Why only mammals have tusks?

Image courtesy of Muhammad Mahdi Karim, GFDL 1.2 

Joel Kontinen

Elephants have with tusks, but some other animals have them also, for instance warthogs, hippopotamuses and Arctic-dwelling walruses with tusks,

Researchers have found our that only mammals have them. They say that only mammals, who lived at a later stage of evolution,  have them.

In a new paper published October 27 in the Proceedings of the Royal Society B researchers trace the first tusks back to ancient mammal relatives that lived before the dinosaurs. No fish, reptiles, or birds with have tusks.

The simple reason is that God made them. Their trunk is intelligenty made, 

Source:

Harvard University. 2021. Fossil dental exams reveal how tusks first evolved and why they are unique only to mammals Harvard University. 27 October.