Tamias, Illiger, 1811

Sehgal, Ramesh Kumar, Singh, Abhishek Pratap, Singh, Ningthoujam Premjit, Gilbert, Christopher C., Patel, Biren A. & Patnaik, Rajeev, 2023, First report of rodents from the Miocene Siwalik locality of Dunera, Pathankot District, Punjab, India, Palaeontologia Electronica (a 49) 26 (3), pp. 1-27 : 4-8

Genus TAMIAS Illiger, 1811

Remarks. Tamias , Eutamias , and Neotamias are here considered subgenera of the genus Tamias (cf. Nowak, 1999; Wilson and Reeder, 2005).

Type species. Tamias (Eutamias) urialis (Munthe, 1980)

cf. Tamias urialis (Munthe, 1980)

Figure 2

Holotype. H-GSP 2013 , left mandible fragment with m1-m2.

Type locality. H-GSP locality 18, upper Chinji Formation, Miocene.

Referred materials. WIMF /A 4743 right M1/2 ( Figure 2A ); WIMF /A 4749 left m1/2 ( Figure 2B ).

Occurrence. Dunera locality, Punjab, India (study area); Middle Miocene of Dehari locality, Ramnagar, India; Middle Miocene to Late Miocene of Potwar Plateau, Pakistan; early Late Miocene Tapar locality, Kutch, India.

Descriptions. WIMF /A 4743 ( Figure 2A ) is an upper M1 or M2 with a U-shaped occlusal outline, tapering slightly from the buccal to the lingual side of the tooth. It is buccolingually broad compared to mesiodistal length ( Table 1). A paracone, metacone, and protocone are present, and these three cusps are similar in size and prominence. A hypocone appears to be absent, or otherwise indistinct in the distolingual portion of the tooth. A paraconule is absent, but a very small metaconule is present on the metaloph. The protoloph and metaloph are relatively well-defined, resulting in a prominent ‘V’-shape in the center of the occlusal surface. The protoloph is complete and relatively uniform in shape, while the metaloph becomes pinched as it approaches the protocone (i.e., between the metaconule and protocone). The anterior cingulum is well-developed, and a parastyle appears to be present in the mesiobuccal corner of the tooth. A small ridge or cuspule, perhaps interpretable as a small mesostyle, is present on the buccal margin of the tooth between the paracone and metacone.

WIMF /A 4749 ( Figure 2B ), a left m1/2, is rounded on its distal end and slightly wider than long ( Table 1). The three visible cusps, the protoconid, metaconid, and hypoconid are distinct, whereas the paraconid, entoconid, and hypoconu-

PALAEO- ELECTRONICA.ORG lid are indistinct or absent. The protoconid is the tallest of the three cusps. The hypoconid is slightly shorter and connected to the protoconid by a mesiodistally oriented cristid obliqua (=ectolophid) running between the bases of these two cusps. A very short mesial or anterior cingulum is present in the mesiobuccal corner of the tooth, forming a small mesiobuccal fovea (i.e., the anterosinusid) between the protoconid and the paralophid. A short protolophid (= metalophid) is very low and incomplete, running from the base of the protoconid turning mesially towards the anterior border of the tooth near the midline. A mesoconid and mesostylid are absent. The lingual side of the tooth is bordered by a ridge that continues around the distal end to connect with the posterolophid, forming a broad and open talonid basin. The tooth has four roots.

Comparison and Remarks. Munthe (1980) described the first fossil sciurid Eutamias urialis from the Middle Miocene Siwalik deposits of Daud Khel area of Pakistan. Wessels et al. (1982) collected additional fossil sciurid remains from the Chinji Formation (Middle Miocene) exposed in Banda Daud Shah and identified them as Tamias urialis (Munthe, 1980) , Sciurinae gen. et sp. indet. and Marmotini gen. et sp. indet. Cheema et al. (1983) recovered sciurid remains cf. Eutamias urialis from Siwalik deposits near Jalalpur in Pakistan, and then Cheema et al. (2000) further classified them as Eutamias urialis (gracile specimens) and Sciurinae gen. et sp. indet. (robust specimens). Flynn (2003) recognized additional sciurids, Callosciurus sp. from the Middle Miocene (14 Ma), Ratufa sylva from the Late Miocene (10.5 Ma) and cf. Ratufa sp. from the Early Miocene (17 Ma), Potwar Plateau, Pakistan. Where overlapping dental positions exist, the cf. Ratufa sp. upper molars from the Early Miocene of Pakistan are easily distinguished from the present M1/2 by their extensive enamel crenulation, the presence of a paraconule, a large metaconule, and a distinct mesostyle. In the Indian Siwaliks, Parmar et al. (2018) and Bhandari et al. (2021) reported Tamias urialis from the Middle Miocene Chinji Formation of Ramnagar and the Late Miocene of Tapar locality in Kutch, respectively. Most recently, Patnaik et al. (2022) described a new species of sciurid, Tamias gilaharee , from Tapar. The M1/2 of Tamias gilaharee is distinguished from WIMF /A 4731 and T. urialis by the combination of larger upper molars, a metaloph with a very large metaconule, a thick protoloph with a distinct protoconule, a constricted lingual metaloph, and a more distinct hypocone. As per Munthe (1980) and Wessels et al. (1982), the upper molars of Tamias urialis are more typically characterized by having high, thin protolophs, metalophs, posterolophs, a low lying anteroloph, a

Square Elements Mean length Mean width Mean root of Taxon Locality (n=sample (range) (range) width/ Age Reference width* size) in mm in mm length length

Tamias cf. eviensis Yapıntı, M 1/2 (n=1) 1.73 Turkey

Tamias cf. eviensis Yapıntı, M 1/2 (n=1) 1.72 Turkey

Tamias Altıntas 1, M1/2 (n=34) 1.53 anatoliensis Turkey (1.41-1.68)

Tamias Altıntas 2, M1/2 (n=16) 1.53 anatoliensis Turkey (1.45-1.62)

Tamias atsali Maramena, M 1/2 (n=9) 1.56 Turkey (1.50-1.60)

Tamias cf. eviensis Karaozu, M 1/2 (n=1) 1.46 Turkey

Tamias cf. eviensis Karaozu, M 1/2 (n=1) 1.51 Turkey

Tamias cf. eviensis Hayranlı 1, M1/2 (n=1) 1.56 Turkey

Tamias cf. eviensis Hayranlı 1, M1/2 (n=1) 1.49 Turkey

Tamias atsali Kangal 1, M1/2 (n=1) 1.59 Turkey

Tamias atsali Kangal 1, M1/2 (n=1) 1.54 Turkey

Tamias urialis Daud Khel, M 1/2 (n=13) 1.35 Pakistan (1.26- 1.44)

Tamias aff. atsali Suleymanlı 2, M1/2 (n=1) 1.41 Turkey

Tamias urialis Jalalpur, M 1/2 (n=1) 1.5 Pakistan

Tamias urialis Dehari, M 1/2 (n=1) 1.3 Jammu

( India)

Sciurinae Jalalpur, M 1/2 (n=1) 1.75 gen. et sp. indet. Pakistan

Tamias gilaharee Tappar, M 1/2 (n=1) 1.65 Kutch, India

Tamias urialis Banda daud M1/2 (n=1) 1.55 Shah

( H-GSP 107)

Tamias urialis Banda daud M1/2 (n=1) 1.48 Shah

( H-GSP 107)

Tamias urialis Banda daud M1/2 (n=1) 1.57 Shah

( H-GSP 107)

Sciurinae Banda daud M1 (n=1) 1.81 gen. et sp. indet. Shah

( H-GSP 107)

cf. Tamias urialis Dunera, M 1/M2 (n=1) 1.54 ( WIMF /A 4731) Punjab, India

Tamias Altıntas 1, m1 (n=14) 1.54 anatoliensis Turkey (1.42-1.65)

Tamias Altıntas 2, m1 (n=11) 1.63 anatoliensis Turkey (1.53-1.73)

Tamias atsali Maramena, m 1 (n=7) 1.70 Turkey (1.58-1.87)

Tamias atsali Kangal 1, m1 (n=1) 1.84 Turkey

2.1 1.21 1.91 Early Bosma et al., 2018 Miocene

2.05 1.19 1.88 Early Bosma et al., 2018 Miocene

1.93 1.26 1.72 Late Bosma et al., 2013

(1.75-2.06) Miocene

1.92 1.25 1.71 Late Bosma et al., 2013

(1.82-2.11) Miocene

1.98 1.27 1.76 Late Bosma et al., 2013

(1.92-2.07) Miocene

1.81 1.24 1.63 Late Bosma et al., 2013 Miocene

1.87 1.24 1.68 Late Bosma et al., 2013 Miocene

1.82 1.17 1.68 Late Bosma et al., 2013 Miocene

1.8 1.21 1.64 Late Bosma et al., 2013 Miocene

1.82 1.14 1.70 Late Bosma et al., 2013 Miocene

1.94 1.26 1.73 Late Bosma et al., 2013 Miocene

1.71 1.27 1.52 Middle Munthe, 1980

(1.48-1.80) Miocene

1.84 1.30 1.61 Late Bosma et al., 2013 Miocene

1.8 1.20 1.64 Late Cheema et al., 2000 Miocene

1.42 1.09 1.36 Middle Parmar et al., 2018 Miocene

2.3 1.31 2.01 Late Cheema et al., 2000 Miocene

2.1 1.27 1.86 Late Patnaik et al., 2022 Miocene

1.88 1.21 1.71 Middle Wessels et al., 1982 Miocene

1.92 1.30 1.69 Middle Wessels et al., 1982 Miocene

1.76 1.12 1.66 Middle Wessels et al., 1982 Miocene

2.5 1.38 2.13 Middle Wessels et al., 1982 Miocene

1.87 1.21 1.70 Middle This study Miocene

1.63 1.06 1.58 Late Bosma et al., 2013

(1.47-1.75) Miocene

1.64 1.01 1.63 Late Bosma et al., 2013

(1.55-1.74) Miocene

1.67 0.98 1.68 Late Bosma et al., 2013

(1.54-1.82) Miocene

1.83 0.99 1.83 Late Bosma et al., 2013 Miocene metaloph with a small metaconule, an indistinct hypocone, and a protoloph often lacking a protoconule.

The m1/2 of Tamias urialis is mainly characterized by the presence of three prominent cusps (metaconid, protoconid, and hypoconid), the absence of a mesostylid, entoconid, and mesoconid, a nearly complete metalophid ridge between the metaconid and protoconid, and a sharp ridge connecting the protoconid and hypoconid (Munthe, 1980; Wessels et al., 1982). Overall, the present lower molar ( WIMF /A 4749) is similar to the m1/2 of Tamias urialis except for its very short and incomplete metalophid. Tamias gilaharee m1/2 is characterized by the presence of four main cusps (protoconid, metaconid, hypoconid, and entoconid), a distinct anteroconid, a prominent hypolophid, anterosinusid, mesoconid, and a discontinuous anterolophid. The absence of an entoconid, mesoconid, anteroconid, and mesostylid in WIMF /A 4749 distinguish it from the m1/2 of Tamias gilaharee .

WIMF /A 4743 and WIMF /A 4749 are both within the size and shape range for upper and lower first and second molars of the sciurid Tamias urialis (see Figure 3 A-B). In addition, the observable positions and development of the cusps and crests in the Dunera specimens are also consistent with those previously described for T. urialis and distinct from other species of Tamias . Therefore, in light of the small sample size, these two specimens from Dunera are most similar to Tamias urialis , we tentatively classify them as cf. Tamias urialis .

Figures

FIGURE 2. 3D surface models of cf. Tamias urialis in occlusal views. A) WIMF/A 4743 right M1/2 (mirror-imaged); B) WIMF/A 4749 left m1/2. Note: Mesial towards the left and distal towards the right in all panels.

FIGURE 3. Scatterplot of molar size (sq. root of width*length) vs. shape (max. width/length) of Siwalik Tamias specimens. A) M1/M2; B) m1/m2. See Table 1 for data used in the plots. Note that minimum, mean and maximum values were used to approximate ranges of variation in large samples of Tamias anatoliensis, T. urialis, and T. atsali.