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Earth Analogues

Eptenyctans have no direct analogue on Earth. Functionally, of course, they are similar to bats, since they are flying nocturnal mammals. But the eptenyctans evolved much sooner in mammalian history on Sedes than did bats on Earth.

The earlier appearance of flying mammals results in two primary differences. First, the eptenyctans evolved flight while mammals were still mostly egg-layers (originally all mammals were egg-layers; only later did various groups evolve such arcane alternatives as we see in the major modern mammal subclasses: the Marsupialia and Placentalia).

For flyers, it is a great boon to be egg-layers. Of the major groups of modern vertebrates (fish, amphibians, "reptiles", birds, mammals), all of those groups except one include a mix of both egg-laying and live-bearing species. The only group that doesn't include both strategies is the birds, due to the advantages for a flyer to limit as much as possible the time they must carry the weight of their developing young by depositing fetal young as eggs in nests.

Earthly bats are not able to do this, since they evolved only after placental mammals had firmly fixed their reproductive traits; and this has landed them with several difficulties they have need to adapt to. Eptenyctans side step many of these by retaining their egg-laying strategy.

The second effect of eptenyctans evolving earlier is that they appeared closer after the first birds on Sedes, and have been somewhat more succesful at competing for niches that, on Earth, the well-entrenched birds were able to mostly exclude them from. On the Hajasith, for example, there are no owl-type avian nocturnal predators. Instead there are large eptenyctan predators.


The scientific name of the order was coined from epten "I fly", nyctos "night". Since the eptenyctans are significantly divergent from Earthly bats, I have not used the order name for Earth bats (Chiroptera, "hand-wing"), even though it would be as accurate a description for the eptenyctans (and vice versa).

I sometimes refer to the eptenyctans as "pseudo-bats", since the word "bat" accurately conveys flying, nocturnal mammals, and the eptenyctans replace (and exclude the development of) placental bats on the Hajasith. But the Eptenyctans diverge significantly enough from Earth bats to warrant "pseudo".


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