Muttaburrasaurus is a genus of herbivorous ornithopod dinosaur that lived in what is now north-eastern Australia during the Albian-Cenomanian stages of the Cretaceous period. It has been recovered in some analyses as a member of the iguanodontian clade Rhabdodontomorpha, but more recent research has suggested a more basal position in the ornithopod family tree, potentially as a member of Elasmaria. After Kunbarrasaurus, it is Australia's most completely known dinosaur from skeletal remains. It was named after Muttaburra, the site in Queensland, Australia, where it was found. The dinosaur was selected from twelve candidates to become the official fossil emblem of the State of Queensland.
Discovery
thumb|left|Maps and photos of the [[holotype locality]]
The species was initially described from a partial skeleton found by grazier Doug Langdon in 1963 at Rosebery Downs Station beside Thomson River near Muttaburra, in the Australian state of Queensland, which also provides the creature's generic name. The remains were collected by paleontologist Dr Alan Bartholomai and entomologist Edward Dahms. After a lengthy preparation of the fossils, it was named in 1981 by Bartholomai and Ralph Molnar, who honoured its discoverer with its specific name, langdoni.
thumb|right|Holotype skull in multiple views
The holotype, specimen QM F6140, was found in the Mackunda Formation. The depositional age of the type locality is suggested to be the Cenomanian stage, specifically 96.3 ± 8.6 million years ago, based on U/Pb detrital zircon samples in the vicinity of holotype. It consists of a partial skeleton with skull and lower jaws. The underside of the skull and the back of the mandibula, numerous vertebrae, parts of the pelvis, and parts of the front and hind limbs have been preserved.
Some teeth have been discovered further north, near Hughenden, and south at Lightning Ridge, More recent research suggests much greater mass estimates for the taxa. Bishop et al. in 2020 used volumetric modeling to suggest a body mass of around 7,916 kg, while a 2026 study by Herne et al. calculated a body mass of around 8,854 kg using stylopodial equations. This would make Muttaburrasaurus comparable in size to some of the larger specimens of T. rex and bull African bush elephants, making it by far the largest ornithischian to retain premaxillary teeth. A 2022 phylogenetic analysis recovered Muttaburrasaurus and Tenontosaurus as basal rhabdodontomorphs and found them to likely represent sister taxa to Rhabdodontidae.
The following cladogram was recovered by Dieudonné and colleagues in 2016:
thumb|right|3D model of the holotype skull
However, in 2024, Fonseca and colleagues considered Muttaburrasaurus to be outside Rhabdodontomorpha and instead classified it as a member of the Gondwanan clade Elasmaria, alongside Fostoria dhimbangunmal. In their 2026 redescription of the Muttaburrasaurus skull, Herne and colleagues comment that several cranial features, including the retention of premaxillary teeth, mean the taxa is likely not a rhabdodontomorph and may even fall outside of the greater Iguanodontia clade. Reanalysis of the holotype skull published in 2026 suggests that Muttaburrasaurus was a selective feeder due to its narrow snout and possessed a strong sense of smell. Additionally, it was proposed in this same study that Muttaburrasaurus may have possessed nasal salt glands, suggesting it fed on plant material that led to excess salt digestion.