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The Allosauroidea thread (allosaurs, carcharodontosaurs and kin)

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  • I like falcons :D




  • Adam Khor wrote: »
    Nothing beats Harris hawks or the Johnny Rook when it comes to pack hunting dinos, tho :D

    Then the crested caracara and the secretary bird hunt on land much more often than sparrowhawks.



    When you can get me some of those that will live on my land all year round and who also will breed there by choice each year, then maybe I will change my tune. Until then Sprawks rule. :p


    As a semi related aside, come the breeding season each year Sprawks can give a good account of themselves in terms of being able to work as a pair, far better than most people will give them credit for. Have seen some fascinating hunting techniques (and I call them techniques due to the fact I have seen them repeated a number of times) being utilised by my resident female and her current male over the past few years especially on smaller corvids or in dense hedging.




  • Apparently they didn´t suffer much from bone abnormalities but they did suffer constant injury due to their lifestyle. Nothing unexpected I suposse:

    http://www.ploscollections.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0063409;jsessionid=9FC937EF0D16A51EA761B589DBCD56BA

    Mapusaurus_skulls.jpg




  • Which of those is Mapusaurus?




  • I think they both are


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  • They look different to me Just by the jawline




  • That's because the smaller one is a juvenile:

    Dinosaurs+Gondwana+Media+Preview+EHVTH_9Q7Avl.jpg

    3646421097_f5822df694.jpg




  • Lower jaw protrudes a bit by the look of it. Injury, bad assembly or deformity I suppose




  • I must confess I don´t see anything strange with it D:




  • I think that's common enough in carcharodontosaurids.


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  • Siats meekerorum, a new giant theropod from North America.

    It was a neovenatorid. The remains of a 9 meter long individual were found in 2008, but, as usual, its a juvenile, suggesting it was as big as Acrocanthosaurus, and potentially the second or third largest carnivorous dino ever found in North America. This creature would've been the top predator of its day; only after its fall would tyrannosaurids rise as the new superpredators.

    http://www.ibtimes.com/new-dinosaur-siats-meekerorum-discovered-kept-early-tyrannosaurs-check-photo-1482478

    dinosaur.jpg




  • I'm guessing it's just the perspective of the picture or did it have a MASSIVE head?




  • I think its the perspective, but earlier carcharodontosaurs did have huge heads... Im not sure if the skull was found




  • Evidence of Allosaurus killed by Stegosaurus. You may already have read this one:

    http://westerndigs.org/allosaurus-died-from-stegosaur-spike-to-the-crotch-wyoming-fossil-shows/

    allosaurus-stegosaurus.jpg?resize=450%2C325




  • not seen that before. Thanks Adam




  • Dear Adam,

    Our world has really grown prosaic and blasé if no one has purchased this extraordinary treasure! Well, the price requested may be high; but surely there are numerous well-funded museums all over the world that should be delighted to possess such an amazingly well-preserved fossil? If I were rich, I'd buy it with pleasure!:rolleyes:

    What would have been the approximate age of Little Al when he died? Any evidence of the cause of death? Teeth marks, fractures, disease?




  • Problem with specimens such as this, which are owned by private parties, is that they're usually unavailable for study, meaning most questions are likely to go unanswered until it goes to a museum or some sort of scientific institution.

    I had never heard of Little Al before this.




  • Looks like an Allosaurus to me (was found at the Morrison formation of Wyomming, and is about 9 meters long). Experts say it may be a new species, tho.
    https://uk.reuters.com/article/uk-auction-aguttes-dinosaur/mystery-dinosaur-skeleton-to-be-auctioned-in-paris-idUKKCN1GR2WV
    mystery-dinosaur-skeleton-expected-to-fetch-2m-at-paris-auction-1521145889495.jpg
    2018-03-15T123910Z_1709400388_RC189268B130_RTRMADP_3_AUCTION-AGUTTE-DINOSAUR.JPG


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  • Siamraptor, a new, rather incomplete carcharodontosaur from Thailand. It may have been around 7.6 m long, so smaller than some of its later relatives, but still a sizeable predator.

    https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0222489

    journal.pone.0222489.g002




  • Lajasvenator, the smallest and oldest carcharodontosaurid known from South America:

    https://www.sciencedirect.com/science/article/pii/S0195667119303957

    1-s2.0-S0195667119303957-fx1_lrg.jpg




  • Asfaltovenator, an early allosauroid from Argentina. This one is about half complete and has a nice skull, for a change!

    41598_2019_53672_Fig1_HTML.png?as=webp

    images?q=tbn%3AANd9GcSn3we5vPFo-AIPZspNvyAGio8DzCvGcWu1pBvs5CdF_K90ytCH


    https://www.nature.com/articles/s41598-019-53672-7?fbclid=IwAR3xJfkkcPCpwBGBX6A8A9TSE40xw5DdAVq2736-cJUVk-NaX3lIqqRkkic
    Asfaltovenator is a large theropod, comparable in size to the well-known Allosaurus. The skull is 75–80 cm long, and the estimated body length of the holotype is 7–8 m.




  • New species of Allosaurus, A. jimmadseni, finally described.

    This is the species to which famous specimen "Big Al" belongs; it was actually discovered in the 90s but is only now formally described.

    https://www.eurekalert.org/pub_releases/2020-01/uou-nso012220.php
    Allosaurus jimmadseni, possesses several unique features, among them a short narrow skull with low facial crests extending from the horns in front of the eyes forward to the nose and a relatively narrow back of the skull with a flat surface to the bottom of the skull under the eyes. The skull was weaker with less of an overlapping field of vision than its younger cousin Allosaurus fragilis. Allosaurus jimmadseni evolved at least 5 million years earlier than fragilis, and was the most common and the top predator in its ecosystem. It had relatively long legs and tail, and long arms with three sharp claws. The name Allosaurus translates as "different reptile," and the second part, jimmadseni, honors Utah State Paleontologist James H. Madsen Jr.

    Three-species-of-Allosaurus-compared-credit-Mark-Loewen-scaled.jpg




  • New study suggests slightly different skull shape for Allosaurus, based on the recently described (but long known) Allosaurus jimmadseni, and casts doubt on the validity of Allosaurus europaeus as a separate species:

    https://peerj.com/articles/8493/

    fig-6-1x.jpg




  • Evidence of theropod on theropod scavenging and possible cannibalism in a late Jurassic fossil site.
    During the part of the Jurassic encapsulated by the Morrison Formation (146 to 156 million years ago) the area now preserved as the Mygatt-Moore quarry would have changed dramatically with the annual wet and dry seasons. In rainy months, the spot was probably a watering hole. The fact that fish, amphibians, crocodiles and other aquatic species are rare in the deposit suggests the water evaporated in the dry season. This setting may have given carnivores more of a chance to pick at carcasses before the returning rainstorms of the wet season washed enough sediment over the bones to bury them and preserve them as fossils. Drumheller-Horton says other details on the fossil bones, such as signs of trampling, indicate they were exposed for a stretch before burial.

    “We think that carcasses would have persisted on the landscape for a pretty long time,” she says. “We’ve been joking that the site probably smelled terrible.”

    The evidence also suggests the carnivores that left teeth marks at the site weren’t in a feeding frenzy but took each bite with intent. “Predators will usually target the high-economy anatomical regions first, like the viscera and the meatiest long bones,” Drumheller-Horton says, “and then work down to the lowest-economy bones, like toes.” If paleontologists find bite marks on the parts without much good meat, then the carnivore was probably late to the party and the more desirable parts were already gone. At Mygatt-Moore, Drumheller-Horton says, the team found a smattering of bite marks all over, so some carnivores may have taken down the prey and gotten first pick while others were left to gnaw on the carcasses later.

    Many of the bones with bite marks come from Apatosaurus, a long-necked herbivore. But the team also found tooth marks on the bones of the carnivorous Allosaurus.

    “The pattern of bite marks indicates that non-theropods have them in nutritious areas of the skeleton, whereas theropods elements tend to be better in lower-nutrition areas,” says bone injury specialist Ewan Wolff, who was not involved in the study. In other words: Whatever was biting the Allosaurus would seem to have gotten to them late, or at least focused on areas that didn’t have much flesh on them.

    The three-horned carnivore Ceratosaurus could have made the marks, but Ceratosaurus is rare at Mygatt-Moore. The only other carnivore that could have made them is Allosaurus itself, which is much more abundant at the site and would mean Allosaurus were eating some of their own.

    Why would Allosaurus eat other Allosaurus? Evidence of dinosaur cannibalism is rare in the fossil record. To date, only two other predatory dinosaurs—Tyrannosaurus and Majungasaurus—have been shown to feed on the carcasses of their own species. Drumheller-Horton notes that cannibalism isn’t all that rare among modern carnivores, though. “Almost no predator will turn down a free meal, so the line between predators and scavengers is fuzzy at best,” she notes.

    The bite marks at the Mygatt-Moore quarry might represent dinosaurs under stress, such as droughts and fires. “The unusually high frequencies of bites we found might be evidence of carnivores trying to scrounge up every available resource to survive rougher parts of the year,” Drumheller-Horton says. Similar trends have been found at places like the La Brea asphalt seeps in Los Angeles, where stressful ecological times match up with a greater number of carnivores gnawing on bones.

    Carnivorous Dinosaurs Like Allosaurus Were Cannibals
    Tooth-marked bones show that huge flesh-eaters had no qualms about chomping their own kind when times got tough
    Allosaurus
    Artist impression of Allosaurus (PLoS One)
    By Riley Black
    SMITHSONIANMAG.COM
    MAY 27, 2020 2:00PM
    40916
    Not far from the Colorado-Utah border, the Mygatt-Moore Quarry bonebed is brimming with hundreds of fossils from Jurassic favorites like Apatosaurus and Allosaurus. Similar dinos have been found at spots around the American West, but the carnivores found here must have been hungry. Dozens of bones bear the toothmarks of massive meat-eaters—including the bones of carnivores themselves, suggesting at least a little dinosaur cannibalism.

    “The site probably smelled terrible”


    Bitten bones and broken teeth are rare finds at dinosaurs digs. That’s because rapid burial is usually required for fossil preservation, and if that happens, then scavengers don’t get much chance to pick at the free meat. However, in a survey of more than 2,000 bones from Mygatt-Moore published today in the journal PLOS ONE, University of Tennessee-Knoxville paleontologist Stephanie Drumheller-Horton and colleagues found that 28 percent of the fossils were punctured, bitten and scratched by carnivores, a far greater percentage than other sites in the Morrison Formation, a huge span of rock in the American West that contains the Mygatt-Moore.

    “While tooth traces in bone are not uncommon in the Morrison, the sheer number of chewed bones at Mygatt-Moore is surprising,” says University of Wisconsin Oshkosh paleontologist Joseph Peterson, who was not involved in the study. The dinosaurs here acted differently, and the environment might offer a clue as to why.

    During the part of the Jurassic encapsulated by the Morrison Formation (146 to 156 million years ago) the area now preserved as the Mygatt-Moore quarry would have changed dramatically with the annual wet and dry seasons. In rainy months, the spot was probably a watering hole. The fact that fish, amphibians, crocodiles and other aquatic species are rare in the deposit suggests the water evaporated in the dry season. This setting may have given carnivores more of a chance to pick at carcasses before the returning rainstorms of the wet season washed enough sediment over the bones to bury them and preserve them as fossils. Drumheller-Horton says other details on the fossil bones, such as signs of trampling, indicate they were exposed for a stretch before burial.

    “We think that carcasses would have persisted on the landscape for a pretty long time,” she says. “We’ve been joking that the site probably smelled terrible.”

    The evidence also suggests the carnivores that left teeth marks at the site weren’t in a feeding frenzy but took each bite with intent. “Predators will usually target the high-economy anatomical regions first, like the viscera and the meatiest long bones,” Drumheller-Horton says, “and then work down to the lowest-economy bones, like toes.” If paleontologists find bite marks on the parts without much good meat, then the carnivore was probably late to the party and the more desirable parts were already gone. At Mygatt-Moore, Drumheller-Horton says, the team found a smattering of bite marks all over, so some carnivores may have taken down the prey and gotten first pick while others were left to gnaw on the carcasses later.

    Allosaurus from the Natural History Museum of Utah
    Allosaurus from the Natural History Museum of Utah (Riley Black)

    When Allosaurus eats Allosaurus

    Many of the bones with bite marks come from Apatosaurus, a long-necked herbivore. But the team also found tooth marks on the bones of the carnivorous Allosaurus.

    “The pattern of bite marks indicates that non-theropods have them in nutritious areas of the skeleton, whereas theropods elements tend to be better in lower-nutrition areas,” says bone injury specialist Ewan Wolff, who was not involved in the study. In other words: Whatever was biting the Allosaurus would seem to have gotten to them late, or at least focused on areas that didn’t have much flesh on them.

    The question is: Who bit them?


    The three-horned carnivore Ceratosaurus could have made the marks, but Ceratosaurus is rare at Mygatt-Moore. The only other carnivore that could have made them is Allosaurus itself, which is much more abundant at the site and would mean Allosaurus were eating some of their own.

    Why would Allosaurus eat other Allosaurus? Evidence of dinosaur cannibalism is rare in the fossil record. To date, only two other predatory dinosaurs—Tyrannosaurus and Majungasaurus—have been shown to feed on the carcasses of their own species. Drumheller-Horton notes that cannibalism isn’t all that rare among modern carnivores, though. “Almost no predator will turn down a free meal, so the line between predators and scavengers is fuzzy at best,” she notes.

    The bite marks at the Mygatt-Moore quarry might represent dinosaurs under stress, such as droughts and fires. “The unusually high frequencies of bites we found might be evidence of carnivores trying to scrounge up every available resource to survive rougher parts of the year,” Drumheller-Horton says. Similar trends have been found at places like the La Brea asphalt seeps in Los Angeles, where stressful ecological times match up with a greater number of carnivores gnawing on bones.

    Bitten Apatosaurus bones from the Mygatt-Moore quarry
    Bitten Apatosaurus bones from the Mygatt-Moore quarry (Riley Black)
    Ancient bites, new insights


    Scientists once thought dinosaurs like Allosaurus rarely ate bones because their bite marks are uncommon at other quarries. The Mygatt-Moore findings rewrite that story. “It is easy to look at a predatory dinosaur like Allosaurus and make a lot of assumptions about how they lived,” Peterson says. Paleontologists have been studying Late Jurassic bonebeds and the dinosaurs within since the 1800s, Peterson notes, yet studies like this new one highlight just how little we know about these familiar environments.

    These findings also might revise how researchers approach other dinosaur sites. In the past, Drumheller-Horton notes, expeditions often focused on well-preserved bones suitable for display or anatomical study. Bones that were damaged or not as aesthetically-pleasing were often left behind or even destroyed. The new insights from Mygatt-Moore partly came from a bulk collecting effort, including damaged and beaten bones in the sample.

    Besides, the toothmarks may reveal the presence of carnivores that have yet to be seen in the bonebed. Striations on one particular bone, created by the serrations of a carnivore’s tooth, are too big to have been created by an average Allosaurus. The biter was either an exceptionally large Allosaurus, a much rarer Jurassic predator called Torvosaurus, or a dinosaur not yet seen. One predator’s bite has left paleontologists with a new mystery to solve.


    https://www.cnet.com/news/jurassic-dinosaur-allosaurus-may-have-been-a-cannibal/

    mmq_cannibals_press_res_1.jpg




  • Purported carcharodontosaur teeth from late Cretaceous Brazil found more likely to be abelisaurid teeth. This study suggests carcharodontosaurs may indeed have been extinct by the late Cretaceous (post-Turonian), with abelisaurids and other theropods largely replacing them in South America at least.

    https://www.sciencedirect.com/science/article/abs/pii/S0031018220303151?via%3Dihub




  • Lusovenator, a small carcharodontosaurid from Portugal, is the oldest northern representative of the group; it would've lived in the late Jurassic, before its family gave rise to some of the largest predatory dinosaurs of all times.

    https://www.tandfonline.com/doi/10.1080/02724634.2020.1768106

    Lusovenator_santosi-novataxa_2020-Malafaia_Mocho_Escaso_et_Ortega--%2540EFMalafaia.jpg


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