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The Ornithopod Thread- Hadrosaurs, iguanodonts and kin

13

Comments

  • Moderators, Society & Culture Moderators Posts: 9,639 Mod ✭✭✭✭Manach


    Very interesting article. One quibble though. AFAIK the atmosphere of those times differed from today's in terms of composition? So should that have been factored into the recreation?


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Right, higher oxygen levels and all that... good question, I really have no idea


  • Registered Users Posts: 218 ✭✭Linnaeus


    Experimentation indicates that, whatever the real purpose of Parasauropholus' tubular crest, this was capable of making a deep trumpet-like sound. I suspect that the hadrosaurs in general developed crests of various dimensions precisely to be able to emit warning cries to their herd. The crests, some palaeontologists have suggested, might also have improved the hadrosaurs' sense of smell, thus giving them another advantage in identifying the presence of approaching predators.

    As hadrosaurs had few effective means of defense, their crests...when present...would therefore probably have served as tools for survival.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Indeed, if it had been for visual display only they probably would've had soft-tissue crests, akin to those of Edmontosaurus if new discoveries are to be trusted.
    Such a complex structure as Parasaurolophus' or Corythosaurus' crest had to serve more than one purpose- kind of like with antelope horns today.


  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,537 Mod ✭✭✭✭Capt'n Midnight


    Manach wrote: »
    Very interesting article. One quibble though. AFAIK the atmosphere of those times differed from today's in terms of composition? So should that have been factored into the recreation?
    https://en.wikipedia.org/wiki/Speed_of_sound
    The speed of sound in an ideal gas is independent of frequency, but does vary slightly with frequency in a real gas. It is proportional to the square root of the absolute temperature, but is independent of pressure or density for a given ideal gas. The speed of sound in air varies slightly with pressure only because air is not quite an ideal gas.

    If you use Helium or Sulfur Hexafluoride you get different sounds, but more because of the molecular mass. Composition of air shouldn't change sound too much as N2, O2 are close and CO2 isn't a million miles away.

    There's a lot of N2 sequestered in the biosphere.


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  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Seems like it. May have had a soft-tissue crest, however, as has been suggested for Edmontosaurus. Who knows?


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  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    By hydrogen sulfide, it appears. These were among the first dinosaurs for which full skeletons were found. (In the picture below, the first ever mounted specimen of Iguanodon).
    https://www.vrt.be/vrtnws/nl/2018/03/09/iguanodons-van-bernissart-stierven-door-giftig-moerasgas/
    Dino_high_19_EN.JPG?itok=ERfIEUy4


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    https://www.tandfonline.com/doi/abs/10.1080/02724634.2017.1398168?journalCode=ujvp20
    (Abstract). 
    Suggests Edmontosaurus was capable of quadrupedal gait from the start, rather than starting as obligate bipeds and becoming quadrupeds later on as had been suggested. 
    (Below, Maiasaura hatchling, probably similar to the new find)
    maiasauraeggWC-58b9a64e5f9b58af5c8557dc.jpg


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    It is called "Choyrodon" and was found in the same place (and is from the same time) as previously known, high-nosed iguanodont Altirhinus. Hmm...

    https://peerj.com/articles/5300/

    fig-2-1x.jpg

    Here's Altirhinus' skull:

    1200px-Altirhinus_kurzanovi.JPG


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Weewarrasaurus, a new ornithopod from Australia. Known from a piece of opalised jawbone.

    https://www.nationalgeographic.com/science/2018/12/exclusive-sparkly-opal-filled-fossils-reveal-new-dinosaur-species-paleontology/?fbclid=IwAR1RSRXCdzgY-RbT4l85z6OmOans7rYR_Cj-PFf_GZywLQC_wmKKbBILJfk

    Not really sure how it difers from other small Australian ornithopods like Laellynasaura and Fulgurotherium, known also from very fragmentary remains...

    _104643415_r0_0_2501_1528_w1200_h678_fmax.jpg


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    South America is known for its wide variety of sauropods and theropods, but ornithopod finds are a lot more unusual. Here are some recent ones that may help complete the puzzle:

    https://www.sciencedirect.com/science/article/pii/S0195667118303586

    https://www.sciencedirect.com/science/article/pii/S0195667118304506

    It appears South America had its own ornithopod fauna, different from the one found in North America at the same time, although we do know at least kritosaurs (a genus of hadrosaurids) did migrate into South America at some point, with Secernosaurus/Kritosaurus australis being the best known example:

    Hadrosaur_museum.jpg


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    https://royaltyrrellmuseum.wpcomstaging.com/2019/06/10/rare-dinosaur-fossils-reveal-new-details-of-prosaurolophus-display-features/?fbclid=IwAR2v-ZhqyrmQglYiJ0sMkd3BmvwhBylcn23239Pu5MzODcq9YycSsDwWTLY

    prosaurolophus-by-julius-csotonyi.jpg?itok=K29YUDEE&c=ef968452b6dfed08c71a4ae5f42ecb31
    “We noticed that the bony crest grew very slowly in Prosaurolophus and remained small, unlike what happened in some duckbills, which rapidly developed a large bony crest,” says lead author Eamon Drysdale, a University of Calgary graduate student. “Instead, rapid changes in the snout as the animal matured suggest that a soft tissue structure may have been associated with the nostrils and used for display. The snout would have been the primary display feature, rather than the large head crest of other duckbills.”

    This new study provides evidence to support the previously-proposed idea of a showy, fleshy snout.

    A skin impression of a juvenile Prosaurolophus dinosaur shows large scales present on the flank of the animal. These scales were also likely present in the adult individuals.

    5-Prosaurolophus-Skin.jpg?resize=676%2C717&ssl=1


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Fostoria, a new iguanodontian described from Australia.

    Dinosaur finds consisting of more than one bone are very rare in Australia; in this case, several elements were found, belonging to several individuals.

    http://www.sci-news.com/paleontology/fostoria-dhimbangunmal-07265.html

    image_7265_2-Fostoria-dhimbangunmal.jpg


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    This kind of pathology was known only from mammals.

    https://www.nature.com/articles/s41598-019-45101-6

    41598_2019_45101_Fig1_HTML.png?as=webp

    Tenontosaurus is an early Cretaceous, long-tailed ornithopod most famous for being apparently the favored prey of the raptor Deinonychus.

    31-Tenontosaurus-tillettorum_0fe9.jpg


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  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Fathom wrote: »
    Hadrosaurs had great variety. Differential reproduction?

    Actually what I find intriguing about them is that postcranially, most of them look VERY much alike, and the head/crest is about the only thing that allows one to tell them apart. Something similar happens with ceratopsians. In both hadrosaurs and ceratopsians it can be extremely difficult even for paleontologists to determine what genus or species they're looking at unless there's a skull, and juveniles (which are yet to develop their distinctive crests) are even more problematic.

    Although I suppose the same would be true of say, many antelopes if all we had to go by were the bones...


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Fathom wrote: »
    Did one species have a snorkel on the top of its head? For breathing at waterline, with rest of animal below surface?

    The snorkel idea was once suggested for Parasaurolophus, perhaps the most iconic of the hadrosaurs (although one relatively rare in the fossil record):

    parasaurolophus-skeleton.jpg

    The idea has long been discarded due to several reasons:

    1. One would expect a snorkel to project more vertically; instead, the crest grows backwards and downwards at the tip.

    2. Not all Parasaurolophus specimens have a long crest; in fact, it has been suggested that only adult males did, whereas females and juveniles had much shorter crests. This strongly suggests a role in courtship and social interaction. If the crest was a snorkel we would expect all Parasaurolophus to have the same equipment.

    3. Most importantly, there is no opening at the tip of the crest. The animal's nasal passages DO go into the crest but it's just a detour; it is currently believed that the crest functioned not just as a visual display but also as a trombone of sorts, amplifying the dinosaur's calls.

    In the 90s, scientists used a computer simulation to calculate how much air a Parasaurolophus would've been able to blow from its lungs, and reconstructed its possible voice. Check it out, it's rather eerie:



    Keep in mind that Parasaurolophus is believed to have prefered more forested areas than other hadrosaurs, so it makes sense that sound would've been an important part of its communication.

    Also worth mentioning that hadrosaurs as a whole are no longer believed to have been semiaquatic, as was once proposed. The idea was that since they had duck-like beaks, they probably dived to feed on aquatic plants, but this has long been disproven; the beaks were only vaguely reminiscent of those of ducks; in life, they were covered by a rather hooked, sharp keratinous cover to crop vegetation, and they had batteries of thousands of tiny teeth to grind hard food. They weren´t feeding on soft water plants.

    Another piece of supposed evidence for their aquatic lifestyle was the fact that a "mummified" hadrosaur was once found which showed what was interpreted to be webbing between its fingers. However, later it was found that this supposed membrane was actually a sort of "mitten" of skin that kept the three central fingers bound tightly together, an adaptation for supporting the animal's weight as it walked on four legs.

    Their tail was also not flexible, but rigid and very heavy, and probably one of their main means of defense against predators (they could use it like a sledghammer to strike a predator ). It was not sinuous and crocodile-like as suggested by early paleontologists.

    So in short, we have no evidence of aquatic or semiaquatic hadrosaurs as of this moment, and absolutely no evidence of any dinosaurs having snorkel-like crests.


  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,537 Mod ✭✭✭✭Capt'n Midnight


    Fathom wrote: »
    Did one species have a snorkel on the top of its head? For breathing at waterline, with rest of animal below surface?
    IIRC 2 meters is the maximum depth underwater humans can breath through a tube to the surface.

    And the guy who tried it died shortly afterwards, so do not try at home.


    Human lungs aren't made for that differential.


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    :eek:

    bur1m.jpg

    I wonder what would happen in this scenario then :B


  • Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,537 Mod ✭✭✭✭Capt'n Midnight


    Adam Khor wrote: »
    :eek:

    https://dino.lindahall.org/img/bur1m.jpg

    I wonder what would happen in this scenario then :B

    In two words I can tell you what's the matter with it: It's im-possible.

    - Samuel Goldwyn


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor




  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Or hadrosauroid. Skeleton said to be nearly complete and as well preserved as if it had died days ago, thus allowing for great, accurate reconstruction:

    https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0208480

    journal.pone.0208480.g033


  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    From the North Dakota Geological Survey's Paleontology Resource Protection Program's Twitter account, comes this very interesting picture which shows the hand of famous Edmontosaurus "mummy" Dakota, one of the best preserved dinosaurs in the world.

    The picture shows that we have been reconstructing hadrosaur "hands" the wrong way; instead of three separate digits each ending in one small hoof, it appears these animals had all three main digits completely covered on a skin and flesh "mitten", and only the third digit had a big, horse-like, weight-bearing hoof. So, externally, the creature would only have one apparent hoofed toe, and a small, spike-like "pinky" that didn´t touch the ground.

    EHFxqa0X0AACIo9?format=jpg&name=medium

    Yet another example of how little we actually know about dinosaurs- even "classic" ones like Edmontosaurus-, and how different they would look with all their fleshy bits on.


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  • Moderators, Science, Health & Environment Moderators Posts: 5,279 Mod ✭✭✭✭Adam Khor


    Big news! Cartilage cells with traces of the original proteins/DNA found in juvenile Hypacrosaurus fossils!

    ?url=http%3A%2F%2Fnewatlas-brightspot.s3.amazonaws.com%2Fa2%2F4c%2F2cf1e0104efdb7bc064cfb3af8e6%2Fdino-dna-2.jpg

    https://newatlas.com/science/dinosaur-dna-proteins-fossils/
    These particular specimens were “nestlings”, meaning that at time of death they weren’t yet old enough to leave the nest.

    Inside the skull fragments, the team spotted evidence of extremely well-preserved cartilage cells. Two of them were still linked in a way that resembles the final stages of cell division, while another contained structures that look like chromosomes.

    The next step was to check whether any original molecules or proteins could still be preserved, and to do so the team conducted two detailed analyses on other skulls from the same nesting ground, and compared the results to samples from young emu skulls that are (obviously) much more recent.

    The first was an immunological test, which involves applying a substance that will react if it detects antibodies from a particular cell type. In this case, the test reacted to antibodies of Collagen II, a protein commonly found in the cartilage of animals. This, the team says, suggests that remnants of the original proteins are still present.

    Understandably, the reaction was far fainter for the dinosaur samples than the emus. The dinosaurs’ staining was also localized in one spot, where as in the emu it was spread across the whole sample.

    In the second test, the team hunted for dinosaur DNA. They isolated individual cartilage cells from the Hypacrosaurus, and applied two different staining substances that bind to DNA fragments. And sure enough, the staining occurred in the same pattern expected for modern cells.

    The implications of potentially finding DNA in these samples are huge. Current thinking says that DNA can only persist for about a million years maximum – but these fossils are 75 million years old.

    "These new exciting results add to growing evidence that cells and some of their biomolecules can persist in deep-time,” says Alida Bailleul, co-lead author of the study. “They suggest DNA can preserve for tens of millions of years, and we hope that this study will encourage scientists working on ancient DNA to push current limits and to use new methodology in order to reveal all the unknown molecular secrets that ancient tissues have.”

    ?url=http%3A%2F%2Fnewatlas-brightspot.s3.amazonaws.com%2Fce%2F3f%2F1431c43249f7b6d4ffc75f3f4f2e%2Fdino-dna-1.jpg
    While Jurassic Park remains firmly in the realm of fiction, the possibility that dinosaur DNA and organic molecules could persist for tens of millions of years is still fascinating, and it could teach us far more about these captivating, ancient creatures.


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