Sylvilagus audubonii, BAIRD 1857

Fox, Nathaniel S., Takeuchi, Gary T., Farrell, Aisling B. & Blois, Jessica L., 2019, A protocol for differentiating late Quaternary leporids in southern California with remarks on Project 23 lagomorphs at Rancho La Brea, Los Angeles, California, USA, PaleoBios (46192) 36, pp. 1-20 : 10

SYLVILAGUS AUDUBONII BAIRD 1857

Referred specimens — LACMP 23-39811, left dentary fragment with p3, p4, m2; LACMP 23-32047, right dentary fragment with p3-m1; LACMP 23-39819, right dentary fragment with p3-m1; LACMP 23-39820, right dentary fragment with partial p3-m2. The following specimens represent complete left p3s: LACMP 23 - 28084, LACMP 23-28555, LACMP 23-28661, LACMP 23-31781, LACMP 23-35608, LACMP 23-35763, LACMP 23-35847, LACMP 23-35885, LACMP 23-35937, LACMP 23-40167, LACMP 23-40209, LACMP 23-40284, LACMP 23-40285, LACMP 23-40286, LACMP 23-40287.The following specimens represent complete right p3s: LACMP 23-28341, LACMP 23-28519, LACMP 23-28556, LACMP 23-28858, LACMP 23-33962, LACMP 23-34117, LACMP 23-35614, LACMP 23-35696, LACMP 23-35836, LACMP 23-35839, LACMP 23-35840, LACMP 23-35881, LACMP 23-35883, LACMP 23-39874, LACMP 23-40166, LACMP 23-40210, LACMP 23-40211. The following specimens represent partial left p3s and left p3 fragments: LACMP 23-28266, LACMP 23-31782, LACMP 23-34259, LACMP 23-34260, LACMP 23-35771, LACMP 23-40039, LACMP 23-40288. The following specimens represent partial right p3s and right p3 fragments: LACMP 23-28105, LACMP 23-35618, LACMP 23-35619, LACMP 23-35645, LACMP 23-39929,

LACMP 23-40110, LACMP 23-40168, LACMP 23-40212, LACMP 23-40291.

Remarks — Fifty-two specimens from Project 23 are assigned to S. audubonii based on moderate or complex p3 crenulation ( Table 2; Figs. 4, 5C). We cannot eliminate the possibility that some specimens belong to S. nuttallii ; however, we consider this unlikely since most p3s with l/w <1.25 (i.e., those not likely belonging to S. bachmani ) exhibit moderate or complex crenulation at the tooth surface and/or base (Fig. 4; Appendix Table 2). If S. nuttalli was present and common in the local region encompassing Project 23, we would expect proportionally more non-narrow p3s to exhibit simple crenulation. Further, S. nuttallii is currently restricted to intermountain regions> 100 miles from Los Angeles ( Hall and Kelson 1959, Chapman 1975). All specimens with more complex crenulation at the tooth base relative to the occlusal surface are considered juvenile individuals of S. audubonii . Excluding suspected juveniles, p3s from Project 23 are, overall, ~9% smaller than extant S. audubonii (mean= 2.55mm, 2.14mm, and 1.19 for p3 length, width, and l/w respectively; Fig. 4, Appendix Table 2). Size changes between extant (n=30) and fossil (n=25) S. audubonii are statistically significant (t=4.6205, df=48.06, p<0.001 for p3 length; t=4.5672, df=51.154, p<0.001 for p3 width).