Paranourosorex, Rzebik-Kowalska, 1975

Zazhigin, Vladimir S. & Voyta, Leonid L., 2022, New Neogene anourosoricin shrews from northern Asia, Palaeontologia Electronica (a 29) 25 (3), pp. 1-36 : 10-11

Genus PARANOUROSOREX Rzebik-Kowalska, 1975

Type species. Paranourosorex gigas Rzebik-Kowalska, 1975

Previous diagnosis. Storch and Zazhigin (1996: 259) stated, “Large-sized shrews. Mandibular articulation highly specialized, lower articular facet shifted anteriorly and interarticular area formed by very narrow ridge. P4/4 and M1/1 accentuated, M2/2 and M3/3 reduced. M1/ with W-shaped ectoloph and labially protruding mesostyle, with slight posterior emargination and usually a distinct metaconule. Lower molars with well-developed hypoflexid. P/4 inflated and with strong tendency to reduce the posterolingual basin. Parastyle P4/ protruded anteriorly and protocone shifted lingually. Trigonid on M/1 not particularly elongated. M/1–2 with moderately to weakly developed entocristids. Upper incisor not fissident. Lower incisor with smooth cutting edge. Three upper antemolars and one lower antemolar in front 4th premolar. The teeth are rather bulbous; cingula are well developed. Coronoid process strong and spatulate, with prominent coronoid spicule; internal temporal fossa located anteriorly.”

Emended diagnosis. From small-sized to large-sized shrews. The generalized Anourosoricini dental formula with three upper (A1–A3) and one lower (a1) antemolars and retained third molars (M3 and m3); the dental formula is 1.3.1.3/1.1.1.3. The teeth bear generalized omnivorous characters such as the massive and bulbous-like lower teeth, the hatchet-like talon of I1, the wrinkled enamel on different parts of the teeth, the expressed Wshaped buccal crests line of M1 with well-developed mesostyle, a presence of the short metaloph; the extremely short metastyle (i.e., short postmetacrista) of M2; the wide trigone basin of M1 and trigonid and talonid basins of m1–m2, the well-developed hypoflexid of m1–m2, p4 subrectangle in shape with the spot-shaped wear facet and extremely weak developed the crown structures (central crest and posterolingual basin).

Differential diagnosis. Paranourosorex differs from Crusafontina , Amblycoptus , Kordosia and Anourosorex in its best developed parastyle of P4 together with a long postcrista; in the mostly expressed W-shaped line of the M1 buccal crests and distinctly buccal protruding of the mesostyle together with the weak developed posterior emargination of P4 and M1 (i.e., a short hypoconal flange); in the subrectangular inflated p4 without developed crown elements and developed ectoand entocingulids (the compared genera have p4 subtriangle in shape with developed central crista and posterolingual basin in different degree); in the shape of I1 talon (the compared genera have hatchet-like talon with deep notch); in relatively short and wide m1 and m2 (the compared genera have the elongated m1 and m2). In addition, Paranourosorex differs from Crusafontina in the smooth cutting edge of i1 ( Figure 3 ) and the strongly shorter postmetacrista of M2 together with expressed W-shaped buccal crests of this tooth in general. In addition, Paranourosorex differs from Amblycoptus , Kordosia and Anourosorex also in the dental formula composition ( Anourosorex : 1.2.1.3/1.1.1.3; expressed dimily in Amblycoptus : 1.3.1.2/1.1.1.2; and Kordosia : 1.2.1.2/1.1.1.2). Differences between Paranourosorex and Ishimosorex gen. nov. see above. Paranourosorex differs from Darocasorex in the general proportion of M1 outline shape ( Darocasorex shows an anteroposterior compression of M1).

Remarks. Paranourosorex is probably the Asian origin group that supposedly arose long before the first appearance of P. seletiensis in the regional paleontological record. The main evolutionary trend of the genus connects with body size increase of species from early to latter members while maintaining omnivorous, which is marked by basic dental characters adapted for tearing and crushing and consumption of various types of food resources. After the study of Storch and Zazhigin (1996) we revised the available north Asian material and expanded the regional species list for Russia and Kazakhstan to three taxa: P. seletiensis Storch and Zazhigin, 1996 , Paranourosorex intermedius sp. nov. and P. gigas .

The Storch and Zazhigin (1996: 259) diagnosis includes several morphological traits that need clarification. A highly specialized craniomandibular articulation is a common character of the tribe. A statement “usually a distinct metaconule” is not entirely accurate; in our interpretation, Anourosoricini has not a true metaconule of M1. Actually, we can see a short metaloph on an unworn tooth. Due to the fact that a metaloph does not reach a metacone base, we observe a metaconule-like bulge on a worn tooth. In addition, the metaloph area of M1 and posterior border of the m1 talonid (hypolophid/entostylid area) shows variations in presence/absence of important characters precisely because these areas are in occlusal contact (Appendix 6) and susceptible to wear.

Stratigraphic and geographic range. At present, the distribution includes 22 localities from Kazakhstan and Russia (Appendix 2) and two European localities ( Rzebik-Kowalska, 1975, 1998; Rzebik-Kowalska and Lungu, 2009). The stratigraphic range covers an interval between the late Miocene Kedey Formation (Turolian, MN 12/13; Kazakhstan) to early Pliocene (Ruscinian, MN 14, Russia (Peshnev Formation); Ruscinian, MN 15, Slovakia).

Figures

FIGURE 3. The characters of the first lower incisors of Paranourosorex gigas from ANR/1A (GIN 1112/1108; A1, lateral, A2, medial views), Ishimosorex ishimiensis gen. et sp. nov. from BRK/1A (GIN 1115/1149, paratype; B1, lateral, B2, medial views), Crusafontina endemica Spanish from Can Llobateres 1 locality (C, CL1 2217, see van Dam, 2004: 746; in lateral view), C. kormosi (D, Polgárdi 4, in lateral view) and A. oligodon (E, Polgárdi 4, in lateral view). Scale bars equal 1 mm; C, unscaled. Abbreviations see in Figure 1.