''Muttaburrasaurus'' was a
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
of
herbivorous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...
iguanodontia
Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include ''Camptosaurus'', ''Dryosaurus'', ''Iguanodon'', '' Tenontosaurus'', and the hadrosaurids or "duck-bil ...
n
ornithopod
Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), 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 wo ...
dinosaur
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
, which lived in what is now northeastern
Australia sometime between 110 and 103
million years ago
The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds.
Usage
Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago) ...
[Holtz, Thomas R. Jr. (2012) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,']
Winter 2011 Appendix.
/ref> during the early Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
period
Period may refer to:
Common uses
* Era, a length or span of time
* Full stop (or period), a punctuation mark
Arts, entertainment, and media
* Period (music), a concept in musical composition
* Periodic sentence (or rhetorical period), a concept ...
. It has been recovered in some analyses as a member of the iguanodontian clade Rhabdodontomorpha
Rhabdodontomorpha is a clade of basal iguanodont dinosaurs. This group was named in 2016 in the context of the description, based on Spanish findings of an early member of the Rhabdodontidae. A cladistic analysis was conducted in which it was f ...
. After ''Kunbarrasaurus
''Kunbarrasaurus'' is an extinct genus of small herbivorous ankylosaurian dinosaur from the Cretaceous of Australia.
Discovery
In November 1989, at Marathon Station near Richmond, Queensland, the skeleton was discovered of an ankylosauria ...
'', it is Australia's most completely known dinosaur from skeletal remains. It was named after Muttaburra
Muttaburra is an outback town and locality in the Barcaldine Region, Queensland, Australia. Muttaburra was the discovery site of the ''Muttaburrasaurus'', one of Australia's most famous dinosaurs.
Geography
Muttaburra is in the central west ...
, the site in Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Queensland in Australia
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, establishe ...
, Australia, where it was found.
Description
''Muttaburrasaurus'' was about and weighed around . The femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates wit ...
of the holotype has a length of .
Whether ''Muttaburrasaurus'' is capable of quadrupedal movement has been debated; it was originally thought to be an "iguanodontid"; thought recent studies indicate a rhabdodont position. Ornithopods this basal were incapable of quadrupedal movement. 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 when seen from above; the back of the head is broad but the snout pointed. The snout includes 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 in 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.
Discovery and species
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
Muttaburra is an outback town and locality in the Barcaldine Region, Queensland, Australia. Muttaburra was the discovery site of the ''Muttaburrasaurus'', one of Australia's most famous dinosaurs.
Geography
Muttaburra is in the central west ...
, in the Australian state
State may refer to:
Arts, entertainment, and media Literature
* ''State Magazine'', a monthly magazine published by the U.S. Department of State
* ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States
* ''Our S ...
of Queensland
)
, nickname = Sunshine State
, image_map = Queensland in Australia.svg
, map_caption = Location of Queensland in Australia
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, establishe ...
, which also provides the creature's generic name. The remains were collected by paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
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 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 descr ...
, who honoured its discoverer with its specific name ''langdoni''.
The holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...
, specimen QM F6140, was found in the Mackunda Formation dating to the 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 113.0 ± 1.0 Ma to 100.5 ± 0 ...
- Cenomanian. It consists of a partial skeleton with skull and lower jaws. The underside of the skull and the back of the mandibula
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...
, 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 may refer to:
*Hughenden, Queensland, a town in Australia
*Hughenden, Alberta, a village in central Alberta, Canada
*Hughenden Valley
Hughenden Valley (formerly called Hughenden or Hitchendon) is an extensive village and civil parish in ...
, and south at Lightning Ridge
Lightning Ridge is a small outback town in north-western New South Wales, Australia. Part of Walgett Shire, Lightning Ridge is situated near the southern border of Queensland, about east of the Castlereagh Highway. The Lightning Ridge area i ...
, in northwestern New South Wales
)
, nickname =
, image_map = New South Wales in Australia.svg
, map_caption = Location of New South Wales in AustraliaCoordinates:
, subdivision_type = Country
, subdivision_name = Australia
, established_title = Before federation
, es ...
. At Lightning Ridge there have been found opal
Opal is a hydrated amorphous form of silica (SiO2·''n''H2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%. Due to its amorphous property, it is classified as a mineraloid, unlike crystalline form ...
ised teeth and a scapula
The scapula (plural scapulae or scapulas), also known as the shoulder blade, is the bone that connects the humerus (upper arm bone) with the clavicle (collar bone). Like their connected bones, the scapulae are paired, with each scapula on eith ...
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 considered by Molnar 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.
Reconstructed skeleton casts of ''Muttaburrasaurus'', sponsored by Kellogg Company
The Kellogg Company, doing business as Kellogg's, is an American multinational food manufacturing company headquartered in Battle Creek, Michigan, United States. Kellogg's produces cereal and convenience foods, including crackers and toas ...
, have been put on display at a number of museums, including the Queensland Museum
The Queensland Museum is the state museum of Queensland, dedicated to natural history, cultural heritage, science and human achievement. The museum currently operates from its headquarters and general museum in South Brisbane with specialist m ...
, Flinders Discovery Centre and National Dinosaur Museum
The National Dinosaur Museum is Australia's largest permanent display of prehistoric specimens, located in Canberra, Australian Capital Territory, Australia. It is located in Gold Creek Village, an area within the suburb of Nicholls.
The museu ...
in Australia.
Phylogeny
Molnar originally assigned ''Muttaburrasaurus'' to the Iguanodontidae
Iguanodontidae is a family of iguanodontians belonging to Styracosterna, a derived clade within Ankylopollexia.
Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dynam ...
. Later authors suggested more basal euornithopod groups such as the Camptosauridae, Dryosauridae
Dryosaurids were primitive iguanodonts. They are known from Middle Jurassic to Early Cretaceous rocks of Africa, Europe, and North America.
Phylogeny
Until recently many dryosaurids have been regarded as dubious ('' Callovosaurus'' and '' Kan ...
or Hypsilophodont
Hypsilophodontidae (or Hypsilophodontia) is a traditionally used family of ornithopod dinosaurs, generally considered invalid today. It historically included many small bodied bipedal neornithischian taxa from around the world, and spanning from ...
idae. Studies by Andrew McDonald indicate a position in the Rhabdodontidae.
Paleobiology
''Muttaburrasaurus'' had very powerful jaws equipped with shearing teeth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, t ...
. Whereas in more derived ornithopod
Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), 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 wo ...
species the replacement teeth alternated with the previous tooth generation to form a tooth battery, in ''Muttaburrasaurus'' they grew directly under them and only a single erupted generation was present, thus precluding a chewing motion. An additional basal trait was the lack of a primary ridge on the teeth sides, which show eleven lower ridges. In 1981 Molnar speculated that these qualities indicated an omnivorous
An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nut ...
diet, implying that ''Muttaburrasaurus'' occasionally ate carrion. In 1995 he changed his opinion, suspecting that ''Muttaburrasaurus''s dental system is evolutionarily convergent with the ceratopsian system of shearing teeth. They would have been an adaptation for eating tough vegetation such as cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male o ...
s.
References
Further reading
*
{{Portal bar, Dinosaurs, Cretaceous, Paleontology, Australia
Iguanodonts
Early Cretaceous dinosaurs of Australia
Paleontology in Queensland
Fossil taxa described in 1981
Taxa named by Ralph Molnar
Ornithischian genera
Albian life