, forelimb unguals, and a fragment of a {{Dinogloss|cervical}} (neck) vertebra.<ref name="Perle1979" /><ref name=Zanno2010/> In 1980, Perle and the paleontologist [[Rinchen Barsbold]] assigned another specimen to ''Segnosaurus''; IGM 100/81 from the Amtgay locality included a left tibia and fibula.<ref name="perle&barsbold80">{{Cite journal |last1=Barsbold |first1=R. |last2=Perle |first2=A. |author2-link=Altangerel Perle |year=1980 |title=Segnosauria, a new infraorder of carnivorous dinosaurs |url=https://www.app.pan.pl/article/item/app25-187.html |url-status=live |journal=Acta Palaeontologica Polonica |volume=25 |issue=2 |pages=187–195 |archive-url=https://web.archive.org/web/20190921004254/https://www.app.pan.pl/article/item/app25-187.html |archive-date=2019-09-21}}</ref><ref name=Zanno2010/>

In 1983, Barsbold listed additional specimens GIN 100/87 and 100/88. In 2010, however, the paleontologist [[Lindsay E. Zanno]] suggested these may refer to paratypes IGM 100/82 and IGM 100/83 (which had already been listed in 1979) because the Russian-to-English translation of Barsbold's article has several typographical errors in regard to specimen numbers. Zanno also noted that by the time of her study, there were numerous problems with the ''Segnosaurus'' IGM specimens, including damage caused since collection, the disappearance of elements of the holotype, incorrect identification of assigned elements, and more than one individual bearing the same specimen number. Holotype elements Zanno was able to access in 2010 included a severely damaged ilium, a sacrum missing the left sacral ribs with damage so it could not conjoin well with the rest of the ilium, and a pubic bone and ischium missing their upper portions. More bones bearing the specimen number IGM 100/82 were located but were not mentioned in Perle's description, while the whereabouts of some paratype elements was unknown.<ref name="barsbold1983">{{Cite journal |last=Barsbold |first=R. |year=1983 |title=Khishchnye dinosavry mela Mongoliy|trans-title=Carnivorous dinosaurs from the Cretaceous of Mongolia |url=https://paleoglot.org/files/Barsbold_83.pdf |url-status=live |journal=Transactions of the Joint Soviet-Mongolian Paleontological Expedition |volume=19 |pages=51–52, 76, 108–109 |archive-url=https://web.archive.org/web/20160313031010/http://paleoglot.org/files/barsbold_83.pdf |archive-date=2016-03-13 |access-date=2019-09-21|language=Russian|translator-last=Siskron |translator-first=C. |translator2-last=Welles |translator2-first=S. P.}}</ref><ref name=Zanno2010/> In a 2016 re-description of the holotype mandible, which had been little studied since 1979, Zanno and colleagues reported the majority of the tooth crowns had been damaged after collection, and most of them were missing their tips. Of the two {{Dinogloss|hemimandibles}} (halves of the lower jaw), the right is nearly complete; only the hindmost part and the upper front of its [[mandibular symphysis]] (the area where the halves of the mandible meet) was missing. The left hemimandible is fragmented and preserves the front part with some displacement of bone due to crushing.<ref name="Zanno2016"/>