John Robert Horner (born June 15, 1946) is an American paleontologist most famous for describing Maiasaura, providing the first clear evidence that some dinosaurs cared for their young.

[3][4] Horner studied at the University of Montana, although he did not complete his degree due to undiagnosed dyslexia, and was awarded a Doctorate in Science honoris causa.

[8] However, he did complete a senior thesis on the fauna of the Bear Gulch Limestone, one of the most famous Mississippian lagerstätten (exceptionally preserved fossil sites) in the world, located in Montana.

[10] In Montana during the mid-1970s, Horner and his research partner Bob Makela discovered a colonial nesting site of a new dinosaur genus which they named Maiasaura, or "Good Mother Lizard".

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.

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.

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

[21] In Las Vegas on January 15, 2012, 65-year-old Horner married Vanessa Weaver, a 19-year-old Montana State University undergraduate paleontology student and volunteer in his lab.

[22] 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.

Research into the mesenchyme tissue of chicken embryos, which direct the growth of teeth, may also aid in the treatment of human sarcomas.

[35] In 2015, an independent group of scientists reported that they had found a way to turn the beaks of chicken embryos back into dinosaur-like snouts, by reverse genetic engineering,[36] and University of Chile geneticists have produced embryos with dinosaur-like leg and foot anatomy including the fibula full-length and reaching the ankle.