Muroidea, Illiger, 1811

Crespo, Vicente D., Ríos, María, Marquina-Blasco, Rafael & Montoya, Plini, 2025, The Early Miocene muroids (Muroidea, Rodentia) of the Ribesalbes-Alcora Basin (Spain): A thriving haven during a time of migration, Fossil Record 28 (1), pp. 187-218 : 187-218

Muroidea indet.

Fig. 8 Z

Localities. MAB 0 A.

Material (number of remains). MAB 0 A (1): 1 M 2.

Description. M 2 ( MAB 0 A; Fig. 8 Z ): small broken tooth. The protoloph is double, the anterior one being transverse and connected to the protocone, and the posterior one incomplete, without contacting the paracone. The mesoloph is double: the anterior is short and the posterior is medium, both parallel. The crest of the protocone is short and does not contact the mesoloph. The ectomesoloph is absent. The sinus is narrow and directed forward. The metaloph is anterior and connects with the entoloph. The posteroloph is long and isolated labially. There is a small posterior ridge of the hypocone, in the posterosinus.

Remarks. The tooth fragment displays characteristics consistent with those observed in Eumyarion , Pseudocricetodon , or Eucricetodon , including the presence of double mesolophs and the posterior crest of the hypocone. Given its diminutive dimensions and the presence of a double protoloph, it seems not plausible that this specimen can be attributed to the Eumyarion species identified at other localities. The Turkish fossil record is replete with small Eumyarion species, yet one m 1 has been described from the Blanquàtere 1 location, which belongs to one of these species ( Aguilar et al. 2010 b). It is imprudent to draw comparisons between the two, as they represent distinct elements. However, this combination of characteristics is absent in E. intercentralis or E. microps from Keseköy ( de Bruijn and Saraç 1991). A specimen from Sabuncubeli exhibits some resemblance but displays a longer mesoloph, and the two crests are fused. Additionally, it is larger in E. orhani ( de Bruijn et al. 2006) . The presence of double mesolophs or the posterior crest of the hypocone has been documented in Eucricetodon aquitanicus Baudelot & Bonis, 1968 from the Early Miocene ( Hugueney 1999 b), and in addition, the presence of double mesolophs has been documented in Eucricetodon atavoides Freudenthal, 1996 from the early Oligocene ( Freudenthal 1996; Gomes-Rodrigues et al. 2013), within the Eucricetodon genus. The species Sindemys aguilari ( Lindsay, 1988) from Pakistan and certain Asian Eucricetodon forms (see plate 7.3, fig. 12; Wessels 2009; Gomes-Rodrigues et al. 2012) exhibit this or a similar configuration, despite originating from outside the European and Turkish regions.

The complicated primitive morphology of the taxon precludes its categorisation within any specific genus. If the specimen were determined to belong to Eumyarion , it would represent the earliest known appearance of this genus in the Levantine basins from the Iberian Peninsula. Conversely, if the specimen belonged to Eucricetodon , it would represent the surviving member of the genus following the absence of representatives of the European MN 3 following the Cricetid Vacuum ( Hugueney 1999 b). Alternatively, it could be an exotic immigrant species from Asia or another continent during a period of widespread intercontinental migration.

Figures

Figure 8. Teeth of Eumyarion weinfurteri, Melissiodon sp., and Muroidea indet. From the Ribersalbes-Alcora-Basin. Eumyarion weinfurteri: A. Left m 1 (MAB 3-161); B. Left m 1 (MAB 3-162); C. Right m 1 (MAB 5-75); D. Left m 1 (MAB 5-76); E. Right m 2 (FS 1-29); F. Left m 2 (MAB 3-203); G. Right m 2 (MAB 3-206); H. Left m 2 (MAB 5-53); I. Right m 2 (MAB 5-54); J. Left m 3 (MAB 3-241); K. Right m 3 (MAB 3-242); L. Left m 3 (MAB 5-56); M. Right m 3 (MAB 5-57); N. Right M 1 (MAB 3-82); O. Left M 1 (MAB 3-83); P. Right M 1 (MAB 5-515); Q. Left M 2 (MAB 3-111); R. Right M 3 (MAB 3-133); S. Left M 3 (MAB 3-134); T. Left M 3 (MAB 3-135). Melissiodon sp.: U. Right m 1 (MAB 3-168); V. Left m 3 (MAB 3-169); W. Left M 1 (BC 1-32); X. Left M 3 (BC 1-31); Y. Left M 3 (MAB 3-727). Muroidea indet.: Z. Right M 2 (MAB 0 A- 43). Scale bar: 1 mm.