Paracricetodon, Schaub, 1925

Maridet, Olivier, Codrea, Vlad A., Fărcaș, Cristina, Solomon, Alexandru A., Venczel, Márton & Tissier, Jérémy, 2025, The record of cricetid rodents across the Eocene-Oligocene transition in Transylvania, Romania: implications for the “ Grande Coupure ” at European scale, Acta Palaeontologica Polonica 70 (2), pp. 291-327 : 312-316

Paracricetodon cf. Pa. walgeri Bahlo, 1975

Fig. 13A–E.

Material.—Two upper molars from Suceag and 4 molars from Cetățuie, Rupelian, lower Oligocene, Dâncu Formation, Gilău sedimentary area, Transylvanian Basin, Romania.

Measurements.—See Table 10. Description.—The molars are characterized by strong loph(id)s and rounded cusp(id)s in lateral view. The molars are slightly smaller than that of Eucricetodon aff. Eu. huerzeleri and Tenuicricetodon arcemis gen. et sp. nov., whereas the crown is proportionally slightly higher.

The M1s have a wide mesial lobe with a strong anterocone bearing two anterostyles associated to a well-developed protostyle. The anterocone is connected to the protocone by a long and thick anterolophule. Additionally, in one tooth a distal spur is starting from the protostyle ( Fig. 13A), but not reaching the protocone; another tooth has a minute parastyle located on the labial border just mesially to the paracone. The teeth have one protolophule connected either on the protocone or on its distal part. The mesostyle is well developed, either connected to the paracone and metacone by a cingulum closing the mesosinus, or isolated on the labial border. A short and low cingulum can be present on the border next to the paracone delimiting a little pit labially to the paracone. The mesoloph is long but does not always reach the mesostyle. The sinus is deep and closed by a low but strong lingual cingulum; one tooth also has a well-developed ectostyle located on this cingulum. The metalophule is straight, transverse, and connects on the hypocone. The posterosinus is small, closed labially and delimited by a short but very thick posteroloph. One M1 shows three roots ( Fig. 13A).

M3s are characterized by a long and strong labial anteroloph whereas the lingual anteroloph is thin and much lower. The labial anteroloph does not reach the paracone but a small cingulum links the anteroloph to the paracone so the anterosinus remains closed labially. The mesial protolophule connects on the anterolophule. A cingulum closes the mesosinus and and connects to the thick posteroloph. Three crests are present in the middle of M3s, connected by the entoloph: the distal protolophule (short), the mesoloph (long and reaching the labial cingulum) and the metalophule (joining the posteroloph labially). The connections between the protocone and the entoloph are either weak or discontinuous, forming a longitudinal valley between a mesosinus and the sinus. The metacone is either absent or too small to be observable. One of the M3s has three preserved roots ( Fig. 13D).

The m2 ( Fig. 13E) has both the lingual and labial anterolophulid equally long and well developed; the anterosinusid and protosinusid are closed respectively lingually and labially. The metalophulid can be present or absent whereas the protoconid hind arm is always well developed and almost reaches the metaconid. The mesolophid can be short or long; it starts from a small entomesolophid. The hypolophulid is slightly oblique and connected on the ectolophid, at a point between the mesoconid and the hypoconid. The mesosinusid is closed lingually by a low cingulid whereas the labial cingulid is discontinuous so the sinusid remains labially open. The posterosinusid is wide, closed lingually, delimited by a long posterolophid. The roots are not preserved.

Remarks.— The size of these teeth from Cetățuie and Suceag ( Fig.12) fall within the range of Paracricetodon walgeri from its type locality of Heimersheim (Bahlo 1975) except for one M2, which is only slightly larger. The teeth are otherwise often smaller than Paracricetodon kodjayarmensis from Kocayarma ( van de Weerd et al. 2018), than Paracricetodon kavakderensis from Kavakdere ( van de Weerd et al. 2018) and than Paracricetodon dehmi from Bernloch (Hrubesch 1957). They are also noticeably smaller than Trakymys saratji , Paracricetodon spectabilis , Paracricetodon cadurcensis and Paracricetodon confluens (see van de Weerd et al. 2018 for an exhaustive size comparison of all species of Paracricetodon ). Finally, they are constantly larger than Paracricetodon stojanovici from Buštranje ( van de Weerd et al. 2018), Paracricetodon gracilis from Valniš ( van de Weerd et al. 2018 a) and Paracricetodon wentgesi from Süngülü B (de Bruijn et al. 2003).

Among the species of closest sizes, the specimens from Transylvania differ from Paracricetodon kodjayarmensis and Paracricetodon kavakderensis in having M1s with rather distally oriented protolophule and straight metalophule. They also differ in missing the hypoconid hind arm and in having a longer mesolophid in m2, and in having more complex M3s with both the protocone hind arm and entoloph joining the hypocone and two mesolophs. In contrast, some features observed on the above-described specimens fit well the diagnosis of Paracricetodon walgeri : The weak or interrupted metalophid as opposed to the well-developed entolophid and protoconid hind arm in m2. The thin or interrupted entoloph in m2. The protoloph oriented backward and connected, either to the distal part of the protocone, or to its hind arm whereas the hypoconid is straight and connects directly to the hypocone in M1. They otherwise differ in missing the protoconid hind arm in m2 and having shorter M3s.

Therefore, considering the few differences compared to Paracricetodon walgeri , and keeping in mind that we do not know much about the variability of this population from Transylvania, we tentatively refer these specimens from Suceag (upper level) and Cetățuie to this species as Paracricetodon cf. Paracricetodon walgeri .

Paracricetodon kavakderensis Ünay-Bayraktar, 1989 Fig. 13F–M.

Material.—One lower molar from Mera, seven molars from Cetățuie and one upper molar from Suceag, Rupelian, lower Oligocene, Dâncu Formation, Gilău sedimentary area, Transylvanian Basin, Romania.

Measurements.—See Table 11. Description.—The molars are characterized by a high crown (at least higher than the other early Oligocene taxa described herein); in lateral view the cusp(id)s are bulk and high separated by deep valleys.

The two M2s have a very long labial anteroloph starting from the protostyle, itself connected directly to the protocone; in contrast, the lingual anteroloph is weak and low. The protocone spur does not reach the anteroloph but instead connect to the paracone forming an mesial protolophule. The distal protolophule is also complete; it starts from protocone ( Fig. 13F) or from the protocone mesial spur ( Fig. 13G). The entoloph interrupts between the mesoloph and the protocone, instead the protocone distal arm connects directly to the mesoloph or distally to the mesoloph. In one M2 ( Fig. 13G), the paracone spur forms a loop delimiting a small pit labially to the paracone, in the other M2 it connects to the mesostyle and a low cigulum delimits the same small labial pit. Additionally, a cingulum between the paracone spur and the metacone closes the mesosinus labially. Lingually the sinus can be open or closed by a small cingulum. The metalophule connects to the entoloph at a point between the hypocone and the mesoloph. One M2 displays additional weakly-developed spurs mesially and distally to the metalophule ( Fig. 13F). The posterosinus is large and the posteroloph is long. One of the M2s has three preserved roots ( Fig. 13G).

The M3 is partly broken (the antero-labial corner and distal part, Fig. 13H). Like the M2s, it has a very long labial anteroloph and a weak and low lingual anteroloph. The protocone spur does not reach the anteroloph or the paracone but ends in the anterosinus. Both the entoloph and the protocone distal arm are present; the entoloph connects the distal protoloph to the mesoloph whereas the protocone distal arm directly connects the protocone to the hypocone. The mesoloph is long, with a very small mesostyle at its extremity. The mesostyle is merged into a cingulum that closes the mesosinus labially. Additionally, a small transversal spur starts opposite to the mesoloph and links the entoloph to the protocone. The M3s has three roots.

In m2s, both the lingual and labial anterolophids are well developed; they are connected to the protoconid by a long anterolophulid. The metalophulid connects on the anterolophulid; additionally, one m2 has a metaconid spur that connects to the lingual anterolophid ( Fig. 13J). The protoconid hind arm is long; it can end in the mesosinusid ( Fig. 13K) or form a loop and connect to the metaconid ( Fig. 13J). The mesoconid is always well developed and is the starting point of both a short mesolophid and a short ectomesolophid. The metaconid ridge is long and reaches the entoconid so the mesosinusid is always closed lingually. Likewise, a cingulum always closes the sinusid labially. The hypolophulid is straight and connects on the ectolophid, mesially to the hypoconid. The hypoconid hind arm is always well developed; it can end in the posterosinusid (2/4) or connect to the entoconid distal slope (2/4). Both the posterosinusid and the posterolophid are well developed too, but in contrast labial posterolophulid and labial posterosinusid are either very weakly (2/4) developed or absent (2/4). The m2s have two roots.

The two m3s display a mesial part similar to that of the m2s: both the lingual and labial anterolophids are well developed and connected to the protoconid by an anterolophulid; the metalophulid also connects on the anterolophulid and one m3 has a metaconid spur that connects to the lingual anteroloph ( Fig. 13L); the protoconid hind arm is long and ends in the mesosinusid. Otherwise, as opposed to m2s, the mesolophid and ectomesolophid are absent, the labial cingulum either is interrupted or absent, so the sinusid remains open. The distal part of the tooth is rounded due to very large posterosinusid and posterolophid, but the hypoconid hind arm, the labial posterolophulid and the labial posterosinusid are absent. The m3s have two roots

Remarks.—Except for two m2s slightly larger, the above specimens fit quite well in the size range of both Paracricetodon dehmi from Bernloch and Paracricetodon kavakderensis from Kavakdere ( Fig. 12). They are otherwise slightly smaller than Pa. kodjayarmensis from Kocayarma and much smaller than Trakymys saratji from Kavakdere. They are also larger than Paracricetodon stojanovici from Buštranje ( van de Weerd et al. 2018), Paracricetodon gracilis from Valniš ( van de Weerd et al. 2018) and Paracricetodon wentgesi from Süngülü B (de Bruijn et al. 2003). Paracricetodon spectabilis , Paracricetodon cadurcensis , and Paracricetodon confluens are also much larger; see van de Weerd et al. (2018) for an exhaustive size comparison of all species of Paracricetodon .

It is worth noticing that one M2 from Suceag ( Fig. 13F) and one m2 from Cetățuie ( Fig. 13I) show more complex occlusal patterns due to the presence of low and weakly developed spurs, which remind the morphology of Trakymys saratji , but in a lesser extant. However, the size and the morphology of the other teeth seem to exclude a close affinity with this species.

Ünay-Bayraktar (1989) noticed the similar size between Pa. kavakderensis and Pa. dehmi but emphasized that they clearly differ in Pa. kavakderensis “having a smaller m3, a weaker hypocone and shallower sinus in the M3”. The size of m3s from Transylvania falls in the range of both species, but the only M3 yielded by the layer of Cetățuie shows a weak hypocone and shallow sinus that better fit the description of Pa. kavakderensis ( Ünay-Bayraktar 1989) . Paracricetodon kavakderensis and Pa. kodjayarmensis are also of similar sizes, but Ünay-Bayraktar (1989) stated that the lower molars of Pa. kavakderensis differs from Pa. kodjayarmensis by being narrower, especially m3s. The width of m3s from Transylvania Fig. 12) is noticeably less than those of Pa. kodjayarmensis which also suggest a similarity with Pa. kavakderensis .

The above specimens and Pa. kavakderensis also share several morphological features that also differentiate them from Pa. kodjayarmensis and Pa. dehmi : generally, longer distal arms of the labial cusps in lower molars and longer mesial arms of the lingual cusps in upper molars. In M2, a well-developed protocone spur connects to the paracone to form a mesial protolophule. Both the mesial and distal protolophules delimiting a large pit between the protocone and paracone; the paracone distal spur forms a loop delimiting a small pit labially to the paracone. In M3 the metalophule is well developed and connects the hypocone to the distal cingulum.

We consequently refer these specimens from Suceag, Cetățuie and Mera to Pa. kavakderensis .

Stratigraphic and geographic range.—Rupelian (Early Oligocene) of Lesser Caucasus ( Turkey) and Transylvania ( Romania)