Pronunciation: BAH-gah-RAH-tan
Meaning: Small hunter
Author/s: Osmólska (1996)
Synonyms: None known
First Discovery: Ömnögovi, Mongolia
Discovery Chart Position: #406
Bagaraatan ostromi
Polish palaeontologist Halszka Osmólska earned a reputation for finding, naming and describing weird dinosaurs, so when she released a paper describing her latest discovery as "unusual", you just knew it was going to be a really weird one. And Bagaraatan is a really weird one.
Its astragalus (ankle), calcaneum (heel), and the thickened lower end of its bowed tibia (shin) and fibula (calf) are all fused, which is a feature present in some ceratosaurs. The ilium bone of its hip has peculiar depressions. And its lower jaw, complete with a shallow and robust-tooth-bearing dentary bone, seems to cherry-pick characteristics from several families of two-legged, carnivorous dinosaurs known as theropods.
In her initial description, Osmólska wouldn't commit to a more specific assignment than Tetanurae (stiff tails) and only went that far because of the massive tail-stiffening slot and notch (hyposphene-hypantrum) joints between the vertebrae that are themselves rarely seen in theropods. But since then, three palaeontologists have concluded that Bagaraatan belongs within their field of expertise. Holtz thinks it's a tyrannosauroid, Coria a troodontid and Rauhut a maniraptoran. And they could all be correct, at least partially, because rumours are rife that Bagaraatan may be a chimaera made up of different critters jumbled together.
Its astragalus (ankle), calcaneum (heel), and the thickened lower end of its bowed tibia (shin) and fibula (calf) are all fused, which is a feature present in some ceratosaurs. The ilium bone of its hip has peculiar depressions. And its lower jaw, complete with a shallow and robust-tooth-bearing dentary bone, seems to cherry-pick characteristics from several families of two-legged, carnivorous dinosaurs known as theropods.
In her initial description, Osmólska wouldn't commit to a more specific assignment than Tetanurae (stiff tails) and only went that far because of the massive tail-stiffening slot and notch (hyposphene-hypantrum) joints between the vertebrae that are themselves rarely seen in theropods. But since then, three palaeontologists have concluded that Bagaraatan belongs within their field of expertise. Holtz thinks it's a tyrannosauroid, Coria a troodontid and Rauhut a maniraptoran. And they could all be correct, at least partially, because rumours are rife that Bagaraatan may be a chimaera made up of different critters jumbled together.
(Ostrom's Small Hunter)Etymology
Bagaraatan is derived from the Mongolian "baga" (little) and "araatan" (wild beast). In this case, "wild beast" is interpreted as "predator".The species epithet, ostromi, honors palaeontologist John H. Ostrom.
Discovery
The remains of Bagaraatan were discovered at Northern Sayr in the Nemegt formation, Ömnögovi Aimag (South Gobi Province), Mongolia, by Zofia Kielan-Jaworowska during the Polish Mongolian Expedition of 1970, 26 years before it was actually described. Its holotype (ZPAL MgD-I/108) is a partial skull and skeleton, including a lower jaw, pelvis, neck and hip vertebrae, and a partial lower leg.
