Fossil Record 12(2): 121-131, doi: 10.1002/mmng.200900002
Skeletochronology and isotopic analysis of a captive individual of Alligator mississippiensis Daudin, 1802
expand article infoN. Klein, T. Scheyer§, T. Tütken|
‡ Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Universität Bonn, Nußallee 8, 53115 Bonn, Germany§ Paläontologisches Institut und Museum, Universität Zürich, Karl Schmid-Straße 4, 8006 Zürich, Switzerland| Steinmann Institut für Geologie, Paläontologie und Mineralogie, Universität Bonn, Nussallee 8, 53115 Bonn, Germany
Open Access
In the present study, bone histology and isotope composition (C, N, O) of a femur and three postcranial osteoderms from an approximately 23–25 year-old captive female Alligator mississippiensis Daudin, 1802 were analyzed to infer the recorded life history. The number of visible annual growth marks in the femur cross-section is less than the known age for the individual concerned, this information clearly shows that skeletochronology has certain limits. However, bone histology reflects very well the traceable life history of this individual and its slow growth in early ontogeny. Bone histology on the basis of the osteoderms shows massive remodeling and an only incompletely preserved growth record, reflecting the egg-laying status of this individual. Interestingly, the carbon and especially the nitrogen isotope compositions of the osteoderms differ from those of the femur. This presumably reflects dietary changes and/or differences in resorption and remodeling processes during tissue formation of these bones. The N, C, and O isotope composition of the femur is consistent with the food and water the alligator had ingested during the last years of its life. Thus, contrary to the osteoderms, the femur yields reliable data for the reconstruction of an individual's dietary and environmental history.