John Robert Horner (born June 15, 1946) is an American paleontologist who alongside fellow paleontologist Bob Makela described Maiasaura, providing the first clear evidence that some non-avian dinosaurs cared for their young.

In addition to his paleontological discoveries, Horner has become a popular scientist among the public: he served as the technical advisor for the first five Jurassic Park films, had a cameo appearance in Jurassic World, and served as a partial inspiration for one of the lead characters of the franchise, Dr. Alan Grant.

Early life and formation

Horner was born and raised in Shelby, Montana on June 15, 1946 from John Horner, the owner of a sand-and-gravel business, and Miriam Horner (née Whitted). He has a brother, Jim Horner, and a younger sister, Rosemary Horner. From an early age, Horner was called "Jack" by everyone. but managed to graduate in 1964. The same year, he enroled at the University of Montana where he majored in geology and zoology, but once again he encountered the same problems when trying to read and learn. He flunked his first year at the university so he decided to withdraw his college studies and, instead, enlist with the Marines. Horner served in the Vietnam War from 1966 to 1968 While Horner was working at Princeton, he and Makela kept prospecting together in north-western Montana during the Summers. In 1978, near Choteau, Montana, they discovered a colonial nesting site of a new dinosaur genus which they named Maiasaura, or "Good Mother Lizard". The dinosaur bones, originating from a juvenile, were first discovered by Marion Brandvold. Horner then studied the bones, and at first, there was a refusal to return the bones to Brandvold. It turned out that the discovered site also contained the first non-avian dinosaur eggs ever discovered in the Western Hemisphere, the first dinosaur embryos, and settled questions of whether some dinosaurs were social, built nests and cared for their young. Because of the important quantity of dinosaur eggs and eggshell pieces it contained, the site ended up by earning the name of "Egg Mountain". The discovery established Horner's career.

In the following years and throughout his career, Horner has been employed by a number of scientific institutions, mainly museums and universities, and he has extensively collaborated with them. Even if at the time of the Maiasaura discovery Horner hadn't completed his bachelor's degree, he nevertheless completed a senior thesis on the fauna of the Mississippian Bear Gulch Limestone, one of the most famous Lagerstätten in the world, located in Montana (Lagerstätten are exceptionally preserved fossil sites).

In the late 1970s Princeton was closing its paleontology department so Horner joined the Academy of Natural Sciences of Philadelphia for a few years. although he claims to have been pushed out after having married an undergraduate student 46 years his junior. He then taught as a Presidential Fellow at Chapman University in Orange, California. The same year, 2016, following a proposal by the University of Washington in Seattle, Washington, Horner was hired as a research associate at the Burke Museum of Natural History and Culture which is the natural history museum of the University. In 2026, his connections with Jeffrey Epstein attracted controversy and in February 2026 his employment with Chapman University ended.

Today Horner remains active in the scientific milieu as a research associate within the Burke Museum in Seattle, Washington.

Scientific heritage

Within the paleontological community, Horner is best known for his work on dinosaur growth research. He has published numerous articles in collaboration with Berkeley paleontologist Kevin Padian, and French dinosaur histologist Armand de Ricqlès, on the growth of dinosaurs using growth series. This usually involves leg bones in graduated sizes from different individuals ranging in age from embryos to adults. Horner also revitalized the contested theory that Tyrannosaurus rex was an obligate scavenger, rather than a predatory killer. While this theory has been widely discussed by the popular press, it has never been a major research focus for Horner. He claimed that he never published the scavenger hypothesis in the peer-reviewed scientific literature, stating that it was mainly a tool for him to teach a popular audience, particularly children, of the dangers of making assumptions in science (such as assuming T. rex was a hunter) without using evidence. In 2000, teams led by Horner discovered five specimens of T. rex and three more the following summer, including one larger than the specimen nicknamed "Sue". The new fossil was 10% larger than other specimens and estimated to weigh 10–13 tons in life. The Museum of the Rockies, as the result of continuing fieldwork, now exhibits the largest Tyrannosaurus rex collection in the world.

After Maiasaura in 1979, Horner has named several other species of dinosaur (including Orodromeus makelai, in memory of his late friend Bob Makela, who had died in a car accident in 1987) and has had three named after himself: Achelousaurus horneri, Anasazisaurus horneri, and Daspletosaurus horneri.

Horner has published over 100 professional papers, twelve books including Dinosaurs Under the Big Sky; the children's book Maia: A Dinosaur Grows Up; a non-fiction book on dinosaurs from Montana, Dinosaur Lives; and numerous articles. He was also a part of a 2005 discovery of soft tissue in a T. rex fossil. Horner was the Curator of Paleontology at the Museum of the Rockies, the Regent's Professor of Paleontology, adjunct curator at the National Museum of Natural History, and taught at the Montana State University in Bozeman, Montana. Over the years he has advised people who have gone on to be leading experts in paleontology, such as Mary Higby Schweitzer, Greg Erickson, Kristi Curry-Rogers, and David J. Varricchio. Horner was awarded an honorary doctorate by Pennsylvania State University in 2006 in recognition of his work.

In 2003, Horner discovered a fossilized tyrannosaur leg bone from which paleontologist Mary Higby Schweitzer was able to retrieve proteins in 2007.

In 2006 and onwards, Horner has also studied the developmental biology of the so-called "parrot-like dinosaurs" (of the Psittacosauridae family), based on 67 individuals discovered all together at the same site in Mongolia.

In 2009, the National Geographic Society released a documentary entitled "Dinosaurs Decoded", which reviews Horner's research into juvenile dinosaurs. He suggests that juvenile dinosaurs looked sufficiently different from adults, and that they have sometimes been mistaken for separate species. The program examines specific changes that occurred as dinosaurs aged and speculates on why the changes were necessary. Horner's research on the topic has gone as far as eliminating several "sub-species" of Triceratops, Pachycephalosaurus, and Tyrannosaurus. Horner also believes that if his research were to continue as much as a third of known dinosaurs would be classified under an existing species.

On his retirement from Montana State University on July 1, 2016, the MacMillan Foundation honored Horner for his work with a $3 million endowment for the John R. Horner Curator of Paleontology Chair for the Museum of the Rockies/ Montana State University - funding the work of his Paleontology successors in perpetuity.

Appearances in media, popularity and controversies

In 1985, the CBS television documentary Dinosaur! showed Horner talking to the camera about the "Egg Mountain" site and its related discoveries. Horner reappeared on television, this time with extended screen time about the Maiasaura discoveries, in another programme, "The Great Dinosaur Hunt", part of The Infinite Voyage series of documentaries. The Great Dinosaur Hunt first aired on January 4, 1989. In 1991 two short documentaries produced by Earthtalk Studios: A Giant Leap for Dinosaurs and Dinosaur Hunters, both directed by Daniel J. Smith, showed Jack Horner at Camp Makela (the scientists' camp that is on site at "Egg Mountain") talking with children and adolescents about the cutting edge of dinosaur research.

Horner was the subject of the 1994 biographical book Jack Horner: Living With Dinosaurs (Science Superstars), authored by Don Lessem and Janet Hamlin.

In 2021 Horner was also the subject of the children's book Jack Horner, Dinosaur Hunter!, written by Sophia Gholz, illustrated by Dave Shephard, and published by Sleeping Bear Press. The book, which has been translated into French, chronicles the life of Horner, from a child in Montana to an adult on the set of Jurassic Park, and discusses Horner's scientific contributions as well as navigating life with a reading disability.

In popular culture, Horner is probably better remembered as one of the scientific advisors who were hired for the Jurassic Park franchise, for which he was called for the first five films.

In 2012 Horner's marriage with Vanessa Weaver, 46 years his junior, caused some controversy describes his plan to recreate a dinosaur by genetically "nudging" the DNA of a chicken. Horner's idea for the project came from an early script for the film Jurassic World.

He had been planning the book as early as June 2005; it was originally planned to be released simultaneously with Jurassic World as a scientific companion volume.

In 2011, Horner pursued the project to develop the animal, which he describes as a "chickenosaurus", with a team of geneticists. By November 2014, Horner and his team had conducted some of the earliest research into the embryonic development of tails. Such research may ultimately lead to new treatments for people with spinal disorders. Research into the mesenchyme tissue of chicken embryos, which direct the growth of teeth, may also aid in the treatment of human sarcomas. George Lucas had funded most of the project's costs up to that point, while an additional $5 million was needed. Horner expected to have a living dinosaur within 10 years. In 2026, released emails from the Epstein files revealed that Horner had discussed the project with Jeffrey Epstein in 2012, and that Epstein had expressed interest in funding the project. and University of Chile geneticists have produced embryos with dinosaur-like leg and foot anatomy including the fibula full-length and reaching the ankle.

Personal life

Jack Horner has been married four times throughout his life. On March 30, 1972 he married his first wife, Virginia Lee Seacotte, with whom he has a son, Jason James Horner. After divorcing from Seacotte in 1982, he married Joann Katherine Raffelson on October 3, 1986, from whom he divorced in 1994. Less than a year after his divorce from Raffelson, Horner married Celeste Claire Roach on January 21, 1995. Their marriage lasted ten years until they divorced in 2005. Also in 1986, he was awarded the prestigious MacArthur Fellowship. In 1989 Horner was granted with the New York Academy of Sciences Children's Science Book Award for his 1988 book Digging Dinosaurs: The Search That Unraveled the Mystery of Baby Dinosaurs. On November 2, 2013, Horner was awarded the Romer-Simpson Medal, the highest honor a paleontologist can receive from the Society of Vertebrate Paleontology.

  • Digging Dinosaurs: The Search That Unraveled the Mystery of Baby Dinosaurs (1988, with James Gorman, Workman Publishing)
  • The Complete T. Rex: How Stunning New Discoveries Are Changing Our Understanding of the World's Most Famous Dinosaur (1993, with Don Lessem, Simon & Schuster)
  • Dinosaur Eggs and Babies (1994, with Kenneth Carpenter and Karl F. Hirsch, Cambridge University Press)
  • Digging Up Tyrannosaurus Rex: The Remarkable Story of the Discovery of the First Complete Tyrannosaurus rex Ever Found (1995, with Don Lessem, Knopf Books for Young Readers)
  • Dinosaur Lives: Unearthing an Evolutionary Saga (1998, with Edwin Dobb, Harcourt)
  • Dinosaurs: Under the Big Sky (2001, Mountain Press)
  • How to Build a Dinosaur: Extinction Doesn't Have to Be Forever (2009, with James Gorman, Dutton Adult)
  • Dinosaurs of Montana (2025, with Raymond R. Rogers, Montana Bureau of Mines and Geology, illustrations by Doug Henderson)

Children's books by Jack Horner

  • Maia: A Dinosaur Grows Up (1985, with James Gorman and Jeri D. Walton, published by the Museum of the Rockies, illustrations by Doug Henderson)
  • Digging Up Dinosaurs (2007, Farcountry Press, illustrations by Robert Rath and Phil Wilson)
  • Lily and Maia: A Dinosaur Adventure (2023, Horner Science Group, illustrations by Grace Hattrup)

Novels by Jack Horner

  • Dinosaur Valley (2025, with Julian Michael Carver, Pteranodon Press)

References

  • http://www.hornersciencegroup.com
  • http://www.jackhornersworldofdinosaurs.com
  • Museum of the Rockies
  • "Where are the baby dinosaurs?" (TEDxVancouver 2011) (also )
  • "Building a dinosaur from a chicken" (TED2011) (also )