before vowels pale- word-forming element used in scientific combinations (mostly since c. 1870) meaning "ancient, early, prehistoric, primitive, fossil," from Latinized form of Greek palaios "old, ancient," from palai "long ago, far back" (from PIE root *kwel- (2) "far" in space or time).

before vowels xanth-, word-forming element meaning "yellow," from Greek xanthos "yellow" of various shades; used especially of hair and horses, of unknown origin. Used in scientific words; such as xanthein (1857) "soluble yellow coloring matter in flowers," xanthophyll (1838) "yellow coloring matter in autumn leaves." Also Huxley's Xanthochroi (1867) "blond, light-skinned races of Europe" (with ōkhros "pale").