A groundbreaking study led by researchers including those from Flinders University has transformed our understanding of Muttaburrasaurus langdoni, one of Australia's most iconic dinosaurs. This large-bodied ornithopod, which roamed central Queensland around 96 million years ago during the mid-Cretaceous period, was long envisioned with a toothless beak suited for broad cropping of vegetation. However, new fossil evidence reveals a much more discerning feeder equipped with an extraordinary sense of smell, allowing it to selectively nibble on the tastiest plants, seeds, and possibly small invertebrates. The research, published today in the open-access journal PeerJ, combines advanced imaging techniques with newly discovered bones to paint a vivid picture of this selective browser's sensory world and behavior.

Muttaburrasaurus langdoni, named after the outback town of Muttaburra where its holotype was found in 1963, has been a symbol of Queensland paleontology. Standing up to 7-8 meters long and weighing around 9 tonnes, it was a dominant herbivore in a landscape fringed by the vast Eromanga Sea. Previous reconstructions depicted a duck-billed or parrot-like beak, but the latest analysis challenges this, highlighting specialized adaptations that set it apart from relatives like Iguanodon or hadrosaurs.

Rediscovering the Fossil Site: 1,300 New Bones Unearthed

The story begins with palaeontologist Dr. Matthew Herne's determined search. After years of effort, he relocated the original 1960s excavation site near Muttaburra in 2020, with permission from local landowners. Surface collecting and sieving yielded over 1,300 new bone fragments belonging to the holotype specimen (QMF6140). These included critical skull elements previously missing or poorly understood, such as premaxillary bones forming the snout tip and nasal structures. This haul, preserved in the Queensland Museum, provided the raw material for reanalysis, underscoring the value of revisiting historic sites as erosion exposes new treasures.

Geological dating via U/Pb detrital zircons pinned the Mackunda Formation to 96.3 ± 8.6 million years old (Cenomanian stage), placing Muttaburrasaurus in a coastal plain ecosystem with gymnosperms, ferns, and early angiosperms. The influx of fragments not only refined the skull reconstruction but also enabled non-destructive CT and neutron tomography at facilities like ANSTO's DINGO beamline and the Australian Synchrotron.

Teeth at the Snout Tip: Shattering the Toothless Beak Myth

One of the most startling revelations was the presence of teeth in the premaxilla, the front of the upper jaw. High-resolution CT scans confirmed five alveoli with conical, caniniform teeth—among the largest known in sizable ornithopods. This dentulous rostrum, transversely narrow with everted oral margins, contrasts sharply with the edentulous (toothless) beaks of advanced ornithopods like Triceratops or hadrosaurs.

Dr. Herne noted, “This was unexpected, because the beak of Muttaburrasaurus was thought to be toothless like many other well-known plant-eating species.” These teeth likely pierced protective coatings on fruits, seeds, bark, or cambium, or even nabbed invertebrates, enabling precise browsing rather than bulk grazing. Cheek teeth, with their spatulate crowns and grinding occlusion (zahnreihen spacing ~2), handled tougher vegetation, akin to modern kangaroos or cows.

🦠 A Supercharged Sniffer: Largest Olfactory Bulbs in Dinosaur History

The pièce de résistance is Muttaburrasaurus' olfactory prowess. Digital endocasts from CT data show olfactory bulbs with an olfactory ratio (OR) of 78.4%—the highest among sampled dinosaurs, surpassing Tyrannosaurus rex (71%) and Thescelosaurus (69.1%). This metric, derived from log OR vs. log body mass regression (R²=0.691, p≤0.05), places it well above the line (residual +0.106), indicating hyper-developed smell processing independent of size.

Paired, transversely broad bulbs (AP 62.8 mm, transverse 58.2 mm) dwarf the cerebrum (57 mm wide). Nasal cavities feature descending turbinate ridges on prenasal processes and superior looped airways diverting flow for prolonged odor exposure. Professor Vera Weisbecker from Flinders University explains these adaptations slowed inhaled air, enhancing faint scent detection for foraging nutrient-rich plants, predator evasion, or social signaling in open terrain.

Possible nasal salt glands in lateral fossae supported a diet including salty coastal flora or crustaceans near the Eromanga Sea, a convergent trait with lambeosaurine hadrosaurs.Read the full PeerJ study here.

Photo by David Clode on Unsplash

High-Tech Palaeontology: CT Scans and Synchrotron Magic

The study's rigor stems from cutting-edge methods. Neutron tomography (voxel 84.4–91.7 µm) and synchrotron micro-CT pierced dense bone, revealing hidden sutures, vascular canals, and soft-tissue imprints. Software like Dragonfly, Mimics, and ZBrush generated 3D models of jaws, teeth wear, and endocrania. Photogrammetry via Agisoft Metashape digitized fossils, while body mass estimates (7,916–10,085 kg) used stylopodial equations and volumetric splines.

Dr. Joseph Bevitt from ANSTO orchestrated scanning: “Neutron scattering excels at organic remnants in fossils.” These tools unveiled prenasal ossifications—unique bones roofing nasal chambers, excluding nasals from nostrils, and ethmoturbinal supports likely cartilaginous in life.

Bipedal Browser? Inner Ear Clues to Locomotion

Semicircular canal geometry (anterior 55.8 mm, posterior 38.1 mm; ECD 20.4 mm) mirrors bipedal theropods like T. rex, suggesting facultative bipedalism. Prof. Weisbecker adds, “Its inner ear was more like dinosaurs that walked on two legs... using front arms for support to crop food closer to the ground.” Wide monocular vision (~336°) aided predator scanning, with binocular overlap up to 34° for precision nipping. Low-frequency hearing (297–2,166 Hz) suited distant calls in vegetated plains.

Dietary Revolution: Selective Feeding in Cretaceous Queensland

• Narrow Toothy Beak: Pierced husks for seeds, fruits, cambium; supplemented with invertebrates.
• Grinding Dentition: Cheek teeth sheared/grinded fibrous plants like ferns, cycads, conifers.
• Sensory Suite: Olfaction pinpointed optimal forage; panoramic vision monitored threats.
• Coastal Niche: Salt glands processed marine-influenced vegetation/crustaceans.

This mosaic—primitive dentulous premaxilla with derived neurocrania—positions it as a non-styracosternan iguanodontian, bridging Gondwanan ornithopods.

Flinders University: Championing Australian Dino Research

Flinders University's Professor Vera Weisbecker brought palaeoneurology expertise, interpreting brain and ear data. Part of the College of Science and Engineering, her work exemplifies how South Australian institutions collaborate nationally. Flinders' focus on evolutionary biology and imaging aligns with this multidisciplinary effort involving UNE, Queensland Museum, ANSTO, and Monash. This study boosts Flinders' profile in palaeontology, attracting talent to its research programs.Flinders University news coverage.

Photo by Josh Withers on Unsplash

Gondwanan Context: Muttaburrasaurus Among Aussie Giants

As Queensland's state fossil, Muttaburrasaurus joins icons like Australovenator (megaraptorans) and Diamantinasaurus (titanosaurs). Its adaptations reflect isolation in Gondwana, evolving unique traits absent in Laurasian kin. Comparisons: unlike bulk-grazing hadrosaurs, its pickiness mirrors smaller elasmarians; olfactory supremacy exceeds carnivores, rare for herbivores.

Future Horizons: Museum Revamps and Ongoing Digs

Museums in Brisbane, Muttaburra, and Hughenden must update displays. Dr. Herne's team plans further sieving at the site. Broader implications refine ornithopod phylogeny, illuminate sensory evolution, and highlight museum collections' untapped potential. For aspiring palaeontologists, this underscores interdisciplinary skills in imaging and fieldwork.

As Prof. Weisbecker reflects, these insights humanize ancient giants, revealing sophisticated foragers attuned to their world.