Etymology
Dinosaur – meaning ‘terrible lizard’ in Greek.
Currently three dinosaurs have been named from the Richmond and Hughenden region:
Austrosaurus mckillopi – The genus name ‘austro’, from the Latin meaning southern and ‘saurus’, from Greek meaning lizard. The species name mckillopi honours the McKillop family that found the specimen and brought it to the attention of the Queensland Museum.
Kunbarrasaurus ieversi – The genus name ‘kunbarra’ (kunbara), from the Mayi word for ‘shield’, and ‘saurus’, from Greek meaning lizard. The species name ieversi honours Mr Ian Ievers, discoverer of the original specimen.
Muttaburrasaurus sp. – The genus name ‘muttaburra’, after the Queensland town where the original specimen was found, and ‘saurus’, from Greek meaning lizard. The ‘sp.’ at the end of the name means this is an unnamed species which is only known from fragmentary remains.
There is also a single Cretaceous bird that has been found around Richmond.Nanantius eos – The genus name ‘nana’, from the Greek meaning dwarf, and ‘antius’, from Greek meaning opposite. The names is in reference to the group of bird it belongs to called Enantiornithes, meaning “opposite birds”. The species name eos, from the Greek meaning dawn, in reference to the early age of these fossils compared with other Enantiornithes.
Relationships
Contrary to popular belief, not all large prehistoric reptiles were dinosaurs. The name belongs to only a specific group of reptiles which had a reduced fourth and fifth digits on the manus (hand); three main toes on the pes (foot); three or more vertebrae composing the sacrum (region of the vertebral column which attaches to the pelvis); and an open acetabulum (hip socket). Other features in the skull, wrist, and ankle joints also separate dinosaurs from their close relatives (such as pterosaurs).
The earliest dinosaurs (such as Eoraptor lunensis) appear around 230 million years ago in the Late Triassic. However, dinosaurs did not become common until after the Triassic–Jurassic extinction event 201 million years ago. During the Jurassic and Cretaceous periods dinosaurs became the dominant terrestrial vertebrates, ruling the Earth for over 135 million years. Yet their success did not last, and approximately 66 million years ago most groups of dinosaur (except birds) became extinct.
Dinosaurs are traditionally separated into two groups, the Saurischia and the Ornithischia. The Saurischia includes all species sharing a more recent common ancestor with birds, while Ornithischia includes all species sharing a more recent common ancestor with Triceratops. However recently a study in 2017 by Dr Matthew Baron and colleagues suggested dinosaurs may instead be separated into four distinct groups; the Herrerasauridae, Sauropodomorpha, Ornithischia and Theropoda. More detailed studies in future will hopefully clarify dinosaur classification.
Representatives from both groups of dinosaur have been found around the Richmond region. Some of the more famous dinosaurs from the area belong to the Ornithischia. The largest of these is an unnamed species of Muttaburrasaurus, an ornithopod dinosaur placed in the family Rhabdodontidae. These were elephant size herbivores that were closely related to dinosaurs like Iguanodon. The other ornithischian dinosaur, Kunbarrasaurus ieversi, was a primitive member of the Ankylosauria. Unlike Muttaburrasaurus the ankylosaurs were typically small, bulky dinosaurs with short limbs and prominent bony armour.
Less famous then their Ornithischia cousins, a few Saurischia have been found around Richmond. The most common members are sauropods, particularly the Titanosauria. These were massive, long necked dinosaurs with relatively small heads. Scientists have currently named one species, Austrosaurus mckillopi, with several other unnamed specimens known from only fragments (such as those of ‘Marlin’s beastie). The other Saurischia group, the infamous Theropoda (meat-eating dinosaurs like Australovenator wintonensis), have never been found in the area.
Surprisingly birds are considered by many scientists to be a group of dinosaurs, having evolved from feathered ancestors within the Theropoda sometime in the Jurassic period. The remains of birds are amongst the rarest fossils found in Richmond. This material mostly consists of isolated limb bones, toe phalanges, claws and jaw bones, possibly from an extinct group known as the Enantiornithes. These primitive birds retained teeth in the jaw and clawed fingers on each wing, but otherwise looked much like modern birds. The best known Australian enantiornithine is Nanantius eos, originally described from a single leg bone found near Boulia. Several other Australian specimens have been assigned to the same genus (including Richmond material) which suggests this primitive bird was widespread.
Discoveries
The first dinosaur discovered near Richmond was Austrosaurus mckillopi, found by station overseer Mr Henry Burgoyne Wade on Clutha Station in 1932. After unearthing a few fossil vertebrae, he alerted the station owner Harley McKillop, who showed the specimens to his brother Dr Martin McKillop (a medical doctor). Marin was intrigued by these large bones and sent them to the Queensland Museum to be identified. These were given to museum director Heber Longman who scientifically described and named the species in 1933. A number of attempts to find more of the original Austrosaurus specimen in the 1970s and 1990s (by Dr Mary Wade and Dr Tony Tony Thulborn) were unsuccessful, which led to the assumption that the site was lost. However, in 2014 Richmond Shire Mayor John Wharton searched Clutha from a helicopter and located two wooden posts marking the original dig site. On rediscovering the posts, Mr Wharton found several pieces of dinosaur bone sitting just above the soil. This proved promising, renewing interest in the site. Excavation in 2015 with a team led by Dr Timothy Holland and Dr Stephen Poropat found six ribs and fragments of backbone, which these are currently on display at Kronosaruus Korner. Potentially more material of this specimen is underneath the ground and will be exposed for collection in the future. Portions of five additional sauropod skeletons were collected from three different localities around Winton in the late 1950s and early 1970s. The majority of these were collected by Dr Alan Bartholomai (a former Director of the Queensland Museum), Dr Mary Wade and Mr Keith Watts. These specimens were described in 1981 by Dr Walter Coombs and Dr Ralph Molnar and assigned to the genus Austrosaurus. However, all but one of these specimens is now thought to represent indeterminate sauropods. The exception, affectionately dubbed “Clancy”, is now known as Wintonotitan wattsi after being redescribed in 2009.
The second dinosaur species uncovered near the Richmond area was a close relative of the famous Muttaburrasaurus langdoni. A small selection of bones attributed to the same genushave found near Richmond, including: isolated teeth and bones collected from Iona Station in the 1980’s and a near complete skull found on Dunluce Station in 1987 by Dr Mary Wade, Mr John Stewart-Moore and Mr Robert Walker. Study of these fragmentary remains in 1996 by Dr Molnar demonstrated they were from a slightly older and more primitive Muttaburrasaurus, possibly representing a second species. A detailed reconstruction of the entire skeleton (based on Muttaburrasaurus langdoni) can be seen at Flinders Discovery Centre.The most impressive dinosaur find in Richmond was in 1989 when Mr Ian Ievers found the best-preserved ankylosaur skeleton in the southern. The discovery was on Ian’s family property, Marathon Station, between Richmond and Hughenden whist he was mustering cattle. Having found ‘Penny the Plesiosaur’ only a few month earlier, he immediately contacted the Queensland Museum which sent a team (led by Dr Molnar) in 1990 to collect the specimen. A provisional description produced in 1996 by Dr Molnar referred the specimen to the genus Minmi as a Minmi sp. However significant differences in the shape of the skeleton (revealed by CT scans in 2015) meant that Dr Lucy Leahey and colleagues assigned the material to a new species and genus, Kunbarrasaurus ieversi. Currently the specimen on display at the Queensland Museum and a replica is shown at Kronosaurus Korner. Recently more dinosaur and bird fossils have been found around Richmond in the last few years, however these are currently awaiting scientific description. These include:
- a shoulder girdle and forelimb bones of a titanosaurian sauropod nicknamed ‘Marlin’s Beastie’ discovered by Mr Marlin Entriken on Toronto Park Station.
- isolated limb bones from an enantiornithine bird found by Mr Mike D’Arcy, Dr Patrick Smith and the Ashton family at Kronosaurus Korner’s Free Fossil Hunting Sites.
These rare finds are just at the tip of the discovery ‘iceberg’ and certainly there will be plenty of new dinosaur material to unearthed around Richmond in the near future.
Geology
Dinosaurs from the Early Cretaceous of Queensland are known all throughout the Late Albian (approximately 100 million years old) units in the Rolling Downs Group. This includes the Toolebuc Formation, Allaru Mudstone and Mackunda Formation. However, dinosaurs are exceptionally rare in these formations since they are primarily marine deposits. On the other hand, the overlying Winton Formation, which is found between Eromanga and Winton, was formed by freshwater lakes is better known for its dinosaur fossils. Bird fossils are even rarer than dinosaur remains in the Rolling Downs Group. Currently they are only known from the Toolebuc Formation in areas around Richmond and Boulia.
Description
Dinosaurs from Richmond range in shape and size, with some as large as an elephant to smaller than a blackbird. However, most are only known from fragments, hence scientists rely on close relatives to help reconstruct these creatures.
All that is known of Austrosaurus mckillopi are seven (possibly eight) eroded vertebrae and six near complete ribs. These vertebrae are quite primitive, lacking many of the weight saving features of more advanced sauropods. Based on the fossils a height of approximately 3.9 metres at the hip and 4.1 metres at the shoulder has been suggest, which would have given Austrosaurus an almost level back. Heber Longman and other approximated the animals length at about 15–20 m based other sauropod species. Although not much else is known about Austrosaurus, we can assumed it looked similar to other related titanosaurs having a relatively small head with large nostrils, small crests and tiny spoon-like or peg-like teeth. The undescribed ‘Marlin’s Beastie’ was probably very similar in appearance.
Kunbarrasaurus ieversi is the most complete dinosaur skeleton in Richmond, consisting of: partial skull, vertebral column up to the middle tail, the left shoulder girdle, the left arm (excluding the hand), the pelvis, both thighbones and most of the body armour. Both the bones and the armour are largely articulated (in life position). This has allowed scientists to reconstruct the animal rather precisely. Overall, the animal would have been approximately 2 m long and weighed about 300 kg. The head seems to have been relatively narrow for an ankylosaur, with a board pair of triangular horns at the back corners of the skull. The body of the animal was rather broad with most of it being covered by a bony armour plating. This natural defence was made up of small ossicle, keeled scutes (bony plates) on the body ordered in parallel longitudinal rows, large plates without keels on the snout, large keeled scutes on the neck, spike-like scutes on the hips, and a combination of ridged and keeled scutes and triangular plates on the tail. The arrangement of armour on the tail in unclear, although the triangular plates may have run on the sides unlike North American cousins, which have large spines or a club at the tip.
Only the skull and teeth of the unnamed Muttaburrasaurus species from Richmond has been described, although it is assumed to be very similar to its close relative Muttaburrasaurus langdoni. Estimates place the animal at approximately 7 m long and 2.5 tonnes in weight. The head appears to have been shallow and board, with an elongated snout surmounted by an enlarged, hollow crest. The teeth grew in slicing rows, unlike most other derived ornithopod species, with the upper and lower jaws fitted together evenly. The forelimbs are relatively short and primitive for an ornithopod, suggesting the animal was only semi-quadrupedal. On each hand original reconstructs show a thumb spike (similar to Iguanodon), however Dr Molnar has since doubted such a structure was present.
The smallest of the Richomd dinosaurs would be the enantiornithine bird specimens. Based on the bones found in Richmond, as well as material described as Nanantius eos from Boulia, these creatures would have been about 20–30 cm in length, and weigh around 80–125 grams (about the size of a modern blackbird). It likely they would appear like a miniature gull with three claws on each wings. The neck and head may have been similar to a feathered theropod dinosaur, although they may have had a toothed beak.
Palaeobiology
Not much is known about the palaeobiology of Austrosaurus mckillopi, presumably like many other titanosaurs they fed on a broad herbivorous diet, eating unselectively using their long necks to feed from tall trees. Tracks of older titanosaurs along the Broome coast in Western Australian may suggest that this group of dinosaurs migrated into and out of the country periodically possibly avoiding the colder winters during breeding seasons.The palaeobiology of Kunbarrasaurus ieversi, by comparison to the other dinosaurs from Richmond, has been documented much better. There is direct evidence for the diet of Kunbarrasaurus (in the form of preserved stomach contents). These consist of fibrous or vascular plant tissue fragments, fruiting bodies, spherical seeds, and pollen. The most common remains are the fibrous or vascular fragments, which are typically rather uniform in size at 0.6 to 2.7 millimetres long and have clean cuts at their ends. Because of the small size of these fragments, they have been interpreted as having been nibbled from plants or chopped in the mouth. These small fragments may have come from twigs or stems, but their size is more suggestive of vascular bundles in leaves. The clean cuts and lack of gastroliths (stomach stones) suggest that the animal relied on processing food in the mouth rather than the stomach (like modern emus and lizards). The seeds and fruiting bodies, by comparison, appear to have been swallowed whole. Most of our knowledge of Muttaburrasaurus palaeobiology comes from the holotype specimen, yet this information is easily applicable to the Richmond species. It has been suggested that the enlarged, hollow crest on the snout of Muttaburrasaurus might have been used for display or to produce distinctive calls. However, no fossilised nasal tissue has been found making this idea only conjectural. This crest was shorter in the older Muttaburrasaurus species, found in Richmond, which suggests that it may had a different function. In 1981 Dr Molnar speculated that the slicing teeth of Muttaburrasaurus indicated an omnivorous diet, implying species occasionally ate dead animals (carrion). However, in 1995 he changed his opinion, suspecting that the dental system is evolutionarily convergent with the ceratopsian (Triceratop relatives). This may have been as an adaptation for eating tougher vegetation such as cycads adapted to the colder climate.Fossils of enantiornithine birds in Australia are rather fragmentary, hence much of our understanding is taken from better preserved material overseas. The genus Nanantius is assumed to have fed on marine invertebrates and small fish, much like a modern waders or seagulls. This is based on similar enantiornithines, such as Eoalulavis hoyasi from Spain, that have preserved the stomach regions with fragments of crustacean cuticles. Further evidence of Nanantius being a shorebird comes from a study done by Dr Benjamin Kear and colleagues, which found a tibiotarsus (leg bone) referrable to the genus in the gut of an ichthyosaur specimen (Platypterygius australis). This suggests the birds were living close enough to the water to be predated upon by large marine reptiles.
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