According to Official Guinness Records,
The largest mouth of all land animals belongs to the hippopotamus (Hippopotamus amphibius) of Africa which can open its jaws to almost 180°. In a fully grown male hippo, this equates to an average gape of 1.2 m (4 ft).Although they are herbivores, they have canine teeth that typically measure 71 cm (28 in) and contiually grow. The largest canine ever recorded for a hippo is 122 cm (48 in). The bowhead whale (Balaena mysticetus) has the record for the largest mouth of all animals.
For a complete list of Unknown date records, please visit Unknown date Guinness Records in Kenya.