Pronunciation: o-PIS-tho-SEE-ly-COR-dee-uh
Meaning: Hollow-backed tail
Author/s: Borsuk-Bialynicka (1977)
Synonyms: None known
First Discovery: Gobi Desert, Mongolia
Discovery Chart Position: #255
Opisthocoelicaudia skarzynskii
Discovered in 1965 but not described until 1977, Opisthocoelicaudia was originally identified as a new type of camarasaurid closely related to Euhelopus by Maria Magdalena Borsuk-Bia?ynicka from the Polish Academy of Sciences, but later research by Salgado and Coria showed it to be a titanosaur, possibly a saltasaurid.
Unlike most Titan Lizards, the first fifteen of its thirty-four tail vertebrae has a hollow on the rear and a dome on the front, so each can slot into the next working towards the creatures head. This "ball and socket" design is said to afford great strength to the tail which—with the help of a reinforced pelvic region thanks to a sixth fused hip vertebra (most titanosaurs have five)—may have been used as a prop when when rearing up to feed from treetops.
Known only from a headless skeleton discovered in Mongolia, Opisthocoelicaudia shares some features with Borealosaurus, Sonidosaurus and Huabeisaurus, but it could turn out to be a specimen of Nemegtosaurus which was discovered in the same formation in 1971 and is, funnily enough, known only from a skeleton-less head.
Unlike most Titan Lizards, the first fifteen of its thirty-four tail vertebrae has a hollow on the rear and a dome on the front, so each can slot into the next working towards the creatures head. This "ball and socket" design is said to afford great strength to the tail which—with the help of a reinforced pelvic region thanks to a sixth fused hip vertebra (most titanosaurs have five)—may have been used as a prop when when rearing up to feed from treetops.
Known only from a headless skeleton discovered in Mongolia, Opisthocoelicaudia shares some features with Borealosaurus, Sonidosaurus and Huabeisaurus, but it could turn out to be a specimen of Nemegtosaurus which was discovered in the same formation in 1971 and is, funnily enough, known only from a skeleton-less head.
Etymology
Opisthocoelicaudia is derived from the Greek "opisthe" (back) and "koilos" (hollow) and the Latin "cauda" (tail) because of the opisthocoelous or opisthocoelian (both mean "hollowed at the rear") structure of its tail vertebrae.
We were hoping the species epithet, skarzynskii, was named to honour Polish aviator Stanislaw Jakub Skarzynski — famous for his transatlantic solo flight in 1933. Alas, it was named after Mr. Wojciech Skarzynski who prepared the specimen.
Preparators
Wojciech Skarzynski.
Discovery
The first remains of Opisthocoelicaudia were discovered at Altan Uul in the Nemegt Formation, Ömnögovi Aimag (South Gobi Province), Mongolia, by Ryszard Gradzinski during a joint Polish-Mongolian Expedition led by Zofia Kielan-Jaworowska in 1965.
The holotype (ZPAL MgD-I/48 - housed at the Institute of Geology in the Mongolian Academy of Sciences, Ulaanbataar) is a partial skeleton, possibly tyrannosaur-scavenged, judging by teethmarks on its pelvis and femur. It was in decent condition, but lacking a skull and neck.
