Ptolus: the Spire Below
Creatures with natural attacks and attacks made with weapons can use both as part of a full attack action. Such creatures attack with their weapons normally but treat all of their available natural attacks as secondary attacks during that attack, regardless of the attack’s original type. Secondary attacks are made using the creature’s base attack bonus -5 and add only 1/2 the creature’s Strength bonus on damage rolls. Characters with natural attacks may select Monster feats to improve their natural attacks, pending GM approval.
The Hoof attack of a centaur or similarly sized animal is 1d6, and the type is Bludgeoning.
The bite attack of a Tengu or other similarly-sized creature is 1d3 Piercing.