Possible Clues:

• Extinct elephant-like mammal
• Elephant ancestor
• Elephant's ancestor
• Tusked animal
• Mother is to put on something so big and out-of-date?
• Tusked beast's mum stood on missing first egg
• Extinct animal that resembled an elephant
• Extinct tusked mammal
• Mammoth's older relative
• Extinct beast old professor found at the pole