Question 1

How do you say Opisthocoelicaudia?

Accepted Answer

Say it like this: oh-PIS-tho-SEEL-ih-KAW-dee-ah. Break it into five chunks and tackle them one at a time: oh, PIS, tho, SEEL, ih, KAW, dee, ah. The trickiest part is the middle, where coeli is pronounced SEEL, not co-ee-lee. A good memory trick is to say 'oh PISS tho SEAL ih CAW dee ah' slowly, then speed it up. The Natural History Museum London uses the pronunciation o-pis-tho-seel-i-cawd-ee-a, which matches this breakdown perfectly.

Question 2

What does Opisthocoelicaudia mean?

Accepted Answer

The name means posterior cavity tail, which sounds strange until you learn what it is describing. The tail vertebrae of this dinosaur have their ball-and-socket joints oriented backward toward the tail rather than forward toward the head. The opistho part comes from Greek and means behind, the coeli part comes from Greek koilos meaning hollow or cavity, and the caudia part comes from Latin cauda meaning tail. Paleontologist Maria Borsuk-Bialynicka chose this name in 1975 because that unusual tail bone structure was the most distinctive thing about the skeleton she was describing.

Question 3

Why did they name it after its tail bones?

Accepted Answer

When Maria Borsuk-Bialynicka described Opisthocoelicaudia in 1975, the tail was the part of the skeleton that most stood out scientifically. In nearly all sauropods the ball part of each vertebra's joint faces forward toward the head, a condition called procoelous. In Opisthocoelicaudia the ball faces backward toward the tail, which is called opisthocoel and is extremely rare. This single feature told scientists they were dealing with a genuinely unusual animal, so it made perfect sense to build the name around it. It is a tradition in paleontology to name dinosaurs after their most distinctive features.

Question 4

Where was Opisthocoelicaudia found?

Accepted Answer

Opisthocoelicaudia was discovered in the Gobi Desert of Mongolia, one of the richest dinosaur fossil sites on Earth. The main skeleton was unearthed in 1965 during a joint Polish and Mongolian Palaeontological Expedition. The fossils came from the Nemegt Formation, a rock unit famous for preserving a vivid picture of a Late Cretaceous ecosystem full of predators and plant-eaters. To date only three specimens have ever been found, all from Mongolia, making it a uniquely Mongolian dinosaur.

Question 5

Why is the head and neck missing from the skeleton?

Accepted Answer

The 1965 skeleton of Opisthocoelicaudia is incredibly complete from the shoulders to the tail, but the head and neck were simply not there when scientists found it. The answer written into the bones is dramatic: large tooth marks and scrape marks left by carnivorous dinosaurs were found on the remaining skeleton. Paleontologists concluded that a massive theropod, possibly Tarbosaurus which lived in the same ecosystem, had fed on the dead animal and physically torn the head and neck away and carried them off. This kind of scavenging behavior is rarely preserved so clearly in the fossil record.

Question 6

How big was Opisthocoelicaudia?

Accepted Answer

Opisthocoelicaudia measured between about 11.4 and 13 metres long, which is roughly 37 to 43 feet. That is about as long as three full-sized SUVs parked bumper to bumper. It was not the absolute largest sauropod ever, but it was a heavyweight titanosaur and would have been one of the biggest animals in its entire Mongolian ecosystem. Its legs were thick and column-like to support its enormous body mass, estimated at around 9,000 kilograms or about 20,000 pounds.

Question 7

What did Opisthocoelicaudia eat?

Accepted Answer

Opisthocoelicaudia was a herbivore, meaning it ate only plants. Like all sauropods it would have consumed enormous quantities of vegetation every day to fuel its massive body. Some researchers think its unusually strong tail may have allowed it to rear up on its hind legs, bracing with its tail like a tripod, to reach high treetop vegetation that other herbivores in its ecosystem could not access. Unfortunately no skull has ever been found for this dinosaur, so scientists do not yet know exactly what its teeth looked like or precisely how it processed plant material.

Question 8

Is Opisthocoelicaudia related to T. rex?

Accepted Answer

No, Opisthocoelicaudia was not related to T. rex at all. It was a sauropod, the group of long-necked plant-eating giants, while T. rex was a theropod and a meat-eater. They are about as different as dinosaurs get. However, they were both alive at roughly the same time, during the very end of the Cretaceous Period around 66 million years ago. In Mongolia, the closest equivalent to T. rex was Tarbosaurus, and it is likely Tarbosaurus that left those dramatic tooth marks on the Opisthocoelicaudia skeleton found in 1965.

Opisthocoelicaudia Pronunciation

Opisthocoelicaudia Picture

What does Opisthocoelicaudia mean?

Name Roots

Fun Facts

Learn More About Opisthocoelicaudia

Related Dinosaurs