Microdyromys legidensis Daams 1981
Creators: name: Crespo, Vicente Daniel
name: Ríos, María
name: Marquina-Blasco, Rafael
name: Montoya, Plini
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Rodentia
Gliridae
Microdyromys
Microdyromys legidensis

description: Microdyromys legidensis Daams, 1981
(Fig. 3 A-AD)
LOCALITIES. — MAB3, MAB5, MAB11, CBR0B, CBR0D, and CBR1.
MATERIAL. — MAB 3: 1 d4, 3 p4, 7 m1, 8 m2, 1 m3, 2 P4, 3 M1, 6 M2, 3 M3; MAB 5: 4 p4, 3 m1, 2 m2, 2 m3, 6 P4, 7 M1, 4 M2, 8 M3; MAB 11: 1 M2; CBR 0B: 1 M2; CBR 0D: 1 P4; CBR 1: 2 M1.
MEASUREMENTS. — Appendix 2
DESCRIPTION
d4 (MAB3)
The tooth is subtriangular, with high and fine crestids. The anterolophid is short. The metalophid is long and connects both sides of the specimen. The mesolophid and the posterolophid are curved, long, and interconnected.The mesolophid is irregular.
p4 (MAB 5)
The tooth is subtriangular in occlusal view, with high and fine crestids and narrow valleys. The anterolophid is short. The metalophid is short and semi-circular. The mesolophid and the posterolophid are long, curved and interconnected. The posterotropid may be well developed (in 1 out of 4 specimens), medium (2 out of 4) or short (1 out of 4). In one specimen the crestids are irregular. In the rest of sites, the material is similar to the one described here.
m1 (MAB 3)
Tooth subrectangular in occlusal view. The anterolophid and the anterotropid are short. The metalophid is curved, and not connected in the lingual side in one specimen. The anteroconid and the metaconid are interconnected. The centrolophid is longer than half of the tooth width, and it is connected with an angle of 90° with the endolophid; in two specimens it is independent. The mesolophid and the posterolophid are long and well connected. The posterotropid is well developed and in one specimen it is connected in the lingual side. The labial cuspids are more developed than the lingual ones. In the material from MAB 5 the centrolophid is always connected in the lingual side.
m2 (MAB 3)
The tooth is of subrectangular shape in occlusal view. The anterolophid may be short (3 out of 7) or long (4 out of 7). The anterotropid may be short (3 out of 8) or long (5 out of 8), in two specimens this crestid is connected with the centrolophid, showing a shorter metalophid, which may be curved (4 out of 6) or straight (2 out of 6); in three specimens the metalophid is not connected in the lingual side. The anteroconid and the metaconid are connected. The centrolophid length exceeds half of the width of the tooth, and the crest is perpendicularly connected to the endolophid. The mesolophid and the posterolophid are long and well connected. There is a well-developed posterotropid. The labial cuspids are better developed than the lingual ones. In the material from MAB 5 the anterolophid is always short, the anterotropid may be absent, the metalophid is always curved and not connected in the lingual side, and the centrolophid is lower than in the MAB 3 material.
m3 (MAB 5)
The outline in occlusal view is subtriangular. The anterolophid has a medium size. The metalophid is curved and not connected with the endolophid. The anteroconid and the metaconid are connected. The centrolophid is as long as half of the tooth width, and is not connected with the metalophid. The mesolophid and the posterolophid are long and well connected. The posterotropid is low. The labial cuspids are better developed than the lingual ones. The material from MAB 3 has a developed anterotropid and the centrolophid is never isolated.
P4 (MAB 5)
Tooth with a rounded outline in occlusal view.The endoloph may be present and complete (2 out of 4) or lacking (2 out of 4). The anteroloph is variable:it may be long and labially isolated (1 out 5), short and connected to both sides (1 out of 5), completely isolated (2 out of 5) or absent (1 out of 5). The protoloph and the metaloph are long, straight, and isolated. The precentroloph may be long and isolated (2 out of 5), or connected (3 out of 5). The postcentroloph may be absent (4 out of 5), or long (1 out of 5). The posteroloph is longer than the anteroloph and labially isolated. In the MAB 3 material the endoloph is complete and the anteroloph is always short. The tooth from CBR 0D is similar to the material from MAB 5 described before.
M1 (MAB 5)
Tooth with a subquadrate outline in occlusal view. The anteroloph may be relatively short (5 out of 6) or long (1 out of 6). The endoloph is complete, although it is narrower in its contact with the anteroloph. The protoloph and the metaloph are independent. The prototrope may be either long (1 out of 6), short and low (3 out of 6), or it may be absent (2 out of 6). The precentroloph is longer than half of the tooth width and may almost reach the lingual side (4 out of 6) or slightly beyond half of the tooth width (2 out of 6); in one specimen it is connected to the protoloph. The postcentroloph may be absent (1 out of 6), and when present it may be short (3 out of 6) or long (2 out of 6), and it may be isolated (2 out of 5) or not (3 out of 5). The posteroloph is short and not-connected in the labial side. The labial cusps are more developed than the lingual ones. The lingual ornamentation is poorly developed. The material from MAB 3 and CBR 1 is similar to the one found in MAB 5.
M2 (MAB 3)
The tooth is subquadrate in occlusal view. The anteroloph may be relatively short (2 out of 4) or long (2 out of 4). The endoloph is complete. The protoloph and the metaloph are independent. The prototrope may be either long and low (2 out of 6), short and low (1 out of 6), or it may be absent (3 out of 6). The precentroloph is longer than half of the tooth width, and almost reaching the lingual side (5 out of 6), or only slightly longer than half of the width tooth (1 out of 6). The postcentroloph is short, and it may show a connection to another crest (2 out of 5), or not (3 out of 5). The posteroloph is short and independent in the labial side. The labial cusps are more developed than the lingual ones. The lingual ornamentation is poorly developed. The material from MAB 5, MAB 11 and CBR 0B is similar to the one described here.
M3 (MAB 5)
The tooth is trapezoidal in occlusal view. The anteroloph is long. The endoloph is complete. The protoloph and the metaloph are independent. The prototrope may be absent (2 out of 6) or present, in which case it is low and can be either long (3 out of 6) or short (1 out of 6). The precentroloph is either longer than half of the tooth width and almost reaching the lingual side (5 out of 6), or just until half of the tooth (1 out of 6); this crest may be isolated (4 out of 5) or not (1 out of 5); in one specimen it is connected to the metaloph. The postcentroloph may be absent (1 out of 6), but when present it is either short (4 out of 6) or long (1 out of 6); it may be either disconnected (4 out of 5) or connected to the endoloph (1 out of 5). In one specimen there is a metatrope, in another one the pattern of crests is chaotic and not easily distinguished. The posteroloph is short and without connection in the labial side. The labial cusps are more developed than the lingual ones. The lingual ornamentation is poorly developed. The MAB 3 material is similar to the one described here.
REMARKS
The genus Microdyromys is widely distributed along the European Cenozoic (Freudenthal & Martín-Suárez, 2007a), and it is probably paraphyletic (Lu et al. 2021; Dalmasso et al. 2022). The first record of this genus is in the locality of Aguatón 2D from the upper Eocene (Freudenthal 2004), while the last representative is Microdyromys sinuosus (Álvarez-Sierra, 1986) from the Upper Miocene of Ampudia 3 (MN10). This genus has also been reported in the Middle Miocene of Asia (Álvarez-Sierra & García-Moreno 1986; García-Paredes et al. 2010).
Three taxa of the genus Microdyromys are present in the Ribesalbes-Alcora Basin as listed below, and they are described for the first time in this basin. After Vianey-Liaud (2003) they can be distinguished based on the following criteria: Microdyromys aff. monspeliensis Aguilar, 1977 is the smallest one and the simplest in teeth morphology, with less extra crests; Microdyromys koenigswaldi De Bruijn, 1966, is the largest species, with a long and well-developed extra crest; and Microdyromys legidensis is the most abundant species, intermediate in size and with short and low extra crests.
Microdyromys legidensis is a species typical from the Early-Middle Miocene basins of the interior region of the Iberian Peninsula (Vianey-Liaud 2003; Van der Meulen et al. 2012), and has been described by Daams (1981) in Villafeliche 2A (local biozone B, MN4). Daams (1981) described different morphotypes depending on the presence or absence of centroloph/ids and extra crests in the upper and lower molars. In the Ribesalbes-Alcora Basin, the dominant morphotypes for upper molars are morphotype H, with the presence of a prototrope, and to a lesser degree morphotype G, characterized by lacking extra crests. This combination of morphotypes is typical of the Calatayud-Montalbán Basin. As for the lower molars, all specimens belong to morphotype 3, with more or less developed anterotropids and posterotropids. It is also the prevailing morphotype in M. legidensis (Daams 1981). The combination of upper and lower molars morphotypes is the expected one for this species according to Vianey-Liaud (2003).
Our material is similar in size to the specimens assigned to M. legidensis and described in Bouzigues, St. Victor la Coste and Villafeliche 2A (Daams 1981), and it is slightly larger than the populations described in Coderet and Montalvos 2 (Hugueney 1969; Hordijk et al. 2015).
description: Published as part of Crespo, Vicente Daniel, Ríos, María, Marquina-Blasco, Rafael & Montoya, Plini, 2023, They are all over the place! The exceptional high biodiversity of dormice in the Early Miocene of the Ribesalbes-Alcora Basin (Spain), pp. 589-641 in Geodiversitas 45 (20) on pages 592-595, DOI: 10.5252/geodiversitas2023v45a20, http://zenodo.org/record/10137206