All right, there is probably some obvious forum thread, wiki page or bug report I've overlooked, and you're all going to think I'm stupid for even posting about this, but for my own part, I honestly can't think how to explain this thing.
Today, I've been beginning to experiment with world generation parameters to get more interesting worlds. So I poked and poked at it until I got something that actually generated a playable region, decided it looked okay and gave it a shot. Imagine my surprise when I found all my dwarves replaced by bronze colossi and clad in "unknown frozen creature substance" clothing!
Wondering if I'd perhaps forgotten to change something back after messing with the raws a bit yesterday, I created an entirely fresh install of DF 0.31.03 and ran the worldgen anew using the same parameters and random seeds. No change.
For what it's worth, these are my worldgen parameters, as dumped by the "export image" option:
Created in DF v0.31.03.
[WORLD_GEN]
[TITLE:CUSTOM]
[SEED:1634510506]
[HISTORY_SEED:1720023014]
[NAME_SEED:889773162]
[CREATURE_SEED:3791154686]
[DIM:65:65]
[EMBARK_POINTS:1274]
[END_YEAR:1050]
[BEAST_END_YEAR:100:80]
[REVEAL_ALL_HISTORY:1]
[CULL_HISTORICAL_FIGURES:0]
[ELEVATION:1:400:202:202]
[RAINFALL:0:100:101:101]
[TEMPERATURE:25:75:101:101]
[DRAINAGE:0:100:101:101]
[VOLCANISM:0:100:101:101]
[SAVAGERY:0:100:101:101]
[ELEVATION_FREQUENCY:1:1:1:1:1:1]
[RAIN_FREQUENCY:1:1:1:1:1:1]
[DRAINAGE_FREQUENCY:1:1:1:1:1:1]
[TEMPERATURE_FREQUENCY:1:1:1:1:1:1]
[SAVAGERY_FREQUENCY:1:1:1:1:1:1]
[VOLCANISM_FREQUENCY:1:1:1:1:1:1]
[TITAN_NUMBER:3]
[TITAN_ATTACK_TRIGGER:80:0:100000]
[DEMON_NUMBER:22]
[GOOD_SQ_COUNTS:6:63:127]
[EVIL_SQ_COUNTS:6:63:127]
[PEAK_NUMBER_MIN:3]
[PARTIAL_OCEAN_EDGE_MIN:1]
[COMPLETE_OCEAN_EDGE_MIN:0]
[VOLCANO_MIN:1]
[REGION_COUNTS:SWAMP:66:0:0]
[REGION_COUNTS:DESERT:66:0:0]
[REGION_COUNTS:FOREST:528:0:0]
[REGION_COUNTS:MOUNTAINS:528:0:0]
[REGION_COUNTS:OCEAN:528:0:0]
[REGION_COUNTS:GLACIER:0:0:0]
[REGION_COUNTS:TUNDRA:0:0:0]
[REGION_COUNTS:GRASSLAND:528:0:0]
[REGION_COUNTS:HILLS:528:0:0]
[EROSION_CYCLE_COUNT:250]
[RIVER_MINS:40:25]
[PERIODICALLY_ERODE_EXTREMES:1]
[OROGRAPHIC_PRECIPITATION:1]
[SUBREGION_MAX:2750]
[CAVERN_LAYER_COUNT:3]
[CAVERN_LAYER_OPENNESS_MIN:0]
[CAVERN_LAYER_OPENNESS_MAX:100]
[CAVERN_LAYER_PASSAGE_DENSITY_MIN:0]
[CAVERN_LAYER_PASSAGE_DENSITY_MAX:100]
[CAVERN_LAYER_WATER_MIN:0]
[CAVERN_LAYER_WATER_MAX:100]
[HAVE_BOTTOM_LAYER_1:1]
[HAVE_BOTTOM_LAYER_2:1]
[LEVELS_ABOVE_GROUND:15]
[LEVELS_ABOVE_LAYER_1:5]
[LEVELS_ABOVE_LAYER_2:1]
[LEVELS_ABOVE_LAYER_3:1]
[LEVELS_ABOVE_LAYER_4:1]
[LEVELS_ABOVE_LAYER_5:2]
[LEVELS_AT_BOTTOM:1]
[CAVE_MIN_SIZE:5]
[CAVE_MIN_SIZE:5]
[CAVE_MAX_SIZE:25]
[MOUNTAIN_CAVE_MIN:6]
[NON_MOUNTAIN_CAVE_MIN:12]
[ALL_CAVES_VISIBLE:0]
[SHOW_EMBARK_TUNNEL:2]
[TOTAL_CIV_NUMBER:10]
[TOTAL_CIV_POPULATION:20000]
[PLAYABLE_CIVILIZATION_REQUIRED:1]
[ELEVATION_RANGES:528:1056:528]
[RAIN_RANGES:264:528:264]
[DRAINAGE_RANGES:264:528:264]
[SAVAGERY_RANGES:264:528:264]
[VOLCANISM_RANGES:264:528:264]
Can someone please tell me what on earth I broke?