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I thought of a flying winged animal that when lands switches into a leg posture when landing

I know that vampire bats can walk but i want a animal that can run at high speeds when its wings switch into a leg my question is how would it switch into a leg posture and for high speeds.

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  • $\begingroup$ What speeds you're talking about? What do you mean by leg posture? Is it a quadruped or a biped? Though either way, a wing won't work as well as an arm or leg from a running creature because each activity requires very different adaptations. Nevertheless, adding this info could help us give a better answer. $\endgroup$
    – ProjectApex
    Jul 11, 2020 at 18:13
  • $\begingroup$ something roughly like this i assume? but with workable wing rather than gliding? $\endgroup$
    – Li Jun
    Jul 12, 2020 at 4:47

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Specialization:

The vampire bat is a great example. Limbs sharing functions are competing for very different functionalities, and mutations that favor one type of lifestyle or another will tend to lead to speciation and specialized lifestyles. Vampire bats don't need to catch bugs while flying. Anything that CAN be survived without will gradually mutate into dysfunction and disappear, so you need strong pressure to keep complex functionality.

Like submarines that can be optimized for underwater or surface sailing, many animals can do multiple jobs but they are not optimized for all of them. Your good runner is going to be a clumsy flier, or vice versa. Birds do both things, but even here the overall body plan pressures them to be either an eagle (good flier, clumsy walker) or a turkey (good walker, but flight is for emergencies only). To be really good (ostrich good) you need to give up trying to do everything and pick which one you want to be an expert at.

If you want merely the ability to fly, but a good runner, I can imagine a terror bird that has slightly improved wings and hunts in a series of dramatic jumps and hops. The legs are specialized, and the wings are there for an assist or occasional awkward flight. Then the wings still give some advantage to the style. It's not quite running, but it's along the ground.

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    $\begingroup$ Agreed that specialisation usually wins out over a generalist approach when measured on a single criteria. However, isn't it possible that there is a set of evolutionary pressures that would encourage speed in both running and flying? Success in two mediums is not unknown - rats are great swimmers and agile runners. $\endgroup$
    – Sean Condon
    Jul 11, 2020 at 13:22
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    $\begingroup$ @Sean Condon I'm not saying it's not possible, but a fish will swim faster and the rat is mostly optimized to walk/run already. Lots of things eat rats, in the water and on land because those things are specialized to do so. Rats are generalists, and do well (it's their niche), but aren't the best at anything (someone is going to argue this). They are good swimmers and good runners, but not great at both/either. $\endgroup$
    – DWKraus
    Jul 11, 2020 at 13:38
  • $\begingroup$ @DWKraus bird don't use the wings to run, in fact the flight mechanism is completely independent of the legs. $\endgroup$
    – John
    Jul 11, 2020 at 17:44
  • $\begingroup$ @John Yes, I know. I was suggesting something to give a creature some of the high-speed mix of flight and running suggested by the question. $\endgroup$
    – DWKraus
    Jul 11, 2020 at 18:20
  • $\begingroup$ @John not quite independent. It's true it's legs serve little purpose to flight, however stronger and legs better at running usually starts to make flight a harder task due to the extra weight. This is shown in how birds with longer and stronger legs capable of running faster tend to rely less on flight. Remember that in addition to specialization, energy consumption is another big factor in which structures get more developed. Sure it can fly well and run well, but is the benefit of maintaining both the powerful wings and legs worth the higher demand of energy and resources? $\endgroup$
    – ProjectApex
    Jul 11, 2020 at 23:51
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How about a flying squirrel?

A flying squirrel

This beast can fly somewhat, and I dare you to catch the critter on your own speed on a flat surface.

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  • $\begingroup$ A flying squirrel can glide it can't fly. $\endgroup$
    – John
    Jul 11, 2020 at 15:15
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    $\begingroup$ @John - that is what they would have you think. $\endgroup$
    – Willk
    Jul 11, 2020 at 16:33
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You can't.

flight puts some very strong constraints on a limb, constraints that just are not comparable with good running. It is like asking for a car that works competitively as both a long haul heavy dump truck and as a formula one race car, there is just no way to mix the two successfully.

A flight limbs needs to be able to complete a flight stroke which is a very different motion than running. meaning your limb needs two drastically different and strong sets of muscles to work the same limb and there just is not enough room to attach all those muscles to the same bones. To top it off the muscles will end up working against each other making both sets weaker. Worse even if you did manage to attach them all all that attachment will make the limb so inflexible that is becomes useless for both jobs.

A great deal of a flying vertebrates mass is concentrated in a wing, it needs to be both large and strong to generate sufficient lift. This concentration of mass is the exact opposite of what you want in a running limb. In a running limb as little of the creatures mass should be in the limb as possible, to make moving the limb faster and less costly. Worse wings need to have as large a surface area as possible to generate lift while a running limb needs to have as little surface area as possible to reduce drag. even if you some how twisted the limb into the lowest drag orientation it will be subjected to strong lateral forces from drag on the wing surface, which is the single biggest thing you don't want on a running limb.

All the animals that can fly and run are birds that use different isolated limbs for each activity (the front limbs for flight the hind limbs for running), this is why birds evolve ground running multiple times and bats and pterosaurs never have, because birds are the only group of flying vertebrates that have a set of limbs not involved in flight.

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Pterosaur

enter image description here

The bony elements of the arm formed a mechanism to support and extend the wing. Near the body, the humerus or upper arm bone is short but powerfully built.[54] It sports a large deltopectoral crest, to which the major flight muscles are attached.[54] Despite the considerable forces exerted on it, the humerus is hollow or pneumatised inside, reinforced by bone struts.[42] The long bones of the lower arm, the ulna and radius, are much longer than the humerus. https://en.wikipedia.org/wiki/Pterosaur

Quetzalcoatlus

enter image description here By Jaime A. Headden (User:Qilong)CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=33532515

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  • $\begingroup$ This doesn't answer the question, please read more than the title. $\endgroup$
    – John
    Jul 12, 2020 at 3:36

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