Fossil evidence of evolutionary convergence in juvenile dental morphology and upper canine replacement in sabertooth carnivores

• Published in: Ecology and evolution 2019-11, Vol.9 (22), p.12649-12657
• Main Author: Wysocki, Matthew Aleksander
• Format: Article
• Language: English
• Subjects: Biomedical materials; Canine teeth; Carnivores; Concavity; Convergence; dental morphology; Evolution; Growth patterns; mammals; Mastication; Morphology; Museums; Natural history; Ontogeny; Original Research; Paleontology; Scholarships & fellowships; Specialization; Teeth; tooth development
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.5732

The convergent suite of morphological traits characterizing the mammalian sabertooth ecomorphology is well documented, including modifications of the dental and osteological portions of the masticatory apparatus from a less‐specialized carnivore condition. Equally important is how those specialized adult morphologies developed through ontogeny because previous studies have shown that growing such specialized craniodental traits may require evolutionary modification of growth patterns and tooth replacement mechanisms. Despite the understanding of convergent morphological specialization in adult sabertooth carnivores, the possibility of a convergent ontogenetic trajectory toward those adult morphologies has not been rigorously examined. The present study examines numerous previously undescribed juvenile nimravid specimens. The results provide insights about nimravid ontogeny and show, for the first time, that the nimravid sabertooth lineage included species in which the permanent upper canine erupted within a lingual concavity of the deciduous upper canine until it reached comparable crown height beyond the alveolar border. Furthermore, this investigation assesses the juvenile morphology and upper canine replacement of felid and barbourofelid sabertooth taxa. The results provide evidence of convergence in deciduous upper canine morphology of three sabertooth carnivore lineages (i.e., nimravid, felid, and barbourofelid), as well as preliminary evidence of convergence in the upper canine replacement process. It might be beneficial for studies of extreme morphological specialization to simultaneously consider convergence in adult morphologies and how morphologies change through ontogeny. The convergent suite of morphological traits characterizing the mammalian sabertooth ecomorphology is well documented, including modifications of the dental and osteological portions of the masticatory apparatus. Equally important is how those specialized adult morphologies developed through ontogeny. All in all, the results of this investigation provide evidence that three sabertooth carnivore lineages (i.e., nimravid, felid, and barbourofelid) converged in both their deciduous upper canine morphology and upper canine replacement process, which suggests that studies of extreme morphological specialization should simultaneously consider convergence in adult morphologies and how morphology changes through ontogeny.