The Scars of a Mastodon’s Tusk and the Story it Reveals About the Mastodon’s Bachelor Experience

Male Mastodon Landscape Use Changed with Maturation (late Pleistocene, North America)

Joshua H. Miller, Daniel C. Fisher, Brooke E. Crowley, Ross Secord, and Bledar A. Konomi

Summarized by Makayla Palm 

What data were used? The tusks from a single male mastodon specimen (the “Buesching” mastodon, housed in the Indiana State Museum) that died in its early thirties were analyzed in two stages of its life (teenage and adult) in order to understand how, as a bachelor, it moved away from its herd and interacted with other adult mastodons in what was likely a breeding ground. The skull and tusks of this particular specimen have scratches, dents and markings likely caused from fighting with other males over potential female mates. These marks inspired researchers to focus on mating behavior; they hypothesized that the place where the mastodon fossils were found was the same location as its summer breeding ground. Scientists also examined modern-day relatives like elephants, which added insight into the following data: isotope changes in both oxygen and strontium and the growth “rings” of the tusks during teenage and adult years, which shed light on how the mastodon might have moved seasonally. 

Methods: In order to test the hypothesis of the mastodon’s seasonal moving in his later years, scientists examined and compared changes in tusk growth throughout its life. The exterior damage on the tusks was observed and recorded to factor into results. The mastodon tusks grew each year by depositing a ring of dentin, which is dense tissue that is bony, similar to what makes up teeth. By looking at the differences in the rings, scientists can determine changes in lifestyle. In particular, to learn about where the mastodon traveled, two different isotopes were measured: one to determine seasonal temperature changes (an oxygen isotope) and the other for change in environment and age (a strontium isotope).

Results: The visible damage observed on the mastodon’s skull is consistent with a hypothesis scientists proposed of males fighting for territory and mates. This happened in seasonal periods of musth, an annual event where male mastodons experienced extra fighting based on increased aggression while on the search for a mate, leading to increased clashing tusks in the height of mating season. The dentin growth deposits show evidence of low nutrition value in the same growth years the male would be expected to separate from the herd. There was also a noticed abundance of nutrients a couple of years later, inferring it had become successful on its own as an adult. Oxygen and strontium isotopic changes in the tusk show that the mastodon traveled to a warmer location around the same time each year; the two isotope ratios indicate a pattern of more frequent visits to its summer ‘bachelor pad’ (or breeding ground) and as the mastodon got older, it was able to travel further from its typical location. 

Two graphs represent the frequency in which the mastodon visited his breeding grounds. The first graph (on the left) represents his teenage years, and the second graph (on the right) represents his adult years. The adolescent years show no interaction at the fossil location site (where the mastodon bred and was later excavated), but consistent travel far away from the breeding ground. The adult graph shows consistent interaction at the breeding site, indicated with a red horizontal bar above the “near fossil location” label. The adult graph indicates the same consistent travel away from the breeding grounds as the adolescent graph, implying the addition of the breeding ground travel was an addition he found as he sexually matured.
The figure represents the changes in the oxygen isotope that indicate warmer temperatures. The warmer temperatures are inferred to be the mating grounds for this particular mastodon. This figure shows no interaction at this site in its adolescent years, but consistent interaction there as an adult. There is a consistent pattern where it left the breeding grounds in both teenage and adult years. The fossil location is where the mastodon was excavated.

Why is this study important? A male mastodon perished after fighting to the death for a mate. Its tusks were analyzed for growth patterns and changes in trace isotopes to better understand where the mastodon went, its pattern of seasonal travel, and its behavior throughout its lifetime.

The big picture: This story sheds light on the behavior of mastodons as they matured over time, as well as male behavior displayed during mating season. The quality of the preserved tusks allowed researchers to learn about this mastodon’s teenage and adult life and compare the differences over time. 

Citation: Miller, Joshua H.,  Fisher, Daniel C., Crowley, Brooke E., Secord, Ross and Konomi, Bledar A.  “Male Mastodon Landscape Use Changed with Maturation (Late Pleistocene, North America).” Proceedings of the National Academy of Sciences, vol. 119, no. 25, 2022,

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