I will preface this suggestion with a note that I am AWARE that this suggestion could be achieved through modding. Note, however, that it is something I'd like to see in vanilla, if only for those who do not know how to mod; plus, it would be easier to implement than most suggestions due to only requiring fiddling with the raws. Now for the actual suggestion part.
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In 31.25, DF has a large number of animalmen:pandamen, capybaramen, badgermen, and many more. Most of them are sponsored animals.
If the mere platypus has a giant and an anthropomorphic version, why doesn't the famed carp or the fearful elephant?
This suggestion would merely require a spare few hours tinkering with the raws, and would vastly widen the wildlife to include all sorts of fearful beasts.
I am not suggesting you make
all animals have giant and anthropomorphic versions, just iconic DF critters and a few other, special ones. A by-biome-of-the-original-creature-IIRC list I made, with only the requirements of either being based on an iconic DF creature or sounding cool:
ANY
Giant Ants
Giant Flies
TROPICAL LAND
Desert Scorpion Men
Elephant Men
Gator Men
Giant Crocodiles
Giant Dragonflies (ideally with a fire-breathing caste)
Giant Elephants (if you want to get insane...)
Giant Mandrills
Giant Rhesus Macaques
Giant Slugs
Giant Snails
Giant Tortoises
Giant Vultures
Tortoise Men
Vulture Men
(Also, tortoises, if not already planned.)
TEMPERATE LAND
Giant Groundhogs
Giant Hedgehogs
Giant Hoary Marmots
Giant Badger Men (giant badgers are the elephants of today's Boatmurdered, after all)
Giant Lizards (monitor lizards)
Giant Monitor Lizards
Giant Wolves
Groundhog Men
Hoary Marmot Men
Hedgehogmen
POLAR LAND
Giant Polar Bears
Giant Walruses
Polar Bear Men
Walrus Men
WATER
Carp Men
Giant Carp
Giant Hippos (see above note on giant elephants)
Giant Leech
Giant Seahorses
Giant Sea Lamprey (the new carp? A new supplement to the old carp?)
Giant Turtles (with caste bearing a small world on its back?)
Hippo Men
Lungfish Men (partly because lungfish seem to be everywhere in my games--even in a waterless desert!)
Toad Men
Turtle Men (no ninjas)
Whale Men
GOOD AREAS
Giant Butterflies (okay, butterflies exist in non-good areas, but I think giant ones should be restricted to good areas)
Giant Fluffy Wamblers
Giant Mountain Gnomes
Giant Unicorns
Unicorn Men
EVIL AREAS
Beak Dog Men (?)
Giant Beak Dogs
Giant Dark Gnomes
Giant Phantom Spiders
Knuckle Worm Men
Large/Giant Demon Rats
SAVAGE AREAS
Giant Moghoppers
Sea Serpent Men
UNDERGROUND
Not all anthropomorphic animals need be included in the Underground Animal Civs clique, but it would be nice. Still, if you think they would ruin the ideals of the underground camps, I'm fine with that.
Cave Spider Men
Giant Creepy Crawlers
Draltha Men
Earthworm Men
Elk Bird Men
Fire Snake Men
Giant Bugbats
Giant Cap Hoppers
Giant Cave Blob
Giant Cave Fish
Giant Cave Lobsters
Giant Cave Spider Men (?)
Giant Crundles
Giant Fire Snakes
Giant Gorlaks
Giant Helmet Snakes
Giant Magma Crabs
Giant Plump Helmet Men (Plump Helmet Giants?)
Giant Purring Maggots (Grazers? Maybe...)
Helmet Snake Men
Mole Men
Pond Grabber Men
Purring maggot Men
Worm Men
DOMESTIC
Ideally, these would not be available at embark, but (some) could be found wandering the wilds and (all) could be bought from some caravan or another.
Cat Man
Giant Cat (ideally able to bring in larger animals, say goblins?, from hunting)
Giant Cavy (for humor; maybe for extra humor, it should be bigger than most other creatures, but whatever.)
Giant Dog (Ideally, with some kind of tag resulting in "Giant War Dog" instead of "War Giant Dog. Maybe that would cut down on the number of tags required to mod in a new giant animal?)
Giant Peafowl (?)
Peafowl Men
(If you want to add an idea, just say so.)
Okay, I implied that a few of those would require extra tags, but I'd be fine with war giant dogs (and don't items already have adjective tags that could theoretically be used on creature variations?) and giant cats unable to bring in larger kills than rats and stuff.
EDIT: Found vermin list; added many giant vermin and vermin men.