Cynorca, COPE, 1867

Maguire, Kaitlin Clare & Schmitz, Joshua X. Samuels and Mark D., 2022, The fauna and chronostratigraphy of the middle Miocene Mascall type area, John Day Basin, Oregon, USA, PaleoBios 35, pp. 1-51 : 27-31

CYNORCA COPE, 1867

“ Cynorca ” hesperia MARSH, 1871 FIGS. 15 , 16

Holotype —From UCMP V67153 : right maxilla with P4 through M3, YPM 11899 .

Referred specimens —From JDNM-4*: cranium with rostrum missing but containing right and left P4 through M3, JODA 1320; partial maxilla with M2 and M3, JODA 2229; right M1 or M 2 in maxillary fragment, JODA 2241. From UCMP V 4945: partial cranium with incomplete palate containing left P2 through P4, M1, M3, partial left M2 and partial left and right canines, mandible with left i1, i2, canine, alveoli of p2 and p3, p4 through m3 and right i1 through 3, canine, alveoli of p2 and p3, p4 through partial m2, m3, distal right humerus, and right proximal ulna and radius, JODA 3773.

Occurrence — UCMP V 67153, UCMP V 4945, JDNM-4*.

Description —YPM 11899,JODA 1320, and JODA 3773 all have upper fourth premolars with a “deep trenchant groove that passes lingually between protocone and metaconule” ( Woodburne 1969, p.304) and unreduced M3, placing them in “ Cynorca ” hesperia ( Figs. 15 , 16 ). JODA 2229 also has an unreduced M3. JODA 1320 is the most complete specimen of “ C.” hesperia containing the palate and most of the braincase with well-preserved auditory bullae; however, most of the rostrum is missing ( Fig. 15 ).The zygomatic arch of JODA 1320 does not flare, resulting in a narrow cranium shape. JODA 3773 contains most of the rostrum, part of the frontals, anterior portion of the left zygomatic arch and palate with left dentition ( Fig. 16 ). The zygomatic arch of JODA 3773 flares laterally causing a wing like projection and broader cranium shape than JODA 1320.

Remarks —YPM 11899 is the type specimen of “ Cynorca ” hesperia ( Woodburne 1969). It was collected by Thomas Condon, from the upper John Day River, OR. Marsh (1871) reported it from “the Pliocene beds of Oregon,” however Woodburne (1969) interpreted the locality as probably the Mascall. Wright (1998) identifies the genus as a nomen dubium and only recognizes two species of “ Cynorca ” (“ C. ” sociale Marsh, 1875 and “ C.” occidentale Woodburne, 1969), which are paraphyletic. “ C. ” sociale falls outside of Tayassuinae, and was renamed Marshochoerus socialis Marsh, 1875 and placed in the subfamily Hesperhyinae by Prothero (2015). “ Cynorca ” occidentale falls within the Tayassuinae. A character that is shared between “ C.” occidentale and YPM 11899 is the presence of a metaconule on the P4 and the trenchant groove that passes lingually between the protocone and metaconule of P4. However, the two differ in that the M3 of YPM 11899 is not significantly smaller than the M1 or M2. The presence of the metaconule of the P4 places YPM 11899 within Tayassuinae; however, this specimen does not belong to “ C. ” occidentale. This specimen is similar to “ M. ” sociale in having an unreduced M3, length of m2 is 10.87 mm (near the average of 11.2 mm reported in Wright (1998)); however, it does not belong to that species because of morphology of the P4 discussed above. Given this, we retain YPM 11899 as “ C.” hesperia and await further reclassification of the remaining species within “ Cynorca ” discussed in Prothero (2015). Because all of the other specimens listed above share the same P4 and M3 morphology as well as size range ( Table 5), they are also assigned to “ C. ” hesperia. The difference in zygomatic arch shape of JODA 1320 and 3773 may be due to sexual dimorphism or cranial ontogeny; however, their tooth morphology and size are identical. Wright (1993) demonstrated that zygomatic arches are a sexually dimorphic character in Tayassuidae and that some Miocene and Pliocene female peccaries have smaller zygomatic arches.

“ Cynorca ” sp. Cope, 1867

FIG.17

Referred specimens —UCMP V4834: partial mandible with complete left canine, left i1, i2, right i1 and partial right canine,JODA 4250; right partial dentary with m1 and m2, JODA 4258. From CIT 1869: P4, LACM 5964.

Occurrence —UCMP V4834, CIT 1869.

Description —JODA 4258 is a right dentary with m1 and m2. The m1 of JODA 4258 measures 11.02 mm anteroposteriorally and 7.78 mm transversally. The m2 of JODA 4258 measure 11.75 mm anteroposteriorally and 10.03 transversally. The simple morphology of the m1 and m2 is similar to “ C.” occidentale and Marshochoerus sociale . JODA 4250 belongs to “ Cynorca ” based on i2 lying posterolateral to i1, i1 and i2 being subconical and the canine having lateral ridges and a lingual groove developed half way up the tooth from the jaw.

Remarks —These specimens are attributed to “ Cynorca ”, but are not assigned to a species because of limited diagnostic material. “ Cynorca ”, as mentioned above, is a nomen dubium, but we await further reclassification of the remaining species within “ Cynorca ” discussed in Prothero (2015). The type specimen for “ C.” hesperia is a partial maxilla and does not contain comparable lower dentition. JODA 3773, assigned above to “ C. ” hesperia, has a comparable lower jaw; however, the m1 and m2 are too worn for morphological comparison. The m1 and m2 of JODA 4258 are the same size as the m1 and m2 of JODA 3773 suggesting that they belong to the same taxon. No other small tayassuid has been recovered from the Mascall Formation. JODA 4250 and 4258 may belong to the same individual. They have similar preservation and were found at the same site. LACM 5964 was collected by Bode in 1929. It is highly worn, so it is impossible to determine if there is a metaconule present or not, and is therefore unidentifiable to the species level.

Figures

Figure 15. “Cynorca” hesperia skull, JODA 1320. A. Dorsal view. B. Lateral view. C. Ventral view. Scale bar=1cm.

Figure 16. “Cynorca” hesperia skull, JODA 3773. A. Dorsal view. B. Lateral view. C. Ventral view of mandible. Scale bar=1cm.

Figure 17. “Cynorca” sp. A. Partial mandible with complete left canine, left i1, i2, right i1 and partial right canine; JODA 4250. B. Right partial denary with m1 and m2, JODA 4258. Scale bar=1cm.