So, as I vaguely remember it. It was set in the distant future were a dictator rules the Earth. By this point carbon dioxide was so high most life outside of humans was extinct. So the dictator built a special zoo with the right atmospheric conditions. Then he sent crews back in time to retrieve things. But, unbeknownst to them they were sliding sideways through the dimensions. So when they went to get a horse they got a unicorn instead, a real drake instead of a komodo dragon, etc. The unicorn gored one of them really bad. The drake burned another pretty bad.

Somewhere along the way they speculate on what happened to the rocs of myth and figured it was the ostrich and they re-enabled the disabled DNA pairs and suddenly had a roc that broke free, escaped, and quickly suffocated to death in the high CO2 atmosphere.

I remember them all nearly dying because someone sent to get the first automobile built by Henry Ford screwed up and accidentally destroyed the original. And that changed time so that Ford never started an auto industry so the air never got polluted, etc., and everyone in the future, accustomed to the high CO2, was dying without it.

Does anyone know the author and book/story names?

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    This is a very good description, do you also remember how old "older" is here i.e. when did you read this and approximately how old was it at the time? Can you edit this in?
    – TheLethalCarrot
    Oct 24, 2018 at 10:04

2 Answers 2


This is The Flight of the Horse by Larry Niven. It's a fixup novel built from a compilation of stories about the hapless Hanville Svetz who is tasked with retrieving the things you mention.

The collection of the unicorn is the first story. During the mission Svetz collapses because his metabolism is adapted to the high carbon dioxide levels of modern Earth and when he goes to the parallel Earth with low CO2 he forgets to breathe:

The air of the cage was the air of Svetz's own time, and was nearly four percent carbon dioxide. The air of 750 Ante Atomic held barely a tenth of that. Man was a rare animal here and now. He had breathed little air, he had destroyed few forests, he had burnt scant fuel since the dawn of time.

But industrial civilization meant combustion. Combustion meant carbon dioxide thickening in the atmosphere many times faster than the green plants could turn it back to oxygen. Svetz was at the far end of two thousand years of adaptation to air rich in CO2.

It takes a concentration of carbon dioxide to trigger the autonomic nerves in the lymph glands in a man's left armpit. Svetz had fainted because he wasn't breathing.

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    And if so, it will be a duplicate of Trying to remember a story about a guy that goes back in time and brings mythical creatures to the future although I'd vouch in favor making the present question the dupe-target.
    – Jenayah
    Oct 24, 2018 at 10:57
  • Rats, I didn't think to check for a duplicate! Oh well, as you say this is the more complete question anyway. Oct 24, 2018 at 10:58
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    @JohnRennie Well we don't close id questions as dupes until the OP has "accepted" an answer so it doesn't matter either way.
    – TheLethalCarrot
    Oct 24, 2018 at 11:09
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    As I understand it, the point of the stories is this: time travel is impossible, therefore a time travel story is fantasy, therefore Svetz found fantasy animals. Oct 25, 2018 at 1:49
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    Yeap! Looks like it. Also looks like I'll have to get a dead tree version, no ebook version exists as far as I can tell. :D Thanks all!
    – BelGarion
    Oct 25, 2018 at 18:10

The Flight of the Horse by Larry Niven matches all the points you list

The book contains seven stories about Hanville Svetz's missions to retrieve objects from the past. There is also a novella set in the same background, Rainbow Mars.

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    This answer has been given ~12 mins before you wrote this one... do you have anything new to add? For example, more description of how this matches.
    – TheLethalCarrot
    Oct 24, 2018 at 11:10
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    @TheLethalCarrot: You're complaining about 12 whole minutes?
    – jamesqf
    Oct 24, 2018 at 16:32
  • 3
    The perils of the doorbell ringing while typing an answer - the answer had not been posted when I started typing :/ Oct 24, 2018 at 19:25

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