Muttaburrasaurus
Encyclopedia
Muttaburrasaurus is a genus
of herbivorous ornithopod
dinosaur
, living in what is now northeastern Australia
between 100 and 98 million years ago during the early Cretaceous
Period. It has been recovered in some analyses as a member of the iguanodont
ian family Rhabdodontidae
. After Minmi
, it is Australia's most completely known dinosaur from skeletal remains.
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
, Queensland
, Australia
, 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.
The holotype
, specimen QM F6140, was found in the Mackunda Formation
dating to the Albian
-Cenomanian
. 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
, in northwestern New South Wales
. At Lightning Ridge there have been found opal
ised teeth and a scapula
that may be from a Muttaburrasaurus. A skull, known as the "Dunluce Skull", specimen QM F14921, was discovered by John Stewart-Moore and 14 year old Robert Walker on Dunluce Station, between Hughenden and Richmond
in 1987. It originates from somewhat older layers of the Allaru Mudstone and was by Molnar considered to be a separate, yet unnamed species, a Muttaburrasaurus sp. The same area produced two fragmentary skeletons in 1989. There have also been isolated teeth and bones found at Iona Station southeast of Hughenden.
Muttaburrasaurus was about 8 metres (26.2 ft) and weighed around 2.8 metric tons (3.1 ST). The femur
of the holotype has a length of 1015 millimetres.
Muttaburrasaurus was capable of either bipedal or quadrupedal movement. The three middle digits of the forelimb were joined together into a hoof-like pad for walking on. Originally reconstructing Muttaburrasaurus with a thumb spike, Molnar later doubted such a structure was present. The foot was long and broad, with four toes.
The skull of Muttaburrasaurus was rather flat, with a triangular cross-section seen from above, the back of the head being broad but the snout pointed. The snout had the form of a strongly enlarged, hollow, upward-bulging nasal muzzle that might have been used to produce distinctive calls or for display purposes. However, as no fossilised nasal tissue has been found, this remains conjectural. This so-called bulla nasalis was shorter with the older Muttaburrasaurus sp., as is shown by the Dunluce Skull. The top section of the bulla of the holotype has not been preserved, but at least the second skull has a rounded profile.
Muttaburrasaurus had very powerful jaws equipped with shearing teeth. Whereas in more derived euornithopod species the replacement teeth alternated with the previous tooth generation to form a tooth battery, with Muttaburrasaurus they grew directly under them and only a single erupted generation was present. This precluded a chewing motion. An additional basal trait was the lack of a primary ridge on the teeth sides, showing eleven lower ridges. In 1981 Molnar speculated that these qualities indicated an omnivorous diet, Muttaburrasaurus at times eating carcasses. In 1995 he changed his opinion, presenting them as a convergence to the ceratopian shearing teeth system. They would have been an adaptation for eating tough vegetation such as cycad
s.
euornithopod groups such as the Camptosauridae, Dryosauridae
or Hypsilophodontidae. In 2010 a study by Andrew McDonald indicated a position in the Rhabdodontidae
.
, have been put on display at a number of museums, including the Queensland Museum
, Flinders Discovery Centre, and National Dinosaur Museum
in Australia.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of herbivorous ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
, living in what is now northeastern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
between 100 and 98 million years ago during the early Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
Period. It has been recovered in some analyses as a member of the iguanodont
Iguanodont
Iguanodonts were herbivorous dinosaurs that lived from the mid-Jurassic to Late Cretaceous. Some members include Camptosaurus, Callovosaurus, Iguanodon, Ouranosaurus, and the hadrosaurids or "duck-billed dinosaurs". Iguanodonts were one of the first groups of dinosaurs to be found...
ian family Rhabdodontidae
Rhabdodontidae
Rhabdodontids were herbivorous ornithopod dinosaurs from the Cretaceous Period. Rhabdodontids were similar to large, robust hypsilophodonts, with deep skulls and jaws. The family was first proposed by David B. Weishampel et al. in 2002...
. After Minmi
Minmi (dinosaur)
Minmi, named after Minmi Crossing, Australia , is a genus of small ankylosaurian dinosaur that lived during the early Cretaceous Period, about 119 to 113 million years ago. The type species, M. paravertebra, was described by Ralph Molnar in 1980...
, it is Australia's most completely known dinosaur from skeletal remains.
Discovery and species
Thomson River (Queensland)
The Thomson River is situated in western Queensland, Australia, and forms part of the Lake Eyre Basin. The river was named by the explorer, Edmund Kennedy, in the 1840s....
near Muttaburra
Muttaburra, Queensland
Muttaburra is a small grazing town located in central western Queensland, Australia. The town is located on the banks of the Thomson River, approximately north of the town of Longreach and north of Aramac. Muttaburra is located within the Barcaldine Region...
, Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, 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
Ralph Molnar
Ralph E. Molnar is a paleontologist who had been Curator of Mammals at the Queensland Museum and more recently associated with the Museum of Northern Arizona. He is also a research associate at the Texas natural Science Centre. He co-authored descriptions of the dinosaurs Muttaburrasaurus, Kakuru,...
, who honoured its discoverer with its specific name langdoni.
The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
, specimen QM F6140, was found in the Mackunda Formation
Mackunda Formation
The Mackunda Formation is a geological formation in Queensland, Australia whose strata date back to the Early Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.-Vertebrate paleofauna:-References:...
dating to the Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
-Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
. 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
Hughenden, Queensland
Hughenden is a town in Queensland, Australia situated on the banks of the Flinders River. It was named after Hughenden Manor, the home of former British Prime Minister Benjamin Disraeli. At the 2006 census, Hughenden had a population of 1,154.-History:...
, and south at Lightning Ridge
Lightning Ridge, New South Wales
Lightning Ridge is a town in north-western New South Wales, Australia, in Walgett Shire, near the southern border of Queensland. The Lightning Ridge area is a world epicentre of the mining of black opals and other opal gemstones. Lightning Ridge has the largest known deposits of black opals in the...
, in northwestern New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
. At Lightning Ridge there have been found opal
Opal
Opal is an amorphous form of silica related to quartz, a mineraloid form, not a mineral. 3% to 21% of the total weight is water, but the content is usually between 6% to 10%. It is deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most...
ised teeth and a scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
that may be from a Muttaburrasaurus. A skull, known as the "Dunluce Skull", specimen QM F14921, was discovered by John Stewart-Moore and 14 year old Robert Walker on Dunluce Station, between Hughenden and Richmond
Richmond, Queensland
Richmond is a town in western Queensland, Australia. The town is located on the Flinders Highway, 498 km west of Townsville and 406 km east of Mount Isa. It is the administrative centre of the Richmond Shire. At the 2006 census, Richmond had a population of 554.The Flinders River forms...
in 1987. It originates from somewhat older layers of the Allaru Mudstone and was by Molnar considered to be a separate, yet unnamed species, a Muttaburrasaurus sp. The same area produced two fragmentary skeletons in 1989. There have also been isolated teeth and bones found at Iona Station southeast of Hughenden.
Paleobiology
Femur
The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...
of the holotype has a length of 1015 millimetres.
Muttaburrasaurus was capable of either bipedal or quadrupedal movement. The three middle digits of the forelimb were joined together into a hoof-like pad for walking on. Originally reconstructing Muttaburrasaurus with a thumb spike, Molnar later doubted such a structure was present. The foot was long and broad, with four toes.
The skull of Muttaburrasaurus was rather flat, with a triangular cross-section seen from above, the back of the head being broad but the snout pointed. The snout had the form of a strongly enlarged, hollow, upward-bulging nasal muzzle that might have been used to produce distinctive calls or for display purposes. However, as no fossilised nasal tissue has been found, this remains conjectural. This so-called bulla nasalis was shorter with the older Muttaburrasaurus sp., as is shown by the Dunluce Skull. The top section of the bulla of the holotype has not been preserved, but at least the second skull has a rounded profile.
Muttaburrasaurus had very powerful jaws equipped with shearing teeth. Whereas in more derived euornithopod species the replacement teeth alternated with the previous tooth generation to form a tooth battery, with Muttaburrasaurus they grew directly under them and only a single erupted generation was present. This precluded a chewing motion. An additional basal trait was the lack of a primary ridge on the teeth sides, showing eleven lower ridges. In 1981 Molnar speculated that these qualities indicated an omnivorous diet, Muttaburrasaurus at times eating carcasses. In 1995 he changed his opinion, presenting them as a convergence to the ceratopian shearing teeth system. They would have been an adaptation for eating tough vegetation such as cycad
Cycad
Cycads are seed plants typically characterized by a stout and woody trunk with a crown of large, hard and stiff, evergreen leaves. They usually have pinnate leaves. The individual plants are either all male or all female . Cycads vary in size from having a trunk that is only a few centimeters...
s.
Phylogeny
Molnar originally assigned Muttaburrasaurus to the Iguanodontidae. Later authors suggested more basalBasal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
euornithopod groups such as the Camptosauridae, Dryosauridae
Dryosauridae
Dryosaurids were primitive iguanodonts. They are known from Middle Jurassic to Early Cretaceous rocks of Africa, Europe, and North America.-Phylogeny:...
or Hypsilophodontidae. In 2010 a study by Andrew McDonald indicated a position in the Rhabdodontidae
Rhabdodontidae
Rhabdodontids were herbivorous ornithopod dinosaurs from the Cretaceous Period. Rhabdodontids were similar to large, robust hypsilophodonts, with deep skulls and jaws. The family was first proposed by David B. Weishampel et al. in 2002...
.
Reconstructed skeleton casts
Reconstructed skeleton casts of Muttaburrasaurus, sponsored by Kellogg CompanyKellogg Company
Kellogg Company , is a producer of cereal and convenience foods, including cookies, crackers, toaster pastries, cereal bars, fruit-flavored snacks, frozen waffles, and vegetarian foods...
, have been put on display at a number of museums, including the Queensland Museum
Queensland Museum
The Queensland Museum is the state museum of Queensland. The museum currently operates four separate campuses; at South Brisbane, Ipswich, Toowoomba and Townsville.The museum is funded by the State Government of Queensland.-History:...
, Flinders Discovery Centre, and National Dinosaur Museum
National Dinosaur Museum
The National Dinosaur Museum is the southern hemisphere's largest permanent display of prehistoric material, located in Gold Creek Village near Canberra, Australian Capital Territory, Australia...
in Australia.
External links
- Australian Age of Dinosaurs
- Muttaburrasaurus langdoni, from Dann's Dinosaurs. (article)