in the story i'm writing there is an island of mostly Monotremes which have diversified into a variety of ecological niches from giant platypus's to megafauna larger than the largest Placental Mammal to even Griffins which rule over the mountainous regions. Now some characteristics of these Griffins include:

  • lay eggs (of course)
  • are Tetrapods instead of Hexapods like classical Griffons
  • 15% smaller than a mountain lion
  • are quadrupeds (optional)
  • males will collect shiny objects to there nests to attract mates
  • are carnivores
  • have an eagle like head
  • have lion like hindlimbs and tail
  • have bird like wings
  • can glide but can't fly (or at least for very long)
  • are solitary
  • are covered in fur
  • have fur which resembles feathers on their wings and head (optional)
  • lay eggs which are gold in coloration (optional)

given this how realistic are they and what evolutionary pressures might lead to them?

NOTE: magic does not exist in my story

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    $\begingroup$ This is probably a duplicate, though I am not going to go looking just now. To wit: I don't see why being monotremes would be an issue; either you can satisfy the rest of the criteria, and laying eggs is not a problem, or you can't, and laying eggs doesn't matter. $\endgroup$ – Matthew Mar 5 '20 at 21:03
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    $\begingroup$ What are your criteria for "realistic"? $\endgroup$ – Upper_Case Mar 5 '20 at 21:09
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    $\begingroup$ What's "feather like fur"? If they're a tetrapod with wings does that mean they only have hind legs or forelegs? Because wings count as limbs. Classical griffons are hexapods. $\endgroup$ – kleer001 Mar 5 '20 at 21:27
  • $\begingroup$ @Upper_Case that it is believable from an evolutionary standpoint $\endgroup$ – icewar1908 Mar 5 '20 at 21:27
  • $\begingroup$ @kleer001 "feather like fur" in this case means fur which resembles feathers and yes they only have hindlimbs with the forelimbs being the wings. $\endgroup$ – icewar1908 Mar 5 '20 at 21:30

Be Flexible With What Counts as Wings

Your griffons are four legged as the common depictions show, but rather than wings separate from the limbs instead there is a gliding membrane like that of a sugar glider or flying squirrel.

A lion’s body plan is simply unsuited for flight, but there are multiple mammalian quadrupeds that glide.

Gliding has evolved independently in both marsupials and placentals, so it’s not unreasonable for it to appear in monotremes.

The griffins could live in forests and glide from tree to tree to chase prey.


Having fur look like feathers isn’t difficult, as long as you’re flexible on what kind of feathers it’s supposed to look like. Ratties have feathers that look rather hair like from a distance. The griffons could have very downy fur.

Beak and Eggs

Monotremes have these features.

Lion Features

Convergent evolution, consider how similar the thylacine was to canines in its body plan

Egg coloration, collecting objects, carnivorous diet, and some of the other cosmetic features are very straightforward.


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