A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Appendix

Udanoceratops
Taxon: Ceratopsia Protoceratopidae
Name means: “Udan horned face”
Pronounced: oo-DAHN-o-SER-a-tops
Length: about 15 ft (4.5 m)
Time: Late Cretaceous, 86 – 83.5 mya
Place: Mongolia

This large protoceratopsian may have been the largest ceratopsian dinosaur to retain the ability to walk on only its hind legs. Udanoceratops was named for the Udan Sayr fossil locality in Mongolia in 1992.

Uintasaurus
Name means: “Uinta lizard”
Pronounced: yoo-IN-ta-SAWR-us

This dinosaur is now known to be CAMARASAURUS.

Ultrasauros
Name means: “ultra lizard”
Pronounced: UHL-tra-SAWR-ose

The fossilized remains of this immense sauropod are now recognized as belonging to both SUPERSAURUS and a large specimen of BRACHIOSAURUS. “Ultrasauros” was to be named Ultrasaurus before it was discovered that the name had already been used for a South Korean sauropod, which is now also considered invalid as a genus.

Unenlagia
Taxon: Theropoda Coelurosauria ?Maniraptora
Name means: “half bird”
Pronounced: oon-en-LAHG-ee-a
Length: 6.5 – 10 ft (2 – 3 m)
Time: Late Cretaceous, c. 93.5 – 86 mya
Place: Argentina

A very bird-like dinosaur, Unenlagia might have had feathers, but was too large to ever have been a flyer. Due to the many anatomical similarities between the two, Unenlagia may have shared a common ancestor with Archaeopteryx. Some researchers suggest that this dinosaur, which was named in 1997, may have been a juvenile Megaraptor or the land-bound descendant of a flying “dino-bird.”

Unquillosaurus
Taxon: Theropoda
Name means: “Unquillo lizard”
Pronounced: oong-KEE-yo-SAWR-us
Length: about 6.5 – 13 ft (2 - 4 m)
Time: Late Cretaceous, c. 83 – 73 mya
Place: Argentina

This meat-eating dinosaur was named in 1979 for the Unquillo River in Argentina. Originally said to be some 36 feet (11 meters) in length, Unquillosaurus has been considerably shrunk with further study. Some researchers believe that this was the same animal as Unenlagia.

Utahraptor
Taxon: Theropoda Dromaeosauridae
Name means: “Utah plunderer”
Pronounced: YOO-tah-RAP-tor
Length: 16 – 23 ft (5 – 7 m)
Time: Middle Cretaceous, 125 mya
Place: Utah

This giant dromaeosaurid was twice the size of Deinonychus. Doubtless a ferocious and deadly predator, Utahraptor carried a huge, sickle-like slashing talon on each foot and bore flattened, bladelike claws on its hands. Its long, stiffened tail provided balance while running, leaping, or kicking at prey with its lethal slashing claws. Utahraptor was named in 1993.