SALT LAKE CITY (REUTERS) - A Utah man has admitted stealing and then throwing away a very rare fossilised dinosaur footprint, but will not spend any time in prison, according to court documents.

Jared Ehlers, a 35-year-old construction worker, pleaded guilty on Wednesday in US District Court in Salt Lake City to one federal charge of removing a paleontological resource.

Under the terms of the plea deal, he will be fined US$15,000 (S$18,633) and serve a year's probation, including six months of home confinement. In return for his plea, prosecutors dropped charges including theft and depredation of government property, and destruction of evidence.

The footprint was embedded in a 70-kg rock slab in the Sand Flats Recreation Area, near Moab, about 380 km southeast of Salt Lake City. The area is popular for its mountain bike trails, rugged red rock landscape and wealth of fossilised remains.

The print dates from the Jurassic period and is thought to be about 190 million years old, according to paleontologists from the Bureau of Land Management. It is one of just 26 similar three-toed dinosaur prints known in the area.

Federal prosecutors say Ehlers stole the rock on Feb 17, but tossed the artifact into the nearby Colorado River on March 8 after he was questioned by authorities. A search of the river by officers from the Grand County Sheriff's Office and the Utah Department of Public Safety failed to recover the fossil.

By pleading guilty, Ehlers avoided a trial, which had been set for this week, and a possible prison term of up to 45 years, plus some US$250,000 in fines, according to court documents. Prosecutors have said they will recommend a judge accept the negotiated punishment when he is sentenced in October.