BILLINGS (AP) -- An Ekalaka student whose science fair project studied the bite force of a Tyrannosaurus rex finished in fourth place at the International Science and Engineering Fair in Albuquerque, N.M.

Nathan Carroll was one of 1,512 high school students from 50 countries who competed in the weeklong science fair that ended Friday.

His project, ''Tooth Structure Functionality of Tyrannosaurus rex vs. Crocuta crocuta,'' involved a heavy steel apparatus attached to a bronze casting of a T. rex jaw and a bronze hyena jaw. Using the device, the Carter County High School graduate conducted experiments that compared the bite force of the two jaws and determined how the jaws and teeth functioned.

Carroll hauled the apparatus to the Science Expo 2007 in Billings, but for the international expo in Albuquerque he had to be satisfied with showing a video detailing his experiments. He also had resin casts of the dinosaur teeth used in the experiments.

Carroll won a $500 prize for his fourth-place showing in the animal sciences division of the fair sponsored by Intel. The winning entry in that division looked at the ''Maternal Effects of Diet Restriction in Fruit Flies'' and was presented by a student from Georgia.

Carroll said he had to leave Albuquerque a day early to make it back to Ekalaka in time for graduation on Saturday.

''I had a valedictory address to give, which I wrote on the plane ride home,'' he said. He has received a Presidential Scholarship to Montana State University, where he intends to major in paleontology.