Oldest Alligator in SE USA: Tables

TABLE 1. Measurements of the premaxilla UF 422816 from the Brooksville 2 fossil site. All measurements given in mm. Note: Measurements of the 3rd premaxillary alveolus are not provided here because it is incomplete.

TABLE 2. Length measurements of the premaxillary-maxillary suture in Alligator. When possible, these were measured on both the left (L) and right (R) sides. In these cases, the value is an average of those two measurements. All A. mississippiensis specimens were from wild populations. Institutional abbreviations: ETMNH-Z, East Tennessee State University Museum of Natural History - Zoology Collection; UF, Vertebrate Paleontology Collection at the University of Florida, Florida Museum of Natural History.

TABLE 3. Dorsal skull lengths used as a proxy for body size in basal Alligator and its ancestors. Alligator mississippiensis with locations specified are from wild populations; specimens with “No Data” may be from either wild or captive populations. ETMNH-Z 10937 and 17916 are known captive specimens. Data are plotted in Figure 7. Institutional Abbreviations: AMNH, American Museum of Natural History, New York, New York, USA; CM, Carnegie Museum of Natural History, Pittsburg, Pennsylvania, USA; ETMNH-Z, East Tennessee State University Museum of Natural History - Zoology Collection, Johnson City, Tennessee, USA; FMNH, Field Museum of Natural History, Chicago, Illinois, USA; MCZ, Museum of Comparative Zoology, Vertebrate Paleontology Collection, Harvard University, Cambridge, Massachusetts, USA; SDSM, South Dakota School of Mines Museum of Natural History, Rapid City, South Dakota, USA; SMM P, Science Museum of Minnesota Paleontology Collection, Saint Paul, Minnesota, USA; UF, Vertebrate Paleontology Collection at the University of Florida, Florida Museum of Natural History, Gainesville, Florida, USA; USNM; United States National Museum of Natural History, Vertebrate Paleontology Collection, Washington, D.C., USA; YPM-PU, Yale Peabody Museum and Princeton University Vertebrate Paleontology Collection, New Haven, Connecticut, USA.

¹Estimated from Mook (1961; figure 1) using the preserved craniomandibular joint to approximate distal end of skull.
²Determined from Plate 11, figure 3 of Gilmore, 1946.

TABLE 4. Statistical support for linear regressions of different premaxillary measurements against dorsal skull length for study set of extant Alligator mississippiensis specimens (n = 22; see Table 2). R² values are calculated for a ‘best fit’ line. Due to its higher congruence with the data, we selected the premaxillary-maxillary suture length as the best proxy for estimating dorsal skull length.