Comparing Late Pleistocene hyena species with living species by looking at the wear and tear of their teeth

Diet and ecological niches of the Late Pleistocene hyenas Crocuta spelaea and C. ultima ussurica based on a study of tooth microwear

Summarized by Saddie Fortner,  a senior geology major at The University of South Florida. She plans to attend graduate school in volcanology and pursue her PhD afterwards. She plans to work as a professor at a university and continue doing research. Her hobbies include playing video games, painting her nails, and crocheting.              

What was the hypothesis being tested (if no hypothesis, what was the question or point of the paper)? The purpose of this study was to compare the feeding habits two extinct species of hyenas, Crocuta spelaea and C. ultima ussurica, by comparing the scratches and pits on their fossilized teeth, also called microwear. Environmental roles, such as predator and scavenger, were determined. Feeding differences of juveniles and adults were also tested using tooth microwear.

What data were used?:  Tooth specimens of Crocuta spelaea were collected from Crimea and eastern Kazakhstan (Figure 1). Tooth specimens of C. ultima ussurica were collected from eastern Russia. Teeth from the living species of Crocuta were used as a comparison. Bones of hyenas’ prey were collected from the caves.                                                                      

Methods: Features such as small and large pits, scratches, gouges, and puncture pits, also called microwear, were counted. The two extinct species’ teeth were compared to extant species’ teeth to determine their feeding habits and environmental roles. This was done by comparing the amount of microwear on the extant hyena’s teeth to the extinct hyena’s teeth. Since the feeding habits and environmental roles of living hyenas is known, the fossil teeth that are similar to the extant hyena’s teeth likely would have had similar feeding habits and environmental roles. Bones of the hyenas’ prey were also collected, as they contained teeth marks from gnawing juveniles and evidence of ingestion by the hyenas.

Results: The microwear patterns on the teeth of Crocuta spelaea and C. ultima ussurica suggest that the extinct hyena species had a similar diet and role in the environment to the extant spotted hyenas. The teeth from Crimea and Russia contained a high number of gouges, small pits, and coarse scratches, which is similar to the extant spotted hyenas who are known for cracking the bones of their prey in extreme ways. The number of scratches found on the teeth from Russia exceed those from the extant spotted hyena and more closely resemble those of a present-day lion. This is supported by the long length of the upper molar found in Russia. The two extinct species do not have similar microwear to the two extant hyenas, striped hyenas and brown hyenas. This is because the striped hyenas live on a diet of meat and bone, but less bone than the spotted hyena. The brown hyena ingests not only meat and bone, but also fruit. The adult and juvenile microwear patterns of all the collected fossil teeth had similar quantities of pits and scratches. The only difference was the absence of cross scratches on the juvenile teeth. This could be due to the greater proportion of meat to bone that juveniles would have consumed compared to adults. Conclusive results could not be drawn due to the small quantity of juvenile fossil samples. The specimens from eastern Kazakhstan were not included in this assessment due to the small number of specimens.

There are two close-up pictures of fossilized teeth. Each picture shows an area 2 mm long and 1.8 mm high. The top picture, A, is of a Crocuta spelaea tooth. The tooth has many coarse scratches of different lengths. The coarse scratches are going diagonally from the top right to the bottom left. There are two gouges. One is at the top left and the other is at the bottom right of the picture. Both gouges are about 1 mm in length. The gouges are in the same direction as the coarse scratches, but are steeper. The bottom picture, B, is of a Crocuta ussurica tooth. The tooth has many coarse scratches. The scratches have lengths ranging from .1 mm to 1.8 mm and no shared orientation. This tooth contains many small pits. The pits are sub-circular and have diameters ranging from .1 mm to .05 mm.
Figure 1: Close-up image of a tooth from (A) Crocuta spelaea and (B) Crocuta ussurica. The Crocuta spelaea tooth shows many scratches and some gouges. The Crocuta ussurica tooth shows many coarse scratches and small pits.

Why is this study important?:  The study shows how we can recreate the behavior of extinct hyenas by looking at something as simple as teeth. By comparing the tooth wear of extinct hyenas to extant hyenas, whose diet and behavior we know, we can determine what the extinct hyenas ate, how they ate, and how they fit into the environment in which they lived. The study also found bones of the Late Pleistocene hyenas’ prey in the caves where the teeth were found. This provides further information about the type of wildlife that was found in their environments, which could be used to determine many other species’ historical range. A species’ historical range is the area in which a species used to live. An example of this would be the lion. The lion’s historical range was Africa, southern Europe, and western Asia. The lion’s current range is only a small part of Africa.

Broader Implications beyond this study: Tooth microwear is not limited to hyenas. The study can be applied to many other carnivorous species such as the famous saber-toothed cats, also known as Smilodon, or the lesser-known American cheetah that lived during the Pleistocene. It might be interesting to see how the American cheetah’s and the Modern cougar’s tooth microwear differ from each other, considering the two species are closely related. Furthermore, this study could be adapted to herbivores to study their diets and the vegetation that occurred during their time.

Citation: Rivals, F., Baryshnikov, G., Prilepskaya, N., & Belyaev, R. (2022). Diet and ecological niches of the Late Pleistocene hyenas Crocuta spelaea and C. ultima ussurica based on a study of tooth microwear. ScienceDirect. 601, p.111125.