Celebrating its 25th anniversary in 2006 is Australia 's most famous dinosaur, Muttaburrasaurus , and what a 25 years it's been. Though not the most famous of dinosaurs, it has been one of the most important, evidence of which are the changes to it in the dinosaur family tree that even today are hotly debated.
But before we get to that, a quick history lesson.
In 1963, grazier Douglas Langdon was checking found himself along the Thompson river running through the Rosebury station near the central Queensland town of Muttaburra, checking on reports of strange bones sticking out of the ground there, an area that was once at the bottom of an interior waterway called the Eromanga sea.
Recognising that the remans were something unusual, Mr. Langdon sent a report to the Queensland museum, which promptly fielded a team led by Dr Alan Bartholomai (Palaeontologist) and Dr Edward Dahms (Entomologist).
What they found was exciting and disturbing. There were defiantly dinosaurs bones in ‘them thar' hills', but the bones had been exposed to the weather and the clumsy hooves of the stations cattle and sheep for nearly 100 years and lately, had been picked over by locals souvenir hunting when the importance of the remains became all to apparent.
The team set about collecting what they could, while a request was sent to the local community for the return of the bones- no questions asked. A sterner waring from the local constabulary that if anyone was found with the remains, they would be arrested followed this up. This all lead to many of the remains being returned anonymously (some 50 large pieces in the first day), with bones still appearing 3 years after the appeal.
Thanks to the efforts of the public and the Queensland museum team, around 60% of the dinosaur was shipped to the museum, by far the most complete dinosaur found in Australia (only surpassed by Minmi, the small ankylosaur- for more read Mega-issue 5).
Unfortunately the bones were in a tough marine sediment which required both mechanical and chemical preparation to extract the bones from the stone so it wasn't until 1981 that the museum, in conjunction with American palaeontologist Ralph Molnar named and escribed the dinosaur Muttaburrasaurus langdonii (QM F6140)- firstly after the town of Muttaburra were it was found and secondly after its discoverer, Douglas Langdon.
In 1987, a second skull (QM F14921) was found by a local family (in the nearby Dunluce station), who'd been using the skull as a doorstop. Palaeontologists Mary Wade, while visiting the area found out about the skull and quickly procured it from the family. Though crushed and showing signs of part of the skull having been weathered away, the Dunluce skull was more complete then the Rosebury downs skull, yet it was around 1 million years younger (the soil formation it was in is actual situated under the formation the first skull was found in), and seemed to show some slight differences.
In 1989, 2 more partial skeletons were found in Hughenden while Dr Molnar described some teeth that had been found at lightning Ridge in NSW as those belonging to a Muttaburrasaurus .
Muttaburrasaurus was a medium sized dinosaur at around 10m in length a 5m high (maximum), that was mostly likely a quadruped that could occasionally move about on its rear legs- perhaps when looking for danger or reaching into trees. Its most striking features was its large head and broad snout that ended in a large bulbous nose (called the nasal bulla) that may have equally been used as for making loud bleating calls and smelling for danger/food.
Originally it was placed with the iguanodont family as it was believed many of its features resembled Camptosaurus , a basal member of the group. This relationship was strengthened by the presence of a small thumb spike that is the distinguishing feature of the family. The second skull, though clearly a Muttaburrasaurus , differed in some important ways (in the dentition, skull and even the nasal bulla), and though the differences could be down to differences in individuals, or perhaps in sexual dimorphism (males and females looking different), as the skulls are different ages, the most likely answer is that they are ancestral rather then the same species.
This relationship was also tenuous and research in the 1990's suggested Muttaburrasaurus was more important than that. For starers the bone that may have been the spiky thumb, also might not have been as it was crushed, worn and broken. Even its exact origin in conjunction the rest of the skeleton (were it was found in relation to the hand), came under doubt, and as a growing list of features were decidedly not iguanodon like, Muttaburrasaurus was now linked with Tenontosaurus , possibly the largest member of the hypsilophodont family -an important group for Australia that could be considered the kingdom of hypsilophodonts as it has so many ( Leaellynasaura , Qantassaurus etc).
This however wasn't to last as the relationship that Tenontosaurus had with the hypsilophodont was about to change. Instead of being the most advanced (and largest) hypsilophodont and ancestral to the iguanodonts (which in turn are ancestral to the hadrosaurs like Parasaurolophus ), Tenontosaurus is now considered the most basal (primitive) of the iguanodonts, placing it in the family tree evolving after (or even from) Muttaburrasaurus .
This places our most famous dinosaur as the link between the smaller and earlier herbivorous hypsilophodonts and the huge and incredibly successful hadrosaurs and iguanodonts. Palaeontologist think they've even found a direct link thanks to the similarities, yet more primitive dental features on an advanced Australian Hypsilophodon , Atlascopcosaurus and Muttaburrasaurus .
It's also these teeth that make Muttaburrasaurus stand out from what came before it as it seems to have been the first dinosaur to be an efficient chewer. Until its time, herbivorous dinosaurs had numerous shaped teeth from the peg like sauropods to the small, leaf shaped teeth of the hypsilophodonts. Muttaburrasaurus on the other hand had broad, even teeth that ended in a sharp ridge at the back. Not only did this create a broad surface allowing the dinosaur to chew, the sharper rear teeth made some palaeontologists suggest that plants weren't the only thing on the menu as this ridge would allow the animals to eat meat (though likely it was for cutting tough fibrous plants like cycads), while the uniformity of the teeth suggested that the animal would replace all the teeth at the same time, rather then replacing individual teeth. These teeth were also powered by enormous jaw muscles, as the area that attaches them at the back of the skull in Muttaburrasaurus is larger then almost any other dinosaurs. In fact Muttaburrasaurus could only be out-chewed by the later hadrosaurs and ceratopsians, which had mouths full of hundreds, if not thousands of self-sharpening, self-replacing teeth.
Things may be on the move again however for Muttaburrasaurus as new research shows that its teeth closely resemble those on dryosaurs, a more advanced form of iguanodont, so whatever happens in the future, it seems the final word is yet to be written about Australia's most famous dinosaur!