A protocol for differentiating late Quaternary leporids in southern California with remarks on Project 23 lagomorphs at Rancho La Brea, Los Angeles, California, USA Author Fox, Nathaniel S. Author Takeuchi, Gary T. Author Farrell, Aisling B. Author Blois, Jessica L. text PaleoBios 2022 46192 36 1 20 journal article 10.5070/P9361046192 0031-0298 SYLVILAGUS BACHMANI WATERHOUSE 1839 Referred specimens — LACMP 23-32045, left dentary fragment with p3. The following specimens represent complete left p3s: LACMP 23-29229, LACMP 23-33861. The following specimens represent complete right p3s: LACMP 23-28082, LACMP 23-34262, LACMP 23-35844, LACMP 23-36615. Remarks — Seven specimens from Project 23 are assigned to S. bachmani based on simple p3 crenulation at the occlusal surface and base of the tooth, p3 lengths < 3.1 mm , and a mean p3 l/w>1.25 ( Table 2 , Figs. 4, 5D). Since adult individuals of this species usually exhibit simple crenulation (Table 1; Fig. 4), it is difficult to identify juveniles from surface-base changes in crenulation complexity. However, specimens can be identified as juvenile if the width at the occlusal surface is less than the width at the tooth base (White 1991). Excluding potential juvenile p3s of S . bachmani from Project 23, the sample is ~11% smaller than recent S . bachmani (mean= 2.19mm , 1.71mm , and 1.28 for p3 length, width, and l/w respectively; Fig. 4; Appendix Table 2 ). Size changes between extant (n=30) and fossil (n=7) S . bachmani are statistically significant (t=2.8861, df=8.2077, p=0.0198 for p3 length; t=4.6124, df=12.923, p<0.001 for p3 width).