Sister thread: Dorite's Sagan 4 Creature Art Tips

I've been thinking a lot about things like how to position eyes in carpozoans, or how one might make a more plausible version of the rejected "horndog", or what implications there are in the anatomy and evolution of saucebacks. I'll post replies to this thread with individual topics, then link them in this table of contents.

Note that in this thread I cover living species and lineages that I consider to be implausible, especially in the context of common mistakes. I do not call for their immediate extinction unless they violate the laws of physics; however, if they are at a severe competitive disadvantage, it would be logical for better-fit organisms to displace them naturally.

Table of Contents:

General
Making Of A Plausible Genus Group
Earth Clones (The Good, The Bad, and The Undone)
Keeping and Losing Flight
A Time and A Clade: One Bird's Implausible is Another Bird's Innovation

Common Mistakes
Atavism (Evolving Backwards)
"Atavism Larvae"

"How To Kill" series
How To Kill Saucebacks

Binucleida
(none yet)

Carpozoa
(none yet)

Mancerxa
Plent Pigments
Don’t Do Skinny Tail-Like Butt Nostrils!

Biome-Related
What's That Biome? Chaparral
What's That Biome? Tundra
What's That Biome? Riparian
What's That Biome? Cold Seep

Miscellaneous
(none yet)

There's still the issue of all of its descendants, though.

I have several different ideas for how these may go in the future. My "main line" idea actually does something quite different with the ears.

This would have to be explained as far back as Bristlesquid, though. Bristlesquid is outright depicted with one of its tentacles up its butt.

The Bristlesquid features clear misinterpreted anatomy, with the mouth and anus swapping places. It was too complex for this to be possible as it was in early bilaterians on Earth. Given how its descendants evolved from there, including evolving eyes on the wrong end of the body and putting armor over where the actual mouth should be, it would be impossible to redesign to fix it, and a transitional form insert would not do either because the external appearance remains the same.

More primitive filtersquids that never swapped their mouth and anus still exist, and forms that echo back to quids could be re-evolved from them. Unless someone has an idea on how to repair quids, I'd like to propose they be wiped out somehow. I have some ideas for it that are hopefully more interesting than just having a suspension-of-disbelief pandemic.

I admit though that this species is certainly among my more ambitious ideas. It takes some inspiration from Serina's metamorphic birds; ancestrally, they similarly hatch as fetuses with overly developed forelimbs, and one branch went down a pretty similar path where babies started breathing through their skin in addition to breathing air. Since nobody's really yelled at Sheather about that--and believe me, they would if they had a reason to--I assume such a path is probably possible in Shrews too.

Note this is not a rip-off of any Serina species (I'm not pulling a horndog here); I don't think there are any species on Serina that are quite like this. It's convergent evolution, and my ideas for where to take it next are quite a bit different from what metamorphic birds do.

The joeys must still breathe air periodically. They will still eventually drown, especially as they get older. Newborn joeys, being literal fetuses, don't have especially high metabolisms; the need to breathe air grows with age, but so does their ability to get to the air on their own. I've edited to make that clearer.

I'm not sure about marsupials, but human reproductive organs are apparently able to straight-up sense the potential of sperm and prevent specific sperm cells from reaching the egg. I could see whatever mechanism is used there to also be repurposed to detect problems with embryos.

River Scrambler (Geminatisorex allojuvenilis)
Creator: Disgustedorite
Ancestor: Scrambled Shrew
Habitat: Blood Tropical River, Blood Tropical Riparian, Bardic Tropical River, Bardic Tropical Riparian, Kenotai Tropical River, Kenotai Tropical Riparian, Pipcard Tropical River, Pipcard Tropical Riparian, Wright Tropical River, Wright Tropical Riparian, Terra Tropical River, Terra Tropical Riparian, Dixon-Darwin Boreal (Dixon side only)
Size: 20 cm long
Diet: Carnivore (Miniswarmers, Larvaback, River Foi, Thorny Toadtuga tadpoles, Spineless Toadtuga tadpoles, Honey Toadtuga tadpoles, Axebeak Gilltail juveniles, Shardscale juveniles, Wright Pumpgill juveniles, Eusuckers, Minikruggs, Silkruggs), Ovivore (Ramchin, Mountain Flunejaw, Montemsnapper)
Reproduction: Sexual (Male and Female, Live Birth, Pouch and Milk)

The River Scrambler split from its ancestor. This small shrew has moved to riparian habitats, where it hunts small swimming fauna. This is an unusual accomplishment for something with marsupial-like reproduction. One would expect it to have taken a route similar to the Terran water opossum, or to Sagan 4’s own Seashrog, where the pouch can close. However, the River Scrambler has taken a different, more novel route.

The skin of the River Scrambler’s fetal joeys is highly vascularized and permeable, comparable to the skin covering the gills of the Terran axolotl. They are able to take in oxygen from the surrounding water while their mother swims. The pouch still envelops them and keeps them warm, though they are also more resilient when being chilled by exposure and do not need to be kept at a constant temperature; in fact, they can recover even if their core temperature drops to near freezing, though a drop that significant would also delay their growth considerably. The mother must still leave the water periodically, as the joeys can still drown if they are submerged for too long, due to skin-breathing being less efficient than lungs. The joeys develop webbed toes and a powerful swim stroke before they are old enough to leave the pouch, so they are able to surface for air on their own and swim to their mother to nurse. They retain their bright red highly vascularized skin even after they leave the pouch and their fur starts to grow in, allowing them to nurse underwater for longer without suffocating. The switch to less permeable skin is associated with weaning, as the ability to absorb oxygen from the water is no longer needed. Unweaned joeys must stay moist, as their skin loses moisture very quickly, but they still need to breathe air regularly, especially as they get older and their metabolism increases.

Weird babies aside, the River Scrambler lives mainly in the tropical rivers of Dixon. It can also disperse, traveling between them through the Dixon side of the Dixon-Darwin Boreal, mostly eating Minikruggs and similar creatures during the trek. It will also consume eggs if it stumbles upon a nest. It swims with a combination of paddling and an up-down undulation of its body. It has marsupial-like reproduction, giving live birth to fetal larvae which suckle from teats contained in a pouch. It breeds 6 times a year and has 5-12 joeys at a time. It is generally solitary and sleeps in burrows, typically within riparian biomes. It has lost most of its sexual display structures, as they created too much drag while swimming, and it now has a fully furred, slightly flattened tail. It retains its ancestor’s high mutation rate, though it has evolved a defense against the fatal “scrambling” mutation that occasionally afflicted its ancestor--that is, to avoid wasting resources, any embryo that undergoes a dramatic shift in tissue placement is reabsorbed.

I will continuously object to this species' approval unless its ancestor is successfully completely rewritten to be plausible, though I am now calling for its decanonization because I don't believe a rewrite is possible without a redraw, and the level of change required at that point is so extreme that it will no longer be recognized as the same organism. The ancestor should not have been approved because it is possibly the least plausible organism approved since the orbit voltflora; this is just as implausible by proxy.

Why was Diaminarm approved in the first place? It gained muscles, a nervous system, tactoreceptors, statocysts, advanced locomotion of several types, and coiling ability all at once, through its mycelium--a cell type physically incapable of gaining any of such structures or abilities--in a matter of 2.5 million years. I thought I commented on it at the time and gave my disapproval of it.

The ancestral state of terrestrial Spondylozoa is to have a backwards knee. However, this was misinterpreted several times independently to be the heel of a digitigrade leg. The original backwards knee is depicted correctly in iconic species such as the Nomad, so it's baffling that this has happened so many times without being caught--some instances being as recent as Week 24 (and it's a miracle that the correct backwards knee survived that long at all). Only a few species are left extant that have the correct backwards knee, mostly snappers and some dwellers (though at least one living branch of dwellers got misinterpreted).

Because this happened so many times and so inconsistently that it would be impossible to retcon and undesirable to plague or mass-replace, the only thing I can think of is to replace or redesign the most recent instances (such as in flunejaws and grubnubs) and find a way to explain the rest. I think a possible option would be that the "heel" is still a knee, and the additional uppermost leg segment is derived from part of the pelvis. Maybe the default hindlimb setup is something between a hip and a shoulder, having both flexible and inflexible parts, unlike the inflexible pelvis of tetrapods on Earth.

I don't think iron fauna shells are literally made of just iron?

If I have my chemistry right, exposure to water and oxygen should turn the exoskeleton into sulfuric acid. I don't think that's desired behavior.

Octhermas, not octothermas

So, blood and sap. They don't work that way.

First, blood.
- Crastrums, as small primitive algae-like planimals, have no need for blood (or true sap for that matter) and are never said to have evolved any. If they have any circulatory system at all, it should be filled with clear, sugary hemolymph.
- Gastroboskia are unicellular organisms and should not have blood at all.
- Many of these blood pigments seem to have been added for the sake of variation instead of being even remotely realistic.
- Cobalt-based blood is not pink!
- Plents cannot function biologically with chlorophyll as their blood pigment. All plents should be suffocating to death from syrupy blood that cannot flow. It would be more plausible for them to have red blood, either hemoglobin (chlorophyll with iron in place of manganese) or leghemoglobin (an oxygen-carrier used by plants in real life). Pinnaglobin (brown blood) may also be feasible, since plents use manganese for their chlorophyll, they should have access to hemoglobin anyway (as it is present in all aerobic organisms), hemoglobin can be swapped out for hemocyanin pretty easily, and pinnaglobin is just hemocyanin with a manganese.
- Not all animals should have blood! They don't just get it from existing!

And then there's sap:
- Sap does not contain chlorophyll. None of these sap colors make sense as a result. They should be clear or tinted; crystal flora sap is almost certainly pink or reddish due to the red pigmentation of the core.
- Only vascular flora have sap! Stuff doesn't just get sap from existing!

I really, really hate this post. Extensive blood and sap rant to follow.

I actually sent the artwork to Hydro asking if it was the bloodiest image on Sagan 4 (in the context of his old rejected species the Horndog, which was very bloody (though it was completely unrelated to the reasoning for its rejection)). He responded with a hoard of images of sagan 4 species with some amount of blood included

Coolsteph Sorry to ping, but why haven't you commented on this yet? You usually comment on everything.

It's more that it's a waste to keep producing the stuff that makes it waterproof. It's not a major anatomical feature like wings are.

Plains is the second most arid biome flavor Sagan 4 has. That particular plains biome is also surrounded on all sides by other biomes which would justify these adaptations.

Bristlepile (Polycaudofolium setum)
Creator: Disgustedorite
Ancestor: Fuzzpile
Habitat: Dixon-Darwin Desert, Dixon-Darwin High Desert, Dixon-Darwin High Grassland, Dixon-Darwin Rocky, Darwin Plains, Darwin Chapparal, Vivus High Desert, Vivus High Grassland, Vivus Rocky
Size: 6 meters tall
Diet: Photosynthesis
Reproduction: Sexual (Hermaphrodite, Puffy Spores, Berries)

The Bristlepile split from its ancestor. It tends to be found in drier biomes and up in the mountains, where avoiding water loss is important. In order to do this, it has shifted away from hair-like leaves and more towards thicker, stiffer ones comparable to those of a Terran Joshua Tree which resist desiccation. The waxy component that previously made their berries waterproof has been repurposed for making the leaves more resistant to desiccation as well. Its leaves are set on the ends of branch, rather than growing along the trunk. Its bark can now perform photosynthesis, making up for some of the lost surface area in its leaves. It has lost its adaptive trunk, not needing it in open environments.

In some parts of its range, such as Darwin Plains, the Bristlepile follows a typical seasonal appearance of berries in the spring. However, in the rest of its range and up in the mountains, it instead produces them when it rains, as it has a surplus of water during that time. The berries grow between the leaves and along the branches. Its berries are very sweet, attracting herbivores and small fauna to devour them and therefore spread it around. The blue-hued berries remain sticky and glue-like, though this is partly from unintentional pollination from ancestor, which resides in bordering biomes. The berries are no longer waterproof, because they don’t need to be.

The Bristlepile has adapted a thicker trunk and tubers in its roots in order to help it survive in the desert.

MNIDJM ?

Okay, Seashrog edits to fit this retroactive species:

QUOTE

The Seashrog replaced its ancestor and developed omnivory and tool use. Originating as an accidental discovery, the Seashrog learned to craft spears by cutting sticks at an angle. Initially, these were used for self-defense against its predator, the Pirate Waxface, but before long the Seashrog started using them for something new--spearfishing. It was able to develop the dexterity to accomplish this as an inevitable conclusion of its existing advanced nest-building skills.

Plus this paragraph added to the "relationships with other species" section:

QUOTE

Though most of the species spread by the Seashrog were either food or a nuisance, its expanded range has also had the effect of expanding the range of another species, the Pirate Waxface, which is the Seashrog's predator. As a result, the Pirate Waxface is now present in all habitats which the Seashrog is also present in.

Minor edit proposal for lizardworm jaws, as well, which didn't make sense before but can maybe make some sense now:

QUOTE

The lizardworm branched off from the leatherback scuttlecrab after the scuttlecrab colonized the Irinya Islands. It feeds on its ancestral scuttlecrabs using its newly formed jaw. This feature is the result of the insectoid mandibles of the scuttlecrab fusing together and attaching to the fleshy real head inside of the pseudo-head, allowing them to move up and down rather than together and apart. The oral ring muscles of its original head serve to open and close the jaw, and the teeth of the oral ring are now anchored to the pseudo-head and mandible-jaw sclerites to increase their effectiveness. The pincers of the scuttlecrab became down turned and specialized for walking, while its first rear legs moved further towards the rear. The body lengthened and became more worm-like. They evolved a primitive endoskeleton in addition to their exoskeleton. Its second rear legs degenerated and became a pair of small spines halfway down and on each side of its tail. At some stage during its evolution, the lizardworm lost its symbiotic relationship with testudohexapodia spherus. The lizardworm is native to the Irinya Islands.

As a bonus, the teeth are now explained too.

QUOTE (Cube67 @ Feb 3 2021, 04:56 PM)

Yarr... Yer hooved worm-animal is mighty good. Good thing it's a carnivore so it won't get scurvy. I don't see any issues with it really, but I question the tail-feather brooding thing. Do the babies hold on with their little teeth?

The feet actually have fleshy pads, not hooves, in waxface; this is no exception.

The tail brooding comes from the ancestor. As stated, they use snorkels coming from their spiracles to hold on.

if it isn't clear the shrew currently being murdered in the image is a tamjack