Walbeckodon girardi, Hooker & Russell, 2012
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publication ID |
https://doi.org/ 10.1111/j.1096-3642.2011.00787.x |
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DOI |
https://doi.org/10.5281/zenodo.10544450 |
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persistent identifier |
https://treatment.plazi.org/id/03DE8792-FF95-6540-FC63-FB1AFB7BFCD8 |
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treatment provided by |
Marcus |
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scientific name |
Walbeckodon girardi |
| status |
sp. nov. |
WALBECKODON GIRARDI SP. NOV.
( FIGS 5A View Figure 5 , 6A–H View Figure 6 , 7A View Figure 7 , 8 View Figure 8 )
vp 1885 Adapisorex remensis Lemoine ; Lemoine: p.
210, pl. 10, fig. 2. vp 1927 Adapisorex sp. ; Teilhard de Chardin: p. 10. vp 1964 Adunator lehmani Russell : 47–50, pl. 3,
figs 1–3. vp 1964 Paschatherium ?; Russell: p. 240 (CRL-825). vp 1964 Paschatherium petri Russell : p. 305 (CRL-
825).
Etymology: After Monsieur J.-L. Girard for finding key specimens of the species.
Holotype: L dentary fragment with M 1–3, MNHN.F.CR-330, Cernay.
Paratypes: RP 3, MNHN.F.CR-134-Ph; RP 4, MNHN. F.CR-4412; three LM 1 s, MNHN.F.CR-81-Pn, CR-7-Bn, CR-4442; 2 RM 1 s, MNHN.F.CR-1229, CR-329-Bn; RM 2 , MNHN .F.CR-116-Ph; RM 3 , MNHN .F.CR-334-L; L dentary with P 4 –M 2, MNHN.F.CRL-825; R dentary with M 1–2, MNHN.F.CR-331; LP 4 , MNHN .F.CR-1225;
OR, observed range; SD, standard deviation; V, coefficient of variation (SD as percentage of the mean).
two RP 4 s, MNHN.F.CR-11906, CR-168-Bn; three LM 1 s, MNHN.F.CR-13778, CR-12-Pn, UCMP. 62075(CR-329); two RM 1 s, MNHN.F.CR-1753-Pn, UCMP.62003(CR-4409); three LM 2 s, MNHN.F.CR- 11992, CR-58-Pn, CR-73-Pn; four RM 2 s, MNHN.F.CR- 189, CR-11889, CR-109-Bn, NMB.CY-953; two RM 3 s, MNHN.F.CR-230-Bn, CR-951-Pn; all Cernay.
LM 2, MNHN.F.BRL-1-P; L dentary with M 1 (broken)-M 2, and M 3 and premolar alveoli, MNHN. F.BRL-10-Pn; R dentary with P 4 –M 1, MNHN.F.BRL- 17-G; all bed 4, Berru.
R dentary with M 1–2, MNHN.F.I-207; bed 5, Berru.
Referred specimens: LM 2, MNHN.F.CR-661; RM 2, MNHN.F.CR-188; L dentary with P 4 -M 1, MNHN. F.CR-1753-Pn; 3 LM 2 s, MNHN.F.CR-474, CR-11910, CR-11992; RM 2, MNHN.F.CR-4411; all Cernay.
Age and distribution: Sables de Châlons-sur-Vesle supérieurs, late Thanetian, Late Palaeocene, Cernay and Berru (beds 4, 5), France.
Diagnosis: P 4 and upper molars lack distinct postparaconule crista. P 4 paraconid small to medium, unbasined lingually, and confluent with paracristid in most individuals. Upper molars relatively transversely elongate. P 4 and M 1–2 metacone much lower than paracone with very weak to absent precingulum. P 4 and M 1 postcingulum joining confluent postmetaconule crista and metacingulum in most individuals. M 1 with rounded distobuccal corner. M 3 with hypocone. M 1–2 pre-entocristid with concave edge and without entoconulid.
Description
P 3: The tooth is 1.33 mm long by 1.00 mm wide, so relatively narrow. The dominant paracone is relatively mesially situated with a smaller metacone ( Fig. 6A View Figure 6 ). There is a low, shelf-like parastyle. There is a small basined protocone lobe, symmetrically arranged, not canted mesially as in similar-sized Paschatherium dolloi . There are weak pre- and postprotocristae. The former abuts the base of the paracone, whereas the latter divides into a short premetaconule crista and weak metacingulum that does not reach the metastyle. Otherwise cingular development is restricted to a partial ectocingulum that is restricted to the distal half of the buccal margin. Other cresting is restricted to a centrocrista and postmetacrista.
P 4: In addition to the characters in the diagnosis, the single representative of this tooth type has a small paraconule, which lacks a postparaconule crista ( Fig. 6B View Figure 6 ). Having a metaconule with cristae makes it more molariform than W. krumbiegeli . It is 1.67 mm long by 2.12 mm wide.
M 1: There is variation in development of the premetaconule crista. It is present in three ( Fig. 6C View Figure 6 ) and lacking in a further three specimens. Only one specimen has any representation of a precingulum and in this it is very faint. This is an autapomorphy and represents a reduction from the state in W. krumbiegeli . In one specimen, the otherwise consistently present postmetaconule crista is missing as in Pa. dolloi . The postparaconule crista is more variable. Extremes are strongly present versus completely lacking along with a very weak paraconule. Less variable is the postcingulum, which differs from the diagnostic state in only one specimen, in which it does not join the confluent postmetaconule crista and metacingulum.
M 2: The small size of the metacone with respect to the paracone is more marked than on M 1 and the distolingual corner along with the metacone is lingually retracted ( Fig. 6D View Figure 6 ). Of three M 2 s, only one has a very weak precingulum, in the other two it is missing entirely. The postparaconule crista is weak in one, missing in the other two. A premetaconule crista is present in all three. Similarly, the postcingulum joins the postmetaconule crista–metacingulum in all three. M 3: The specimen is 1.09 mm long by 1.93 mm wide. It is damaged mesially, mesiobuccally, and mesiolingually, so that nothing can be said about the preprotocrista, paraconule, or parastyle ( Fig. 6E View Figure 6 ). The metacone is about half the height of the paracone, thus larger than in W. krumbiegeli . There is slight development of a cingular mesostyle and a faint ridge passing up the buccal wall to the centre of the centrocrista. There is a strong premetaconule crista that reaches the centre of the trigon. The distal projection of the small hypocone produces a gentle concavity in the distal margin.
P 4: The paraconid is a simple small cusp in most specimens. In this way it differs from the consistently basined structure in W. krumbiegeli , Pa. dolloi , Paschatherium yvettae , Berrulestes phelizoni , and Berrulestes pellouini and from the crestiform shape in the last two species. There is variation, however. The paraconid ranges in height from one third ( Fig. 7A View Figure 7 2 View Figure 2 ) to one half of the height of the protoconid ( Fig. 6G View Figure 6 2 View Figure 2 ) as seen in buccal view. One specimen has a small lingual paraconid basin, whereas another has the paraconid separated from the paracristid ( Fig. 6F View Figure 6 ), but these are exceptions. There is also variability in the size and shape of the talonid basin and of its cusps. The entoconid may be the same size as in Figure 6G View Figure 6 or smaller than the hypoconid ( Fig. 7A View Figure 7 4 View Figure 4 ), whereas the hypoconulid may be present or absent. Length ranges from 1.62–1.91 mm (mean 1.75) and width from 0.89–1.00 mm (mean 0.94).
M 1: The large size and cuspate shape of the paraconid is consistent ( Figs 6H View Figure 6 , 7A View Figure 7 1 View Figure 1 , A 4 View Figure 4 ). The hypoconulid is also notably large. The precingulid is strong but short. There is slight variation in how near the paraconid is to the lingual edge. However, it is never at the edge or as far buccal as the midline. The orientation of the cristid obliqua is consistent, but in one out of eight specimens it joins the back of the trigonid, ascending it slightly, rather than stopping short.
M 2: This is similar to M 1 in general morphology and level of variation. Unlike in Paschatherium , it is smaller than M 1 ( Fig. 6H View Figure 6 ). Its trigonid is shorter with a smaller, more buccally situated paraconid and slightly weaker precingulid. As with M 1, one specimen has a cristid obliqua that joins the back of the trigonid, ascending it slightly.
OR, observed range; SD, standard deviation; V, coefficient of variation (SD as percentage of the mean).
M 3: The paraconid is near the midline and smaller than on M 2. The talonid is nearly as wide as the trigonid, with hypoconid, entoconid, and hypoconulid as distinct cusps, the hypoconulid protruding distally ( Fig. 6H View Figure 6 ). The entoconid is slightly distal of the hypoconid in two specimens, much more distal in a third. M 3 s of other species have smaller talonid basins with smaller cusps, tending to become subsumed by crests. Length ranges from 1.48–1.54 mm (mean 1.51) and trigonid width from 0.95–1.10 mm (mean 1.04).
Dentary: Five fragmentary specimens show the position of mental foramina. Three show the posterior foramen below the trigonid of M 1, whereas in a fourth it is below the middle of M 1 and in a fifth below the junction of P 4 and M 1 ( Fig. 7A View Figure 7 3 View Figure 3 ). One dentary (MNHN.F.BRL-10-Pn) extends anteriorly as far as the canine alveolus, showing two-rooted P 3–4 alveoli, an elongate alveolus for P 2 with two fused roots, and a one-rooted P 1 alveolus ( Fig. 5A View Figure 5 ). The anterior mental foramen is below the mesial half of P 2. The depth of the dentary reduces posteriorly of M 3 in this specimen.
Discussion
This species is slightly smaller than the contemporaneous Pa. dolloi ( Fig. 8 View Figure 8 ) according to the molar dimensions of the Dormaal type assemblage (López- Martínez et al., 2006: table 2). It differs from similarsized Paschatherium species in the large size of its lower molar paraconids and hypoconulids and the fact that its M 2 is smaller than M 1 ( Figs 6H View Figure 6 1 View Figure 1 , 7B View Figure 7 ).
One of Lemoine’s two syntypes of Ada. remensis Lemoine, 1883 belongs to W. girardi . This is MNHN.F.CRL-825, a left dentary with worn P 4 and broken and abraded M 1–2, the subject of Lemoine’s (1885) pl. 10, fig. 2. Russell (1964: 59) regarded the other syntype, MNHN.F.CRL-824, a left dentary with M 3 and almost all the alveoli of the remaining tooth loci and the subject of Lemoine’s (1885) pl. 10, fig. 1, as the type, thereby selecting it as lectotype. This accords with Teilhard de Chardin’s (1922) synonymiz- ing of Ada. remensis with the type species Adapisorex gaudryi Lemoine, 1883 , and releases MNHN.F.CRL- 825 from being a name bearer of Ada. remensis . Although not shown in Lemoine’s 1885 illustration, MNHN.F.CRL-825 has a posterior mental foramen situated below the middle of M 1, distinguishing it from the genus Adapisorex . Its P 4, although worn, supports its identification as W. girardi .
| MNHN |
Museum National d'Histoire Naturelle |
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