Dental eruption in afrotherian mammals
- PDF / 633,990 Bytes
- 11 Pages / 610 x 792 pts Page_size
- 99 Downloads / 184 Views
BioMed Central
Open Access
Research article
Dental eruption in afrotherian mammals Robert J Asher*1 and Thomas Lehmann2 Address: 1Department of Zoology, University of Cambridge, Downing St., Cambridge CB2 3EJ, UK and 2Museum für Naturkunde, Humboldt Universität zu Berlin, Abteilung Forschung, Invalidenstr. 43 10115 Berlin, Germany Email: Robert J Asher* - [email protected]; Thomas Lehmann - [email protected] * Corresponding author
Published: 18 March 2008 BMC Biology 2008, 6:14
doi:10.1186/1741-7007-6-14
Received: 2 January 2008 Accepted: 18 March 2008
This article is available from: http://www.biomedcentral.com/1741-7007/6/14 © 2008 Asher and Lehmann; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract Background: Afrotheria comprises a newly recognized clade of mammals with strong molecular evidence for its monophyly. In contrast, morphological data uniting its diverse constituents, including elephants, sea cows, hyraxes, aardvarks, sengis, tenrecs and golden moles, have been difficult to identify. Here, we suggest relatively late eruption of the permanent dentition as a shared characteristic of afrotherian mammals. This characteristic and other features (such as vertebral anomalies and testicondy) recall the phenotype of a human genetic pathology (cleidocranial dysplasia), correlations with which have not been explored previously in the context of character evolution within the recently established phylogeny of living mammalian clades. Results: Although data on the absolute timing of eruption in sengis, golden moles and tenrecs are still unknown, craniometric comparisons for ontogenetic series of these taxa show that considerable skull growth takes place prior to the complete eruption of the permanent cheek teeth. Specimens showing less than half (sengis, golden moles) or two-thirds (tenrecs, hyraxes) of their permanent cheek teeth reach or exceed the median jaw length of conspecifics with a complete dentition. With few exceptions, afrotherians are closer to median adult jaw length with fewer erupted, permanent cheek teeth than comparable stages of non-afrotherians. Manatees (but not dugongs), elephants and hyraxes with known age data show eruption of permanent teeth late in ontogeny relative to other mammals. While the occurrence of delayed eruption, vertebral anomalies and other potential afrotherian synapomorphies resemble some symptoms of a human genetic pathology, these characteristics do not appear to covary significantly among mammalian clades. Conclusion: Morphological characteristics shared by such physically disparate animals such as elephants and golden moles are not easy to recognize, but are now known to include late eruption of permanent teeth, in addition to vertebral anomalies, testicondy and other features. Aware
Data Loading...
