Manthi et al.—Giant Pleistocene lion from East Africa
skull has been crushed transversely such that the right maxilla is angled medially (from dorsal to ventral). The P3 has lost enamel on the mesiolingual edge and is
damaged distally and distolingually. It is a robust tooth lacking a mesial accessory cusp. The main cusp is tall and slightly worn. The distal accessory cusp is prominent, set free from the main cusp, and followed distally by a cusplet on the distal cingulum. Enough remains of the tooth to obtain an accurate measure of length,while thewidth of the tooth can only be estimated. The P4 has sustained more damage than P3. The parastyle is chipped and broken, the protocone apex is broken, the paracone is nearly entirely lost except for a small part of the distolingual face, and the metastyle is buccally and distally damaged. Thus, for all intents and purposes, what remains of this tooth is its outline. However, themesial end can be estimated by the better-preserved distal P3 and an assumption that the two teeth abut. The distal end can be estimated by the distal end of the alveolus, together with comparisons with extant lions and the difference between the distal end of the alveolus and distal end of P4 in those specimens. Thus, just enough remains to obtain minimum estimates of
LP3, WP3, LP4, WaP4, PL, and BL (see Abbreviations). These measurements in turn provide estimates of various aspects of the specimen’s size and proportions (dental compared to cranial). The specimen can be identified as felid because of the
dental reduction, the relatively slender P3 with prominent distal accessory cusp, and the reduced protoconid on the upper carnassial. It can be identified as Felinae (conical-toothed cat) rather that Machairodontinae (sabretooth cat) based on the relatively robust upper cheek teeth and the oval upper canine. It can be identified as lion, Panthera leo, based on size, because lion is the largest of the Felinae in Africa and there is no reason based on the present material to hypothesize the presence of any previously unknown Felinae species on the continent in the late Middle Pleistocene.
Metric analysis.—The measurement data for the specimen are given in Table 1, together with our estimated uncertainty for each one. Summary statistics on the measurement data of the comparative samples are given in Table 2 and the raw data in Supporting Information. In the following we focus attention on two measurements: LP3 and PL, because these are the dental and cranial measurements, respectively, that are the most accu- rate, and, at the very least, were no smaller than the values given. The sample size for P. spelaea PL is very small (N=3). This has no important bearing on the conclusions, but to increase veracity BL is also included. This measurement is probably somewhat less accurate than PL, but is available for more specimens of P. spelaea.
Table 1. Measurement data for KNM-ND 59673. All measurements are mini- mum estimates. Uncertainty legend: *** fairly accurate, error estimated to ≤1%; ** reasonably accurate, error estimated to >1%, ≤2%; * poorly accu- rate: error estimated to >2%. Importantly, since all measurements are mini- mum estimates, the analyses will also provide minimum estimates of the overall size of the specimen. For abbreviations, see Material and Methods.
Measurement LP3
LP4 PL BL
Value (mm) 27.6
196 380
38.3
Uncertainty **
*** **
*
309
Table 2. Basic statistics for the three comparative taxa and four variables used in the paper. Raw data are given in Supplementary Information. For abbreviations, seeMaterial and Methods.
Group
LP3 Mean
LP4 Mean
Standard deviation Minimum Maximum
Standard deviation Minimum Maximum
Mean
Standard deviation Minimum Maximum
Mean
Standard deviation Minimum Maximum
Panthera leo Panthera spelaea Panthera atrox
24.0 21.2
N35 29.3
35.8 32.5
40.0
N35 PL
142.2 116
N35 BL
170
268.7 220
312 N30 24.576 14.090 2.000 1.851
27.0 23.5
31 51
39.7 33.5
44.7 54
178.3 167
192 3
326.1 291
375 9
29.379 12.662 2.653 2.000
27.3 23.9
30.6 34
45.0 36
39.6 35.0
176.7 143
212 24
405 24
333.6 269
34.034 18.684 2.488 1.915
The selected measurements were analyzed using box-and-
whisker plots (Fig. 4). The plot of LP3 (Fig. 4.1) shows extant P. leo to have a much shorter P3 than the two fossil species, P. atrox (Leidy, 1853) and P. spelaea. This is, of course, well known and corroborated by the t-tests (Table 3). The difference between the two fossil species is not significant. The length of the P3 of KNM-ND 59673 is greater than all but one of the extant lions in the comparative sample. The latter specimen is unfortunately of unknown origin. It should be noted that lions from South Africa are relatively underrepresented in the sample, and if Bergmann’s Rule holds for lions, as suggested by Klein (1986), the largest lions would be expected to come from there. The South African lions included are among the largest in the sample. Figure 4.1 also shows that P3 length in KNM-ND 59673 lies within the 4th quartile of both P. atrox and P. spelaea, although it is not among the very largest. Thus, P3 in KNM-ND 59673 is unusually long for an extant lion, but within the range of variation of the species. The relationships seen for P3 length also largely apply to
P4 length, although it is noteworthy that P4 is relatively much shorter than P3 in comparison to the other samples (Fig. 4.2). It is still longer than most specimens of P. leo, but does not lie outside the 95% confidence interval of that taxon. Relative to P. atrox and P. spelaea, the P4 of KNM-ND 59673 is well below median length. The same relationships between the comparative samples
apply to the variables PL and BL as to LP3 (Fig. 4.3, 4.4). These measurements in KNM-ND 59673 are, however, substantially larger than those of any extant lion. Compared to P. spelaea, KNM-ND 59673 is larger than all available specimens with a measurable PL (N=3 only) and BL (N=9). Compared to the much larger samples of P. atrox, KNM-ND 59673 is larger than all but two for both PL and BL. These comparisons show that in terms of skull length, KNM-ND 59673 is of the size of a large specimen of P. atrox, which in turn was a much larger species than the extant P. leo.
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