Berrulestes poirieri, Hooker & Russell, 2012
|
publication ID |
https://doi.org/ 10.1111/j.1096-3642.2011.00787.x |
|
persistent identifier |
https://treatment.plazi.org/id/03DE8792-FF8A-6556-FCB8-FD0DFC55FE14 |
|
treatment provided by |
Marcus |
|
scientific name |
Berrulestes poirieri |
| status |
sp. nov. |
BERRULESTES POIRIERI SP. NOV. ( FIGS 8 View Figure 8 , 13, 14 View Figure 14 )
vp 1964 Louisina mirabilis Russell ; Russell, pl. 15,
fig. 2b (M 2).
Etymology: After Monsieur M. Poirier for finding key specimens of the species.
Holotype: RM 1 , MNHN.F.I-725, bed 5, Berru.
Paratypes: LP 3 , MNHN.F.CR-465-Ph; RM 2 , MNHN. F.CR-316-L; two LM 2 s, MNHN.F.CR-86-Bn, CR-371- Pn; five RM 2 s, MNHN.F.CR-1119, CR-99-Bn, CR-286- Bn, CR-1692-Pn, IRSNB.CR-101A-Wouters; RM 3 , MNHN.F.CR-208; all Cernay.
LM 1, MNHN.F.BRL-194-P; LM 3, MNHN.F.BRL-18- Pn; both bed 4, Berru. RP 3, MNHN.F.PM(Poirier- Manganaste)L-037, bed 4, Berru?
RP 4, MNHN.F.I-573; LM 2, MNHN.F.BR-17478; two RM 2 s, MNHN.F.I-688, I-693; RM 3, I-261; all bed 5, Berru.
Referred material: Two LM 2 s, MNHN.F.CR-318-L, CR-320-L; two RM 2 s, MNHN.F.CR-319-L, CR-312-Bn; all Cernay. RDP 4, MNHN.F.BRL-5-F; bed 4, Berru. RM 3, MNHN.F.I-713; bed 5, Berru.
Cast in MNHN.F: LM 2, B-234-CGH, bed 5, Berru.
Age and distribution: Sables de Châlons-sur-Vesle supérieurs, late Thanetian, Late Palaeocene, Cernay and Berru (beds 4, 5), France.
Diagnosis: Large Berrulestes , length of M 1 3.44 mm. Cusps of cheek teeth somewhat bulbous (shared with B. phelizoni ). P 4 with metaconid restricted mesially. M 1 with connate paracone and metacone and postcingulum not joining confluent postmetaconule crista and metacingulum (shared with B. phelizoni ). M 1 hypocone significantly lower than protocone. M 1–2 comparable. Instead it appears to occlude better with P 3 of the holotype of B. phelizoni , where contact would have been between the tips of the protocone and hypoconid. However, this P 3 is too large to belong to B. phelizoni so is referred instead to the closely related but larger B. poirieri .
M 1: It is the largest of this tooth type in the collection of louisinines ( Fig. 13B). It is 3.48 mm long by 4.21 mm wide. It is therefore relatively transversely elongate. The paracone and metacone are connate and there is no premetaconule crista. These proportional and morphological characters differ from the otherwise similar B. phelizoni . In common with B. phelizoni , the postcingulum dips basally and dies out without joining the metacingulum.
with shallow postflexi (shared with B. pellouini ). Lower molars with paraconid very small to absent. Lower molar precingulid an extensive ridge, not bulging mesially. M 1 talonid shorter and narrower than trigonid. M 1–2 protoconid height less than tooth width.
Description
P 3: This tooth is Paschatherium -like in general outline (e.g. see Teilhard de Chardin, 1927: fig. 3e, g). MNHN.F.CR-465-Ph is 3.43 mm long by 3.12 mm wide, whereas MNHN.F.PML-037 is 3.19 mm long by 3.06 mm wide. The former ( Fig. 13A) is slightly more worn than the latter, but the latter is slightly eroded basally. They are large, with thick enamel and relatively bulbous cusps, although the buccal wall is vertical not lingually tilted as in upper cheek teeth of G. meyeri (q.v.). The paracone is the dominant cusp, with a much smaller metacone developed on its distal flank. The protocone is tiny with a distal cingulum that extends as far as a tiny metastyle. The parastyle is very low and crestiform. The distal half of the buccal wall is bordered by an ectocingulum, which ends mesially by rising a short distance up the paracone wall. The protocone is too small to occlude well with the relatively extensive talonid basin of the P 3 of the large G. meyeri , although enamel thickness is M 2: The tooth is damaged buccally. It is of similar size and cusp structure to M 1 ( Fig. 13C). It is 3.17 mm long. It differs in being mesiodistally narrow lingually, in the metacone being more lingually situated than the paracone, and in the postcingulum joining the metacingulum. There is no link to the metaconule, which lacks a postmetaconule crista. A confluent paracingulum–precingulum reaches lingually scarcely farther than the level of the weak paraconule. The appearance of distal attenuation matches the reduced talonid of M 2.
P 4: The tooth is 3.54 mm long by 2.11 mm wide at the trigonid ( Fig. 13E). The trigonid is proportionally longer and wider than that of any B. phelizoni P 4 s. This and the large size suggest that this tooth belongs to B. poirieri , rather than to B. phelizoni , although there are not enough specimens to demonstrate it statistically ( Fig. 8C View Figure 8 ).
M 1: The tooth is 3.44 mm long by 2.90 mm wide. It is similar to that of B. phelizoni . However, the trigonid and talonid are more erect and the protocristid, even with relatively light wear, is not notched ( Fig. 13F). The cristid obliqua is longer and stronger and less steeply dipping, whereas the back of the talonid is more vertical, allowing occlusion of an upper molar with equal-sized paracone and metacone, rather than of a Gigarton - type upper molar with an enlarged metacone. In fact the tooth is more like an enlarged version of a B. phelizoni M 2, but with wear beginning to fuse the protoconid and metaconid at a greater height on the crown. The main reason for identifying it as M 1 rather than M 2 is because it has a slight ectoflexid, immediately distal of which the talonid bulges slightly buccally. For occlusion, the M 1 fits it well, the connate paracone and metacone matching the reduced size of the talonid compared to B. phelizoni . In addition, lower molars with relatively smaller talonids can be attributed to M 2 (see below).
M 2: These teeth are like a very inflated version of B. phelizoni M 2 s, but larger ( Fig. 8B View Figure 8 ) and with a shorter, narrower talonid with weaker cristid obliqua ( Fig. 13G, I). The trigonid is massive and the talonid greatly reduced. Trigonid width shows substantial variation ( Table 4). The paraconid is either tiny ( Fig. 13G) or absent ( Fig. 13I 2–I View Figure 2 4 View Figure 4 ). The paracristid is very weak and recurves to join the base of the metaconid. Unlike B. phelizoni , the metaconid lacks a strongly mesially convex premetacristid. The valley between the protoconid and metaconid varies in depth, but may extend mesially as far as the paracristid. There is much variation in relative widths and heights of the trigonid and talonid. There is also variation in the extent of the precingulid. There is sometimes a small ectostylid ( Fig. 13I 3 View Figure 3 , I 4 View Figure 4 ).
M 3: All four teeth are distinctly bunodont, have a very small paraconid, and a buccally bowed paracristid as on M 2 ( Fig. 13H, J). Three of them have a relatively short narrow talonid in contrast to B. phelizoni and B. pellouini ( Figs 13H 1 View Figure 1 , J, 14 View Figure 14 ). The exception, MNHN.F.I-713, the largest at 3.42 mm long, appears to have a relatively longer talonid, but it is corroded buccally and may have originally had proportions similar to the others. In length–width proportions, they differ from the otherwise similar but smaller B. phelizoni . MNHN.F.I-261 and MNHN.F.CR-208 have lingually positioned hypoconulids and the latter also lacks an entoconid ( Fig. 13J).
DP 4: This tooth is broken in the region of the parastyle and the metacone–metastyle region has been refitted slightly crookedly ( Fig. 13D). A width measurement of 3.30 mm seems reliable and as such it is the largest probable DP 4 in the collection. Wear is very light. The main cusps are relatively gracile and the enamel is relatively thin. Despite mesial breakage, the tooth appears to have been longer than wide and would originally have tapered somewhat mesially. All these are features of a DP 4. The paraconule is fairly weak and has no postparaconule crista. There is a strong metaconule and a postmetaconule crista that is confluent with the metacingulum. There is almost no premetaconule crista. The postcingulum does not meet the postmetaconule crista–metacingulum, giving rise to a sharp postflexus. The trigon basin is relatively deep. Two features suggest that it does not belong to B. phelizoni : a size that is larger than most M 1 s of that species; and small size of the hypocone. Both are instead suggestive of B. poirieri .
Discussion: Although not represented by all the main tooth loci, the features of large size and the trigonid– talonid proportions of the lower cheek teeth in combination with the occlusally matching closely spaced M 1 paracone and metacone make this species distinctive and distinguishable from its close relative B. phelizoni (q.v.).
| MNHN |
Museum National d'Histoire Naturelle |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.