Meleagridinae

Meleagridinae

Meleagris sp. Linnaeus

Material. USNM PAL 641967, l humerus: proximal half missing the deltopectoral and bicipital crests and a portion of the shaft below the head, collected July 2002 (Fig 1C). The bone appears to be from a full adult.

USNM PAL 641969, l humerus: nearly complete shaft missing articular surfaces of both ends and the crista bicipitalis, collected October 8, 1999 (Fig. 1A). On the caudal surface of the shaft, near the distal end, there are four distinct circular perforations and several similar lesions that do not fully perforate the bone (Fig. 1A). These are likely to be carnivore tooth punctures, resulting from an act of predation or scavenging. They show no sign of healing so they likely occurred at the time of death or afterwards.

USNM PAL 641971, r carpometacarpus: severely abraded proximal end and the proximal 1/3 of the shaft, missing the minor metacarpal, collected October 8, 1999.

CM 34028, l coracoid: dorsal portion, reported by Brodkorb & Mourer-Chauviré (1984).

USNM PAL 641968, r femur: the shaft and the abraded head are preserved; collected October 8, 1999, by Trent Spielman. The bone is immature as indicated by pits and striations on the shaft.

Measurements. The following bone measurements correspond with measurements reported by Steadman (1980). I have repeated Steadman’s letter designations and wording for ease of comparison with his extensive statistical tables. USNM PAL 641969, humerus measurement C (width of midshaft) 12.5, humerus measurement D (depth of midshaft) 10.4. USNM PAL 641971, carpometacarpus measurement B (proximal depth) 15.9, measurement C (length of metacarpal one) 10.3. USNM PAL 641968, femur measurement D (width of midshaft) 9.4, measurement E (depth of midshaft) 7.3.

Description. Bones of the genus Meleagris are distinguished by very large size in the context of Phasianidae. The bones listed above are assigned to Meleagris based on size and morphological agreement. The bone measurements from fossils can be compared with Steadman’s summary statistics for approximately 70 specimens of modern M. gallopavo. Measurements of humerus USNM PAL 641969 fall below the reported range for males of M. gallopavo. The width of midshaft of the humerus is near the mean for M. gallopavo females, whereas the depth of midshaft is 0.1 mm greater than the range for females. The proximal depth of the carpometacarpus, USNM PAL 641971, falls below the reported range for males and females of M. gallopavo by 0.8 mm, and its length of metacarpal one falls within the range for both male and female M. gallopavo. Measurements of the femur USNM PAL 641968, an immature bone, fall below the range for males of M. gallopavo. Its width of midshaft is within the range for females, and depth of midshaft is below the reported range for females by 0.8 mm. Published measurements for the coracoid, CM 34028, are within the range for females of M. gallopavo.

Remarks. The comparative osteology and fossil record of Meleagris have been extensively studied (e.g., Steadman 1980; Bocheński & Campbell 2006). The two extant species of Meleagris show few fixed osteological differences and considerable intra-specific variation, including pronounced sexual size dimorphism. Only Pleistocene sites with large numbers of Meleagris bones provide an adequate basis for taxonomic assessment taking into account variability. The detailed study by Bocheński & Campbell confirmed that the abundant bones from the Rancho La Brea tar pits (Los Angeles, California) can be diagnosed as a distinct species, M. californica (Miller 1909a), closely related to M. gallopavo. Steadman studied the Pleistocene fossil record before the Rancholabrean land mammal age, including larger samples from an Irvingtonian (Coleman 2A, University of Florida Vertebrate Fossil Locality SM001) and a late Blancan (Inglis 1A, University of California Vertebrate Fossil Locality CI001) site in Florida. The Irvingtonian turkeys tended to be larger than those from the late Blancan, and the late Blancan birds lacked a pneumatized scapula which is present in later time periods. Steadman considered it likely that one or more successive fossil species of Meleagris had a very broad distribution in North America (similar to that of modern M. gallopavo) and had geographically variable morphology during the Early and Middle Pleistocene. He posited that most known Blancan and Irvingtonian fossil turkeys represent archaic forms of M. gallopavo.

Steadman (1980) and Bocheński & Campbell (2006) both reported osteological character states that differ at least in prevalence among various named taxa and local fossil assemblages of Meleagris, but unfortunately, none of them can be observed in the fossils from Cumberland Bone Cave. Considering their lack of diagnostic specieslevel traits, I have refrained from assigning the fossils a species-level identification, while recognizing that the combined evidence of morphology and biogeography suggests that they represent an archaic form of M. gallopavo, as envisioned by Steadman. This small collection of mid-Pleistocene turkey bones provides no evidence to refute Steadman’s finding that Meleagris in North America has increased in body size since the late Blancan.