DINOSAURICON PQ

oktober 2, 2012 2 reacties

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Life restoration of Pachycephalosaurus.

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0036227
Pachycephalosaurus  // The unique Pachycephalosaurus had a thick, dome-shaped head with some remains measuring up to 10 inches thick. While it had been believed that the Pachycephalosaurus used its thick skull to ram head-to-head against other males and predators as defense and as a sign of dominance, further studies have disproven this myth. The domed area of its skull was actually made of porous and fragile bone that would have crumpled had two skulls collided. All of the remains found so far show no signs of scarring, leading scientists to believe that Pachycephalosaurus never rammed its head into anything as hard as its own skull. More likely, it would ram another or a predator in the side, damaging internal organs and causing massive bruises while suffering little to no damage itself.
the dome-headed dino would not automatically start ramming a predator, though. Running was its first line of defense and, despite traveling in herds, it would much rather flee than risk its own life. Two powerful hind legs carried the Pachycephalosaurus’ body, and it had two short forelimbs that may have let it walk (and possibly run) on all four limbs while scavenging for food. Its tail was stiff, filled with a mesh of tendons around the base. What purpose this could have served is unknown, but it may have aided in balance while charging at a predator or could even have allowed for fast whipping actions.ORDER: Ornithischia
SUBORDER: Pachycephalosauria
INFRAORDER: Carnosauria
GENUS: Pachycephalosaurus
Additional Sources:
Zoom Dinosaurs,
http://www.enchantedlearning.com/subjects/dinosaurs/

 

http://ombdinotopia.proboards.com/index.cgi?board=dinotopia&action=display&thread=360&page=4

http://www.cbv.ns.ca/marigold/history/dinosaurs/datafiles/parasaurolophus.html

 

Dinosaurus. Het fossiele skelet van het reptiel, bekend als de Pariesaur opgegraven in de Karoo woestijn in Zuid-Afrika. De pariesaur is tentoongesteld in het Walker museum op de universiteit van Chicago, Verenigde Staten van Amerika 1933. Foto: De vinder en curator van het museum Paul Miller en Miss Helen Galllagher.

http://nl.wikipedia.org/wiki/Pareiasaurus

Dinosaurus. Het fossiele skelet van het reptiel, bekend als de Pariesaur opgegraven in de Karoo woestijn in Zuid-Afrika. De pariesaur is tentoongesteld in het Walker museum op de universiteit van Chicago, Verenigde Staten van Amerika 1933. Foto: De vinder en curator van het museum Paul Miller en Miss Helen Galllagher.

04 oktober 2012   18

Wetenschappers hebben een nieuwe soort dinosaurus ontdekt. De dino woog minder dan de huiskat, had vampierachtige hoektanden en lange, stugge haren op bijna zijn gehele lichaam.

De fossiele resten van de dinosaurus werden enkele decennia geleden al in het zuiden van Afrika teruggevonden. Ze verdwenen in de fossielencollectie van de Harvard Universiteit en daar heeft onderzoeker Paul Sereno ze nu opgediept en geïdentificeerd. De dinosaurus heeft de naam Pegomastax africanus gekregen en leefde zo’n 200 miljoen jaar geleden.

Pegomastax africanus. Afbeelding: Todd Marshall.

Papegaai
P. africanus moet er bijzonder uitgezien hebben. De dinosaurus was ongeveer 60 centimeter lang en woog minder dan een huiskat. De kop van het beest is slank en nog geen acht centimeter lang en de bek doet sterk denken aan de snavel van een papegaai. In de bek vonden de onderzoekers scherpe hoektandjes terug.

Zelfverdediging
Die tandjes verbaasden Sereno. P. africanus is namelijk een planteneter. “Heel zeldzaam dat een planteneter zoals Pegomastax scherpe, vergrote hoektandjes heeft die doen denken aan een vampier.” Maar waar gebruikte hij de tandjes dan voor? Zelfverdediging, vermoedt Sereno. En voor het vechten met andere soortgenoten in een poging een vrouwtje voor zich te winnen.

Een andere opvallende eigenschap van de dinosaurus zijn de stugge haren die bijna het gehele lichaam van P. africanus bedekten. Met die haren moet P. africanus eruit gezien hebben als een vlug stekelvarken op twee pootjes, stelt Sereno.

File:Pegomastax africana holotype cropped.jpg

Holotype of Pegomastax africana: Partial Skull with jaw fragments and teeth, photo and drawing.

Bronmateriaal:
“Dwarf species of fanged dinosaur emerges from southern Africa” – Uchicago.edu

http://phenomena.nationalgeographic.com/2013/01/28/p-is-for-pelecanimimus/

Art by Steveoc 86, image from Wikipedia.Art by Steveoc 86, image from Wikipedia.
Harpymimus – seen here – was a close relative of the archaic, feathery Pelecanimimus from Spain.
i-cf4fef9589bbe1f550c0888bb2a41840-VilleSinkkonenPelecanimimus.jpg      Pelecanimimus polyodon  
pelecamiminus
 

Phuwiangosaurus-sirindhornae-(< click on left photo )

Phuwiangosaurus : a giant sauropod of Thailand’s North-East 110 million years ago: a titanosaur of the Early Cretacous period.

Discovered by a team of geologist in 198: they found the fossil near a dried up stream called Huay Pratu Tee Mah in Khon Kaen province.

During that era lived in thailand various dinosaurs( like the unname sauropod that is still being studying,)Iguanodon, Psittasaurus, Gallimimus, and Siamosaurus.
Vier andere soorten van dinosauriërs opgegraven in Phu Wiang zijn onder andere de Siamotyrannus isanensis (een kleinere versie van Tyrannosaurus rex), de Siamosauraus suteethorni (een krokodil-achtig wezen), de Compsognathus (‘s werelds kleinste dinosaurus) en een Ornithomimosaur (een struisvogel-achtige dinosaurus).

In de buurt van de Chaiyaphum provincie zijn twee andere nieuwe dinosauriër soorten ontdekt, de Psittacosaurus sattayaraki (een papegaai-billed dinosaurus) en de Isanosaurus attavipachi (die vergelijkbaar is met Phuwiangosaurus).

Phuwiangosaurus only (potential) enemy was the local tyrannosauride Siamotyrannus
.

 ; Holotype AMNH 6523,
incomplete skull and maxilla, first cervical vertebrae and some dermal scutes.
Other referred material are a well preserved skull and almost complete postcranial skeleton of a young individual, another complete postcranial skeleton and fragmentary remains of postcrania and armour. In total more than 15 specimens including 1 complete and 4 partial skulls, nearly complete skeleton with armor.
The skull was 300 mm long and 340 mm wide.
The postcranial skeleton is relatively light, the limb bones are slender, the manus is pentadactyl and the the pes tetradactyl.
From Dinodata.org
Image: Tim Bekaert
” up to date ” Description —> http://en.wikipedia.org/wiki/Plateosaurus

Plateosaurus is een geslacht van uitgestorven plantenetende dinosauriërs dat behoorde tot de groep van de Sauropodomorpha en leefde in het late Trias (Norien–Rhaetien).

De soort Plateosaurus engelhardti is door Von Meyer in 1837 beschreven — dus nog voordat de term “dinosauriër” bestond — op grond van een vondst uit 1834 bij Heroldsberg door Johann Friedrich Engelhardt; de soortaanduiding eert de ontdekker. De naam werd door Von Meyer niet nader toegelicht; het klassiek Griekse platys kan “plat”, “sterk” of “krachtig” betekenen.

Plateosaurus is zeer goed bekend door de vondst in 1910 in Saksen-Anhalt door Von Huene van tientallen vrijwel complete skeletten. Deze werden in 1914 door Otto Jaekel beschreven als een tweede soort: P. longiceps.

Voor een dinosauriër was Plateosaurus vrij klein, maar met een lengte tot tien meter en een gewicht van een kleine ton naar huidige maatstaven bepaald geen kleintje. Hij was zeer langwerpig gebouwd met een lange nek, een lange romp en een krachtige en hoge maar opnieuw lange staart. Hij kon vermoedelijk op twee benen lopen, net als zijn vleesetende voorouders; maar de armen waren sterk, van geduchte klauwen voorzien en zeker in staat om het voorste deel van het lichaam te dragen. Volgens recent onderzoek van Parrish konden de handpalmen echter niet richting grond gedraaid worden; is dat juist, dan was voortbeweging op vier poten onmogelijk. Bij het eten kon hij zich oprichten en de lange nek lijkt geëvolueerd te zijn om zijn bereik nog groter te maken.

Hieruit is wel afgeleid dat ook de Sauropoda hun overeenkomstige kenmerken voor hetzelfde doel gebruikten. Het hoofd was klein en langwerpig, met veel tanden om plantendelen los te scheuren. Door de vondst van vele fossielen op één plek heeft men gedacht dat Plateosaurus in kudden leefde.

Infraklasse: Archosauromorpha
Superorde: Dinosauria
Orde: Saurischia
Onderorde: Sauropodomorpha
Familie: Plateosauridae
http://dinosaurpalaeo.wordpress.com/2012/05/23/theropod-thursday-19-the-mysterious-frickopod/

The Sauriermuseum Frick in Frick, Switzerland, exists because of the Tongrube Keller in Frick is one of the three localities in Europe yielding large numbers of skeletons of Plateosaurus.Plateosaurus was an obligate saurischian biped, but it’s most certainly NOT a theropod,http://www.sauriermuseum-frick.ch/index.php?id=21&L=1
http://dinosaurpalaeo.wordpress.com/2012/05/23/theropod-thursday-19-the-mysterious-frickopod/
http://en.wikipedia.org/wiki/Plateosaurus
The clay pit from which the material comes

The Plateosaurus layer is exposed at the bottom right, where you can just about make out an ongoing excavation above the red marls.

http://dinosaurpalaeo.wordpress.com/2012/07/13/its-time-for-even-more-plateosaurus-prosauropod-proportions/

It’s time for even more Plateosaurus! (prosauropod proportions)

…..It’s been an awfully long time since I last postedon that poor critter, in fact over six weeks,
Plateosaurus engelhardti MSF 23, Sauriermuseum Frickin Frick, Switzerland,This time I have some stunning visuals, courtesy of the go-to guy for skeletal drawings, Scott Hartman – blogs at skeletaldrawing.org.
Having played around an awful lot with my awesome digital Plateosaurus skeleton I soon found that there were many more uses for it than simple digital range of motion (ROM) analyses. Or using it as a basis for CAD model, which can then be used to check center of mass and so on. One thing that was fun to do was helping colleagues in South America who contacted me about a Riojasaurus mount. How to place the body and limbs? Given the fact that P. and R. are both fairly closely related “prosauropods” one might be tempted to just c&p the posture of one to the other. Given the fact that the limbs of R. look much more sturdy than those of P., one might be tempted to place it into a typical sauropod posture, with fully erect and pillar-like limbs.
I came up with a fairly simple way of testing different postures. From the literature I took measurements of R. limb bones. Femur length was especially important, but I also got those of forelimb and distal hind limb bones. Then, I scaled my digital files using these values. Once, I scaled each bone to have the length it has in Riojasaurus. The second time, I applied the scaling factor for the femur to all bones of Plateosaurus. Here’s what I got
Red = Plateosaurus, all bones scaled with factor that achieves
same femur length in P. and Riojasaurus
Green = P. scaled for femur+tibia length of Riojasaurus, forelimb scaled
separately to match R. size
Orange = P. scaled for femur length of R., forelimb scaledseparately
to match R. size
As can be clearly seen, Riojasaurus has a much longer humerus than Plateosaurus. That alone may not mean too much, but don’t forget that I scaled isometrically. That means that the scaled-up bones are not as study proportionally for the bigger animals as the normal sized ones are for the small one – the real bones of R. are a lot more massive, too. Additionally, the forelimb of R. are over-proportionally thick, thus even more sturdy than if I had scaled allometrically. That’s indicative of rather massive forces acting on the forelimb.
But that’s not all: I now used R.-scales limbs on my P.digital mount.Pretty obviously, R. makes a much better quadruped than P.!
But how much more obvious are these differences if not only the limbs, but the entire skeletons are used in the comparison? This is where the Master of Skeletal Drawings comes in! Scott sent me these drawings of “prosauropods” with permission to post:Pretty much same size (thus differing scales), top to bottom:
Massospondylus
Melanorosaurus
Plateosaurusof the three, Massospondylus is the smallest, and Melanorosaurus the largest. It’s easy to see how the forelimb and the shoulder girdle are much more massive and more sturdy, as well as larger in Melanorosaurus. Unsurprising, as Melanororsuarus is much closer to sauropods than the other two. Interestingly, it has the proportionally shortest neck….. weird!

protoceratops.jpg

http://ombdinotopia.proboards.com/index.cgi?board=dinotopia&action=display&thread=360&page=4
Protoceratops andrewsi

 

Protoceratops May 17, 2011

Filed under: Ceratopsia
When scientists found Protoceratops’ nests in the Mongolian desert, it was proof that dinosaurs laid eggs and that some lived in family groups or herds.
There have been dozens of skeletons of Protoceratops found, both adult and juvenile, and so the whole growth pattern is known. It was found by the expeditions to the Gobi Desert undertaken by the American Museum of Natural History in the 1920s. It seems to have lived in herds, and its remains are so abundant that it has been termed the “sheep of the Cretaceous”.
Protoceratops was a small dinosaur, only about the size of a large dog. Although it looked fierce, with its heavy head, sharp, beak-like mouth and large bony frill around its neck, Protoceratops ate only plants. It had a heavy, squat body, with a long, thick tail. Protoceratops walked on its four stumpy legs, but moved quite quickly when in danger.Protoceratops is a heavy animal with short legs, a deep tail and a heavy head. Although a member of the horned dinosaurs, it does not have true horns. Two forms of adult are known, a lightweight form with a low frill, and a heavier form with a big frill and a bump on the snout where a horn would have been. These probably represent the two sexes, with the males having the heavier head.
There was a bony frill or shield around its neck, which grew bigger and broader as the dinosaur grew older. The frill protected the neck ofProtoceratops from attack by carnivorous dinosaurs. Males also used their frills for display, to attract females at the beginning of the mating season. Their frills made them look intimidating, which helped to ward off rival males.
Protoceratops had large, strong muscles around its jaws. These helped it bite off tough leaves and woody plants with its hooked beak. It then sliced up the plants with its scissor-like teeth.
In 1922, a scientific expedition to the Gobi Desert in Mongolia unearthed nests of Protoceratops’ eggs. These contained the first dinosaur eggs ever found. The discovery proved for the first time that dinosaurs laid eggs. Until then, no-one knew if they laid eggs or gave birth to live young. As many as thirty eggs were found in one nest. It is unlikely that one female laid so many eggs at once, so scientists speculated that two or more Protoceratops females may have shared the same nest.
Several nests have been found close together. This seems to show that Protoceratops lived in family groups or small herds. Once the eggs had hatched safely, the babies which broke out of the shells were about 30cm long. The adult females brought food to the nests until their young had grown large enough to find it for themselves.
Skeletons of Protoceratops found in Mongolia range from tiny ones still inside the eggs to small babies and fully grown adults. Some of the adults vary slightly. They have differently shaped frills, for example. Scientists have suggested that this is because the males were bigger than the females, with larger heads, frills and crests.
Protoceratops had to guard its nests against predators such as Oviraptor, whose name means ‘egg-stealer’. Dinosaur eggs would have made an ideal meal for it. A fossilised Oviraptor skeleton, with its skull smashed in, was found above a nest of Protoceratops’ eggs. Perhaps an angry parent had killed it when it tried to rob the nest.

http://sauropedia.wordpress.com/2011/05/17/protoceratops/
http://www.thehistoryblog.com/archives/date/2011/11/30

Protoceratops andrewsi is een neoceratopische dinosauriër uit het late Krijt (Campanien).

Fossielen van dit dier zijn gevonden in Mongolië door Chapman Andrews naar wie de soortaanduiding ook vernoemd is. Volwassen dieren waren gemiddeld twee meter lang met uitschieters tot ongeveer drie meter. Achterop de kop droeg het een groot nekschild. Het had geen hoorns, maar wel een hoornen neuskam aan de voorkant van de kop.

De paleontoloog Peter Dodson ontwikkelde een theorie die stelde dat er sekseverschillen bestonden waarbij de vrouwtjes lagere schedels en een kleiner nekschild hadden. De oudste mannetjes hadden de grootste nekschilden, en men gaat er dan ook van uit dat deze in onderlinge gevechten werden gebruikt.

De achterpoten van Protoceratops waren langer dan de voorpoten. Algemeen wordt aangenomen dat het dier zich alleen op vier poten voortbewoog, vergelijkbaar met de hedendaagse neushoorn, hoewel het dier veel kleiner was, zo’n twee meter lang. De bek was voorzien van een benen, vermoedelijk met hoorn beklede, snavel die waarschijnlijk werd gebruikt om harde vegetatie de baas te worden.

Meestal wordt aangenomen dat het zich basaal in de groep van de Neoceratopia bevindt als lid van de Protoceratopidae. Protoceratops behoort per definitie tot de klade van de Coronosauria. De geslachtsnaam betekent “voorloper van de Ceratopidae”. Het is echter geen directe voorouder van deze groep. Het meervoud van de naam is “protoceratopia”.

In de jaren twintig was Protoceratops de eerste dinosauriër waarvan men meende eieren en nesten gevonden te hebben. De eieren waren langwerpig, 10-15 cm. lang. Ze waren opvallend goed behouden, en sommige zelfs volledig onbeschadigd. In de eieren werden fossielen van de embryo’s gevonden. Toen echter een embryo onderzocht werd, bleek in 1994 dat de eieren van Oviraptor waren. Tegenwoordig wordt weer van andere eieren vermoed dat ze van Protoceratops waren en weten we ook dat al veel eerder, toen niet herkende, resten van dinosauriëreieren gevonden zijn.

Een beroemd fossiel toont een protoceratops en een velociraptor, in een fel gevecht gewikkeld op het moment van overlijden. Waarschijnlijk zijn ze tijdens hun strijd bedolven door een instortend door regen verzadigd zandduin
.

http://blogs.scientificamerican.com/tetrapod-zoology/2012/04/07/ryan-et-al-horned-dinosaurs/
Skull of Protoceratops andrewsi (though this one is without the sclerotic rings you need to determine eye size). Photo by Jordi Payà, from wikipedia.
  
  Marginocephalia
Taxonomy: Ceratopia Neoceratopia Protoceratopidae
Age: Late Cretaceous (?Santonian Campanian)
Locality: Djadochta Formation, Beds of Toogreeg, ?Beds of Al
Length: 2.3 meters
Width: 0.55 meters
Height: 0.85 metersDescriptionThe abundant species Protoceratops.
There are about 80 skulls from this species, some skeletons juvenile to adult.
Protoceratops (first horned face) was discovered by an American expedition to Mongolia in the early 1920s. The numerous skeletons belonged to four- legged plant-eaters with outsize heads, bony neck frills, sharp, shearing cheek teeth, and parrot- like beaks. Re-examining some of the dozens of Protoceratops fossil skulls, from hatchlings to old individuals led a Russian scientist in 1990 to re-identify two as belonging to a new genus Breviceratops, Protoceratops (and Breviceratops retain premaxillary teeth all other neoceratopians have lost themPic Copyright © infoseekProtoceratops, was a sheep-sized (1.5 to 2m long) herbivorous ceratopsian dinosaur, from the Upper Cretaceous Period of what is now Mongolia. Unlike later ceratopsians, it lacked well-developed horns.
Protoceratops had a large neck frill, which may have served to protect the neck, to anchor jaw muscles, to impress other members of the species or combinations of these functions.Discovery and speciesProtoceratops was discovered during the 1920s, in the Gobi desert, in Gansu, Inner Mongolia. Many skeletons were discovered by the American expedition. the type species, P. andrewsi, was formally described by Granger and Gregory in 1923. The fossils date from the Campanian epoch of the Upper Cretaceous (83.5 to 70.6 Million Years Ago).In 1971, a fossil was found that captured a Velociraptor clutched around a Protoceratops in Mongolia. It is believed that they died simultaneously, while fighting, when they were either surprised by a sand storm or buried when a sand dune collapsed on top of them.
A second species, P. hellenikorhinus, was named in 2001 from the Bayan Mandahu formation in Inner Mongolia, China and also dates from the Campanian epoch of the Upper Cretaceous. It is notably larger than P. andrewsi.In the 1920s, Roy Chapman Andrews discovered the first known fossilized dinosaur eggs, in the Gobi Desert of Mongolia. Due to the proximity of Protoceratops, these eggs were believed at the time to belong to this species. The nearby theropod Oviraptor was thought to have been engaged in the process of stealing and eating them. However, later discoveries indicate that the eggs were in fact Oviraptor’s own.Copyright © 2006 Answers Corporation
Oct 26, 1012
by Neal for group ffd
as published in 2012 in Paleontological Research 16(3): 179-198.
This quote from the abstract says:Four skull specimens (MPC-D 100/537, 100/538, 100/539 and 100/540) of Protoceratopsidae from the Upper Cretaceous in Udyn Sayr, Mongolia are described, and their ontogenetic stage and expression of sexual dimorphism are estimated. These specimens are identified as Protoceratops andrewsi (MPC-D 100/53, 100/539), P. cf. andrewsi (MPC-D 100/538), and Protoceratops sp. (MPC-D 100 540), respectively. MPC-D 100/537 and 100/539 are attributed to subadult “female” and MPC-D 100/538 to subadult “male”. MPC-D 100/540 is adult with unknown sex.
Based on the frill morphologies, the Udyn Sayr specimens are classified into three types: type 1 (MPC-D 100/539), well developed ridge on the lateral surface of the squamosal; posteriorly projected posterior margin of the squamosal; type 2 (MPC-D 100/537), posteriorly rounded posterior margin of the squamosal; developed ridge on the posterior margin of the parietal; and type 3 (MPC-D 100/540), large size, posteriorly curved posterior margin of the squamosal; the rugose surface texture on the dorsal side of parietal MPC-D 100/538 could not be categorized because the specimens’s frill is not preserved. These frill morphologies differ from those of Protoceratops from the Djadokhta Formation in the adjacent dinosaur locality Tugrikin Shire. The morphological differences among the Udyn Sayr specimens may indicate intraspecific variation of Protoceratops.

http://blogs.scientificamerican.com/tetrapod-zoology/2012/04/07/ryan-et-al-horned-dinosaurs/
Psittacosaurus preserved alongside the turtle Manchurochelys – proof of aquatic habits in a psittacosaurid! (irony). Image by Christopher, Tania and Isabelle Luna, from wikipedia

http://ombdinotopia.proboards.com/index.cgi?board=dinotopia&action=display&thread=360&page=12image: Arthur Weasley
   
             New dinosaur, Psittacosaurus gobiensis: Parrot-like dinosaur found in Mongolia
Psittacosaurus-
http://blogs.scientificamerican.com/tetrapod-zoology/2012/04/07/ryan-et-al-horned-dinosaurs/
That famous psittacosaurid with the quilly tail – so far the only one known to have these structures (from Mayr et al. 2002).
Psittacosaurus(pronounced /ˌsɪtəkɵˈsɔrəs/, from the Greek for ‘parrot lizard’) is a genus of psittacosaurid ceratopsian dinosaur
from the Early Cretaceous Period of what is now Asia, about 130 to 100 million years ago. It is notable for being the most species-rich dinosaur genus. At least ten extinct species are recognized from fossils found in different regions of modern-day China, Mongolia and Russia, with a possible additional species from Thailand.All species of Psittacosaurus were gazelle-sized bipedal herbivores characterized by a high, powerful beak on the upper jaw. At least one species had long, quill-like structures on its tail and lower back, possibly serving a display function. Psittacosaurs were extremely early ceratopsians and, while they developed many novel adaptations of their own, they also shared many anatomical features with later ceratopsians, such as Protoceratops and the elephant-sized Triceratops.Psittacosaurus is not as familiar to the general public as its distant relative Triceratops but it is one of the most completely known dinosaur genera. Fossils of over 400 individuals have been collected so far, including many complete skeletons. Most different age classes are represented, from hatchling through to adult, which has allowed several detailed studies of Psittacosaurus growth rates and reproductive biology. The abundance of this dinosaur in the fossil record has led to its use as an index fossil for Early Cretaceous sediments of central Asia.Different species of Psittacosaurus varied in size and specific features of the skull and skeleton, but shared the same overall body shape. The best-known species, P. mongoliensis, reached 2 meters (6.5 ft) in length. The maximum adult body weight was most likely over 20 kilograms (44 lb) in P. mongoliensis. Several species approached P. mongoliensis in size (P. major, P. neimongoliensis, P. xinjiangensis), while others were somewhat smaller (P. sinensis, P. meileyingensis). P. ordosensis was the smallest known species, 30% smaller than P. mongoliensis. The largest were P. lujiatunensis and P. sibiricus, although neither was significantly larger than P. mongoliensis.The skull of Psittacosaurus was highly modified compared to other ornithischian dinosaurs of its time. The skull was extremely tall and short, with an almost round profile in some species. The portion in front of the orbit (eye socket) was only 40% of total skull length, shorter than any other known ornithischian. The lower jaws of psittacosaurs are characterized by a bulbous vertical ridge down the center of each tooth. Both upper and lower jaws sported a pronounced beak, formed from the rostral and predentary bones, respectively. The bony core of the beak may have been sheathed in keratin to provide a sharp cutting surface for cropping plant material. As the generic name suggests, the short skull and beak superficially resembled those of modern parrots. Psittacosaurus skulls shared several adaptations with more derived ceratopsians, such as the unique rostral bone at the tip of the upper jaw, and the flared jugal (cheek) bones. However, there was still no sign of the bony neck frill or prominent facial horns which would develop in later ceratopsians. Bony horns did protrude from the skull of P. sibiricus, but these are thought to be an example of convergent evolution.Psittacosaurus postcranial skeletons were more typical of a ‘generic’ bipedal ornithischian. In P. mongoliensis, similarly to other species, the forelimbs were only 58% as long as the hindlimbs, indicating that these animals were almost totally bipedal in life. There were only four digits on the manus (‘hand’), as opposed to the five found in most other ornithischians (including all other ceratopsians). Overall, the four-toed hindfoot was very similar to many other small ornithischians.TaxonomyPsittacosaurus was named in 1923 by Henry Fairfield Osborn, paleontologist and president of the American Museum of Natural History (AMNH) in a paper published on October 19. The generic name is composed of the Greek words ψιττακος/psittakos (‘parrot’) and σαυρος/sauros (‘lizard’), suggested by the superficially parrot-like beak of these animals and their reptilian nature.Over a dozen species have been referred to the genus Psittacosaurus, although only nine to eleven are considered valid today. This is the highest number of valid species currently assigned to any single dinosaur genus (not including birds). In contrast, most other dinosaur genera are monospecific, containing only a single known species. The difference is most likely due to quirks of the fossil record. While Psittacosaurus is known from hundreds of fossil specimens, most other dinosaur species are known from far fewer, and many are represented by only a single specimen. With a very high sample size, the diversity of Psittacosaurus can be analyzed more completely than that of most dinosaur genera, resulting in the recognition of more species. Most extant animal genera are represented by multiple species, suggesting that this may have been the case for extinct dinosaur genera as well, although most of these species may not have been preserved. In addition, most dinosaurs are known solely from bones and can only be evaluated from a morphological standpoint, whereas extant species often have very similar skeletal morphology but differ in other ways which would not normally be preserved in the fossil record, such as behavior, or coloration. Therefore actual species diversity may be much higher than currently recognized in this and other dinosaur genera.
Over a dozen species have been referred to the genus Psittacosaurus, although only nine to eleven are considered valid today. This is the highest number of valid species currently assigned to any single dinosaur genus (not including birds). In contrast, most other dinosaur genera are monospecific, containing only a single known species. The difference is most likely due to quirks of the fossil record. While Psittacosaurus is known from hundreds of fossil specimens, most other dinosaur species are known from far fewer, and many are represented by only a single specimen. From wikipedia.com.Psittacosaurus (parrot lizard)was a two-legged herbivore that resembled the ornithopod Hypsilophodon, but had a deeper, longer body, a shorter tail, longer arms, and four -fingered, grasping hands. The fourth finger and the first of the four toes were very short. But Psittacosaurus oddest feature was its short. deep head with a parrot-like beak, formed partly by the rostral bone unique to ceratopians.
Valid Psittacosaurus species
Psittacosaurus mongoliensis — Mongolia, northern China
Psittacosaurus sinensis — northeastern China
Psittacosaurus meileyingensis — north-central China
Psittacosaurus xinjiangensis — northwestern China
Psittacosaurus neimongoliensis — north-central China
Psittacosaurus ordosensis — north-central China
Psittacosaurus mazongshanensis — northwestern China
Psittacosaurus sibiricus – Russia (southern Siberia)
Psittacosaurus lujiatunensis – northeastern China
Psittacosaurus major – northeastern China
Psittacosaurus gobiensis – Inner Mongolia
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Possible Psittacosaurus species
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?Psittacosaurus sattayaraki – ThailandClassification
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http://www.nu.nl/wetenschap/3548342/drie-dinosauriersoorten-blijken-soort-.html

Drie dinosauriërsoorten uit het geslacht Psittacosaurus blijken in werkelijkheid tot één soort te behoren, zo blijkt uit nieuw wetenschappelijk onderzoek.

12 augustus 2013

Fossielen van de plantenetende dinosauriërs Psittacosaurus lujiatunensis, Psittacosaurus P. major en Hongshanosaurus houi verschillen zo weinig van elkaar dat de dieren ten onrechte worden beschouwd als verschillende soorten.

Waarschijnlijk zijn kleine vervormingen van de fossielen aangezien voor kenmerken op basis waarvan soorten worden ingedeeld.

Dat schrijven onderzoekers van de Universiteit van Pennsylvania in het wetenschappelijk tijdschrift PloS One.

Lasers

De wetenschappers analyseerden 30 verschillende schedels van de drie dinosauriërsoorten met behulp van geometrische morphometrie, een techniek waarbij de vorm van fossielen zeer nauwkeurig in kaart wordt gebracht met lasers.

Vervolgens bleek dat de dieren op basis van de op de scans gevonden eigenschappen slechts ingedeeld konden worden bij één soort, Psittacosaurus lujiatunensis.  

De wetenschappers vermoeden dat de fossielen eerder verkeerd zijn ingedeeld doordat niet alle schedels op dezelfde manier fossiliseren. Tijdens het proces kunnen er deukjes en scheuren in het bot ontstaan, waardoor fossielen van dezelfde soort een iets verschillend uiterlijk krijgen. Met de laseranalyse kunnen dit soort oneffenheden beter worden herkend.

Eindeloze mogelijkheden

“Tijdens onze studie hebben enkele valse soorten gevonden die niet kunnen worden beschouwd als biologische soorten, maar zijn ontstaan door het fossilisatieproces”, verklaart hoofdonderzoeker Peter Dodson op nieuwssite ScienceDaily.

“Hopelijk zal dit ervoor zorgen dat meer paleontologen geometrische morphometrie gaan gebruiken”, aldus onderzoeker Brandon Hedrick. “Deze techniek biedt eindeloze mogelijkheden voor het onderzoek naar dinosauriërs.”

Dinosauriërs van het geslacht Psittacosaurus leefden ongeveer 125 miljoen jaar geleden. De naam betekent ‘papegaaireptiel’.  De dinosauriërs hebben de naam te danken aan hun scherp gebogen snavel, die leek op die van een papegaai.

 
Landmark locations. The locations of the 3D landmarks are presented here in (A) dorsal and (B) lateral views on ZMNH M8137. Since the landmarks were not reflected on either side of the skull, the left lateral landmarks have different landmark numbers than the right lateral landmarks. A 3D model of the skull of ZMNH M8137 is included in Multimedia S1 for reference. Scale = 50 mm. (Credit: Brandon P. Hedrick, Peter Dodson. Lujiatun Psittacosaurids: Understanding Individual and Taphonomic Variation Using 3D Geometric Morphometrics. PLoS ONE, 2013; 8 (8): e69265 DOI: 10.1371/journal.pone.0069265)
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Door: NU.nl/Dennis Rijnvis

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antwoorden aan  creationisten =

er zijn weinig dino’s <–

dinosauriërsoorten blijken één soort’  <–

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Psittacosaurus is the type genus of the family Psittacosauridae, which was also named by Osborn in 1923.
Only one other genus, Hongshanosaurus, is currently classified in this family alongside Psittacosaurus.
Psittacosaurids were basal to almost all known ceratopsians except Yinlong and perhaps Chaoyangsauridae. While Psittacosauridae was an early branch of the ceratopsian family tree,
Psittacosaurus itself was probably not directly ancestral to any other groups of ceratopsians. All other ceratopsians retained the fifth digit of the hand, a plesiomorphy or primitive trait, whereas all species of Psittacosaurus had only four digits on the hand. In addition, the antorbital fenestra, an opening in the skull between the eye socket and nostril, was lost during the evolution of Psittacosauridae, but is still found in most other ceratopsians and in fact most other archosaurs. It is considered highly unlikely that the fifth digit or antorbital fenestra would evolve a second time.Although many species of Psittacosaurus have been named, their relationships to each other have not yet been fully explored and no scientific consensus exists on the subject. The most recent and most detailed cladistic analysis was published by Alexander Averianov and colleagues in 2006. It has been suggested that P. lujiatunensis is basal to all other species. This would be consistent with its earlier appearance in the fossil record.ProvenancePsittacosaurus is known from over 400 individual specimens, of which over 75 have been assigned to the type species, P. mongoliensis. All Psittacosaurus fossils discovered so far have been found in Early Cretaceous sediments in Asia, from southern Siberia to northern China, or possibly as far south as Thailand. The most common age of geologic formations bearing Psittacosaurus fossils is from the late Barremian through Albian stages of the Early Cretaceous, or approximately 125 to 100 Ma (million years ago). Nearly all terrestrial sedimentary formations of this age in Mongolia and northern China have produced fossils of Psittacosaurus, leading its use as an index fossil for this time period in the region, along with the very common pterosaur Dsungaripterus.The earliest known species is P. lujiatunensis, found in the lowest beds of the Yixian Formation. Over 200 specimens attributed to this genus have been recovered from these and other beds of the Yixian, the age of which is the subject of much debate. Although many early studies using radiometric dating put the Yixian in the Jurassic Period, tens of millions of years outside of the expected temporal range of Psittacosaurus, most recent work dates it to the Early Cretaceous. Using argon-argon dating, a team of Chinese scientists dated the lowest beds in the formation to about 128 Ma, and the highest to approximately 122 Ma. A more recent Chinese study, using uranium-lead dating, suggests that the lower beds are younger, approximately 125 Ma, while agreeing with an age of 122 Ma for the upper beds. This work indicates that the Yixian is early Aptian in age, or possibly late Barremian to early Aptian.PaleobiologyDietPsittacosaurs had self-sharpening teeth that would have been useful for cropping and slicing tough plant material. However, unlike later ceratopsians, they did not have teeth suitable for grinding or chewing their food. Instead, they used gastroliths, stones swallowed to wear down food as it passed through the digestive system. Gastroliths, sometimes numbering more than fifty, are occasionally found in the abdominal cavities of psittacosaurs, and may have been stored in a gizzard, as in modern birds.Growth rateSeveral juvenile Psittacosaurus have been found. The smallest is a P. mongoliensis hatchling in the AMNH collection, which is only 11 to 13 centimeters (4–5 inches) long, with a skull 2.8 centimeters (1 in) in length. Another hatchling skull at the AMNH is only 4.6 centimeters (1.8 inches) long. Both specimens are from Mongolia. Juveniles discovered in the Yixian Formation are approximately the same age as the larger AMNH specimen. Adult Psittacosaurus mongoliensis approached 2 meters (6.5 ft) in length.A histological examination of P. mongoliensis has determined the growth rate of these animals. The smallest specimens in the study were estimated at three years old and less than 1 kilogram (2.2 lb), while the largest were nine years old and weighed almost 20 kilograms (44 lb). This indicates relatively rapid growth compared to most reptiles and marsupial mammals, but slower than modern birds and placental mammals. An age determination study performed on the fossilized remains of Psittacosaurus mongoliensis by using growth ring counts suggest that the longevity of the basal ceratopsian was between 10 or 11 years.Copyright © 2009 Answers
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CorporationPSITTACOSAURUShttp://en.wikipedia.org/wiki/PsittacosaurusP Mongoliensis
Meaning Of Name: Parrot reptile
Classification: CERATOPSIA; Psittacosauridae
Age: Early Cretaceous (Aptian-Albian), Barunbayan Formation, lOO-l25 million years ago
Locality: Gobi Desert, Southwestern Peoples’; Republic of Mongolia
Skeleton Cast Size: l50cm in lengthThis dinosaur which spent most of its time standing on its two hind legs is thought to have been near the ancestry of the horned dinosaurs (neoceratopsians), which include such well known forms as Triceratops .
The generic name for this dinosaur, Psittacosaurus , means the ‘parrot-like lizard’ in reference to its prominent parrot-like beak. This feature was one of the principal advances of this form from the generalised bipedal fabrosaurids and hypsilophodontids that gave rise to it.
Psittacosaurus was the first step on the path towards the four-footed, horned descendants that were to appear more than twenty millions years later. It had a special bone called the rostral, found in the horned dinosaurs, even though in many ways, such as in the construction of its teeth, it is still very similar to hypsilophodonts in a way.
Psittacosaurus is a missing link between two large groups of dinosaurs!
Psittacosaurus was one of the most common dinosaurs in the Early Cretaceous collections from Mongolia sometimes making up over 90% of all the dinosaur bones found, most frequently in lake and stream deposits.
Psittacosaurus was a plant eater with leaf-shaped teeth that sliced past one another like the blades of scissors. It must have grabbed plants with its parrot-like beak, chopped them up, and then smashed them up with gizzard stones, which have been found inside the body cavity of some skeletons of this little dinosaurhttp://www.ainakrine.org/dinosaure/info/Psittacosaurus.html

De Psittacosaurus – een kleine rechtop lopende dinosauriër met een papegaaiachtige snavel – maakte pas na zijn vierde levensjaar een groeispurt door waarbij zijn achterpoten flink in lengte toenamen. Tot die tijd kroop het dier waarschijnlijk op vier poten rond.

Dat melden Chinese en Britse onderzoekers in het wetenschappelijk tijdschrift Nature Communication.

De wetenschappers kwamen tot het nieuwe inzicht door een biomechanische analyse te maken van skeletten van het dier. Ook werden dwarsdoorsnedes gemaakt van enkele botten om meer inzicht te krijgen in de groei van de dinosauriër.

“Sommige botten van baby’s waren slechts een paar millimeter dik, ik moest er heel voorzichtig mee omgaan om goede dwarsdoorsnedes te maken”, verklaart hoofdonderzoeker Qi Zhao in de Britse krant The Telegraph.

Voorpoten

Uit het onderzoek bleek dat tussen het eerste en derde levensjaar van het dier vooral zijn voorpoten hard groeiden. Pas na de groeispurt van zijn achterpoten, tussen zijn vierde en zesde levensjaar, kregen de ledematen van de Psittacosaurus de juiste verhouding om rechtop te lopen. Voor die tijd bewoog het dier zich waarschijnlijk kruipend voort.

Volgens Mike Benton, een paleontoloog van de Universiteit van Bristol die niet bij het onderzoek was betrokken, suggereert de studie dat de voorouders van rechtop lopende dinosauriërs ook op vier poten liepen.

“De kruipende baby’s en peuters wijzen erop dat op een eerder punt in de geschiedenis zowel de jeugdige dinosauriërs en volwassen dieren zich op vier poten voortbewogen”, verklaart hij. “Het suggereert dat de Psittacosaurus en dinosauriërs in het algemeen pas in tweede instantie op hun achterpoten zijn gaan lopen.”

 Dinosaurs crawled on all fours like toddlers before switching to two feet when they grew up, experts have discovered.

(Door: NU.nl/Dennis Rijnvis )

Q

http://en.wikipedia.org/wiki/List_of_dinosaurs

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