Trinacromerum is an extinct genus of sauropterygia

Sauropterygia

Sauropterygia were a group of very successful aquatic reptiles that flourished during the Mesozoic before they became extinct at the end of the era. They were united by a radical adaptation of their shoulder, designed to support powerful flipper strokes...

n reptile belonging to the plesiosaur

Plesiosaur

Plesiosauroidea is an extinct clade of carnivorous plesiosaur marine reptiles. Plesiosauroids, are known from the Jurassic and Cretaceous Periods...

 suborder. It lived during the Late Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 period in what is now Kansas

Kansas

Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...

. It was 3 meters (10 feet) long. Its teeth show it fed on small fish.

The long flippers of Trinacromerum enabled it to achieve high swimming speeds. Its physical appearance was described by Richard Ellis

Richard Ellis (biologist)

Richard Ellis is an American marine biologist, author, and illustrator. He is a research associate in the American Museum of Natural History's division of paleontology, special adviser to the American Cetacean Society, and a member of the Explorers Club. He was U.S...

as akin to a "four-flippered penguin."