Fulgurotherium

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Fulgurotherium australe: a questionable Australian dinosaur

Fulgurotherium australe is a dubious dinosaur from the Late Cretaceous, living about 99–96 million years ago in what is now New South Wales, Australia. The only certain specimen is a piece of the femur (BMNH R.3719) found in the Griman Creek Formation at Lightning Ridge and preserved as opal.

Discovery and name
The fossil was first mentioned in 1909. In 1932, German paleontologist Friedrich von Huene named it Fulgurotherium australe, thinking it was a large coelurosaur related to Ornitholestes and Oviraptor. The name combines Latin fulgur, meaning “lightning,” with therion, meaning “beast,” a nod to the Lightning Ridge site.

Classification history
The bone was originally misidentified, which led to it being placed among theropods and later moved to the Ornithomimidae. In 1986, Molnar and Galton reinterpreted the femur as belonging to a hypsilophodont‑like dinosaur related to Leaellynasaura and Nanosaurus, and they and others referred several more femora from Dinosaur Cove to Fulgurotherium. For a time, it was listed as one of a few valid hypsilophodonts from Australia.

In 1999, Rich and Vickers-Rich argued that the holotype was too worn to be a reliable type specimen and considered the name a nomen dubium (an invalid name). Since then, the status has remained doubtful. Some analyses suggest the holotype and related material may belong to a non-mammal iguanodontian, while others have proposed an elasmarian affinity, depending on the study.

Size
The holotype bone is about 7 cm long and 4.5 cm wide, making it one of the larger basal ornithischian femora found in Australia.

Meaning
The genus name means “lightning beast,” even though it is not a mammal.