Craterosaurus

Craterosaurus is a genus of stegosaurian dinosaur that lived during the Early Cretaceous period, with its fossils originating from the Woburn Sands Formation in England. The genus is considered dubious, or a "nomen dubium," due to the extreme incompleteness of its fossil remains. Only a single partial vertebra has ever been recovered, making definitive classification challenging.

Naming and Classification

The fossil was discovered in a brown sandstone layer near Potton, Bedfordshire, and was described by palaeontologist Harry Govier Seeley in 1874 as Craterosaurus pottonensis. Initially, Seeley interpreted the fossil as part of a braincase and suggested uncertain relationships within Dinosauria, possibly aligning with Ceteosauria or Iguanodon. Later, in 1912, Franz Nopcsa re-evaluated the specimen, correctly identifying it as part of the neural arch of a dorsal vertebra. This allowed Nopcsa to tentatively place Craterosaurus within Stegosauria, noting its similarity to Stegosaurus. However, subsequent reviews, including those by Susannah Maidment and colleagues, have concluded that the fossil lacks diagnostic features, solidifying its status as a dubious genus.

Physical Characteristics and Time Period

Based on the limited fossil evidence, Craterosaurus is estimated to have measured around 4 meters (13 feet) in length and weighed approximately 560 kilograms (1,230 pounds). It is believed to have been a quadrupedal herbivore, characteristic of stegosaurian dinosaurs. The precise temporal range is thought to be the Aptian stage of the Early Cretaceous, though it is possible the fossil material has been reworked from older sediments. Its anatomical features, while incomplete, show characteristics consistent with the Stegosauria group. Due to its fragmentary nature, Craterosaurus is sometimes considered a potential junior synonym of the related stegosaurian Regnosaurus.