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What are the Differences Between Tyrannosaurus and Tarbosaurus?

Saturday, February 25, 2017

Tarbosaurus skull

A more subtle difference is the shape of the lacrimal bone, which made up the front part of the eye socket and was also part of the dinosaur’s skull ornamentation. In Tyrannosaurus rex, the top portion of the lacrimal has a concave shape, but in Tarbosaurus bataar the same portion of bone is domed.

Tarbosaurus bataar is in a sense the Asian version of the Tyrannosaurus rex, they are close cousins,” said Lawrence Witmer, an anatomist and paleontologist at Ohio University.

Both had powerful jaws and teeth, big back legs and tiny arms, although Tarbosaurus had arms that were even smaller than those of T. rex, according to Philip Currie, a paleontologist at the University of Alberta.

Just as this dinosaur specimen, a relative of Tyrannosaurus rex, went up for auction on May 20, a question arose as to whether or not it was taken illegally from Mongolia. Credit: Wynne Parry

The largest Tyrannosaurus found measured about 45 feet (14 meters) long, while the largest Tarbosaurus measured about 40 feet (12 meters) long, Currie told LiveScience in an email. “But there is always the possibility that bigger specimens will eventually be found for one or both.”

While clearly identifiable, tarbosaurs have only been found in a roughly 70-million-year-old rock formation in Mongolia, Tyrannosaurus rex remains have turned up in many fossil beds in North America. Both were apex predators, meaning they were at the top of the food chain, and, thanks to their lineage, both are considered tyrannosaurs.

Source: www.livescience.com

10 Facts About Abelisaurus

Friday, February 24, 2017

Abelisaurus by atrox1

Dinosaurs are not mythical. They used to be very much real and inhabited the earth millions of years ago. Some were mere vegetarians but some were ultimate killers that feasted on flesh and blood. Abelisaurus was one such frightening dino that could have wreaked havoc on us if it were alive today. Thanks to Mother Nature and its process of evolution that we have been spared! Abelisaurus is pronounced as AY-bell-ih-SORE-us. Let us learn 10 interesting facts about Abelisaurus!

Size comparison of the Carnotaurins (left to right) Carnotaurus, Abelisaurus, Pycnonemosaurus, Aucasaurus and Quilmesaurus. Basis for all skeletons is Carnotaurus skeletal by Jaime Headden (on commons) with modified proportions and heads to fit other taxa. By IJReid

At a glance: Lived: 85-80 million years ago.

Food: Meat.

Species: A. comahuensis. Abelisaurus is named after discoverer Roberto Abel.

1. Abelisaurus used to live in South American woodlands during the late Cretaceous period, i.e. some 85-80 million years ago.

Abelisaurus home by Teratophoneus

2. Abelisaurus is actually a Greek name for Abel’s Lizard. This dinosaur was named Abel’s Lizard because its remains were discovered by Roberto Abel, an Argentinian paleontologist.

3. Interesting fact about Abelisaurus is that it is known by only one skull. Put in other words, only the skull was found and the rest of the carnivore was reconstructed using that skull.

Skull of Abelisaurus. Cráneo de un Abelisaurus comahuensis. Fotografía obtenida de la exposición temporal “Dinosaurios de Patagonia”, en Alicante, España (Spain). Photo by Kokoo

4. It is estimated that this dinosaur measured around 30 feet in length and weighed around 2 tons. Considering the behemoth sizes of other dinosaurs, 2 tons is actually a lightweight candidate but is enough to crush humans.

5. Scientific studies led to the belief that Abelisaurus were scaled-down or smaller versions of Tyrannosaurus rex.

6. Abelisaurus used to have bipedal locomotion and had very short arms that literally didn’t help much in any activity like eating, hunting, running etc.

7. Abelisaurus had a large head with small teeth. However, the most notable feature of the head was the presence of a collection of large holes on the skull right above the jaws. Though the exact reason for these holes are not known, scientists believe that they might have been caused by the process of evolution. It was actually a balancing act. The skull being massive, the absence of these holes could simply unbalanced the entire body weight of the dinosaur.

8. Abelisaurus actually gave its name to an entire theropod dinosaur family. The family is known as “Abelisauridae”.

Abelisauridae by Tim Horton

9. Abelisaurs as a whole lived in Gondwana Island Continent during the Cretaceous period. Today that area actually consists of South America, Madagascar and Africa.

10. Abelisaurs includes other efficient carnivore dinosaurs like Majungatholus and Carnotaurus. So, do you know any other facts about Abelisaurus? If you do, let us know! We will be glad to learn new and interesting facts.

Sources: 12

Bistahieversor

Tuesday, February 21, 2017

Bistahieversor by Dinoraul

Bistahieversor (meaning “Bistahi destroyer”) is a genus of tyrannosaurid dinosaur. Bistahieversor existed in the Late Cretaceous Hunter Wash member of the Kirtland Formation, which has been dated to 74.55 ± 0.29 Ma.

The name Bistahieversor comes from the Navajo Bistahí, or “place of the adobe formations” in reference to the Bisti/De-Na-Zin Wilderness where it was found, and eversor, meaning “destroyer.”

Bistahieversor size by PrehistoricWildlife.com

Bistahieversor is a genus of derived dinosaur currently classified in the subfamily Tyrannosaurinae. It is more derived than Teratophoneus but less derived than Lythronax. It forms the sister taxon of a group including LythronaxNanuqsaurusTyrannosaurusTarbosaurus and Zhuchengtyrannus.

Bistahieversor differs from other tyrannosaurs in the possession of 64 teeth, an extra opening above the eye, and a keel along the lower jaw. The opening above the eye is thought to have accommodated an air sac that would have lightened the skull’s weight. Bistahieversor also had a complex joint at its “forehead” that would have stabilized the skull, preventing movement at the joint.

The first remains now attributed to Bistahieversor, a partial skull and skeleton, were described in 1990 as a specimen of Aublysodon. Additional remains, consisting of the incomplete skull and skeleton of a juvenile, were described in 1992. Another, complete, skull and partial skeleton were found in the Bisti/De-Na-Zin Wilderness of New Mexico in 1998, known colloquially as the “Bisti Beast”. In a 2000 paper, Thomas Carr and Thomas Williamson re-examined these four specimens and suggested that they did not belong to Aublysodon, but rather to one or more new species of Daspletosaurus. However, it was not until 2010 that Carr and Williamson published a thorough re-description of the specimens and found that they belonged to a new genus and species of more generalized tyrannosauroid, which they named Bistahieversor sealeyi.

Skeletal reconstructions and postcranial elements of Utah tyrannosaurs. (A) Skeletal outlines showing recovered elements of Lythronax argestes (UMNH VP 20200) and (B) Teratophoneus curriei (UMNH VP 16690). Selected postcranial elements of Teratophoneus in left lateral view: (C) cervical vertebra 3; (D) cervical vertebra 9; (E?G) three caudal vertebrae; (H) right ilium (photoreversed with left illium in the background in grayscale); (I) pubis; (J) ischium; (K) right femur in lateral view; (L) right tibia in anterior view; and (M) right fibula in medial view. Elements of Lythronax figured include: (N) the left pubis in lateral view; (O), left tibia in anterior view (photoreversed); and (P) left fibula in medial view (photoreversed). Scale bar for a and b is 1 meter, c-g 5 cm and h-p 10 cm. Abbreviations: ac, acetabulum; af, astragalar facet; bf, brevis fossa; cc, cnemial crest; dp, diapophysis; ep, epipophysis; ff, fibular flange; ffa, fibular facet; ft, fourth trochanter; if, iliofibularis muscle scar; ip, ischial peduncle; lt, lesser trochanter; mff, fibular fossa; ns, neural spine; of, obturator flange; pa, parapophysis; pb, pubic boot; pc, pleurocoel; pp, pubic peduncle; poz, postzygapophysis; prz, prezygapophysis; sac, supraacetabular crest; sar, supraacetabular ridge; tp, transverse process. Author: Scott Hartman

 

Material from both adolescent and adult individuals has been found in the Kirtland Formation of New Mexico, United States. Adult Bistahieversor are estimated to have been around 9 metres (30 ft) long, weighing at least a ton. The snout is deep, indicating that the feature is not unique to more derived tyrannosaurs such as Tyrannosaurus. Geographical barriers such as the newly forming Rocky Mountains may have isolated the more southerly Bistahieversor from more derived northern tyrannosaurs.

Bistahieversor differs from other tyrannosaurs in the possession of 64 teeth, an extra opening above the eye, and a keel along the lower jaw. The opening above the eye is thought to have accommodated an air sac that would have lightened the skull’s weight. Bistahieversor also had a complex joint at its “forehead” that would have stabilized the skull, preventing movement at the joint.

Skull at the New Mexico Museum of Natural History and Science. Photo by Lee Ruk

Tarbosaurus

Tuesday, February 21, 2017

Tarbosaurus by Herschel Hoffmeyer

Tarbosaurus (meaning “alarming lizard”) is a genus of tyrannosaurid theropod dinosaur that flourished in Asia about 70 million years ago, at the end of the Late Cretaceous Period. Fossils have been recovered in Mongolia, with more fragmentary remains found further afield in parts of China.

Tarbosaurus size by PrehistoricWildlife.com

Although many species have been named, modern paleontologists recognize only one, T. bataar, as valid. Some experts see this species as an Asian representative of the North American genus Tyrannosaurus; this would make the genus Tarbosaurus redundant. Tarbosaurus and Tyrannosaurus, if not synonymous, are considered to be at least closely related genera. Alioramus, also from Mongolia, is thought by some authorities to be the closest relative of Tarbosaurus.

Skeleton of Tarbosaurus baatar in Barcelona. Author Jordi Payà

Like most known tyrannosaurids, Tarbosaurus was a large bipedal predator, weighing up to five tonnes and equipped with about sixty large teeth. It had a unique locking mechanism in its lower jaw and the smallest forelimbs relative to body size of all tyrannosaurids, renowned for their disproportionately tiny, two-fingered forelimbs.

Tarbosaurus skeleton by Szymoonio

Tarbosaurus lived in a humid floodplain criss-crossed by river channels. In this environment, it was an apex predator at the top of the food chain, probably preying on other large dinosaurs like the hadrosaur Saurolophus or the sauropod NemegtosaurusTarbosaurus is represented by dozens of fossil specimens, including several complete skulls and skeletons. These remains have allowed scientific studies focusing on its phylogeny, skull mechanics, and brain structure.

Restoration of Tarbosaurus in Late Cretaceous Mongolian environment by Dimitri Bogdanov

Tarbosaurus hunting and possible prey specialization

The highly developed sense of smell combined with the underdeveloped sight can be used to draw the easy conclusion that Tarbosaurus was adapted more for scavenging than active hunting.‭ ‬However such a quick conclusion may not be the correct one when you look at the fossils of the rest of the animal as well as potential prey items.‭ ‬Dinosaurs,‭ ‬particularly predatory ones,‭ ‬are always studied for signs of stress fractures,‭ ‬injuries and damage caused by repeated actions throughout the animals life.‭ ‬The key area for stress fractures in Tarbosaurus was surprisingly found in the hands,‭ ‬an area that could not be in contact with the ground.‭ ‬The most plausible explanation for the presence of an injury caused by repeated behavior would be contact with another large dinosaur,‭ ‬another of its own kind or perhaps a large prey item.

Tarbosaurus also did not have the acute stereoscopic‭ (‬binocular‭) ‬vision associated with its North American cousins.‭ ‬Some possible prey items were large hadrosaurs like Saurolophus,‭ ‬but there were also titanosaurid sauropods such as Nemegtosaurus.‭ ‬These large dinosaurs would not require exceptional vision to find and hunt and would have quite possibly been slow on their feet making them viable prey for capture.‭ ‬Their size however would require Tarbosaurus to get close and physical to make a kill,‭ ‬a possible explanation for the stress fracture to the hand.

Tyrannosauridae

Many of the other dinosaurs in the region would have been smaller and often swifter than Tarbosaurus,‭ ‬meaning that it would have been restricted to the larger dinosaurs that other smaller tyrannosauroids like Alioramus were better adapted to catch.‭ ‬Whereas the potential is there for Tarbosaurus to have been an active hunter,‭ ‬it may still have had a greater tendency to turn to scavenging to augment its diet than others of its group.‭ ‬It may have even used its sheer size and bulk to intimidate other smaller predators into giving up their kills,‭ ‬behaviour that can be observed in carnivores that are still active predators today.

Saichania

Tuesday, February 21, 2017

Saichania by Román García Mora-CG Artist

Saichania (Mongolian meaning “beautiful one”) is a genus of herbivorous ankylosaurid dinosaur from the Late Cretaceous period of Mongolia and China.

The first fossils of Saichania were found in the early 1970s in Mongolia. In 1977 the type species Saichania chulsanensis was named. The description of this species has been based on limited fossil material; especially the rear of the animal is not well known.

Saichania size by Prehistoric Wildlife

Saichania was a large ankylosaurid. Maryańska estimated its length at seven meters. Other estimates roughly confirmed this, stating a maximum length of about 6.6 metres (22 ft) long. However, Gregory S. Paul in 2010 gave a lower estimate of 5.2 metres, with a weight of two tonnes. Finds of tail clubs of gigantic individuals suggest larger sizes but their reference to Saichania cannot be substantiated as the holotype, the only specimen sufficiently described, only consists of the front of the animal.

Saichania shared the general ankylosaurid build, being a low-slung, broad, heavily armoured dinosaur, with short forelimbs. Even for an ankylosaurid however, Saichania is exceptionally robust, its rump strengthened by ossifications and fusions of the vertebral column, ribs, shoulder girdle and breast bones.

Saichania was over five metres long and weighed over two tonnes. It was more robustly built than other members of the Ankylosauridae. Neck vertebrae, shoulder girdle, ribs and breast bones were fused or firmly connected. Its body was flat and low-slung, standing on four short legs. The forelimbs were very powerful. The head was protected by bulbous armour tiles. It could defend itself against predators like Tarbosaurus with a tail-club. On the torso keeled osteoderms were present. Saichania bit off plants in its desert habitat with a horny beak and processed them in its wide hindgut.

Tarbosaurus and Saichania by Plioart

It is belived that Saichania lived in a hot, arid, desert-type environment – and it seems to have possessed a number of adaptations to this environment. Saichania’s skull was equipped with complex air passages that would have helped it keep cool. Additionally, it may have a salt gland near its nostrils.

Body armour

The holotype preserves the front body armour in articulation. The neck is protected by two cervical halfrings, each made of six rectangular segments positioned next to each other: two at the top, two at the upper sides and two at the lower sides. Each segment has a keel parallel to the long axis of the body. The keel of the lower side segments is the largest. The segments are connected to an underlying continuous band of bone, mainly by a broad fusion at the front edge, but also by a narrow strip at the rear. The seams between the segments are covered by a rectangular zone of small oval osteoderms. Between the upper and lower side segment a larger central osteoderm is present, forming a rosette. The front halfring is smaller than the rear one.

Cast of a fossil skull, specimen PIN 3142/250, initially referred to Tarchia kielanae, in 2014 referred to Saichania. Both are extinct ankylosaurid dinosaurs from Mongolia. Photo by Ghedoghedo

Maryańska classified Saichania as a member of the Ankylosauridae, related to Pinacosaurus and observed that these two dinosaurs differ from all others in the structure of their nasal cavities.

Stan the Tyrannosaurus rex

Thursday, February 9, 2017

Stan the Tyrannosaurus rex

The skeleton of Stan the Tyrannosaurus rex (T. rex) was excavated by the Black Hills Institute in 1992, after its discovery by an amateur palaeontologist, Stan Sacrison. The fossil remains were found in an outcrop of Badlands (rough terrain) near Buffalo (South Dakota) in the USA. The excavation required the removal of the rock above the specimen, called overburden, with the help of a Bobcat (a small earth moving machine), a jackhammer, picks and shovels. Knives, scribes and brushes were used to expose the fossil bones and teeth, while glues and other chemicals were applied to stabilise and preserve the surface of the fossils. Before removal of the fossils, each one was drawn on a ‘map’ using a grid set over each section of the site. The fossils were then covered with aluminium foil and encased in a field jacket, layered burlap (sack-cloth) and plaster, so they could be moved without breakage. All excavated material was then transported to the lab for specialised cleaning, called preparation.

“Sue”, AMNH 5027, “Stan”, and “Jane”, to scale with a human. By Matt Martyniuk

Abundant well-preserved leaves and a few palm fronds found with Stan have given us new information about the environment and climate in which he lived. Other evidence from the site shows that Stan’s body probably remained exposed for a few months before a flood scattered a variety of bones and buried his skeleton, entombing it for 65 million years. The excavation was carefully documented with photographs, video and scientific notations for future study of the specimen and public education. Since the initial excavation, the Black Hills Institute teams have returned to the site twice to search further into the hillside for bones. The continuing excavation has yielded several more bones and additional material. To date 199 of Stan’s bones have been found – 70% of a complete skeleton – making Stan the second most complete T.rex found so far.

Stan ‘n Sue comparison by ScottHartman on DeviantArt

When Stan was collected in north-western South Dakota in 1992, it was clear that Stan Sacrison had made a significant discovery. It was only after the bones were prepared, however, that it became clear that this specimen included the best skull of all the Tyrannosaurus rex specimens ever collected. Not only was Stan’s skull virtually complete, but the bones were preserved in pristine condition. Perhaps even more importantly, the many bones of the skull were found mostly disarticulated (separated), allowing for a more detailed study than any other T.rex skull.

Stan’s teeth

The teeth of Tyrannosaurus rex were specialised: they had tiny serrations to help them cut through flesh and are round in cross-section for breaking through bone. The crown of the tooth was covered with hard enamel. The long dentine roots were dissolved and re-used by new teeth as they grew. Eventually, the old tooth, worn from use and weakened at the root, would break-off while feeding (called a shed tooth), making room for the new germ tooth to grow into position. Unlike mammals, dinosaurs grew new teeth throughout their lifetimes.

Stan Tyrannosaurus in Manchester Museum

Many of Stan’s teeth were found loose in the rock around the bones. Because each tooth ‘socket’ produces a different shaped tooth, it was possible to put those teeth back into the appropriate sockets of the 58 available positions. Wear surfaces on the teeth show that the lower jaws closed inside the upper, like giant shears, enabling T. rex to bite through even the leg bone of another T. rex.

Pathologies

Pathologies are evidence of injury or disease. Stan’s fossil skeleton exhibits various pathologies. Several healed puncture wounds in his skull and on a rib suggest that T.rex fought each other as he had certainly not bitten himself! One terrible injury gave Stan a very stiff and painful neck and, probably, horrible headaches. Two of his neck vertebrae were fused together and a great deal of extra bone had grown around the injury. In other words, Stan survived!

Stan’s skull preserves a number of pathologies, or healed injuries. The cheeks (jugals) and lower jaws reveal the presence of irregular openings that are not duplicated on the opposite side. One possible explanation for these holes is that they were puncture wounds received in battles with another T. rex. Smoothed edges around the holes indicate that the wounds healed in time. Perhaps the most interesting pathology is found at the back of the skull on the bones that make up part of the braincase. A portion of the top of the crest, where the powerful neck muscles once attached is missing. Below this we find a round hole that is a perfect match for a tooth from the lower jaw of another T.rex. Despite very serious injuries, Stan healed and lived to fight another day.

Cranial kinesis

Cranial kinesis is the technical term for movement of the joints between the bones in the skull. It is cranial kinesis that allows a snake to swallow things larger than its head, and keeps a woodpecker from addling its brain. Careful examination of Stan’s disarticulated skull shows that T.rex had a kinetic skull. There are hinge, screw, and slip joints that allowed Stan to open wide both the upper and lower jaws, greatly increasing bite area. These joints also acted as shock absorbers, protecting both the bones of the skull and Stan’s teeth from breakage when biting through the bones of prey.

Reconstructing dinosaurs

Of course, no-one has ever seen a living dinosaur! What we know of them comes from careful study before, during and after cleaning and conservation of their fossil remains. Skilled workers known as preparators spent 25,000 hours using small air-powered chisels and air-abrades (miniature sand-blasters) to take away the matrix that had encased Stan’s fragile bones since their burial. Interesting clues about Stan’s life emerged during this process. After moulding the bones using special silicone rubber to ensure that even the smallest detail would be preserved, a polymer was poured into the moulds to create an accurate copy of Stan’s skeleton, which was then mounted on an internal steel framework known as an armature.

Stan’s cast in a dynamic hunting pose at dinopolis, Teruel’s museum of paleontology (Spain).

Are birds living dinosaurs?

Scientists who study meat-eating dinosaurs, known as theropods, have noted their similarity to living birds. Stan’s feet, for instance, are very bird-like in appearance. Recent discoveries of wishbones, called furculas, in theropods (including T.rex), and feather-like structures preserved with theropod skeletons from China, provide further evidence. In addition, the bones in Stan’s neck and body are also thin-walled and ‘airy’ with an inside ‘honeycomb’ structure. These same features are found today only in birds, and double as part of their respiratory system (consisting of lungs and air-sacs). Birds breathe in a very different way from other animals. They have a network of air-sacs which occupy the bones and one-way lungs with two openings. Birds’ lungs are constantly bathed with fresh oxygen, giving them energy for a very active life. These similarities lead many scientists to conclude that birds are living theropod dinosaurs.

Male or female?

Over thirty incomplete skeletons of T.rex have been discovered so far. They can be divided into two body shapes, called morphotypes. One type has much larger and heavier bones and is the robust morphotype. The other has smaller and lighter bones and is the gracile morphotype. A wider pelvis with a larger passageway for eggs, a difference in the first chevron, and other clues in the robust morphotype lead scientists to believe that these skeletons were female. Stan’s skeleton is gracile, so we believe he was a male.

Original article on www.museum.manchester.ac.uk

Tsintaosaurus

Friday, February 3, 2017

Tsintaosaurus by Keiji Terakoshi

Tsintaosaurus (meaning “Qingdao lizard”, after the old transliteration “Tsingtao”) is a genus of hadrosaurid dinosaur from China. It was about 10 metres (33 ft) long, 3.6 metres (12 ft) tall and weighed 3 tons. The type species is Tsintaosaurus spinorhinus, first described by Chinese paleontologist C. C. Young in 1958.

A hadrosaur, Tsintaosaurus had a characteristic ‘duck bill’ snout and a battery of powerful teeth which it used to chew vegetation. It usually walked on all fours, but could rear up on its hind legs to scout for predators and flee when it spotted one. Like other hadrosaurs, Tsintaosaurus probably lived in herds.

Tsintaosaurus skeleton. National Geographic

Crest

Tsintaosaurus was originally reconstructed with a unicorn-like crest on its skull. The crest, as preserved, consists of an about forty centimetres long process, protruding almost vertically from the top of the rear snout. The structure is hollow and seems to have a forked upper end. Comparable structures with related species are unknown: they possess more lobe-like crests. In 1990, David Weishampel and Jack Horner cast doubt on the presence of the crest, suggesting that it was actually a broken nasal bone from the top of the snout distorted upward by a crushing of the fossil. Their study further suggested that, without the distinctive crest to distinguish it, Tsintaosaurus was actually a synonym of the similar but crestless hadrosaur Tanius. However, in 1993 Eric Buffetaut e.a., after a renewed investigation of the bones themselves, concluded that the crest was neither distorted nor an artefact of restoration; besides, a second specimen with an upright crest part had since been discovered, indicating that the crest was indeed real and Tsintaosaurus is likely a distinct genus.

Pre-2013 restoration showing outdated crest shape. By Dimitri Bogdanov

Tsintaosaurus may form a clade in Lambeosaurinae with the European genera Pararhabdodon and Koutalisaurus (probable synonym of Pararhabdodon).

The position of Tsintaosaurus in the evolutionary tree according to a 2013 study by Prieto-Márquez e.a. is indicated by this cladogram:

Source: www.Wikipedia, www.NatGeo.com

10 Famous Australian Dinosaurs

Friday, February 3, 2017

10 Famous Australian Dinosaurs

The first find of an Australian dinosaur was a partial skeleton found on Cape York. Later named Agrosaurus, this small plant-eater from the Triassic period was found during an exploration of the area by HMS Fly. A large claw of a meat-eating dinosaur was found near Inverloch, Victoria around the turn of the Century and bones of a long-necked sauropod dinosaur, Rhoetosaurus, were found near Roma in Queensland in the 1930s. Other dinosaurs include a plant-eater similar to Iguanodon that was later named Muttaburrasaurus and a small armoured dinosaur named Minmi.

It was not until the 1980s and 1990s that significant numbers of dinosaurs began to be excavated from Australia. These principally came from excavations at Dinosaur Cove in Victoria and Lightning Ridge in New South Wales. Most of these fossils are from dinosaurs that are new to science and are still being studied.

Why are there so few Aussie dinosaurs? 
In the dinosaur stakes, Australia was dealt a poor hand for a number of reasons. Firstly, when dinosaurs were roamed the earth, there were few places where the right kinds of rocks were being deposited. Dinosaurs tend to be preserved in sediments laid down by rivers and lakes. During the reign of the dinosaurs most of Australia was covered by a shallow sea.

Secondly, since the age of dinosaurs, there has not been much mountain-building in Australia. If land is lifted up and eroded back, it’s possible to see into the rock beds and find the fossils inside. This has happened in a number of the worlds famous dinosaur deposits elsewhere in the world but not here in Australia.

Lastly, compared to many other places in the world, Australia has very few paleontologists looking for fossils and a very large area to cover. This is slowly changing and the recent increase in dinosaur fossil finds is a result of more paleontologists getting out and digging around.

What do Aussie dinosaur fossils tell us about Australia in the age of dinosaurs? 
During the age of dinosaurs Australia was much closer to the South Pole than it is now. This meant that Australia was much colder than it is today and that there were long periods of darkness each year. Dinosaurs such as Leaellynasaura are small with large eyes. It is unlikely that they could have migrated in and out of what is now southern Victoria so they must have been able to see in low light conditions and keep warm in the long, cold winters.

Australia was also connected to Antarctica and South America during the time of the dinosaurs. This allowed some movement of dinosaurs and other animals across continents that are now separated by vast oceans. Similarities between some Australian dinosaurs to others found on the other southern continents indicate a long history of movements back and forth between Australia and neighbouring continents.

What else lived with the dinosaurs in Australia? 
Australia has a very good record of the animals that lived in the seas while dinosaurs roamed the land. Long-necked plesiosaurs such as Woolungasaurus were preyed upon by their short necked relatives Kronosaurus. Ichthyosaurs torpedoed through the water like modern dolphins. Ammonites and huge platey relatives of oysters filled the waters and covered the sea floor.

On the land there was a range of turtles, crocodiles and other smaller reptiles as well as a few mammals related to modern platypus and echidna. The air was home to several types of flying reptiles but their fragile bones were rarely fossilised. Toward the end of the age of dinosaurs birds made their first appearance in Australia, poised to take over from the dinosaurs after the great Cretaceous Extinction.

Australovenator

Australovenator wintonensis by Sergey Krasovskiy

os-TRA-loh-VEN-ah-tor (Australian hunter) Australovenator was one of the first ever large carnivores to have been found in Australia. Now, that’s saying a lot, considering that dinosaurs in Australia didn’t grow as large as their mainland cousins. At 6 meters in length (20 ft), it was a slender, agile killer.

Rapator

Rapator by Julius T. Csotonyi

RAH-pa-tore The name could have been a pronunciation error by a German paleontologist that tried to pronounce “raptor” but whatever. The name’s there. Rapator is known from only one fossilized finger, and is NOT even a raptor. It may have been the same kind of animal as Australovenator!

Ozraptor

An artist's illustration of Ozraptor subotaii

oz-RAP-tore (Australian thief). Like most Australian dinosaurs, Ozraptor is known from a few body parts, in this case, a tibia. Or part of one. It lived in the Jurassic period 175 million years ago.

Kakuru

Kakuru by paleoartist dc4a

KA-ku-roo (Rainbow serpent) Again known from a small tibia, Kakuru is a small, slender, elegant dinosaur related to other small, slender, and elegant dinosaurs in other parts of the world. The way that Kakuru’s bones were fossilized, however, is really cool. The bones have turned into pure opal, which is extremely rare.

Diamantinasaurus

 Diamantinasaurus

dye-AH-man-TEE-nah-saw-rus (Diamantina lizard) Named after the river that it was kinda sorta found near at, Diamantinasaurus was a relatively small titanosaur, at 15–16 m (49–52 ft) in length. It was one of the other dinosaurs described in 2009, along with Australovenator.

Wintonotitan

Wintonotitan

WIN-tone-OH-tie-tan (Winton titan) Wintonotitan was much like Diamantinasaurus, the only thing is that its bones were not as thick. Not much is known about this Early Cretaceous Australian titanosaur.

Rhoetosaurus

Rhoetosaurus brownei

ree-TOH-saw-rus (Rhoetos lizard) Named after the Greek Titans of old (well not as old compared to the dinosaurs), Rhoetosaurus was a medium sized animal for its family, at 15 meters in length (50 ft). Described in 1926, authors have since then misspelled its name like “Rhaetosaurus”, or “Rheteosaurus”. Some have even have called it Rapetosaurus, although that is another sauropod living in Madagascar.

Muttaburrasaurus

Muttaburrasaurus by paleoguy

muh-TAH-buh-rah-saw-rus (Mutaburra lizard) Living in Australia must be fun, considering you have weird names for places. Naming dinosaurs after weird places would be even more fun. Muttaburrasaurus is one of the most well known dinosaurs from Australia (and that’s a lot, considering that Australia doesn’t have a lot of fossils to offer). Reaching up to 8 meters in length (26 ft), it was a type of iguanodont, a family that would give rise to the hadrosaurs.

Leaellynasaura

Leaellynasaura

lee-ay-lyn-AH-saw-RAH (Leaellyn’s lizard) One of the very few dinosaurs to be named after a girl, Leaellynasaura was a small, 3 meter long (10 ft) herbivore that lived near the polar circle. At the time, Australia was near the South Pole, and although the climate was warm, the occasional winter did bring some snow.

Minmi

Minmi

meen-me Named after Minmi Crossing where it was found For many, many, many years Minmi was considered to have the shortest name of any known dinosaur. Then came along Mei and Kol from Asia, and Zby from Europe. It was a small dinosaur, at 3 meters (10 ft), and was relatively well protected. However, the size of its brain compared to the size of its body was way off, meaning that Minmi wasn’t the brightest in the dinosaur world.

Gigantspinosaurus

Thursday, February 2, 2017

Gigantspinosaurus by paleoguy on deviantArt

Gigantspinosaurus (meaning “giant-spined lizard”) is a genus of herbivorous ornithischian dinosaur from the Late Jurassic. It was a stegosaur found in Sichuan, China.

The first fossil was found in 1985 by Ouyang Hui at Pengtang near Jinquan and was reported upon in 1986 by Gao Ruiqi and colleagues, mistaking it for a specimen of Tuojiangosaurus. The type species, Gigantspinosaurus sichuanensis, was described and named by Ouyang in 1992 in an abstract of a lecture. The generic name is derived from Latin gigas or giganteus, “enormous”, and spina, “spine”, in reference to the gigantic shoulder spines. The specific name refers to Sichuan.

1.Dacentrurus 2.Lexovisaurus 3.Huayangosaurus 4.Wuerhosaurus 5.Gigantspinosaurus – by Kawasaki Satoshi

At a glance the name Gigantspinosaurus gives the impression of an oversized Spinosaurus,‭ ‬a particularly exciting but frightening prospect when you consider what that dinosaur was.‭ ‬In realty however Gigantspinosaurus actually a stegosaur,‭ ‬perhaps the farthest a dinosaur can get from being one of the spinosaurs.

The name Gigantspinosaurus is actually a reference to the huge shoulder spines that grown from the shoulder area,‭ ‬similar to some like Kentrosaurus but upon a larger scale.‭ ‬These spines are thought to have provided Gigantspinosaurus with additional defence from large theropod dinosaurs like Sinraptor,‭ ‬but the exaggerated size may have also served as a display function.‭ ‬The other plates and spines were small in comparison to other stegosaurs,‭ ‬and this seems to fit in with the notion that Gigantspinosaurus is one of the most basal stegosaurs known.‭ ‬Primitive forms are noted for having shoulder spines and small plates,‭ ‬while more advanced forms like Stegosaurus have better developed plates but lack shoulder spines.

Gigantspinosaurus sichuanensis / Ouyang, 1992 Art by Corey A. Ford

Gigantspinosaurus was described by Peng and colleagues as a “medium-sized stegosaur”. It was estimated by Gregory S. Paul in 2010 to have been about 4.2 metres (14 ft) long and 700 kilograms (1,500 lb) in weight. Gigantspinosaurus has a distinctive appearance with relatively small dorsal plates and greatly enlarged shoulder spines, spinae parascapulares, twice the length of the shoulder blades on which they rested via large flat bases. The plates on the neck are small and triangular. The head must have been relatively large with thirty teeth in each lower jaw. The hips are very broad and the low neural spines of the four sacral vertebrae and the first tail vertebra have been fused into a single plate. The forelimbs are robust.

The skin impressions were described by Xing Lida and colleagues in 2008. They cover a surface of 414 square centimetres (64.2 sq in) and show rosettes with a central pentagonal or hexagonal scale surrounded by thirteen to fourteen ridged smaller square, pentagonal or hexagonal scales with a diameter of 5.7 to 9.2 millimetres (0.22 to 0.36 in).

A study by Maidment indicated that Gigantspinosaurus is the most basal known member of the Stegosauria. Peng and colleagues, however, placed it in the Huayangosaurinae.

Source: www.NatGeo.com, www.Wikipedia.com

Siats: The Giant before the Tyrant!

Tuesday, January 24, 2017

Siats by Julio Lacerda

Tyrannosaurs weren’t the only big carnivores to tromp through the Mesozoic of North America. Before the tyrant lizards were huge, there was another giant terrorizing the American West: Siats! Named for a Ute mythological giant, Siats was a bus-sized carnivore in the middle of the Cretaceous of Utah (99 million years ago). The giant had close relatives – the neovenatorids – on almost all the continents. This is a bit of a mystery because the continents were getting spread out by 99 million years, making it tough to explain how the neovenatorids conquered the world. In North America, this global dynasty replaced another family of giants: the carcharodontosaurids which included Acrocanthosaurus the top carnivore of the Early Cretaceous of Western and Eastern North America. The discovery of Siats shows two things: 1) different lineages of carnivorous dinosaurs could get really big and 2) T. rex is just the last monarch to fill the giant carnivore niche in North America. It’s a toothy, terrifying tale on Past Time!

Siats size by Prehistoric Wildlife

Past Time Prequel: The Dy-nasties before the Tyrants!

Most people know who Tyrannosaurus rex was: a carnivorous giant from North America who closed the Age of the Dinosaurs 65 million years ago. But T. rex wasn’t the only giant to stomp through the North American continent.

Lythronax lived 80 million years ago and started the tyrannosaur dynasty that lasted until the end of the Mesozoic (Age of Dinosaurs). But that doesn’t mean North America was a quiet, safe place until Lythronax showed up. Instead, Lythronax and the rest of the tyrannosaurs were filling in a large-bodied carnivore niche that had been filled by many different species of giants that were not closely related to tyrannosaurs.

Artwork by NatGeo.com

All meat-eating dinosaurs belong to a large group called the Theropoda. The theropod lineage was really diverse, ranging from the large toothy giants like Majungasaurus and Tyrannosaurus, to bizarre, toothless bipeds like Oviraptor and Gallimimus, on down to small feather friends like hummingbirds and Velociraptor.

Within the group Theropoda there were a lot of experiments in becoming giant carnivores. One of most iconic North American dinosaurs to reach monstrous proportions was Allosaurus (meaning “Other Lizard”…not the most creative name ever concocted). Allosaurus stomped through the Jurassic of North America about 150 million years ago and is well-known from plenty of fossils found in the American West where she is often shown stalking the giant sauropods that shared the environment with the giant carnivore. At first glance, Allosaurus might look like a lighter version of T. rex, but details of her anatomy show her lineage was distinct from the tyrannosaurs.

After Allosaurus went extinct, the large-bodied carnivore niche was filled in during the Early Cretaceous ( about 110 million years ago) by AcrocathosaurusAcrocanthosaurus had a distinctive profile with an almost sail-like ridge running down her back. Fossils of Acrocanthosaurus have been found in the North American West from Early Cretaceous deposits, but this animal is also near-and-dear to Adam’s heart because some large theropod fossils found on the East Coast of North America in Maryland may have belonged to Acrocanthosaurus.

Acrocanthosaurus and its closest relatives are called the carcharodontosaurids (meaning “Great white shark-toothed lizards) and they are distinct from the Allosaurus lineage that and distinct from the lineage that would lead to Lythronax and T. rex. The carcharadontosaurids, such as Acrocathosaurus, dominated the large carnivore niche for millions of years.

But then there was a gap in the fossil record during the middle Cretaceous where there didn’t seem to be any large carnivores until a giant was discovered in Utah…

Artwork by DinoClub

Paleontologists from the Field Museum in Chicago, including Dr. Lindsay Zanno and Dr. Peter Makovicky, announced the discovery of Siats (pronounced “See-atch”) on November 22, 2013 in the scientific journal Nature Communications. As experts in theropod evolution, Dr. Zanno and Dr. Makovicky knew by looking at the pieces of the skeleton they had recovered from 99 million year old rocks in Utah that they had a new genus and species of dinosaur and it didn’t belong to the group that includes Allosaurus, OR the group Carcharodontosauridae that includes Acrocanthosaurus, OR the tyrannosaurs.

Instead, Siats belonged to a whole different lineage called the Neovenatoridae (meaning “New hunters”). There are a lot of names to juggle here, but that’s part of the point. There were all these different groups of dinosaurs converging on the same massive, meat-eating body plan over and over again, telling paleontologists that there was some kind of evolutionary advantage selected for being big in each of these groups. Tyrannosaurus was not a monstrous outlier in North American dinosaur evolution, but the final successor to a long-occupied giant carnivore niche.

Siats is a giant from Ute Indian mythology who would snatch up small children who wandered too far from camp at night. Ninety-nine million years ago, the earliest relatives of Lythronax and Tyrannosaurus were small-bodied theropods that would have reminded you of Velociraptor more than the giant tyrants they would become. One of these is illustrated in the body size diagram in this post. They probably would have seen Siats as a terrifying monster waiting to snatch them up, too!

Artwork by NatGeo.com

Siats’s family, the neovenatorids, were not a quiet off-shoot in dinosaur evolution, filling in the gaps left by the carcarodontisaurids, but a global dynasty. Species belonging to the Neovenatoridae have been found all over the world including Eurasia, South America, Africa, and Australia. Carcharodontosaurids covered a lot of ground, as you can see in the map, but they didn’t have the global reach of the neovenatorids, including Siats.

With the discovery of Siats the history of theropod diversity, neovenatorid biogeography, and North American carnivores becomes even more complicated and even more interesting! Each new fossil discovery fills in another gap in the fossil record making it possible to understand the relationships between continents and ecosystems across vast amounts of time and space, telling paleontologists about past ecosystems so we can better understand the present!

Source: www.NatGeo.com

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