Mus musculus Linnaeus, 1758

Denys, Christiane, Gabriel, Nadine W., Lalis, Aude & Jenkins, Paulina, 2024, Subfossil rodents and tenrecs of Children’s Cave, Madagascar, Journal of Natural History 58 (25 - 28), pp. 796-839 : 809-811

Mus musculus Linnaeus, 1758

This small species is found today in all anthropogenic and natural ecosystems of Madagascar from 0 to 2500 m a.s.l. ( Soarimalala and Goodman 2011). Genetic studies have demonstrated that these mice belong to the subspecies M. m. gentilulus Thomas, 1919 and originated from Yemen ( Duplantier et al. 2002). Archaeological bone remains included material of M. musculus excavated from a late ninth to tenth century Islamic port site south of Ambanja ( Radimilahy 1998), and very few subfossils were listed. Mus musculus of unknown age is attested to in the south-eastern site of Andrahomana ( Burney et al. 2008), where some endemic rodents were dated between 4500 and 1500 BP, and at Ankilitelo ( Muldoon et al. 2009). Many M. musculus were also described from the Lavajaza site ( Denys et al. 2021). In Children’s Cave we found numerous remains of small murids that we can attribute to M. musculus based on small size, the disposition of the cusps of the prelobe of m1 and the presence of a hook on the upper incisor ( Figure 4f ).

Attributed material: Upper Stratum: 10 maxillaries; 52 mandibular rami; see Appendix.

On these specimens, the incisive foramen enters deeply into the palate and stops at the level of the t1 cusp of M1. The molars are relatively narrow. On M1 the cusps are arranged in three convex lobes, with t1 and t4 ending posteriorly to t3 and t6. The t1 cusp is compressed laterally. On M2 the t1 is very large and bunodont. On the very small M3 only two small anterior cusps and one small distal cingulum are visible. On m1 the four cusps of the prelobe are well linked together but the antero-labial one is very small and situated posteriorly compared to the large anterior antero-lingual cusp. On the anterolabial side of m1 and m2 one can see a small oblique cingulum. The m1 and m2 display a small posterior cingulum of about the same size. On the very small m3 one can see two rows of cusps. The first row is composed of two equal cusps while the second row has only a small median cusp ( Figure 4f ).

The size of the upper molar rows as well as the width of M1 fit well with modern Mus musculus specimens of Madagascar ( Table 3, Figure 7 ).

Figures

Figure 4. Rodent dental material from Childrens’s Cave.(a) Left upper molar row of B. betsileoensis NHMUK PV M 105365; (b) Right lower molar row B. betsileoensis NHMUK PV M 105196; (c) Right upper molar row R. rattus NHMUK PV M 105616; (d) Left upper molar row of M. cf. bastardi NHMUK PV M 102315; (e) Left upper molar row of M. cf. bastardi NHMUK PV M 102316;(f) Right lower molar row of Mus musculus NHMUK PV M 105164-sequence; (g) Right lower molar row M. cf. bastardi NHMUK PV M 105123; (h) Left m1 M. cf. bastardi NHMUK PV M 104879; (i) Left m1 and m3 M. cf. bastardi NHMUK PV M 105124.

Figure 7. Scatter diagram of dental measurements of modern Mus musculus and specimens from Lavajaza. Top:LS13:length of the upper molar row, WM1: width of M1. Measurements in mm. Bottom: length of the mandible (LMDB), L13: length of the lower molar row.