Bile salts of snakes. The bile salt variation of snakes is overlaid on a tree that represents a summary of current knowledge of snake phylogeny based on molecular data. Major bile salts are those constituting more than 50% of total biliary bile salts. Minor bile salts account for less than 50% but more than 10% of total bile salts. Abbreviations: CA, cholic acid; 23R-OH, 23R-hydroxylated C24 bile acids (mainly 23R-hydroxylated cholic acid); Δ22, C24 bile acids with double bond at C22-23; C23, C23 bile acids; pythoCA, pythocholic acid.