Paradelomys sp.
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publication ID |
https://doi.org/10.1186/s13358-022-00245-3 |
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persistent identifier |
https://treatment.plazi.org/id/497F1B1D-FFEB-DF62-C75F-456DFE11FA99 |
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treatment provided by |
Felipe |
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scientific name |
Paradelomys sp. |
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Paradelomys sp. in Hartenberger (1990)
Material. Ek H003, one fragment of right lower jaw bearing p4–m3; from Egerkingen α, (Swiss Jura); middle Eocene, MP 14.
Remark. According to Hartenberger (1969: 54–55),” this lower jaw is very small; with a reduced p4 indicating a primitive character, while the long hypolophid and the metaconid and entoconid equally robusts seem more evolved. Te anteroconid connected to the metaconid from the anterolophid (“cingulum antérieur”), the deep sinusid and the rather square shape of m1–m2 evoke Paradelomys ” (translation from French). He considered this as the most probable hypothesis given the absence of upper teeth.
Description of Ek H003. ( Fig. 54 View Fig ).
Dentary. Te body of the mandible is fragmentary, but the upper masseteric crest and the masseteric tubercle are preserved. Te position of the latter is much mesial, below the p4, while it is clearly more distal on Protadelomys cartieri and P. lugdunensis . Te ascending ramus starts between m2 and m3, while it is more posterior (after m3) on Protadelomys . Comparatively, on the lower jaws of Paradelomys crusafonti (MP16), the masseteric tubercle is below m1, and the uplift of the ascending ramus recalls the situation observed in Protadelomys .
p4. Tis tooth is much smaller (1.14 × 0.94 mm) than the molars (m1 = 1.34 × 1.16 mm). Te metaconid is mesial. Te protoconid is leaning against the metaconid buccally, being slightly lower as can be estimated on this moderately worn tooth. Te postprotocristid is relatively short. A weak mesiodistal extra-ridge descends distally from the metaconid. Te postmetacristid is well marked and short. Te asymmetrical sinusid is rather deep buccolingually. Te ectolophid is interrupted and lies low below the wear surface; it allows a communication between the sinusid and the mesoflexid. Te entoconid and hypoconid are isolated and relatively bulbous. Te entolophid is reduced to a short ridge from the entoconid and the prehypocristid is minute.
m1–m2–m3. Te m1 (1.34 mm) is shorter than the m2 (1.53 mm); its buccal border is damaged. Te m3 is a little shorter than the m2 (1.44 mm) but this length could be underestimated, as the buccal part of the posterior lobe is missing. Te anteroconid is located close to the mesial border of the protoconid from which it separates by a narrow antesinusid. Tis antesinusid separates from the anteroflexid on m2, due to the presence of an anterolophulid. Te latter is very low and does not reach the occlusal surface on m1 and m3. Te anterolophid prolongs the anteroconid and can be distinguished from the lingual part of the metalophulid I (premetacristid). Tis premetacristid connects, through an angle, to the buccal part of the metalophulid I. Tis buccal metalophid I reaches the top of the protoconid. Te postprotocristid is oblique and long, ending with a short spur/ ridge directed buccolingually towards the basin; there is no distinct mesoconid. Te ectolophid is short, interrupted at the level of the hypoconid mesial flank. Te entolophid bears an entoconulid, well distinct on m2 and m3. It is shrunken or discontinuous at the junction with the mesial end of the prehypocristid. Te posterolophid is continuous and follows the post-hypocristid. Te hypoconulid is not particularly swollen between the posterolophid and the post-hypocristid. Te posterolophid fuses with the distal flank of the entoconid on the m1 and m2, while it is more distinct on m3 due to the reduction of the posterior lobe. On the m3, the anterolophid runs straighter towards the lingual part of the metalophulid I. Its buccal part is not as well preserved and distinct as in the other molars.
Comparisons
Elfomys catalaunicus from Frontyana 1 (MP15; Bonilla-Salomón et al., 2016) most resembles this new taxon. Many similarities were observed between the two taxa: the shape of the postprotocristid, the short mesiodistal ectolophid, the absence of mesolophid, the deep sinusid, as well as the relationships between the anterolophid, metalophulid I, metaconid, and protoconid. However, E. catalaunicus is slightly smaller, whereas the p4 and m3 are longer than in the new species from Egerkingen.
Tis species differs from Paradelomys santjaumensis ( Bonilla-Salomón et al., 2016) a contemporaneous species of E. catalaunicus , even if they share a deep oblique sinusid together with a long postprotocristid. Te ectolophid is oblique, aligned with the postprotocristid in Paradelomys , whereas it is mesiodistal in Elfomys and in Ek H003.
Te morphology of these worn lower teeth could be compatible with that of the two weakly worn m2 and m3 from Laprade, previously referred to as Elfomys sp. (Hartenberger, in Sudre et al., 1990), but differs in the absence of a mesolophid.
| MP |
Mohonk Preserve, Inc. |
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