Rook et al.—Pliocene Canidae from Sighnaghi, Georgia
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Table 1. Cranial measurements of Nyctereutes megamastoides (Pomel, 1842) from Kvabebi. A-B = akrokranion-basion (height of the cranium without the sagittal crest); BL = basion-prosthion (basal length of the cranium); CBL = prosthion-occipital condyles (condylobasal length of the cranium); Ect = ectorbitale- ectorbitale (frontal breadth); ECW = external C1 alveoli width; Eu = greatest neurocranium breadth; FL = prosthion-frontal midpoint (facial length); FMW = width of the foramen magnum; GPW = greatest palatal width; GWOC = greatest width of occipital condyles; NcL = akrokranion-frontal midpoint (neurocranium length); PL = prosthion-staphylion (palatal length); PoCW = least breadth of postorbital constriction; SH = skull height (with sagittal crest); TL = akrokranion-prosthion (total length of the cranium); Zyg = zygion-zygion (zygomatic breadth).
MG 29-2013/455 (K234)
TL NCL FL Eu Ect PocW SH A-B GWOC BL PL CBL ZyG ECW GPW FMW -
- 129.2 [58.0] 73.5 49.1 46.1 30.3 36.6
- -
66.3 59.6 -
76.9 - - - - 42.2 - - 35.2 26.8
MG 29-2013/457 (K220) 137.6 63.6 76.8 62.9 45.1 31.9 [42.5] [35.9] MG 29-2013/567 (K4173) - MG 29-2013/568 (K215) MG 29-2013/573 (K233) MG 29-2013/581
- -
- -
- 46.9 43.8 27.1 43.0 34.7 23.3 - 42.0 42.7 28.2 36.5 -
23.6 - -
- -
123.2 64.9 129.7 82.1 23.2 -
- 67.4 -
- - -
- - -
- - -
- 16.8 34.6
- - -
40.3 -
- - -
-
12.9 10.4 8.0 - -
Table 2. Associated upper teeth measurements of Nyctereutes megamastoides (Pomel, 1842) from Kvabebi. L = mesiodistal length; LCR = upper cheek tooth- row length (P1–M2); LMR = upper molar row length (M1–M2); LPR = upper premolar row length (P1–P4);W = buccolingual width.
MG 29-2013/455 (K234) L - R
-
C1 L C1W P1 L P1W P2 L P2W P3 L P3W P4 L P4W M1 L M1W M2 L M2W LCR LPR LMR -
MG 29-2013/456 (K217) L 5.7 3.7 4.7 2.5 6.9 2.7 R -
MG 29-2013/457 (K220) L 5.4 3.7 3.7 2.8 6.1 2.6 7.0 2.8 R -
MG 29-2013/573 (K233) L 6.1 R -
- - -
- -
4.0 2.9 6.0 2.7 4.5 4.7
- -
7.2 7.0
- -
8.1 8.3
-
on the morphological features described above. Compared to N. procyonoides and to the Eurasian Pliocene species of raccoon dog-like canids, Nyctereutes from Kvabebi is similar in size to N. megamastoides, N. sinensis, and N. donnezani, but smaller than N. tingi. Some morphological features (e.g., the high angle of the corpus of the mandible in the region of the subangular lobe, subquadrate M1, mesiodistally enlarged M2, etc.) are suggestive of a derived form of Nyctereutes, thus differing from primitive morphologies like those characterizing N. tingi and N. donnezani (e.g., poorly developed subangular lobe, reduced width of upper molars). Therefore, Nyctereutes from Kvabebi is more similar to species like the extant N. procyonoides, N. sinensis from the Yushe Basin, and N. megamastoides from Western Europe. Among these latter species, N. procyonoides possesses the greatest number of dental differences compared to Nyctereutes from Kvabebi (e.g., the P4 protocone more mesially placed, a stronger parastyle on P4, proportionally bucco- lingually shorter M1 and M2, the M1 metacone and metaco- nule reduced in development, the pointy and higher M1 hypocone, the individualized metaconid and reduced bucco- lingual width of the talonid on the m1). Nyctereutes sinensis and N. megamastoides are similar in size and in morphological features, so they could represent a single taxon with a wide zoogeographic range (Tedford and Qiu, 1991). Nevertheless, as pointed out by Tedford andQiu (1991), N. megamastoides has a better-developed subangular lobe and more quadrangular upper molars compared to N. sinensis. Furthermore, the P4 protocone of N. sinensis lies more mesially when compared to the mesial
- - -
- ----- 11.9 6.3 11.0 11.0 -
- ------ - - -
- 12.6 5.8 11.0 12.6 7.0 - -
- -
- 10.9 - 11.0
- -
-
12.1 7.0 -
7.5 3.1 14.1 7.2 11.4 12.6 7.5 -
-
14.0 6.8 11.1 12.9 7.7 5.6
7.7 7.2
8.0 -
8.6 -
- - -
9.8 54.4 38.3 18.7 9.0
- 48.7 34.0 17.1 - 52.0 - 18.2
margin of the tooth, more than it does in N. megamastoides; this species has an equal-sized M1 paracone and metacone, in con- trast to those of N. sinensis, which appear well developed in F: AM 96759 (Tedford and Qiu, 1991); the latter species does not possess any or strongly reduced protoconule on M1, which is present in the Villaroya and Dafnero N. megamastoides; the mesiolingual cingulum on M1 of N. sinensis is not continuous and does not form the cuspid-like enlargement on the mesial side of the M1 of N. megamastoides; the M2 of the Chinese species is reduced compared to that of N. megamastoides, which has a peculiar “D”-like shape; N. megamastoides from Villaroya and Dafnero-1 has a large protoconule and protocone and a low metaconule on the M2, whereas N. sinensis seems to possess only a large and prominent protocone; the m1 metaconid of N. megamastoides is larger than that of N. sinensis;in N. megamastoides, the m1 talonid is considerably enlarged compared to the trigonid, whereas in N. sinensis the talonid is not oversized compared to the trigonid; the m2 is generally slender in N. sinensis compared to N. megamastoides in which it is oval in shape. The m2 protoconid and metaconid are subequal in size in N. megamastoides,whereas N. sinensis has a larger pro- toconid; this latter species does not possess any accessory cuspulids on the disto-lingual side of m1, whereas N. megamastoides generally shows the entoconid and may possess accessory cuspu-
lids.Considering these differences, the Kvabebi raccoon dog can be assigned to Nyctereutes megamastoides. Cranial, dentognathic, and postcranial measurements of the Nyctereutes sample from Kvabebi are shown in Tables 1–4.
Figure 2. Nyctereutes megamastoides (Pomel, 1842) from Kvabebi. MG 29-2013/820, left hemimandible, in buccal (1), lingual (2), and occlusal (3) views; MG 29-2013/592 (K4177), right hemimandible fragment, in buccal (4), lingual (5), and occlusal (6) views; MG 29-2013/458, left humerus (K251) and ulna (K250), in caudal (7) and right lateral (8) views; MG 29-2013/602 (K503), right pelvis, in lateral view (9); MG 29-2013/600 (K226), right femur, in dorsal view (10); MG 29-2013/597 (K253), left metacarpals with phalanges, in dorso-lateral view (11); MG 29-2013/460 (K254), left phalanges, in lateral view (12). Scale bar = 1 cm.
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