nandi's blog

Muttaburrasaurus

Friday, December 2, 2016

Muttaburrasaurus by PaleoGuy on DeviantArt

Muttaburrasaurus was a genus of herbivorous ornithopod dinosaur, which lived in what is now northeastern Australia sometime between 112 and 99.6 million years ago during the early Cretaceous Period. It has been recovered in some analyses as a member of the iguanodontian family Rhabdodontidae. After Kunbarrasaurus, it is Australia’s most completely known dinosaur from skeletal remains. It was named after Muttaburra, the site in Queensland, Australia, where it was found.

Muttaburrasaurus was about 8 metres (26 ft) and weighed around 2.8 metric tons (3.1 short tons). The femur of the holotype has a length of 1015 millimetres.

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.

Reconstructed skeleton at the Queensland Museum

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, in the Australian state of Queensland, 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.

Molnar originally assigned Muttaburrasaurus to the Iguanodontidae. Later authors suggested more basal euornithopod groups such as the Camptosauridae, Dryosauridae or Hypsilophodontidae. Studies by Andrew McDonald indicate a position in the Rhabdodontidae.

Reconstructed skeleton casts of Muttaburrasaurus, sponsored by Kellogg Company, have been put on display at a number of museums, including the Queensland Museum, Flinders Discovery Centre, and National Dinosaur Museum in Australia.

Mounted skull of a Muttaburrasaurus langdoni at the Australian Museum, Sydney. Photo by Matt Martyniuk (Dinoguy2)

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, 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 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 cycads.

Source: www.ifls.com / www.nageo.com

Kunbarrasaurus

Wednesday, November 30, 2016

An artist impression of Kunbarrasaurus ieversi. Image credit: © Australian Geographic.

Kunbarrasaurus is a genus of small herbivorous ankylosaurian dinosaur from the Cretaceous of Australia.

In November 1989, at Marathon Station near Richmond, Queensland, the skeleton was discovered of an ankylosaurian. In January 1990 it was secured by a team led by Ralph Molnar. In 1996, in a provisional description, Molnar concluded that it could be referred to the genus Minmi as a Minmi sp. Subsequently, the specimen was further prepared by an acid bath and investigated by a CAT scan. The new information led to the conclusion that the species could be named in a separate genus of ankylosaur.

In 2015, Lucy G. Leahey, Ralph E. Molnar, Kenneth Carpenter, Lawrence M. Witmer en Steven W. Salisbury named and described the type species Kunbarrasaurus ieversi. The genus name is derived from Kunbarra - the word for 'shield' in the Mayi language of the local Wunumara people. The specific name ieversi honours Mr Ian Ivers, the property manager who originally found the fossil. The description was limited to the skull. Kunbarrasaurus was one of eighteen dinosaur taxa from 2015 to be described in open access or free-to-read journals.

Kunbarrasaurus By cisiopurple

The holotype, QM F1801, was found in a layer of the Allaru Formation, marine sediments dating from the late Albian, or possibly the early Cenomanian. It consists of an almost complete skeleton with skull, containing the vertebral column up to the middle tail, the left shoulder girdle, the left arm minus the hand, the pelvis, both thighbones and most of the body armour. Both the bones and the armour are largely articulated. In the belly region remains have been found of the animal's last meal. The specimen represents the most complete dinosaur skeleton ever found in Eastern Gondwana (Australia, Antarctica, Madagascar and India) and the most complete ankylosaurian skeleton from the entirety of the Gondwanan continents

Kunbarrasaurus was a small armoured dinosaur, that was quadrupedal and had a long tail.

CT scan of the skull, showing internal components

In 2015, some distinguishing traits of the skull of Kunbarrasaurus were established. The roof of the skull is almost perfectly flat, apart from a limited convex profile of the postorbital bone and the nasal bone. The edges of the skull top, formed by the prefrontal, supraorbital and postorbital bones, make a right angle with the skull sides. The supraorbital is made up of one bone instead of two or three.

Kunbarrasaurus was in 2015 placed in the Ankylosauria. The same year Victoria Arbour e.a. had entered QM F1801 and the Minmi holotype as separate operational taxonomic units in their analysis. Whereas Minmi was recovered as a basal member of the Ankylosauridae, QM F1801 had a basal position in Ankylosauria, i.e. was too "primitive" to be included in either the Ankylosauridae or Nodosauridae. In the 2015 description of Kubarrasaurus on qualitative considerations such a position was indeed deemed likely.

Minmi

Wednesday, November 30, 2016

Minmi by atrox1

Minmi is a genus of small herbivorous ankylosaurian dinosaur that lived during the early Cretaceous Period of Australia, about 119 to 113 million years ago.

Minmi was a small herbivorous quadrupedal armoured ankylosaurian. In 2010, Gregory S. Paul estimated its length at three metres, its weight at three hundred kilogrammes. For an ankylosaurian, Minmi had long limbs, perhaps used to quickly search cover under brushes when threatened by large predators which might have been able to flip the small animal on its back.

Unlike other ankylosaurians, Minmi had horizontally oriented plates of bones that ran along the sides of its vertebrae, hence its specific name, paravertebra. Molnar in 1980 acknowledged that these were ossified tendons, but denied that they were homologous to the ossified tendons of other Ornithischia and claimed that they resembled the pathological tendon aponeurosis of modern crocodiles. Victoria Megan Arbour in 2014 deemed this unlikely and could find only one autapomorphy in the holotype: the high vertical extent of the musculus articulospinalis tendon ossification at its outer front end, wrapping itself around the side process of the vertebra. In 2015, Arbour and Philip Currie concluded that even this was not unique, which would mean the holotype had no diagnostic features and Minmi would be a nomen dubium. However, the 2015 description of Kunbarrasaurus announced that new distinguishing traits of Minmi had been discovered and that it should be considered a valid taxon.

Image of Minmi skeleton by Gary Cranitch, © Queensland Museum.

In 1980, Molnar placed Minmi in the Ankylosauria. In 1987, he thought it was a member of the Nodosauridae. In 2011, a new cladistic analysis performed by Thompson et al. recovered Minmi as the basalmost known ankylosaurid. Arbour & Currie entered Minmi and Minmi sp. as separate operational taxonomic units in their analysis and recovered Minmi as the basalmost ankylosaurid but Minmi sp. (= Kunbarrasaurus) as a more basal ankylosaurian, too "primitive" to be included in either the Ankylosauridae or Nodosauridae. Paul in 2010 suggested that both taxa were part of a Minmidae, an ancient and very basal ankylosaurian lineage, also including Antarctopelta, that had become isolated on Gondwana.

Megalosaurus

Wednesday, November 30, 2016

Artist’s impression of how Victorian paleontologists thought Megalosaurus bucklandii looked (right), compared with how we now understand it to have looked (left). Image credit: Mark Garlick / University of Warwick.

Megalosaurus (meaning "Great Lizard") is a genus of large meat-eating theropod dinosaurs of the Middle Jurassic period (Bathonian stage, 166 million years ago) of Southern England. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic.

Megalosaurus was, in 1824, the first genus of non-avian dinosaur to be validly named. The type species is Megalosaurus bucklandii, named in 1827. In 1842, Megalosaurus was one of three genera on which Richard Owen based his Dinosauria. On Owen's directions a model was made as one of the Crystal Palace Dinosaurs, which greatly increased the public interest for prehistoric reptiles. Subsequently, over fifty other species would be classified under the genus, originally because dinosaurs were not well known, but even during the 20th century after many dinosaurs had been discovered. Today it is understood these additional species were not directly related to M. bucklandii, which is the only true Megalosaurus species. Because a complete skeleton of it has never been found, much is still unclear about its build.

Size comparison (human in blue, lectotype in pink, largest specimen in red)

Buckland had not provided a specific name, as was not uncommon in the early nineteenth century, when the genus was still seen as the more essential concept. In 1826, Ferdinand von Ritgen gave this dinosaur a complete binomial, Megalosaurus conybeari, which however was not much used by later authors and is now considered a nomen oblitum. A year later, in 1827, Gideon Mantell included Megalosaurus in his geological survey of southeastern England, and assigned the species its current valid binomial name, Megalosaurus bucklandii. Until recently, the form Megalosaurus bucklandi was often used, a variant first published in 1832 by Christian Erich Hermann von Meyer – and sometimes erroneously ascribed to von Ritgen – but the more original M. bucklandii has priority.

During the last part of the eighteenth century, the number of fossils in British collections quickly increased. According to an hypothesis published by science historian Robert William Theodor Gunther in 1925, among them was a partial lower jaw of Megalosaurus, acquired in October 1797 by Christopher Pegge for 10s.6d. and added to the collection of the Anatomy School of Christ Church college.

Lithography from William Buckland's "Notice on the Megalosaurus or great Fossil Lizard of Stonesfield", 1824. Caption reads "anterior extremity of the right lower jaw of the Megalosaurus from Stonesfield near Oxford".

In the early nineteenth century, more discoveries were made. In 1815, John Kidd reported the find of bones of giant tetrapods, again at the Stonesfield quarry. The layers there are currently considered part of the Taynton Limestone Formation, dating to the mid-Bathonian stage of the Jurassic Period. The bones were apparently acquired by William Buckland, Professor of Geology at the University of Oxford and dean of Christ Church. Buckland also studied a lower jaw, according to Gunther the one bought by Pegge. Buckland did not know to what animal the bones belonged but, in 1818, after the Napoleonic Wars, the French comparative anatomist Georges Cuvier visited Buckland in Oxford and realised that they were those of a giant lizard-like creature. Buckland further studied the remains with his friend William Conybeare who in 1821 referred to them as the "Huge Lizard". In 1822 Buckland and Conybeare, in a joint article to be included in Cuvier's Ossemens, intended to provide scientific names for both gigantic lizard-like creatures known at the time: the remains found near Maastricht would be named Mosasaurus – then seen as a land-dwelling animal – while for the British lizard Conybeare had devised the name Megalosaurus, from the Greek μέγας, megas, "large". That year a publication failed to occur, but the physician James Parkinson already in 1822 announced the name Megalosaurus, illustrating one of the teeth and revealing the creature was forty feet long and eight feet high. It is generally considered the name in 1822 was still a nomen nudum ("naked name"). Buckland, urged on by an impatient Cuvier, continued to work on the subject during 1823, letting his later wife Mary Morland provide drawings of the bones, that were to be the basis of illustrating lithographies. Finally, on 20 February 1824, during the same meeting of the Geological Society of London in which Conybeare described a very complete specimen of Plesiosaurus, Buckland formally announced Megalosaurus. The descriptions of the bones in the Transactions of the Geological Society, in 1824, constitute a valid publication of the name. Megalosaurus was the first non-avian dinosaur genus named; the first of which the remains had with certainty been scientifically described was Streptospondylus, in 1808 by Cuvier.

Fossil specimens referred to M. bucklandii, Oxford University Museum of Natural History. The display shows most of the original syntype series, including the lectotype dentary, identified by Buckland in 1824

Early reconstructions

The first reconstruction was given by Buckland himself. He considered Megalosaurus to be a quadruped. He thought it was an "amphibian", i.e. an animal capable of both swimming in the sea and walking on land. Generally, in his mind Megalosaurus resembled a gigantic lizard, but Buckland already understood from the form of the thighbone head that the legs were not so much sprawling as held rather upright. In the original description of 1824, Buckland repeated Cuvier's size estimate that Megalosaurus would have been forty feet long with the weight of a seven foot tall elephant. However, this had been based on the remains present at Oxford. Buckland had also been hurried into naming his new reptile by a visit he had made to the fossil collection of Mantell, who during the lecture announced to have acquired a fossil thighbone of enormous magnitude, twice as long as that just described. Today, this is known to have belonged to Iguanodon, or at least some iguanodontid, but at the time both men assumed this bone belonged to Megalosaurus also. Even taking into account the effects of allometry, heavier animals having relatively stouter bones, Buckland was forced in the printed version of his lecture to estimate the maximum length of Megalosaurus at sixty to seventy feet. The existence of Megalosaurus posed some problems for Christian orthodoxy, which typically held that suffering and death had only come into the world through Original Sin, which seemed irreconcilable with the presence of a gigantic devouring reptile during a pre-Adamitic phase of history. Buckland rejected the usual solution, that such carnivores would originally have been peaceful vegetarians, as infantile and claimed in one of the Bridgewater Treatises that Megalosaurus had played a beneficial rôle in creation by ending the lives of old and ill animals, "to diminish the aggregate amount of animal suffering".

1854 reconstruction in Crystal Palace Park guided by Richard Owen presents Megalosaurus as a quadruped; modern reconstructions make it bipedal, like most theropods

In 1824, Buckland assigned Megalosaurus to the Sauria, assuming within the Sauria a close affinity with modern lizards, more than with crocodiles. In 1842, Owen made Megalosaurus one of the first three genera placed in the Dinosauria. In 1850, Prince Charles Lucien Bonaparte coined a separate family Megalosauridae with Megalosaurus as the type genus. For a long time, the precise relationships of Megalosaurus remained vague. It was seen as a "primitive" member of the Carnosauria, the group in which most large theropods were united.

In the late 20th century the new method of cladistics allowed for the first time to exactly calculate how closely various taxa were related to each other. In 2012, Matthew Carrano et al. showed that Megalosaurus was the sister species of Torvosaurus within the Megalosaurinae

Megalosaurus By Manuelsaurus

Living in what is now Europe, during the Jurassic Period (~201 to ~145 million years ago), Megalosaurus may have hunted stegosaurs and sauropods. Repeated descriptions during the nineteenth and early twentieth century of Megalosaurus hunting Iguanodon (another of the earliest dinosaurs named) through the forests that then covered the continent are now known to be inaccurate, because Iguanodon skeletons are found in much younger Early Cretaceous formations. The only specimens belonging to Megalosaurus bucklandii are from the Lower/Middle Bathonian of Oxfordshire and Gloucestershire. No material from outside of the Bathonian formations of England can be referred to Megalosaurus. It lived alongside the theropods Cruxicheiros, Iliosuchus and Streptospondylus, and the sauropods Cardiodon, Cetiosaurus, and possibly Cetiosauriscus. The pterosaur Rhamphocephalus, and indeterminate sauropod and ornithopod remains have also been found alongside fossils of Megalosaurus.

Massospondylus

Wednesday, November 30, 2016

Massospondylus

Massospondylus is a genus of sauropodomorph dinosaur from the Early Jurassic Period (Hettangian to Pliensbachian ages, ca. 200–183 million years ago). It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found at other locations in South Africa, Lesotho, and Zimbabwe.
 
Massospondylus was lightly built for a prosauropod, and much of its length was accounted for by its long neck and tail. Its body was similar in size to that of a large dog. The enlarged sickle-like thumb claws seen in other prosauropods were particularly well developed. We do not know exactly how Massospondylus used these huge claws. They would no doubt have made formidable weapons when the animal reared up on its hind legs to ward off predators-or perhaps to fight rival member of the species for mates. They may also have been useful in gathering food.

Mounted Massospondylus skeleton cast at the Natural History Museum, London, showing an outdated quadrupedal pose. Author: Ballista

Although Massospondylus was long depicted as quadrupedal, a 2007 study found it to be bipedal. It was probably a plant eater (herbivore), although it is speculated that the early sauropodomorphs may have been omnivorous. This animal, which was 4–6 metres (13–20 ft) long, had a long neck and tail, with a small head and slender body. On each of its forefeet, it bore a sharp thumb claw that was used in defense or feeding. Recent studies indicate that Massospondylus grew steadily throughout its lifespan, possessed air sacs similar to those of birds, and may have cared for its young.
 
As with all dinosaurs, much of the biology of Massospondylus, including its behavior, coloration, and physiology, remains unknown. However, recent studies have allowed for informed speculation on subjects such as growth patterns, diet, posture, reproduction, and respiration

10 Mamenchisaurus Facts

Wednesday, November 30, 2016

Mamenchisaurus by Sergey Krasovskiy

China’s overstuffed with awesome dinosaurs, and today we’re taking a look at one of their most famous.

1. MAMENCHISAURUS NECKS WOULD’VE MADE GIRAFFES FEEL SELF-CONSCIOUS

Mamenchisaurus necks approaching 30 feet in length have been documented, and one poorly-known species—M. sinocanadorum—is believed to have had nearly 50 feet separating its head from its shoulders. Let’s put that in perspective, shall we?  Regulation NFL goalposts have an 18’6” gap between their uprights. The largest (reliably) documented great white shark measured 19.5 feet from end to end. The average giraffe boasts a 6-foot neck. Meanwhile, yours is probably only around 10-12 inches long. How pathetic…

2. SOMETHING NASTY HAPPENED TO ONE POOR SPECIMEN’S TAIL

As paleontologist Dave Hone notes on his wonderful blog, a Mamenchisaurus skeleton that currently resides at China’s Chengdu University of Technology has an unnatural-looking growth above one of its tail vertebrae. This, he explains, was caused by either a broken and re-healed backbone injury or “an infection that spread inside the tail causing the build-up of ossified tissue.”

3. AN ESPECIALLY HUGE SPECIES WAS ASIA’S LARGEST DINOSAUR

We still don’t know which dino was the world’s all-time biggest, but at an estimated 115 feet in length, Mamenchisaurus sinocanadorum clearly deserves to be part of this discussion.

4. ANOTHER SPECIES HAD AN ODD SPINAL COLUMN

Paleo-artist Gregory S. Paul points out that the vertebrae above this dinosaur’s hips are fused together in a strange, V-shaped orientation. Therefore, M. youngimight have had to permanently hold its tail at an upturned, awkward-looking 20-degree angle.

5. MAMENCHISAURUS FEATURED “SPATULA-SHAPED” TEETH

These broad chompers were ideal for gathering bundles of leaves in huge gulps, unlike the pencil-shaped teeth of such massive herbivores as Diplodocus, a dino which nimbly stripped them from narrow branches.

6. AT LEAST ONE VARIETY HAD A CLUBBED TAIL

Although Mamenchisaurus hochuanensis rocked a small, bony knob at the end of its tail, some scientists claim that this thing would’ve been practically useless as a weapon. Interestingly, M. houchanensis was far from the only Asian sauropod (“long-necked dino”) to have had one. Omeisaurus and Shunosaurus were also card-carrying members of the prestigious “Tail-Club Club”.

7. THE CZECH REPUBLIC BOASTS AN ANIMATRONIC MAMENCHISAURUS

Next time you’re in Prague, be sure to visit this guy at the Harfa DinoPark (and don’t forget the kids)!

Speaking of cool displays, NYC’s American Museum of Natural History temporarily housed some reconstructed Mamenchisaurus organs. Sadly, this exhibit’s no longer in town, but feel free to check out several neat photos here.

8. IT HAD HUGE “NECK RIBS”

Mamenchisaurus hochuanensis Young & Zhao, 1972 sauropod dinosaur from the Jurassic of China (public display, Field Museum of Natural History, Chicago, Illinois, USA) (cast based on on CCG V 20401, Chengdu College of Geology (Chengdu Institute of Geology/Chengdu University of Technology), Chengdu, Sichuan, China). This sauropod dinosaur had a 22 meter long body (~72 feet) and a hyperelongated neck (>9 meters long – about 31 feet). Author James St. John

Take a gander at this picture. Notice those long, pointy things on the bottom of this Mamenchisaurus’ neck? They’re called “cervical ribs,” and they probably acted as a load-bearing mechanism. However, these would have also cost the dino some flexibility in that area. Alas, life frequently demands such trade-offs.

9. ACCORDING TO ONE STUDY, MAMENCHISAURUS PREFERRED LOW-LYING VEGETATION

In 2013, an international paleontological team took a good, hard look at Mamenchisaurus youngi and its magnificent vertebrae. Their research concluded that, based on its relative stiffness, M. youngi “had a nearly straight, near horizontal neck posture and browsed at low or medium heights.”

10. MAMENCHISAURUS MAY HAVE PLAYED A PART IN THE HISTORY OF CHINESE MEDICINE

Are mythical dragons and long-gone dinosaurs really one and the same? Written sometime during the Jin Dynasty (265-317 C.E.), an invaluable book called The Chronicles of Huayang records the discovery of “dragon bones” in what is now China’s Sichuan Province. Jurassic fossil deposits—including a few which have produced Mamenchisaurus material—are widespread throughout the area. Perhaps this period’s dinosaurs helped give rise to the legendary, fire-breathing reptiles of Chinese folklore.

Furthermore, it was once widely believed that dragons harbored some medicinal qualities. In fact, as recently as 2006, dinosaur fossils were still being sold as “dragon bones” (at around 25 cents per pound), mashed up, and “boiled with other ingredients and fed to children to treat dizziness and leg cramps.” Ask your doctor if Mamenchisaurus is right for you!

Original article by www.mentalfloss.com

Mamenchisaurus

Wednesday, November 30, 2016

Mamenchisaurus skeleton

Mamenchisaurus is a sauropod dinosaur genus including several species, known for their remarkably long necks which made up half the total body length. It is known from numerous species which ranged in time from 160 to 145 million years ago, from the Oxfordian to Tithonian ages of the late Jurassic Period of China, and the largest species may have reached 35 m (115 ft) in length and possibly weighed 50 to 75 tons.
 
The longest neck of any animal known to us from any time belonged to Mamenchisaurus. It made up half the animal’s total length. Reaching perhaps 49 feet (15 m) long, this incredible structure was supported by 19 vertebrae – no other dinosaur had as many neck vertebrae. Because these vertebrae were hollow – and in places the bone was as thin as egg shells – the neck was very light. Long bony struts running between the neck vertebrae would have limited its flexibility, and many reconstructions of Mamenchisaurus show it with the neck held straight as a ramrod. Some of these bony struts would have overlapped three or four vertebrae.

Mamenchisaurus Species Scale by Steveoc86

Mamenchisaurus was first discovered in 1952 on the construction site of the Yitang Highway in Sichuan, China. The partial skeleton fossil was then studied, and named Mamenchisaurus constructus in 1954, by the renowned Chinese paleontologist Professor C. C. Young. The type specimen had an incomplete neck with 14 vertebra preserved and none of these were complete. M. constructus has been estimated around 13 m (43 ft) and 15 m (49 ft) in length.

Only a few skull fragments have been found of Mamenchisaurus. These suggest that it had a relatively short snout with robust, blunt teeth in the front and along the sides of the mouth. The particularly heavy teeth give a clue to its diet. These teeth could have dealt with the coarser, harder parts of plants and would have been especially good for shredding cycads and other fibrous fronds.

Artist’s impression of M. hochuanensis by Dimitri Bogdanov
Although superficially Mamenchisaurus looks similar to North American sauropods such as Diplodocus and Apatosaurus, we now think that it was part of a group of sauropods unique to Asia. By the late Jurassic, the early Atlantic Ocean had become wide enough to restrict the flow of animals between North America and Europe and, although Europe and Asia were connected by land, there were deserts and mountain ranges that would have restricted the movement of large land animals from east to west.

Species

  • M. anyuensis He, Yang, Cai, Li & Liu, 1996. Approximately 21 meters (69 ft) in length. Known from both the Suining Formation and Penglaizhen Formation.
  • M. constructus Young, 1954: (Type species) The holotype specimen, represented by a partial skeleton that was 13 m (43 ft) long.
  • M. hochuanensis Young & Zhao, 1972: Four partial skeletons. Known from Shaximiao Formation and 22 m (72 ft) in length.
  • M. jingyanensis Zhang, Li & Zeng, 1998. Known from Shaximiao Formation and estimated between 20 to 26 metres (66 to 85 ft) in length.
  • M. sinocanadorum D. Russell & Zheng, 1993: Partial skull, isolated bones (type), referred, nearly complete skeleton. Known from the upper part of the Shishugou Formation (about 160 Ma ago), it may include one of the largest complete dinosaur specimens known, measuring 35 metres (115 ft) in length.
  • M. youngi Pi, Ouyang & Ye, 1996: Mamenchisaurus youngi (pronunciation YOUNG-eye) was unearthed in Xinmin County, Zigong City in Sichuan Province, China, in 1989. The species was named in honour of Young. It was a very complete and articulated specimen preserving all the vertebra from the head up until the 8th tail vertebra. It had 18 neck vertebra. At 16 meters (52 ft) long with a 6.5-meter (21 ft) neck, is relatively small among various species of Mamenchisaurus.

Maiasaura

Wednesday, November 30, 2016

Maiasaura by Alain Beneteau

Maiasaura (from the Greek “μαία” and the feminine form of Latin saurus, meaning “good mother reptile” or “good mother lizard” ) is a large herbivorous hadrosaurid (“duck-billed”) dinosaur genus that lived in the area currently covered by the state of Montana in the Upper Cretaceous Period (mid to late Campanian), about 76.7 million years ago.

The first fossils of Maiasaura were discovered in 1978. In 1979, the genus was named. The name refers to the find of nests with eggs, embryos and young animals, in a nesting colony. These showed that Maiasaura fed its young while they were in the nest, the first time such evidence was obtained for a dinosaur. Hundreds of bones of Maiasaura have been dug up. Evidence suggest the “Maiasaura” was covered rapidly by a global flood. This preserved the nesting site and fossils.

Illustration of a herd of Maiasaura walking along a creekbed, as found in the semi-arid Two Medicine Formation fossil bed. This region was characterized by volcanic ash layers and conifer, fern and horsetail vegetation. Author: Debivort

Maiasaura was about nine metres long. Young animals walked on their hind legs, adults on all fours. Maiasaura was probably closely related to Brachylophosaurus.

Maiasaura were large, attaining a maximum known length of about 9 metres (30 ft). They had a flat beak typical of hadrosaurids, and thick noses. They had a small, spiky crest in front of the eyes. This crest may have been used in headbutting contests between males during the breeding season.

Maiasaura peeblesorum skeletal mount, Brussels Natural History museum (2009).

Maiasaura were herbivorous. They were capable of walking both on two (bipedal) or four (quadrupedal) legs. Studies of the stress patterns of healed bones show that young juveniles under four years old walked mainly bipedal, switching to a mainly quadrupedal style of walking when they grew larger. They appeared to have no defense against predators, except, perhaps, its heavy muscular tail and their herd behavior. Herds were extremely large and could have comprised as many as 10,000 individuals. Maiasaura lived in an inland habitat.

Maiasaura lived in herds and it raised its young in nesting colonies. The nests in the colonies were packed closely together, like those of modern seabirds, with the gap between the nests being around 7 metres (23 ft); less than the length of the adult animal. The nests were made of earth and contained 30 to 40 eggs laid in a circular or spiral pattern. The eggs were about the size of ostrich eggs.

Reconstructed nest

It appears that young Maiasaura grew quickly. To some researchers, this suggests that they were warm-blooded. The nests that Horner and Makela found also throw light on the social organization of these hadrosaurs. The number and proximity of the nests indicate that females nested in large groups. Some scientists believe that Maiasaura were strongly social animals that lived in herds of many thousands.

Maiasaura is a characteristic fossil of the middle portion (lithofacies 4) of the Two Medicine Formation, dated to about 76.4 million years ago. Maiasaura lived alongside the troodontid Troodon and the hypsilophodont Orodromeus, as well as the dromaeosaurid Bambiraptor and the tyrannosaur Daspletosaurus.

10 Facts About Ceratosaurus

Wednesday, November 30, 2016

The large Ceratosaurus at the Natural History Museum of Utah. Photo by Brian Switek.

Ceratosaurus popped up in Jurassic Park III at one point – but what do we know about the dinosaur?

Like a ’56 T-Bird parked in a car park full of hybrids, Ceratosaurus shared its range with several less-archaic carnivores. This primitive predator really stands out in films and in museums, which helps explain the odd dino’s enduring popularity.

1. Ceratosaurus Had an Armored Backside.

A row of bony plates called osteoderms ran down the animal’s spine. They probably didn’t offer much defense, but they sure helped Ceratosaurus score some major style points!

2. It Might Have had Semi-Aquatic Habits.

Like modern gators, Ceratosaurus came with a strong, broad, and flexible tail—and the animal’s teeth are sometimes found scattered near lungfish skeletons. So was it amphibious? According to paleontologist Robert Bakker, the idea has merit. He’s even envisioned Ceratosaurus as a wannabe crocodile of sorts, stealthily lurking beneath Jurassic rivers. But while this dinosaur was likely a halfway-decent swimmer, many feel that Bakker’s very speculative hypothesis can’t keep its head above the water.

3. It’s Been a Movie Star for Over 100 Years.

Audiences watched the bonafide celebrity stalk cavemen in Brute Force (1914), take on Triceratops in One Million Years B.C.(1966), and gag at the sight of Spinosaurus poop in Jurassic Park III (2001).

Jurassic Park III (2001)

4. Some Argue that This Creature Directly Competed with the Better-Known Allosaurus.

Both carnivores stalked Utah and Colorado 150 million years ago, and both had nasty jaws designed for slicing (as opposed to crushing bone and all that fun stuff). Because similar bites often mean similar diets, maybe these two titans hunted the same game. Or they might have found separate niches and steered clear of each other—Allosaurus did have proportionately-smaller teeth, after all. Regardless, the late Jurassic was clearly a tough time to be an herbivore.

5. Scientists Still Aren’t Sure About What Ceratosaurus Did With its Dynamic Nasal Horn.

In 1920, an American geologist named Charles Whitney Gilmore wrote that Ceratosaurus’ horn “formed a useful weapon for offense and defense.” Nowadays, however, this thing’s function no longer seems quite so clear-cut.  Thin and probably on the fragile side, most 21st-century specialists hold that Ceratosaurus’ best-known feature was better-suited for display than combat.

6. It Featured Unusually Long Teeth.

Ceratosaurus Juvenile. Author: Deviant Paleoart

One specimen manages to look just as scary with its mouth shut. This dino’s upper teeth are so long that—when the creature’s maw assumes a “closed” position—they extend below the lower jaw!

7. Ceratosaurus was Relatively Rare

Allosaurus seems to have been far more common than Ceratosaurus. The latter, bumpy-snouted predator is only known from a relative handful of skeletons. Meanwhile, very few dinos are as well-represented by the fossil record as Allosaurus: A single quarry contains assorted bones belonging to at least 44 individuals. How many Ceratosaurus specimens has this same site yielded? One.

8. Its Remains Have Been Found on Three Different Continents.

Though frequently cited as a North American creature, Ceratosaurus material has also turned up in Portugal and Tanzania.

9. Size-Wise, Not all Ceratosaurus Were Created Equal.

Ceratosaurus dentisculatus could have really done some damage. While the 18-foot Ceratosaurus nasicornis is, by far, this genus’ most famous species, C. dentisculatus was noticeably longer, with an estimated length of over 23 feet (7 metres)—and it may been twice as massive.

10. Ceratosaurus was Named by One of America’s Greatest Paleontologists.

Skeleton of Ceratosaurus, a theropod dinosaur. Date: 1896 Source: Originally from O. C. Marsh’s book, The Dinosaurs of North America; found in). Author: O.C. Marsh.

Othniel Charles Marsh (1832-1899) also introduced the world to such prehistoric icons as StegosaurusTriceratopsAllosaurusDiplodocus, and Apatosaurus. Plus, he lobbied for Native American rights, regularly corresponded with Charles Darwin, and was among the first to suggest that present-day birds evolved from dinosaurs.

Source: www.mentalfloss.com

Leaellynasaura

Wednesday, November 30, 2016

Leaellynasaura

Leaellynasaura (meaning “Leaellyn’s lizard”) is a genus of small herbivorous ornithischian dinosaurs from the Albian stage of the Early Cretaceous (dated to between 118 and 110 million years ago), first discovered in Dinosaur Cove, Australia. The only known species is Leaellynasaura amicagraphica. It was described in 1989, and named after Leaellyn Rich, the daughter of the Australian palaeontologist couple Tom Rich and Patricia Vickers-Rich who discovered it. The specific name L. amicagraphica translates to “friend writing” and honours both the Friends of the Museum of Victoria and the National Geographic Society for their support of Australian paleontology.

Leaellynasaura is a relatively small dinosaur, about 90 centimeters (3 feet) in length. It is known from several specimens including two nearly complete skeletons and two fragmentary skulls. It has been variously described as a hypsilophodontid, a primitive iguanodontian and primitive ornithischian (Genasauria). The most recent assessment describes it as a non-iguanodontian ornithopod.

During the early Cretaceous, Victoria was well within the Antarctic polar circle. This means that Leaellynasaura was living, and apparently thriving, at latitudes that no reptile lives at today. The fact that even juveniles had enlarged optic lobes suggests that this dinosaur had large eyes that helped it to see its way through the long, dark polar winters.

A female Leaellynasaura feeds her young. Walking with Dinosaurs | BBC Earth

The type species is Leaellynasaura amicagraphica. It was described in 1989; It was named after Leaellyn Rich, the daughter of the palaeontologist couple Tom Rich and Patricia Vickers-Rich who discovered it. Leaellynasaura was a hypsilophodont, a rather basal ornithopod. Like all ornithopods, it was a herbivore. So far, no complete skeletons have been found of Leaellynasaura. It stood at about one metre (3 feet).

Leaellynasaura appeared on the fifth episode of Walking with Dinosaurs. Evolved cold-weather Leaellynasaura appeared in Stephen Baxter’s “Evolution” in the chapter “The Last Burrow.”

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