Bison sp.
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publication ID |
https://doi.org/ 10.26879/1285 |
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persistent identifier |
https://treatment.plazi.org/id/542C8794-FFDA-FF8E-B88E-FAB48385FBBE |
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treatment provided by |
Felipe |
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scientific name |
Bison sp. |
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Referred material. Cranium fragment with right horn core and lacking facial bones ( BUAPAL 755, incomplete right mandible with a fragment of p3 and complete m1 to m3 ( BUAPAL 756), complete molar M2 ( BUAPAL 781), proximal scapula fragment ( BUAPAL 761), a fragment of the proximal epiphysis of the right ulna ( BUAPAL 754), an almost complete left metacarpus ( BUAPAL 764), right talus ( BUAPAL 763), fragment of cervical vertebra ( BUAPAL 762), and two lumbar vertebrae ( BUAPAL 758 and 759); Figure 4 View FIGURE 4 .
Description. The cranium fragment (BUAPAL 755) retains part of the left and right frontal from the orbital fossa to the occipital condyle. The right horn core has a length of 200 mm, an internal length of 230 mm, an external length of 295 mm from tip to base, a circumference of 290 mm, a diameter of 100 mm, and an estimated total horn core length from tip to tip (TLTT) of 700 mm.
Comparison and remarks. These horn measurements and the horn cores laterally directed are within the variation of B. antiquus ( Table 4) (Lucas, 1899; Skinner and Kaisen, 1947; Von den Driesch, 1976; McDonald, 1981; Díaz-Sibaja et al., 2020). B. occidentalis despite presenting horn nuclei that moved backwards (Díaz -Sibaja et al., 2020) is considered synonymous of B. antiquus based on ancient DNA studies that demonstrated that both are the same anagenetic lineage (Shapiro et al., 2004; Wilson et al., 2008).
The M2 (BUAPAL 781) has a length = 33.41 mm and a width = 22.06 mm. The occlusal surface is badly damaged, it presents a well-developed entostyle, the fossettes have the characteristic U shape with some folds, and the wear of the molar indicates it belonged to an adult. The incomplete right mandible presents a fragment of pm3 and complete m1, m2, and m3 (BUAPAL 756); the molars are hypsodont with well-developed entostyle, and the shape of the molars are sharp in lateral view with light wear. All of these traits are characteristics of genus Bison (Allen, 1876; Chandler, 1916; Hillson, 2005).
A fragmented right scapula (BUAPAL 761) presents the glenoid fossa with a diameter = 88 mm, the internal border of the scapula has a length = 165 mm, and the total length of the scapula is 430 mm. It is observed that the area immediately dorsal to the glenoid and bordered by the mid-neck ridge and posterior margin is markedly thinned and flattened, which is characteristic of the genus Bison (Von den Driesch, 1976; McCuaig-Balkwill and Cumbaa, 1992; France, 2008; Raymond and Prothero, 2011). The scapula belongs to an adult individual according to the measurements reported by Von den Driesch (1976), McCuaig-Balkwill and Cumbaa (1992), and France (2008).
The ulna is fragmented (BUAPAL 754), it presents a fracture in the diaphysis, the proximal region is preserved with a flattened and well-defined olecranon, with the major cavity in semilunate shape. The curvature of the olecranon has a depth of 14 mm. All these features and the ulna not fused with the radius indicate that the specimen was a juvenile (Ritz and Wing, 2008).
Left metacarpus (BUAPAL 764) is wider and slightly shorter, characteristic observed in Bison ( McDonald, 1981; Skinner and Kaisen, 1947) and its measurements ( Table 5) are close to those of B.antiquus ( McDonald, 1981; McCuaig-Balkwill and Cumbaa, 1992). The articular condyle of the left metacarpal IV (BUAPAL 764) lacks distal epiphysis and it is close to B. antiquus ( McDonald, 1981; Baskin, et al., 2022). However, we do not have diagnostic characteristics to assign it to specific level.
The right calcaneus (BUAPAL 763) shows the lateral articular surface of the distal trochlea covering the distal surface, the tubercle is at the same line with the dorsal portion, features of the genus Bison (McCuaig-Balkwill and Cumbaa, 1992) .
The sixth cervical vertebra (BUAPAL 762) has well-defined caudal and cranial regions, the rostral condyle is convex with a rounded margin, the medullary canal is present; the articular process is wide with a rounded margin, the cranial articular process is flat and incomplete, the transverse processes are flat, large, and present a triangular shape, the articular processes are damaged, and the angle between the lateral branches of the transverse process is wider and deeper, similar to features present in Bison (McCuaig-Balkwill and Cumbaa, 1992) .
The lumbar vertebrae (BUAPAL 758, 759) are almost complete. They exhibit a compression of the vertebral body in the cranial and caudal regions. The cranial region has a height = 52 mm, which is the same as the width of the facies = 52 mm. In the caudal region, the vertebrae present a width in the facies = 59 mm and the length of the vertebrae = 73 mm; the dorsal margin of the anterior articular process is at the same level than the upper part of the articular facet, characteristics observed in Bison (McCuaig-Balkwill and Cumbaa, 1992) . The fossil material was determined to belong to an adult individual because of the similarity with the measurements reported by Von den Driesch (1976) and Skinner and Kaisen (1947).
All postcranial remains are assigned to Bison sp. because they exhibit the morphological characteristics of this genus ( McDonald, 1981) but is very difficult separate species into this genus with postcranial material. Ancient DNA analyzes with 405 remains of Bison aged between 60,000 and recent, demonstrated broad genetic diversity in populations during the Late Pleistocene that are mainly subdivided into four major clades, showing that all Bison sequences are closely related and are not indicative of multiple and independent species (Wilson et al., 2008). Due to the similarity of the isolated horn nuclei and postcranial elements of B.antiquus and B. occidentalis , identification of Late Pleistocene and early Holocene Bison should be made with caution (Wilson et al., 2008).
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