‘Pickstown plesiosaur’ unearthed in South Dakota

The discovery of a new plesiosaur specimen was recently announced by the South Dakota School of Mines and Technology, South Dakota, USA. 11-year-old Devon Zimmerman noticed the skull and part of the backbone on the bank of the Missouri River, near Pickstown, South Dakota, during a vacation with parents Duane and DeeAnn Zimmerman of Sioux City, Iowa.

They reported the discovery to the United States Army Corps of Engineers, who contacted Dr. James E. Martin, executive curator of the Museum of Geology at the South Dakota School of Mines and Technology. Martin and volunteers spent a fortnight unearthing the specimen and have recovered about 60% of the skeleton, including a three-foot long skull – the length of the animal is estimated to be about 20-25 feet long. The fossil is now in storage in the School of Mines and Technology, but the excavation is not complete so additional remains may be found.

The Pickstown plesiosaur is short-necked but it has not been announced whether it is a pliosaurid or a polycotylid. Stomach contents were also found associated with the plesiosaur and consist of three different types of fish. The plesiosaur died with a full stomach. The fossil skeleton was found along with altered volcanic ash known as bentonite, which it has been speculated may have choked the animal to death after its fish supper.

Comments 1

  • I was with the Zimmerman family when they reported their find to the Army Corp of Engineers back in 2008. Is there any update on the work being done to the specimen or any further identification? Hard to believe it has already been 13 years since it was found! I’m hoping some day the local visitor center at Ft Randall Dam will include a picture of how it was originaly found or a cast replica of this great find. Thank you.

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