Australovenator | |
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Reconstructed skeleton, Australian Age of Dinosaurs Museum, Winton, Australia | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | Saurischia |
Clade: | Theropoda |
Clade: | † Megaraptora |
Family: | † Megaraptoridae |
Genus: | † Australovenator Hocknull et al. 2009 |
Species: | †A. wintonensis |
Binomial name | |
†Australovenator wintonensis Hocknull et al. 2009 | |
Australovenator (meaning "southern hunter") is a genus of megaraptoran theropod dinosaur from Cenomanian (Late Cretaceous)-age Winton Formation (dated to 95 million years ago [1] ) of Australia. Some specimens from the Albian-aged Eumeralla Formation as well as the Wonthaggi Formation may belong to Australovenator. It is known from partial cranial and postcranial remains which were described in 2009 by Scott Hocknull and colleagues, although additional descriptions and analyses continue to be published. It is the most complete predatory dinosaur discovered in Australia. It has been suggested that Australovenator is a sister taxon to Fukuiraptor , although some phylogenetic analyses find it to be a more derived member of the Megaraptora, possibly being part of the main Megaraptoridae family itself.
Australovenator is based on a theropod specimen ( AODF 604), affectionately nicknamed "Banjo" after Banjo Paterson, which was found intermingled with the remains of the sauropod Diamantinasaurus matildae at the "Matilda site" (AODL 85). The parts of the holotype as it was initially described, which are held at the Australian Age of Dinosaurs Museum of Natural History, consists of a left dentary, teeth, partial forelimbs and hindlimbs, a partial right ilium, ribs, and gastralia. Australovenator was described in 2009 by paleontologist Scott Hocknull of the Queensland Museum, and colleagues. The type species is A. wintonensis, in reference to nearby Winton. [2] Although the holotype was first discovered in 2006 and first described in 2009, [2] the process of excavating the "Matilda site" is still ongoing and papers describing new elements of the holotype are still being published. Additional arm elements of the holotype were described in 2012, [3] more leg elements were described in 2013, [4] and a right dentary was described in 2015. [5]
For some time, Australovenator was considered to be within the same genus as another Australian Megaraptorid called Rapator . Rapator is based on a metacarpal first described by Friedrich von Huene during the early 1900s and for prior to the recognition of Megaraptora, it was considered to be either an alvarezsaurid, or an intermediate theropod. [6] After the discovery of Australovenator, some scientists noted the similarity between Rapator and Australovenator. While Hocknull et al. (2009) identified a few distinguishing characters between the two taxa, based on a poorly preserved metacarpal I from the holotype of Australovenator. [2] Agnolin et al. (2010), reclassified Rapator, instead finding it a megaraptoran, potentially sister taxon to Australovenator. They mentioned that Megaraptor, the only other taxon also preserving metacarpal I, was less similar to Rapator than Australovenator. However, there were no clear differences between the two latter taxa. [7] The metacarpals of both taxa were redescribed in White et al. (2014), who determined that they were not synonymous, adding multiple features two the potential characters identified by Hocknull et al. and Angolan et al. [1]
In 2019, material from the Eumeralla Formation (Albian age) was referred to cf. Australovenator. [8] In 2020, a heavily eroded specimen was described, belonging to an indeterminate megaraptoran found near the type locality. The fossil material comprises "two fragmentary vertebrae, three partial metatarsals and the distal end of a pedal phalanx" as well as other indeterminate bone fragments. The animal was slightly larger than the holotype individual of Australovenator. [9]
According to Gregory S. Paul, it was estimated at 6 m (20 ft) long, with a body mass of 500 kilograms (1,100 lb). [10] A 2014 study estimated its body mass around 310 kilograms (680 lb). [11] Because it was a relatively lightweight predator, Hocknull coined it as the "cheetah of its time". [12] Like other megaraptorans, Australovenator would have been a bipedal carnivore. [13]
A phylogenetic analysis found Australovenator to be an allosauroid carnosaurian, with similarities to Fukuiraptor and carcharodontosaurids. In the initial analysis, it was shown to be the sister taxon of the Carcharodontosauridae. [2] More detailed studies found that it formed a clade with several other carcharodontosaurid-like allosaurs, the Neovenatoridae. [14] Recent phylogenetic analysis suggests Australovenator is a tyrannosauroid, like with all other megaraptorans. [15] A phylogenetic analysis in 2016 focusing on the new neovenatorid Gualicho found that Australovenator and other megaraptorids were either allosauroids or basal coelurosaurs as opposed to being tyrannosauroids. [16]
The ankles of Australovenator and Fukuiraptor are similar to the Australian talus bone known as NMVP 150070 that had previously been identified as belonging to Allosaurus sp., and this bone likely represents Australovenator or a close relative of it. [2] [17] Alternatively, this bone could belong to an abelisaur. [18]
The cladogram below follows the 2010 analysis by Benson, Carrano and Brusatte. [14] Another study published later in 2010 also found the Australian theropod Rapator to be a megaraptoran extremely similar to Australovenator. [7]
Neovenatoridae |
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The cladogram below follows the 2014 analysis by Porfiri et al. that finds megaraptorans to be tyrannosauroids. [19]
Megaraptora |
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With very comprehensive and well-preserved hand and foot remains, Australovenator has been made a topic of various research papers studying the dynamics of theropod appendages.
A 2015 study tested the range of motion of Australovenator's arms using computer models and found that it had flexible arms, with the forearms capable of making an angle of 144 to 66 degrees with the humerus, an elbow range of motion similar to that of maniraptoriforms. Unusually, its radius could slide independently of the ulna when its arm was flexed, similar to that of birds but unlike most non-avian dinosaurs. However, the study also found that Australovenator's fingers were capable of extension far beyond those of any other sampled theropod, with only Dilophosaurus having capabilities even near it. This study concluded that Australovenator's flexibility, facilitated by a combination of traits in both primitive and advanced theropods, played a role in prey capture, giving it the ability to grasp prey towards its chest to make it easier for its weak jaws to disembowel food. [20] The gracile morphology of the skull also concludes that this genus had a specialisation towards prey capture using its arms and hands. [21]
A 2016 study used CT scans of an emu foot to digitally reconstruct the musculature and soft tissue of an Australovenator foot, as well as determine how soft tissue affects flexibility. The study determined that muscular range of motion is often overestimated when not accounting for soft tissue, and that soft tissue reconstruction is vital for making future analyses of theropod flexibility more accurate. A review of hindlimb elements described in 2013 re-identified several phalanges which were initially positioned incorrectly. In addition, it noted that Australovenator's phalanx II-3 was splayed, a pathology that may have resulted from the impacts of kicking motions. Some modern birds, such as the cassowary, are known to use their second toe as weapons in defensive or territorial fights. [22]
A 2017 followup to the 2016 study used a 3-D printed model of the reconstructed foot to make footprints in a matrix of clay and sand in an effort to understand the creation of dinosaur footprints. The study specifically was designed to clarify the identity of particular controversial footprints from Lark Quarry, which may have been left from either a large theropod (like Australovenator) or an ornithopod (like Muttaburrasaurus ). The study found that the artificial Australovenator footprints were similar to those at Lark Quarry, concluding that the trackways in question were likely those of a theropod. The writers of the study expressed interest in creating a reconstruction of a Muttaburrasaurus foot as an extension of the study, although no Muttaburrasaurus pedal material is known. [23]
AODL 604 was found about 60 kilometres (37 mi) northwest of Winton, near Elderslie Station. It was recovered from the lower part of the Winton Formation, dated to the late Cenomanian. AODL 604 was found in a clay layer between sandstone layers, interpreted as an oxbow lake, or billabong, deposit. Also found at the site were the type specimen of the sauropod Diamantinasaurus , bivalves, fish, turtles, crocodilians, and plant fossils. The Winton Formation had a faunal assemblage including bivalves, gastropods, insects, the lungfish Metaceratodus , turtles, the crocodilian Isisfordia , pterosaurs, and several types of dinosaurs, such as the sauropods Diamantinasaurus and Wintonotitan , and unnamed ankylosaurians and hypsilophodonts. Plants known from the formation include ferns, ginkgoes, gymnosperms, and angiosperms. [2]
Carnosauria is an extinct group of carnivorous theropod dinosaurs that lived during the Jurassic and Cretaceous periods.
Fukuiraptor was a medium-sized megaraptoran theropod dinosaur of the Early Cretaceous epoch that lived in what is now Japan. Fukuiraptor is known from the Kitadani Formation and possibly also the Sebayashi Formation.
Deltadromeus is a genus of theropod dinosaur from the Aoufous Formation of Morocco.
Megaraptor is a genus of large theropod dinosaur that lived in the ages of the Late Cretaceous. Its fossils have been discovered in the Patagonian Portezuelo Formation of Argentina, South America. Initially thought to have been a giant dromaeosaur-like coelurosaur, it was classified as a neovenatorid allosauroid in previous phylogenies, but more recent phylogeny and discoveries of related megaraptoran genera has placed it as either a basal tyrannosauroid or a basal coelurosaur with some studies still considering it a neovenatorid.
Rapator is a genus of theropod dinosaur from the Griman Creek Formation of New South Wales, Australia, dating to the Cenomanian age of the Cretaceous period. It contains only the type species, Rapator ornitholestoides, which was originally named by Friedrich von Huene in 1932.
The Winton Formation is a Cretaceous geological formation in central-western Queensland, Australia. It is late Albian to early Turonian in age. The formation blankets large areas of central-western Queensland. It consists of sedimentary rocks such as sandstone, siltstone and claystone. The sediments that make up these rocks represent the remnants of the river plains that filled the basin left by the Eromanga Sea - an inland sea that covered large parts of Queensland and central Australia at least four times during the Early Cretaceous. Great meandering rivers, forest pools and swamps, creeks, lakes and coastal estuaries all left behind different types of sediment.
Orkoraptor is a genus of medium-sized megaraptoran theropod dinosaur from the late Cretaceous Period of Argentina. It is known from incomplete fossil remains including parts of the skull, teeth, tail vertebrae, and a partial tibia. The specialized teeth resemble those of some maniraptoriform theropods, namely the deinonychosaurs and compsognathids. This and other anatomical features led the authors who described it to suggest that it was a maniraptoran coelurosaur. However, subsequent studies found it to be a megaraptoran. Found in the Cerro Fortaleza Formation of Southern Patagonia, it is one of the southernmost carnivorous dinosaurs known from South America.
Aerosteon is a genus of megaraptoran dinosaur from the Late Cretaceous period of Argentina. Its remains were discovered in 1996 in the Anacleto Formation, which is from the late Campanian. The type and only known species is A. riocoloradensis. Its specific name indicates that its remains were found 1 km north of the Río Colorado, in Mendoza Province, Argentina.
Wintonotitan is a genus of titanosauriform dinosaur from Cenomanian -age Winton Formation of Australia. It is known from partial postcranial remains.
Diamantinasaurus is a genus of titanosaurian sauropod from Australia that lived during the early Late Cretaceous, about 94 million years ago. The type species of the genus is D. matildae, first described and named in 2009 by Scott Hocknull and colleagues based on fossil finds in the Winton Formation. Meaning "Diamantina lizard", the name is derived from the location of the nearby Diamantina River and the Greek word sauros, "lizard". The specific epithet is from the Australian song Waltzing Matilda, also the locality of the holotype and paratype. The known skeleton includes most of the forelimb, shoulder girdle, pelvis, hindlimb and ribs of the holotype, and one shoulder bone, a radius and some vertebrae of the paratype.
Megaraptora is a clade of carnivorous theropod dinosaurs with controversial relationships to other tetanuran theropods. Its derived members, the Megaraptoridae are noted for their large hand claws and powerfully-built forelimbs, which are usually reduced in size in other large theropods.
Siats (/see-ats/) is an extinct genus of large theropod dinosaur known from the Late Cretaceous Cedar Mountain Formation of Utah, United States. It contains a single species, Siats meekerorum. It was initially classified as a megaraptoran, a clade of large theropods with very controversial relationships. Siats may be a neovenatorid allosauroid, a coelurosaur of uncertain phylogenetic position, or a tyrannosauroid. Recent studies suggest however a carcharodontosaurid classification.
Australian Age of Dinosaurs Ltd. (AAOD) is a nonprofit organization located in Winton, Queensland, founded by David Elliott and Judy Elliott in 2002. The organization’s activities include the operation of the Australian Age of Dinosaurs Museum of Natural History, which holds annual dinosaur digs in the Winton Formation of Western Queensland and oversees the year-round operation of Australia's most productive dinosaur fossil preparation laboratory. Since 2005, the AAOD Museum has accumulated the largest collection of Australian dinosaur fossils in the world and holds the holotype specimens of Diamantinasaurus matildae, Savannasaurus elliottorum, Australovenator wintonensis, Australia's most complete theropod skeleton, Ferrodraco lentoni, the first pterosaur to be named from the Winton Formation, and Confractosuchus sauroktonos. The museum is open to the public daily from April to October and is open six days a week from November to March. The site of the museum was designated a dark-sky preserve, the first International Dark-Sky Sanctuary in Australia, in 2019.
Aoniraptor is a genus of possibly megaraptoran or bahariasaurid theropod dinosaur from the Late Cretaceous of Argentina.
Murusraptor is a genus of carnivorous megaraptoran theropod dinosaur from the Sierra Barrosa Formation, part of the Neuquén Group of Patagonia, in Argentina, South America. It is known from a single specimen that consists of a partial skull, ribs, partial pelvis, leg and other assorted skeletal elements.
Savannasaurus is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous Winton Formation of Queensland, Australia. It contains one species, Savannasaurus elliottorum, named in 2016 by Stephen Poropat and colleagues. The holotype and only known specimen, originally nicknamed "Wade", is the most complete specimen of an Australian sauropod, and is held at the Australian Age of Dinosaurs museum. Dinosaurs known from contemporary rocks include its close relative Diamantinasaurus and the theropod Australovenator; associated teeth suggest that Australovenator may have fed on the holotype specimen.
Phuwiangvenator is an extinct genus of megaraptoran theropod that lived during the Early Cretaceous period in what is now Thailand. It contains only the type species, P. yaemniyomi. The generic name of Phuwiangvenator comes from the Phu Wiang mountains, where the holotype was discovered, and the Latin word "venator" meaning hunter. The specific name, "yaemniyomi", is in honor of Sudham Yaemniyom, who was a historical paleontologist from Thailand and the first person to discover fossils there.
Maip is a genus of large megaraptorid theropod dinosaur from the Late Cretaceous (Maastrichtian) Chorrillo Formation of Santa Cruz, Argentina. The genus contains a single species, M. macrothorax, known from an incomplete, disarticulated skeleton. Maip may represent the largest megaraptorid known from South America, and possibly the world.
David Anthon Elliott is an Australian palaeontologist and sheep and cattle grazier who co-founded the Australian Age of Dinosaurs in Winton, Queensland, with his wife Judy and currently serves as Executive Chairman. His significant contributions to the local, national and global communities have been far-reaching, with a profound impact on the field of palaeontology. Through the establishment and development of the Australian Age of Dinosaurs Museum of Natural History, he has pioneered a new form of tourism known as palaeotourism, attracting new visitors to regional Australia.