Repository logo

Dental eruption and growth in Hyracoidea (Mammalia, Afrotheria)

Accepted version



Change log


Asher, RJ 
Gunnell, GF 
Seiffert, ER 
Pattinson, D 
Tabuce, R 


We investigated dental homologies, development, and growth in living and fossil hyracoids, and tested if hyracoids and other mammals show correlations between eruption patterns, gestation time, and age at maturity. Unlike living species, fossil hyracoids simultaneously possess replaced P1 and canine teeth. Fossil species also have shorter crowns, an upper and lower I3 locus, an upper I2, and a hypoconulid on m3. Prenatal specimens of the living Procavia capensis and Heterohyrax brucei show up to three tooth buds posterior to upper dI1 and anterior to the seven upper cheek teeth that consistently erupt; these include an anterior premolar but not a canine. Most lower cheek teeth finish eruption during growth in hyracoids, not after growth as in most other afrotherians. All hyracoids show the m1 at (lower) or near (upper) the beginning of eruption of permanent teeth; M3/m3 is the last permanent tooth to erupt. The living P. capensis erupts most lower antemolar loci before m2. In contrast, fossil hyraxes erupt lower antemolars after m2. While the early eruption of antemolars correlates with increased gestation time and age at maturity in primates and Tupaia (i.e., "Schultz's Rule"), and while modern hyraxes resemble some anthropoid primates in exhibiting long gestation and eruption of antemolars at or before molars, eruption patterns do not significantly co-vary with either life history parameter among afrotherians sampled so far. However, we do observe a shift in eruption timing and crown height in Procavia relative to fossil hyracoids, mirroring observations recently made for other ungulate-grade mammals.



37 Earth Sciences, 3705 Geology, Dental/Oral and Craniofacial Disease

Journal Title

Journal of Vertebrate Paleontology

Conference Name

Journal ISSN


Volume Title



Informa UK Limited
Collection of Fayum hyracoids has been funded by U.S. National Science Foundation grants to E. L. Simons (BCS-0114856), to ELS and E. R. Seiffert (BCS- 0416164), to ERS (BCS-0819186), and to ERS, J. G. Fleagle, G. F. Gunnell, and D. M. Boyer (BCS-1231288). Fieldwork was undertaken in collaboration with the Egyptian Mineral Resources Authority and the Egyptian Geological Museum, and was managed by P. Chatrath. RJA, LH, and DP acknowledge support from the Leverhulme Trust and the Department of Zoology, University of Cambridge. We thank C. Riddle and V. Yarborough for access to fossils and fossil preparation, and C. Soubiran for help with segmentation of extant hyrax CT scans. Some CTscan data presented in this work were produced thanks to the imaging facilities of the MRI Platform and of the LabEx CeMEB (Montpellier).