''West of Eden'' is a 1984 science fiction novel by Creator/HarryHarrison, followed by two sequels: ''Winter in Eden'' and ''Return to Eden''.

Set in an AlternateHistory where dinosaurs never went extinct (outside of North America, where modern mammals and eventually humans evolved), the story centers around the conflict between humans and the Yilanè, a race of intelligent amphibious reptiles. The main character, Kerrick, is a human who was raised by Yilanè.

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!!This book series contains examples of:

* [[AlternateHistory Alternate Prehistory]]: The K-T extinction event never occurred; the dinosaurs are still around, and intelligent mosasaurs rule most of the world, with mammals abundant only in North America.
* BadassBoast: The scientist Ambalasei thinks rather highly of herself:
--> "Fat gilded-beetle to be crushed! Decayed worm from the lowest dungpit! Before you stands Ambalasei highest of the high, eistaa[[labelnote:Translation]]Leader of a city.[[/labelnote]] of science, intelligence of the world, possessor of infinite powers. I should sentence you to death for your ill-speaking. I consider that now."
* BizarreAlienBiology: Intelligent mosasaurs that reproduce like [[MisterSeahorse seahorses]]. Their bio-engineered tools are even more bizarre: living dart guns, microscopes that are actually highly modified ''frogs'', squid and icthyosaur vehicles...
* BlueAndOrangeMorality: The Yilanè's BizarreAlienBiology leads to them having a strange moral compass. For example, lying is impossible (and the concept never even occurs to them until [[spoiler: Vaintè learns about it from Kerrick]]), and they are absolutely loyal to their communities to the point of dying upon exile; exiles who ''don't'' seize up and die are completely insane by Yilanè standards.
* [[CallARabbitASmeerp Call A Dinosaur A Smeerp]]: Nearly all the dinosaurs depicted are referred to by their Yilanè names ("epetruk" for ''T. rex'', "nenitesk" for ''Triceratops'' and so on.)
* {{Cavemen}}: Co-existing with dinosaurs, but there's an [[AlternateHistory in-story reason for this]].
* DeathByChildbirth: Male Yilanè will not survive being pregnant more than three times.
* EncyclopediaExposita: Some editions of the book carry a brief index of Yilanè bio-technology, as well as brief sections on Tanu and Paramutan culture.
* FantasticRacism: Humans and Yilanè are not on speaking terms.
* {{Fictionary}}: Yilanè, Tanu, Sasku and Paramutan glossaries are included alongside the aforementioned EncyclopediaExposita.
* GuiltFreeExterminationWar: Explored. The majority of Yilanè just see massacring ustuzou (humans) as pest control, and most humans return the favor. Vaintè at first considers useful ustuzou like Kerrick to be worth keeping around as tools (and later becomes psychotically obsessed with their destruction), but the Daughters of Life recognize ustuzou as sapient beings worthy of life and respect. Kerrick (after rejoining the humans) rejects the position that Yilanè are AlwaysChaoticEvil, and draws a demarcation between Yilanè who are killing humans and Yilanè who humanity can coexist with.
* [[InterspeciesRomance Interspecies Sex]]: "Romance" isn't the right word for it, but we don't have a simple trope for interspecies rape.
* LadyLand: The Yilanè -- females control politics, science, and the military; males are artisans, poets and brood mares.
* LanguageOfTruth: The nature of Yilanè language and thought processes makes them incapable of lying...[[spoiler:until Vaintè discovers the concept after seeing Kerrick do it]].
* LizardFolk: The Yilanè, human-sized bipedal mosasaurs.
* LivingShip: Yilanè sail the seas using genetically modified icthyosaurs with a compartment in their dorsal fin. They also have modified squid as smaller boats.
* LivingWeapon: ...specifically a genetically modified lizard that shoots poisoned darts.
* MisterSeahorse: Yilanè reproduce in a similar manner to, you guessed it, seahorses.
* MyCountryRightOrWrong: Hardwired into Yilanè biology. If a Yilanè is exiled from its city, its body shuts down. [[spoiler: Some of them, however, are loyal to something other than their city, and their shutdown reflex will occur in response to different stimuli. The Yilanè are not quite sure how to cope with this.]]
* MySpeciesDothProtestTooMuch: Enge, and the other Daughters Of Life.
* OrganicTechnology: ''Everything'' used in Yilanè society is a product of genetic engineering. Even the ancient Yilanè began by hunting using ''living crabs'' instead of stone tools, though one Yilanè scientist suggests that early on, the Yilanè did indeed use "artefacts."
* PunctuationShaker: The Yilanè language, although [[JustifiedTrope the various typographical symbols are intended to represent specific sounds]].
* ReallyGetsAround: The Paramutan are as frisky as bonobos.
* ReptilesAreAbhorrent: Although mammals ("[[FantasticSlurs ustuzou]]") are equally abhorrent to the Yilanè.
* SlidingScaleOfAlternateHistoryPlausibility: "Soft" to "completely implausible," depending whether you see the "the meteor missed Earth" premise as an AlienSpaceBats element or not.
* StarfishAliens: The Yilanè are ''somewhat'' humanoid in shape, but quite different in physiology and psychology. The main conflict of the trilogy stems from them and humans being mutually repulsed by their differences.
* StarfishLanguage: A '''complicated''' combination of spoken words, positioning/gestures and color signals, described as so difficult that many Yilané never even get the hang of it.
* StockDinosaurs: Quite a few ([[CallARabbitASmeerp complete with Yilanè names]]), but the Yilanè themselves are mosasaurs, not dinosaurs.
* ThunderboltIron: The knives Kerrick and his father wear are made of "skymetal."
* TranslationConvention: A given, as the English language doesn't actually exist in the setting. The Yilanè's StarfishLanguage is sometimes rendered with odd syntax ("Fish of great size abound. Desire to catch/eat. Will small/soft go with us?"), especially in ''Return to Eden''.

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