Related Clues:

• One pursues river horse — certainly not one of the big five
• One-horned beast
• Brass with two horns upfront?
• Zoo heavyweight, informally
• Horned African beast
• Endangered African
• Large African animal, for short
• One of the largest megafauna
• Big beast with a horn
• Richardson releases cards from endangered type
• ''Just So Stories'' subject
• Penultimate set from Aretha Franklin — kept tape for wallower
• The Metropolitan Museum's mascot William, for one
• Metropolitan Museum mascot William is a blue one
• Animal is almost river duck