Life history data derived from the dental histological analysis of Giraffa camelopardalis: Implications for the palaeohistology of extinct giraffids

A giraffe's teeth can preserve the moment it was born. A distinct birth-associated line remained visible in the enamel of a lower molar, separating growth before and after that event. Other microscopic lines recorded much shorter rhythms, giving researchers a way to reconstruct tooth formation long after it happened.

Carmen Nacarino-Meneses, Juan Marcos Jannello and Anusuya Chinsamy examined four lower molars from three giraffes in South African collections. They cut ten thin sections through teeth with different stages of development and wear, then measured growth markings under a microscope. Comparing the spacing and position of lines let them distinguish daily enamel layers from finer markings formed within a day.

The fine markings indicated roughly eight-hour growth rhythms, while broader enamel lines repeated daily and others about every three days. Treating every visible line as a full day would therefore give the wrong developmental timetable. Growth rates also varied between tooth regions and between first and third molars, so this small sample cannot provide a single universal clock for giraffe development. It does provide a guide for reading the right markings in the right places. That matters for extinct giraffe relatives, whose teeth may preserve evidence of growth when observations of living animals are impossible.