Spinops sternbergorum weighed around 2 tons when it was alive, but it was overlooked for decades on the shelves of the Natural History Museum in London. Curators decided the fossils, discovered in 1916 by father and son fossil collectors Charles H. and Levi Sternberg, were in no condition to display. Eventually paleontologists recognized the value of the fossils and cleaned them up for study. They finally gave the horned dinosaur a name last year in a paper published in Acta Palaeontologica Polonica.
Image: Copyright Dmitry Bogdanov, courtesy of Raymond M. Alf Museum of Paleontology