• TrickDacy@lemmy.world
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    27 days ago

    I’ve seen a lot of little birds hop around. Not only are birds dinosaurs, but the particular birds I’ve seen hopping are very similar in shape to a T Rex.

  • Ilovethebomb@lemm.ee
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    27 days ago

    I’d love to see an informed response as to why we think they ran instead of hopped. Is there a difference in the skeleton or muscles that would tell us?

      • IAmTheZeke@lemmy.world
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        24 days ago

        They were all made in clay-rich sandstone, which preserved the tracks so well that they have impressions of the scales on the skin of these dinosaurs.

        Oooo so we know for sure what the scale shapes are? Fascinating! Where is dino science on feathers currently? Did some dinosaurs resemble birds more than lizards? Sorry I’m late. Be wild if we had such impressions of feathers somewhere

          • IAmTheZeke@lemmy.world
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            23 days ago

            That’s true… I didn’t know we had more than bones though. Pretty amazing that we know exactly what those scales look like.

      • pyre@lemmy.world
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        27 days ago

        yep, the first thing I noticed was how tiny the kangaroo’s head and upper body is compared to the legs. for the t-rex both the head and the upper body are much more massive compared to the leg’s diameter.

    • Not_mikey@slrpnk.net
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      27 days ago

      Kangaroos hop because they can store a lot of energy in there Achilles tendon and use that to propel them forward without using much energy. It’s good for covering long distances over flat terrain while using as little energy as possible , which is good for the Australian outback as they hop between small patches of vegitation separated by miles of desert. It’s not that good for ambushing or quickly chasing prey in a rainforest like the t rex is probably doing.

      There’s also the issue of scale, a t rex’s Achilles tendon would have to be stronger then steel cable and as stretchy as rubber to store and re use that much kinetic force from its weight.

      • InverseParallax@lemmy.world
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        27 days ago

        Was gonna say, the tendon strength simply doesn’t scale like that, rexes are way too massive.

        Could see it for larger raptors though, except they’re probably better off just running. Predators really need maximum bursts of speed and maneuverability, hopping doesn’t give them that.

    • Swedneck@discuss.tchncs.de
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      27 days ago

      first off AFAIK they don’t even have anything near the amount of muscle in the right places to try hopping, but even if they did manage it i’m pretty sure their legs would snap in half when they landed and then as the rest of the body met the ground they’d crack ribs and stuff as well.

      Imagine trying to jump around while wearing a dishwasher on your back, even if you’re monstrously strong in every part of your body it’s gonna fucking suuuuuuuuck

    • ÞlubbaÐubba@lemm.ee
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      27 days ago

      Most likely the weight difference would be the biggest issue here.

      Same reason why to scale bug wings wouldn’t let you fly, that square cube law can lead to some very unfun conclusions where big beasties are concerned.

      Or some absolutely terrifying ones in Shin Godzilla’s case.

      • Tlaloc_Temporal@lemmy.ca
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        27 days ago

        I wonder if babies and adolescents hopped around? There’s already the theory that T.rexs lived in family groups with adolescents catching lots of small prey and adults catching the occassional large prey and providing protection.

        • Swedneck@discuss.tchncs.de
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          27 days ago

          hopping like a kangaroo is unlikely, but it would probably make sense for them to move like modern birds of the same size and whatever is the most similar ecological niche.

    • NegativeInf@lemmy.world
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      27 days ago

      Probably something to do with strain on the body. Studies show T. rex couldn’t even run. Maybe a fast walk. Additionally, the way the muscles attach to the bones probably don’t support hopping.

      • BudgetBandit@sh.itjust.works
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        27 days ago

        The context of this comment is amazing.

        Imagine a creature, that died over 65 million years ago (earth was at the other side of the galaxy back then) and yet we can detect how the muscles attached to the bone

          • Cypher@lemmy.world
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            26 days ago

            Right now you’re orbiting the galactic core (well basically, its very close) at 240km/s +/- ~30km/s (Earths rotation of the Sun).

            And it still took 65 million years to complete less than half an orbit of the galaxy.

    • geogle@lemmy.world
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      27 days ago

      Mass per volume is density, and I suspect the Trex and kangaroo are similar (~1000 kg/m^3) so yes they’d both bounce in that case. I think what you’re looking for is surface area to volume, which decreases rapidly as an object gets larger while maintaining geometry.

      • leftzero@lemmynsfw.com
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        27 days ago

        It’s worth noting that most extinct dinosaurs were probably more similar to surviving ones (i.e., birds) than to mammals and reptiles when it comes to bones and respiratory systems, and, by extension, density.

        That is to say, they probably could get that big because they were quite literally full of air.
        Some of them (especially sauropods, but maybe also other big species like tyrannosaurs) probably had even more complex and efficient air sac systems than modern birds…