LOPHORHOTHON

Upon discovery in the 1940s, the fossils that would become Lophorhothon were the first dinosaurian remains known from Alabama. Still, almost two decades passed before they were officially named and described, and since then, "strange crested nose" has done much moving and shaking on the ornithopod branch of the dinosaurian family tree.

Initially classified as a member of Hadrosaurinae in 1960, Lophorhothon didn't have to wait long before suspicious palaeontologists pegged it as a juvenile specimen of the same area's Parasaurolophus due to its modest size and similar though more forward-positioned snout crest. In 1998, James Lamb suggested it was an iguanodont, Horner et al. returned it to Hadrosaurinae in 2004, and in 2010 Prieto-Marquez found it to be a basal hadrosauroid. After the latest round of research, it was assigned to Saurolophinae: a family of mostly crestless duck-billed dinosaurs that was formerly known as—guess what?—Hadrosaurinae. So, after six decades, Lophorhothon is more or less right back where it started, albeit without the company of Hadrosaurus, whose dubious remains prompted the family name change.

For an added twist, Hadrosaurinae was resurrected in 2011 by Prieto-Marquez when he found its name-bearer to be valid after all. But it's a bit pointless with Hadrosaurus as the sole member, and no one seems keen to move its former members back there.