Aera Anatomy

[DrTiger]

Attached is my attempt at an centauroid anatomy. While modeling this draft I tried to visually experiment with what I had thought about for a few days now.
To begin with, the head and fore-limbs are more a temporary thingy. I will bother about a more thoughtful anatomy later.
I don't like the idea of a centauroid species. First of all they have two chests. For what reason? I decided to remove the "middle" chest as such, to make the creature more balanced. I will probably put the brain into the erectable chest or into the middle segment.
I tried to make the creature gain some advantage from the three pairs of limbs. I came up with a jungle-inhabitant capable of running on a rain-forest like ground (which is not exactly paved...) and climbing about the lower regions of the trees. My Aera is not well suited for climbing the top of the trees at a reasonable pace.
His middle limbs' are reduced to one finger, just like the horses, but with the possibilty to use the ventral side of the finger as sole, too. This adds another one or two segments to this limb. It is used as a thruster to erect the body and for galopping along. Also this will enable the centaur to step as elegant as a horse does.
The hind legs are the thrusters, but more flexible than a horses' since they are capable of working both like a lizards' and a horses. Also the three finger end organs are very versatile: A good basis for erecting all of the body or galopping forward, but they can also grip a tree or something like that, making for increased security on forest ground.
I would have used more than three fingers on the forehands. Probably smaller ones, to manipulate smaller objects. But the docs say three fingers. As I said before, I'd like my Aera to have some advantages from the way he's built. And more elaborate hands might be very good advantage indeed.
The brain should not be in the head. Being in the "torso" it's protected a lot better. Also I imagine most of the physiology work being done in the abdomen. Maybe even the heart. A heart in the erectable section would cause a lot of problems, but with the brain on the same level it's no problem to put it into the hind section of the body.
The tail also is a tough decision. It's needed for balance, but it mustn't be that heavy and voluminous as it would hinder the Aera in the forest and in anything on the way from the forest to a military space craft...
My lizardlike aproach also enables the Aera to be a better astronaut. Imagine accomodating a horse or deer (a centaur is just that + a torse that's even higher) on a space craft... do they have seats? I imagine the Aera more or less lying on a bench-like seat, with the hind feets easing the pressure of the abdomen (they'd have some bones there probably, too!).
Another possibility would be to ly flat on his back (I assumed some kind of bony chorda...).
Another idea about erecting the body: It will cost this individual very much of energy to hold this kind of position, if there's no elastic bond to tie the erectable portion to the back (just like a horse's head). But if they had something like that, they'd not be able to pull down this part without energy, or even walk with all six legs. So the best solution I think is to reduce the amount of time an aera erects his body, that means whenever he walks casually the fore-torso is down, when running, it's up, and when talking or manipulating, too.
Well, here are the images. As I said before, just drafts.

[jackS]

A first response:

Many points well taken More fingers can often be more useful, but 3 is sufficient (maybe my subconscious just wanted the Aera to be even more miserable than they would otherwise be)

My areas of expertise do not happen to include bio-chem, physiology, xeno-ecology, xeno-physiology, or any number of things that would be useful in having been in charge of developing the aliens - but I'm nonetheless the schmo who attempted, such as I could, to do so. (The astute forum reader might have figured out that I'm a PhD. student in Computer Engineering... and yet I managed to avoid populating the universe with non-carbons - go figure ) I figured that Ret-Cons would be inevitable without a xeno-biology consultant, but we didn't have one, so we just got whatever 17 years (or something like that.. I remember reading Ringworld ~16-17 years ago - don't recall too much of my reading habits before then) of sci-fi reading and an odd imagination could bring me. In short, if I come off as defensive of decisions, it's less that I have any reason to believe that I'm right so much as I'm very interested to find out how and why I was wrong This will be fun!

You've made some assumptions that I didn't, and didn't make some I did, so, to add some more depth to the existing descriptions -

I used the word centauroid primarily to indicate that it had four "feet" and two "hands" - not that they were particularly horse-like in configuration.
I had imagined the 2 front limbs to not be walking capable in much the same way that our front-limbs are not walking capable - dedicated manipulators. The four propulsory limbs I therefore imagined as much thicker and more robust than the manipulator limbs.
As for the erectable section, you have made it much longer in proportion to the rest of the body than I had envisioned it. You have also added a thin, flexible neck. I had envisioned an all-but-absent neck, with the head achieving good vertical flexibility, but only limited side-side flexibility without some twisting of the erectable portion.
The limited size of the erectable section I had envisioned reflected its limited role - it gives a greater range of motion for the manipulators, and augments the limitations of the thick, stout head-torso connection. As said in the documents, the erectable portion was indeed intended to only be raised when active.

I would argue against making the feet in any way hoof-like - as mentioned in the documentation, the Aera evolved in a nearly continent-wide dense rainforest/jungle. There's nowhere to run as such, merely everywhere to sprint in a much more scrambling fashion through dense undergrowth and around and over thickets of low-lying branches and such. The ability to grip the uneven surfaces of living plant masses that were as common as patches of ground, and likewise the ability to amble up into the lower portions of a tree-analog would not be something given up lightly - with limited ground as such, even a reasobly larger animal like an Aera would have to be comfortable being off the ground - the south-american panther comes to mind.

You've gone with a somewhat lizard/salamander-esque leg configuration - but given the relative proportions you've done, the creature would be too slow moving - the four propulsory legs are too small and too squat.
The original descriptions have the shoulder height to length ratio (where length includes the tail) to be somewhere between 2:1 and 3:1, and I continue to see the form of the Aera as one marked by a sleek, muscular skinniness, more agile than something whose locomotion resembles that of a crocodile could seem to be - but perhaps I'm just not seeing how you've envisioned the locomotion. In any case, I think longer, larger legs would seem more suited to carrying as much middle-mass (somewhat less skinny than I'd envisioned) as you've depicted, especially given that you seem to have removed much of the infrastructure that the middle limbs would rely on in order to get any strength.

There are some problems with moving gray-matter away from the sensory apparatus. To put it bluntly, just as in any communications network, high-bandwidth, low-latency cabling is expensive and limited in how far you can take it. This would argue against an agile creature relying on its reflexes in a fast-paced and competitive environment wanting to put its brain any further away from the sources of input than strictly necessary. In my envisioning of a very limited sized upper torso, there would also be issues of where, amidst the bone and muscle, to put said brain, but assuredly, a larger torso could house one.

[DrTiger]

I imagined the one-finger limb to be very flexible, so that it can both be an uncomplicated thrusting base, and, by bending a few of the finger's articulations, it can also have a limited grip on difficult ground.
I don't think the hind legs are too weak. The perspective doesn't show that they are much longer than the middle legs, but bent, for propulsion's sake. Maybe I'll give them the sauropsoid configuration. Either horse-like or cat-like.
Now for the brain. Three important senses sit in our head, visual, auditory and olfactory senses. The only problem might be the eyes. The eye of the mammals develops out of the brain tissue during the embryonal development, that is, the eyes are actually part of it. And that's just another reason, maybe the primary one, why the eyes are close to the brain. Probably putting the head into the brain will be nicer for a human viewer, since it makes the head bigger.
Again for when to put up the torso. In this position it's almost impossible to climb, at least one of the two parts will constantly "hang around" so this joint must be used vigorously. Maybe I'll give him strong muscles to do this, and maybe an apparatus similar to the system horses have in their legs to stand still without using muscles.
Also the muscles must be on the back of the middle part, using some band apparatus to move the other part.