Nipples are evolutionarily older than teeth. Nipples and mammary glands are characteristic features of all mammals, and the evolution of mammals dates back to the Mesozoic era, over 200 million years ago.

Teeth, on the other hand, evolved later in the ancestors of modern mammals. The earliest known teeth in the fossil record are found in fish, dating back around 400 million years ago, but these are not the direct ancestors of mammalian teeth. The teeth that we associate with modern mammals have evolved through a separate evolutionary line that diverged from the toothless ancestors of mammals. Early mammal-like creatures called synapsids had different tooth structures that would eventually lead to the varied and complex dental arrangements seen in contemporary mammals.

So, while nipples (as a feature of mammals) appeared after teeth evolved in the broad scope of vertebrate evolution, the specific type of teeth that we see in modern mammals came after the development of features that define mammals, including nipples and mammary glands.

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