Pronunciation: bee-EN-oh-SOR-us
Meaning: Bien's lizard
Author/s: Dong (2001)
Synonyms: None known
First Discovery: Yunnan Province, China
Acta Ordinal: #481
Bienosaurus lufengensis
The highly fragmentary Bienosaurus lufengensis was described briefly in 2001 and identified as an ankylosaurian dinosaur by Zhiming Dong, who cited four features of its miserably poor fossils as typical of armour-bearing ornithischians and resurrected Scelidosauridae to house it.
A restudy of the material by Raven and colleagues in 2019 concluded that Bienosaurus could not be confidently placed in Ankylosauria or even within Eurypoda: the closest umbrella of Ankylosauria and Stegosauria. At best, it squeeks into Thyreophora as the most primitive member by the skin of its partial right lower jaw. The features identified by Dong as unique simply aren't there.
Bienosaurus is strikingly similar to the equally fragmentary and poorly preserved Tatisaurus from the same formation, which, funnily enough, is also represented by a partial lower jaw, but from the opposite side. The two may represent the same taxon, with the latter taking naming rights because it was described first. However, the pair lack comparative fossils, so synonymising them is unpossible.
A restudy of the material by Raven and colleagues in 2019 concluded that Bienosaurus could not be confidently placed in Ankylosauria or even within Eurypoda: the closest umbrella of Ankylosauria and Stegosauria. At best, it squeeks into Thyreophora as the most primitive member by the skin of its partial right lower jaw. The features identified by Dong as unique simply aren't there.
Bienosaurus is strikingly similar to the equally fragmentary and poorly preserved Tatisaurus from the same formation, which, funnily enough, is also represented by a partial lower jaw, but from the opposite side. The two may represent the same taxon, with the latter taking naming rights because it was described first. However, the pair lack comparative fossils, so synonymising them is unpossible.
(Bien's Lizard from Lufeng)Etymology
Bienosaurus is derived from "bien" (for Chinese palaeontologist Mei Nien Bien) and the Greek "sauros" (lizard).
The species epithet, lufengensis, means "from Lufeng" in Latin.
Discovery
The remains of Bienosaurus were discovered in the Dark Red Beds of the Lower Lufeng Formation, Yunnan Province, China, by Mei Nien Bien between 1938 and 1939. The holotype (IVPP V15311) is a partial lower jaw and some skull fragments.
Originally, this specimen was catalogued as IVPP V 9612. But that had already been attached to the holotype of Sinornithoides youngi, a troodontid theropod dinosaur from the Early Cretaceous Ejinhoro Formation of Inner Mongolia.
