Peter Lars Larson (born 1952) is an American paleontologist, fossil collector, and president of the Black Hills Institute of Geological Research. He led the team that excavated "Sue", the largest and most complete specimen of Tyrannosaurus rex found to date, and has published numerous scientific and popular works on dinosaur paleontology. He is criticized by some academic paleontologists for his commercial enterprises and support of private collections.
Peter Larson grew up on a ranch near Mission, South Dakota. He began rock hunting at the age of four on his parent's ranch. He attended the South Dakota School of Mines to study paleontology. He graduated with a bachelor's degree in 1974. Shortly after graduating college he started Black Hills Minerals.
Larson founded what eventually became the Black Hills Institute in 1974. Partners Robert Farrar and (Larson's brother) Neal Larson later joined the company. In 1990, Larson led the excavation of the Tyrannosaurus rex skeleton later named "Sue". With only a bachelor's degree in geology, Larson has written and co-authored numerous publications on dinosaurs, has excavated more T. rex skeletons than any other paleontologist, and his organization's work on excavation and preparation of fossils has been recognized by paleontologists Robert Bakker, Philip Currie, Phillip Manning, and Jack Horner for its quality. He was one of the first to work with T. rex bone pathologies, has worked to uncover sexual dimorphism in the chevron length of T. rex, and argues that the controversial tyrannosaurid Nanotyrannus is not a juvenile T. rex, as some claim.
In 1992, Larson's team helped to discover second largest Tyrannosaurus rex Stan. Larson, along with paleontologist Kenneth Carpenter, edited the scholarly text Tyrannosaurus Rex, the Tyrant King. Larson and his ex-wife Kristin Donnan wrote the book Rex Appeal, which relates the story of how the U.S. Government took possession of the "Sue" T. rex skeleton following its excavation, and Bones Rock!, a children's book about the history of paleontology and requirements on how to become a palaeontologist.
Following a result of the government seizure of property at the Black Hills Institute, from charges pertaining to paleontological work unrelated to the "Sue" T. rex find, Larson was remanded to the federal penitentiary at Florence, Colorado for his conviction of two felonies and two misdemeanors, charges which some considered politically motivated. The felonies involved the "failure to fill out forms," which resulted from contested instructions from the judge. The trial record shows that the judge told the jury to ignore testimony from the government's own customs witnesses, testimony that normally would have resulted in acquittals in these charges. Richard Howard Battey sentenced Larson two years in federal prison despite the maximum sentence being only six months. In 2015, South Dakota lawmakers have petitioned Barack Obama for a formal full pardon of Larson.
Larson has developed a controversial standing among some academic paleontologists who object to his organization's commercial selling of fossils and his lack of pedigree, yet Robert Bakker has backed Larson as a responsible paleontologist. To date, he has discovered the most tyrannosaurus rex skeletons and is considered by some to have made some of the greatest paleontological discoveries of all time.