Researchers have discovered two different types of benign tumors on a single vertebra from a gigantic, long-necked, plant-eating titanosaur that lived in what’s now southeastern Brazil. The findings are published in the new issue of Cretaceous Research.
Unlike infections or traumatic lesions, evidence of neoplasms (or tumors), either malignant or benign, are extremely rare in the fossils of vertebrate animals. And in dinosaurs, they’ve only ever been found in just one single family: the hadrosaurids, or the duck-billed dinosaurs. However, recent work on dinosaurs from the Upper Cretaceous of Argentina and Brazil – Mapusaurus and a titanosaur called Uberabatitan riberoi, respectively – suggested that this pathological condition is more widespread than researchers previously suspected.
Now, a team led by Fernando Henrique de Souza Barbosa of Universidade Federal do Rio de Janeiro report the first case of documented neoplasia in a non-hadrosaur dinosaur. They studied a specimen called UFRJ-DG 508-R recovered from Late Cretaceous rocks in the Adamantina Formation in the Alfredo Marcondes municipality of State of São Paulo. The caudal vertebral centrum (part of the tailbone) came from a member of the Titanosauridae family, though it’s not possible to identify the animal down to the species level.
The vertebra had an isolated small, bony, button-shaped protuberance that measures 8.6 by 7.5 millimeters (about 0.3 by 0.3 inches), and it occupies a 50.03-square-millimeter area corresponding to 5.45 percent of the surface where articulation occurs. After a series of examinations and CT scanning, the team found two different types of neoplasia in the vertebra: osteoma and hemangioma. An osteoma is a benign, slow-growing, bone-forming tumor, and a hemangioma is a benign vascular tumor. Because of their location and size, these tumors probably didn’t affect the dinosaur much.
The oldest reported case of an osteoma was found in an Early Carboniferous fish called Phanerosteon mirabile from North America some 300 million years ago, and other reports of osteomas include an Upper Cretaceous mosasaur from the U.S., a croc from the Paleocene, and a whale from the Lower Pliocene of Chile. Meanwhile, hemangiomas have been found in duck-billed dinos called Brachylophosaurus, Gilmoreosaurus, Bactrosaurus, and Edmontosaurus. This study is the first time the presence of both osteoma and hemangioma was detected in a single specimen.