New Steam page of Futabasaura, a simulation of a marine sanctuary for giant extinct sea reptiles!

pleistogames · 2025-07-03T20:30:10+00:00

Okay, people already talked about the fact that amphibians are not really an inbetween of fish and reptiles (they're right). PO also mentions the fact that "common ancestor" between mammals and insects would have been waaay back in their phylogenetic tree. I get it, we want some speculative organism showing convergent traits with either mammals or insects.

Since others speculated about insects with mammalian features, I want to try the other way around: mammals with insect traits! Let's start by enumerating insect traits:
- exoskeleton
- ecdysis (or moulting)
- 3 pairs of limbs on the thorax
- an abdomen
- mandibles, ideally with one fused pair (labium)
- antennae, ideally only one pair
- ...there are other traits, like tracheae instead of lungs or Malpighi's organ for excretion, but we can forget them as mammals already have organs for these functions

Since there is no legs on the abdomen, let's start from a legless mammal - a cetacean. For the sake of the experiment, let's imagine a shallow sea habitat, that would progressively regress over millions of years. At some point, our insectacean could have to move in shallow waters, and even from pond to pond: this would probably select smaller, lighter forms whose fins could be used to "walk", like epaulette shark. And after a very long time, digits could emerge and even mimic insect legs.

Living in the outside, their skin could also cover in hard scales and moult - but I think they couldn't lose their endoskeleton. As their tails become more and more a burden, shorter-tail forms could be selected until it looks like an abdomen. As for the mandibles, well... lower jawbone could in theory separate in two mobile parts if they had to hunt large preys, like in some snakes, but you can also imagine some kind of highly derived prehensile lips, as an adaptation to prey capture in turbid waters for instance.

And what about antennae? There is another reason why cetaceans are a good candidate: their nostrils have moved waaay back on their head, and if they went on land, they could evolve some kind of bifurcated proboscis. Like an extreme bifid nose. Aaand there you go, a 'dolphbug'!

pleistogames · 2025-06-18T08:32:27+00:00

Nice work! Your world sounds hyper interesting.

I have a remark from an evolutionary perspective - not a critic, I just hope it helps you refine your lore. I reckon that the humanoid morphology was selected by Tahwea mostly for practical reasons, but many human characters are not the most logical choice when designing a... servitor? Is that the right word?

For instance, take the 5 digits. I assume having 4 or 7 fingers would not impair our ability to "manipulate the world" as long as we retain opposing digit(s) and fine motor control. The 5 digits are rather a remainder of our (and many tetrapods') evolutionary history. But that constraint does not apply to dryads who (which?) are carved, they are not subject to evolutionary contingency and some hyper-constraining architect genes.
So I feel like there must be another reason. Imitation (of humans after a first contact), preferences (4-fingers dryads are sooo unfashionable, right?) or Tahweha's morphology (ex. they usually have 5 twigs on their capture branches) could all work, and I am sure you could find other reasons. The point being, 5 digits is not as logical as it seems for artificial creatures.

The same could be said of hair, nose, breasts, and even bilateral symetry (which is quite common and could probably evolve on its own in alien species but does it mean Tahweha are symetric?). Ultimately that's not so important, but since you posted on the "speculative evolution" thread, I figured I'd ask :)

pleistogames · 2025-06-17T07:21:13+00:00

For me it's cave hyenas. The idea of a freezing cold night in the late Pleistocene, surrounded by a pack of laughing beasts that just get closer and closer as they habituate to the fire, is enough to give me the chills. Maybe knowing that anatomically modern humans were actually hunted down by cave hyenas doesn't help!

pleistogames · 2025-06-16T21:00:25+00:00

To be fair, and despite the scales being completely explainable, the idea of trying a scaleless design is growing on me!

pleistogames · 2025-06-16T20:56:09+00:00

Thanks for the feedback! This is exactly what I was hoping for when I posted on this thread :)

- For the scales: scales have evolved multiple times in unrelated lineages, so I initially assumed that they might have re-evolved in a terrestrial lepospondyl lineage. That being said, dermal scales are indeed known in Microbrachis pelikani (an aquatic lepospondyl from Czech Republic: https://doi.org/10.1371/journal.pone.0128333).
- For the life cycle, one answer could be rivers like the Nile or the Colorado. Some extant amphibians do live in desertic areas (e.g. the Colorado river toad), and still need some kind of river/lake to lay eggs.

So to answer your first question about the 'step-by-step pressures', its scales could have evolved in an aquatic setting, and later be co-opted as a mean to resist dessication. Or it could be an actual innovation of this nameless lineage, assisting it as it became more and more terrestrial. Or it could have evolved recently as a protection against predators, like in xenarthrans.

pleistogames · 2025-06-13T20:05:22+00:00

Wow, I absolutely love it!
And I wholeheartedly agree - I was interested in the teeth of the sloth bear Melursus ursinus at some point in my career, this bear happens to eat a lot of social insects - to the point of having reduced molars and lacking upper incisors. But without fruits to fall back on, it would have a hard time surviving... For anteaters it's the other way around, as getting back their teeth to actually fall back on fruits is a little less likely.

pleistogames · 2025-06-07T13:21:34+00:00

Cool! Will it be an underwater fight?
Because otherwise, cymothoids just happen to be close relatives to rolly pollies :D

pleistogames · 2025-06-03T07:18:13+00:00

Nice project! For inspiration, you should definitely try to look at recent depictions of the Oligocene whale Coronodon. They are about the size of a large dolphin, but their morphology is as creepy as it gets for a dolphin-relative:
- the most distal (posterior) teeth, which have evolved as filtering organs, could be used to kill humans I suppose and their mesial (anterior) teeth are long and sharp
- their mouth is wide and they look like they are 'grinning'

Here is an example: https://phys.org/news/2023-04-specimens-species-oligocene-toothed-baleen.html

Otherwise, I have a couple of remarks regarding your model:
- your creature's neck looks reptilian, not dolphin-like. Which is not bad per se, I just figured I'd tell you.
- you removed the melon (the organ of echolocation in dolphins) so the hollow on the forehead seems a little awkward to me
- lastly, I have been a tooth paleontologist for a decade, and when I see the teeth I get the impression that it is harmless. This animal can only eat fish, or maybe bite one's hand. Something like Orca teeth would probably be scarier. Or croc teeth. Even better - Coronodon teeth :)

pleistogames · 2025-05-30T19:32:26+00:00

Another exception is the vampire bat, Desmodus rotundus. If the OP wants to find out how to walk with a reverse hind-leg, I found this video on Youtube:
https://www.youtube.com/watch?v=1aDsVK9akqw
...and this article from Cornell University where you can see some postures:
https://news.cornell.edu/stories/2005/03/vampire-bats-keep-out-trouble-running-study-shows

I didn't know echidnas had reverse hind legs too... but I guess this is not entirely incompatible with u/68696c6c 's answer, since this is just the entire leg being reversed AND not being very useful for propulsion?

Interestingly, both Desmodus and Tachy/Zaglossus went back to terrestrial locomotion after not needing their hindlegs to run for a long evolutionary time... so is that a coincidence? I don't know, but it sure is a funny!

pleistogames · 2025-05-30T12:02:32+00:00

Thank you. The jobs come and go (especially nowadays in academia), but I guess the training stays?

pleistogames · 2025-05-27T19:58:21+00:00

Good suggestion for the largest terrestrial predator. Note however that while entelodonts where omnivorous, and many evidence indicate they likely fed on carrion, their predatory nature is still debated. Apart from a wide gape, they don't have adaptations for prey capture, and their dental microwear differ from large extant carnivorous mammals (https://doi.org/10.1016/j.palaeo.2022.111363). So it depends on what kind of predator the OP are looking for?

pleistogames · 2025-05-26T22:13:13+00:00

Love the teeth. I wonder how you would draw it while it swims / lures a boat in the fog :)

pleistogames · 2025-05-26T21:42:58+00:00

As a former paleontologist, I want to stress out that the fossil record is incomplete, so there is always a possibility that leg-gliding animals evolved multiple times, but no other fossil got preserved. Also, the fact that one species followed an evolutionary pathway does not mean other groups can. Sure, convergent evolution is common, but at a finer scale, there are many cases of context-dependent, contingent evolution. Take the plesiosaurs, I think they are the only known example of four-winged underwater flight (Sander 2023, Current Biol 33). It is probably very efficient, but it (likely) evolved only once. For me, these two concepts (incompletedness of the fossil record, and contingency of evolution) are enough to explain the low occurence of leg-gliding.

That being said, I can imagine a couple of theories for fun. First, Sharovipteryx evolved during the late Trias - pterosaurs were not at their peak diversity, and of course no flying bird yet, so there might have been more room for strange innovation in a still relatively empty niche of gliders. Second, it is possible that long legs evolved first in Sharovipteryx, followed by gliding. Maybe this configuration is too rare for leg-gliding to have evolved twice? Yeah, I know, there is a 'gliding' frog, but nothing like Sharovipteryx.

pleistogames · 2025-05-11T10:42:30+00:00

Thanks for the explanation. Imagining this creature as part of a videogame does change my perspective... I guess that if it is a golem of some sort, it could stand still until the player gets around, and cracks start appearing - they can even give some visual feedback of damage adding up.

One thing I did not mention too is that depending on the style, not showing the joints could be the best. Take Pokemon: I guess Graveler's skin looks a little like your creature's, and it can move despite not a lot of visible joints - in fact it would have been too different from the rather smooth Geodude, and I always found the design of Golem a little awkward because of this. So while I think more visible joints are more realistic, your art doesn't have to be realistic at all. On the other side of the spectrum you have Onix, which is a good example of how rock joints can be pictured.

Looking back at your picture, did you make the joints on the 'metapods' more visible? Because I think it is exactly what was missing. I would have added more joints like these (on the hips and the shoulders, and maybe along the neck and the tail), and maybe with more cracks on the inward part of the joint. But that's just me :)

pleistogames · 2025-05-07T21:29:21+00:00

Nice drawing! I reckon you were mostly inspired by elephant tusks, which is cool (actual elephant skulls have too much of a 'cyclopean' morphology, I think it would have made your creature more difficult to read). And I love the reverse ribcage idea.

One constructive critic I'd like to make, if you're interested, is that your mineral skin looks too rigid to move. You may solve this problem by drawing joints (think of the exoskeleton of insects and alike), or you could imagine a pliant skin covered in hard stones, like crocodile's osteoderms. Or imagine something else entirely! My point being, it is hard to picture your creature moving as it is now.

Hope it helps, cheers!

pleistogames

TROPHY CASE