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So, after a long unplanned hiatus, I have started designing alien creatures again, and one image that eve before that hiatus I could not get out of my head is that of a creature which has both the pointed piercing/shearing teeth of a carnivore, and the side-facing eyes of a herbivore. The thing is, though, I don't want to just handwave it and say that I'll do it anyway because it looks good to me; I will if I have to, but I would rather have a reason.

Why, then, would teeth that only make sense for an exclusive meat-eater occur in the same species as eyes that only make sense for an exclusive plant-eater?

Now, I've asked questions on here before and subsequently, from not giving enough criteria, gotten unhelpful results, so I'll say a bit more about the creature I'm imagining; It:

  • Is vaguely humanoid
  • Is at least nearly human-sized
  • Has a sense of smell not significantly better than that of a human, although much better hearing
  • Has retractable claws on both hands and feet
  • Is at least partially warm-blooded
  • Is naturally evolved, not having been subject to any artificial genetic engineering, although it is not from Earth or related in any way to any Earth life
  • May be either digitigrade or plantigrade (I have not decided), but may not be specifically unguligrade

My question then is this: Why would a creature meeting all the above criteria have both the teeth of a carnivore and the side-facing eyes of a herbivore?

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    $\begingroup$ While it might be generally true that carnivores tend to have eyes in the front, the "fact" that all of them do is easily disproved by the fact that sharks exist. Especially hammerhead sharks. $\endgroup$ Jul 16 at 17:34
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    $\begingroup$ @KlausHaukenstein also crocodilians, whales, and dolphins, it is less useful for aquatic or semiaquatic predators. $\endgroup$
    – John
    Jul 16 at 18:19
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    $\begingroup$ Pandas and gorillas are herbivores with front-facing eyes. Crocodiles and falcons are carnivores with side-facing eyes. (And note that humans have pretty good hearing. Animals with better hearing than humans are not uncommon, but having much better hearing is quite hard.) $\endgroup$
    – AlexP
    Jul 16 at 19:00
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    $\begingroup$ Perennial reminder - evolution has no end game and no strategy. The only rule is that those who have propagated probably did so for reasons. Sometimes the reasons aren't apparent, are counter intuitive, or nonsensical. $\endgroup$
    – Nohbdy
    Jul 17 at 0:25
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    $\begingroup$ "[side-facing eyes] eyes that only make sense for an exclusive plant-eater?" <-- You're mixing up your causes and effects. Side-facing eyes are not because the animal is a herbivore. Primarily, eyes are side-facing to give 360 degree visibility in order to watch for predators which might eat that animal. Herbivores are, obviously, potential prey, so tend to have this adaptation, but the adaptation is because they are prey, not because they are herbivores. $\endgroup$
    – Makyen
    Jul 17 at 20:26

11 Answers 11

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Your creature evolved within an ecosystem where it was both hunter and prey.They've exclusively hunted smaller prey but there was one or more other carnivores that hunted them as well. They've hunted their own prey by sound. Visual acuity was unimportant. But it did help in avoiding being ambushed.

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    $\begingroup$ Came here to say this. It can be a terrifying predator in it's own right, but seeing it has eyes on the sides could be a foreboding hint of what's yet to come upon the scene. $\endgroup$ Jul 17 at 0:08
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    $\begingroup$ I was thinking about this idea before I posted the pug thing and it occurred to me that a meerkat is what you describe: carnivore but also prey. Their eyes are carnivore standard in front, maybe because birds are their predator. I could not think of a middle trophic animal that had the predator mouth and goat eyes. $\endgroup$
    – Willk
    Jul 17 at 2:41
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    $\begingroup$ Just wanted to say there are also extinct species to choose an example from. Allusauri were ambush predators and it was important for them to approximate distance to their prey while sitting in some thick jurassic bushes. Facts taken from some Russian pop-science article, so take it with a grain of salt. $\endgroup$
    – Xobotun
    Jul 17 at 12:36
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    $\begingroup$ You don't even have to look at pre-history to find an example. Barracuda are a well known species of carnivorous fish who have side-facing eyes and are also prey to larger aquatic carnivores (like sharks). $\endgroup$
    – Zibbobz
    Jul 18 at 17:54
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I think the best way to make this work would to make the animal a scavenger. Carnivorous teeth are best to tear and slice decomposing meat, and the side facing eyes would be used to scan for danger as the creature eats.

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  • $\begingroup$ pure scavengers are almost non-existent, so it is still going ot have to hunt sometime. $\endgroup$
    – John
    Jul 18 at 13:50
  • $\begingroup$ @John yeah, but PRIMARILY scavengers is enough to explain it. $\endgroup$
    – Hobbamok
    Jul 19 at 10:59
  • $\begingroup$ @Hobbamok the closest match on earth would be lions, which have very forward facing eyes. $\endgroup$
    – John
    Jul 19 at 16:44
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Your animal is brachycephalic.

Brachycephaly is a mutation that produces a foreshortened face. Brachycephalic mammals have shortened muzzle or no muzzle. I have heard humans called brachycephalic chimps.

Your animal is a brachycephalic carnivore, very much like a pug dog.

animals

As a visual aid here I have images of a pug dog with eyes very nearly on the sides of its head. This is not because the eyes have moved but the entire skull is squashed flat. Next to it as exemplifying the protoherbivore with eyes on the sides of its head is a noble pygmy goat. On the side and wondering why it is in with these two is a smug wolf, with front facing carnivora standard eyes.

You will see in the comparison of pug and wolf skull that the dentition of both canids is carnivore standard, in so far as there is room in the pug jaw. This pug skull demonstrates a typical pug underbite which your animal might very well have.

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Why would a protowolf evolve into a pug? We know in our world it is because pugs are snorty and friendly but there was artificial breeding involved which your OP precludes.

Why then would a chimp evolve into a brachycephalic human? Chimps have a wicked attack bite but humans struggle to attack with a bite because our noses get in the way. The answer is that other adaptive traits came along with brachycephaly. For your animal, maybe smaller bodies conferred better fitness in lean times when elk prey was scarce but grasshopper prey common? Maybe the arrival of new predators made side facing goatish eyes helpful? Maybe the wicked attack bite meant too many pups killed by getting bit, and so the ability to bite hard was selected against? Maybe snorty awesomeness helps cement social bonds and group fitness?

In any case: pug animals. Picture would be welcome. Remember the underbite please.

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Many dinosaurs had carnivore teeth and side facing eyes.

dinosaur

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    $\begingroup$ many (most?) theropods have forward-facing eyes, to my knowledge including the one you've pictured here (moros intrepidus). a more specific example than "many dinosaurs" would be helpful here i think. $\endgroup$
    – kyeugh
    Jul 18 at 14:49
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While it may be a predator, it could not be the Apex

There are many animals that are predatory, yet they have their own predator(s) that will hunt them down. For your animal, it could have their eyes like that because they have a bigger, scarier animal that is out to hunt them. Depending on how dangerous the animal is, and what environment your species lives in, it needs to see more areas and be aware at all times. The alternative is that the prey it hunts is quick and stealthy, so it needs to be aware and look around to know where its food is.

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You are assuming "sharp" teeth - incisors,shark like teeth, etc - with a predator. However, you are not understanding the reason for the teeth. Teeth evolve to adapt to what it eats. What it eats doesnt have to be prey. A plant can have a fleshy like substance and therefore needs to be torn off, ripped, sliced, etc.

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  • $\begingroup$ a few days late, but I believe this a valid explanation. $\endgroup$
    – Keltari
    Jul 19 at 17:13
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If you improve the sense of smell I would say "because it is a scavenger". It bullies other carnivores away from kills.

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The notion of side-facing eyes for survival amid other predators seems pretty sound. And since you provide carnivorous teeth as a given, then could it obtain prey by some means other than visually hunting? Like say:

  1. By using a web
  2. Listening for movement and spraying poison in a general direction
  3. Luring prey to it
  4. Scavenging, as other have suggested
  5. Observing prey and setting traps or chasing them off cliffs or other semi-intelligent tactics
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Vision is not it primary sense. It might have something like echo location for hunting prey at short to medium distances and only use vision for detection at longer distances.

An electrical field sense might also work.

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It's a whale

enter image description here

Your carnivore has eyes on the side of your head because it's a whale. Toothed whales are carnivores. Baleen whales are carnivores. All whales have eyes on the side of their heads.

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Reasons:

binocular vision helps to locate the distance to the prey animal. Why would not not need this?

Possibly the predator is MUCH faster than the prey. Imagine a giant sloth on the ground. Safe in a tree, but easy prey on the ground.

The predator is also prey, OR there is an escapable but fast moving hazard. Imagine being in a forest where trees fall randomly, but frequently.

The side view eyes are a relic. The animal lives in an environment where vision isn't used for hunting. Think bat sonar.

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