Thoughts on Why Dinosaurs Such as Tyrannosaurus Rex, i.e., Meraxes Gigas, Have Small Arms and Hands
My Updated and
Complete Reply to a Science Article Posted on Facebook on 07-08-2022 on Why
Dinosaurs with a Similar Body Architecture to That of T-Rex, i.e., Meraxes
Gigas, Have Small Arms and Hands (or biological analogs of hands), cited online
article’s click-on hyperlink at https://abcnews.go.com/Technology/giant-meat-eating-dinosaur-species-discovered-argentina/story?id=86386556&cid=social_fb_abcn
The precise reason that their arms are small can be deduced from looking
at extant bipedal or semi-bipedal species such as humans, (penguins), kangaroos, wallabies,
kangaroo mice, praying mantises (insects
that typically stand on 4 legs, with two others functioning as arms, instead of
6 legs that are the standard for insects), as well as less so the great apes and lesser
apes, respectively of chimps, bonobos, gorillas, orangutans and gibbons,
Barbary apes, as well as the ground-dwelling monkeys of various species of
baboons, which is because they no longer walk and run, as a matter of course,
or characteristically, at all or materially as much on their front limbs, which
were previously strictly legs and feet, when they were four-legged, four-footed
animals, with all limbs, and their attached four feet too then, ground-bound
and propping up and supporting their bodies and body weight. With the freeing
of their once front legs and feet from being ground-bound and weight-bearing
and the repurposing of the front limbs and feet to being characteristically
arms and hands free/d from bearing body weight, or in such a transition as in
the case of the referenced apes and baboons, there would be, over generations
of their descendant posterity, substantial or appreciable bone, muscle-mass and
connective tissue diminishment of or loss for them, in a sense adaptation-related
limited atrophy for them in their new bio-architectural form and usage as arms
and hands or hand analogs. The more characteristically upright standing a
species is in its mobility and awake-state activities, over a numerous critical
number of generations of descendent offspring, the less in appearance and function
its leg-and-feet front limbs would tend to be and the more arm-and-hand
appearing and functioning they would tend to be. The hind legs and feet of the
changed animal species would tend to gain size and bone, muscle and
connective-tissue mass with them taking over the burden and workload of bearing
the weight of the body on their own that is no longer or much less supported by
the front limbs (except in the case of the praying mantis insect, retaining
four legs for standing and holding up the bulk of its body while using its
forelimbs as arms and hands or analogs of them), become or in the state of
transition to arms and hands, or analogs of hands, [as adjuncts] for predation.
In the case of T-rex body-architecture shaped, bipedal dinosaurs with enormous heads and bodies and small arms and proportional hands or hand analogs to their arms, because of the giant size of their heads and protruding mouths and many huge teeth, like hyenas, wolves, dogs, monitor lizards, alligators and crocodiles of our time, they would both be superlatively efficient bite-attack hunters and bite fighters as well as protective of their head and the rest of their body with their greatly larger head, mouth and many such teeth, with the additional advantage afforded to them with their characteristic upright mobility stature of panoramic vision over their environments, prey and combatant competitors bound to the ground with their four legs and four feet attached to their legs, and of comparatively rapid upper-body, including perhaps independently their head and whole-body swaying, swiveling, bending forward and back and turning and turnaround ability, as well as the potential or capability to rapidly hop high and long lengths with both of their bipedal legs and feet and to kick with a leg and foot, obviating their need for using their arms for hunting and combat or defense, although their arms and hands or analogs of hands very well may have been formidable for swatting off and felling lesser prey and pack or leaping predator-competitor animals with them for their common prey animals that were not large dinosaurs, such as lions, tigers, bears, etc., if they existed during their geological era, or small and modest-sized dinosaurs of their era. Incidentally, lions, tigers, cats of all kinds in general and bears have dual use front limbs that function as two of their normal four legs and feet for ground mobility and as a set of two arms and clawed paws for climbing trees and swatting, mauling, clutching, subduing and killing prey and other predator-competitor animals. Unlike with male cats, which have retractable genitalia that are internal until they engage in sexual intercourse, it is risky and a disadvantage for canines to bipedally stand and locomote upright because in doing so they would, especially males, expose their externalized vulnerable reproductive and pain highly susceptible genitalia to assault and injury or destruction by other attack animals, a disadvantage in upright stature and locomotion that dinosaurs, predecessors and relatives, if not the progenitors, of birds, with a T-rex like body architecture, might not have had in their possibly having had, for males, internal genitals, kept within the cloaca as in the case of birds, that could, like in male birds, be externalized for reproductive coitus with females. In societally primitive humans, clothing, such as a loin cloth or covering at a minimum, as well as the human weapons of stick or torch wielded fire, knives, spears and shields could respectively hide, and possibly protect against and fend off or kill attacker animals before they could attack their genitalia. What the latter have in common with the referenced primate species is that both of these kinds of animals regularly or occasionally climb up, about in and down trees and are lineage climbers of and residents or sojourners in or of trees, which work as an ecological niche in establishing and maintaining the arms and hands or paws of their putatively once strictly front legs and feet. The arms and bladed or clawed hands of T-rex body-like dinosaurs could have been used to push and poke, or slash, or possibly even stab, other animals, and scrape meat from the bones of a carcass that they might desire to savor while eating it, and to help them upright themselves, their bodies, from falls to the ground or from sitting or reclining related to rest or sleep, as in pushing in a needed direction (on a side or from side to side and/or below and behind), along with their tails, against the ground to initiate the uplifting of their bodies, as well as to help them seat or recline themselves for rest or sleep and to lift and handle their infants and to tussle with and box one another like kangaroos and wallabies of our age ritualistically do. Their tremendous size and weight insinuate that their body architecture and type were highly successful in feeding and prospering themselves in hunting and fighting. Though their circa 3-foot-long arms might have been as large and powerful as those of the most powerful grizzly bears of our time, the small size of their arms relative to their huge dinosaur bodies would make more biological sense in purposefulness if they attached to penguin-like, bat-like or great-blue-heron-bird-like, etc., wings on the T-rex dinosaur model scale. I saw a video of a penguin facing down on glacial or snow-covered ground lift its body upright by pressing its wings forward against that ground.
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Photos of kangaroos: https://www.istockphoto.com/photos/kangaroo
Photos of wallabies: https://www.istockphoto.com/photos/wallabies
Photos of praying mantises: https://www.istockphoto.com/photos/praying-mantis
Photos of penguins, https://www.istockphoto.com/search/2/image?phrase=penguins+photos
Photos of winged bats: https://www.istockphoto.com/photos/bat-wing
Photos of great heron birds: https://www.istockphoto.com/photos/bird-of-prey-hunt, https://www.istockphoto.com/photos/bird-catching-fish, https://www.istockphoto.com/photos/grey-heron, https://www.istockphoto.com/photos/Great-Blue-Heron
The cited online article’s click-on hyperlink is https://abcnews.go.com/Technology/giant-meat-eating-dinosaur-species-discovered-argentina/story?id=86386556&cid=social_fb_abcn
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