Afrodon gheerbranti, Bast & Sigé & Smith, 2012
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publication ID |
https://doi.org/ 10.4202/app.2010.0115 |
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persistent identifier |
https://treatment.plazi.org/id/038C87D1-FFBE-C10B-FF9C-0F754B6BFD99 |
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treatment provided by |
Felipe |
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scientific name |
Afrodon gheerbranti |
| status |
sp. nov. |
Afrodon gheerbranti sp. nov.
Fig. 2 View Fig ; Table 1.
Etymology: In honour of Dr Emmanuel Gheerbrant who described the first species of the genus Afrodon , and his contribution to the knowledge of the family Adapisoriculidae .
Type material: Holotype: IRSNB M1982 View Materials (N2−17), right M2 . Paratypes: IRSNB M1985 View Materials (Q2−28), right M1 ; IRSNB M1983 View Materials (N2−16), right M3 ; IRSNB M1986 View Materials (Q2−32), right p4 ; IRSNB M1987 View Materials (N2−13), right m1 ; IRSNB M1988 View Materials (Q1−06), right m2; and IRSNB M1989 View Materials (N2−06), left m3 .
Type locality: Hainin , Hainaut province, Belgium .
Type horizon: Early Palaeocene, Hainin Formation, Mons Basin.
Referred material.—R1−13, right M1; Q2−35 right M2; R1−47, left M2; R1−82, right M2; R1−70, left M3; R1−71, left M3; N2−34, left p4; N2−12, left m1; N2−13, right m1; O1−03, left m1; Q2−31, left m2; Y1−6, right m2; N2−62, antero−labial part of right M1; N2−09, anterolabial part of right M2; R1−33, lingual part of left M1 or M2; Q2−08, trigonid of right m1; R1−22, trigonid of right m1; R1−42, talonid of left m3; P2−05, trigonid of left m2 or m3; Q2−17, trigonid of right m2 or m3; Y1−04, trigonid of left m2 or m3.
Diagnosis.—Differs from other species of the genus in its larger size and smaller degree of transverse development of the upper molars. Differs from A. germanicus in the presence of a less deep ectoflexus and an anteroposteriorly longer protocone of the upper molars. Lower molars differ from A. chleuhi in possessing a talonid as wide as the trigonid, and from A. germanicus and A. ivani in the presence of a medial hypoconulid and a less strongly developed hypoconid. p4 differs from that of A. germanicus and A. tagourtensis in the presence of a single talonid cusp and a smaller metaconid.
Measurements.—See Table 1.
Description.—The M1 ( Fig. 2A View Fig ) shows a moderate degree of transverse development. The wide stylar shelf bears two well marked cusps, the parastyle and stylocone. The ectoflexus is moderately deep and asymmetrical. The parastylar lobe is long and directed anteriorly, whereas the metastylar lobe points posterolabially. The prepara− and postmetacristae are long, the latter being more oblique with regards to the labiolingual axis of the tooth. The preparacrista extends up to the stylocone. The paracone and metacone are well separated and linked by a rectilinear centrocrista. The paracone is taller and situated more labially than the metacone. The paracingulum is well marked; the metacingulum is very narrow, short and terminates at the posterolingual base of the metacone. The lingual part of the tooth is more developed transversely than its labial part. The protofossa is deep, wide and well delimited. The paraconule and metaconule are well developed and have long and sharp internal cristae. The postparaconule crista extends on to the lingual flank of the paracone, giving a triangular aspect to its base (along with the preparacrista and the centrocrista). The protocone is markedly procline, and is the smallest of the three main cusps.
The M2 ( Fig. 2B View Fig ) is similar to M1, with a larger stylar shelf and a greater degree of transverse development. The tooth is slightly shorter anteroposteriorly, and the parastylar lobe points anterolabially. The preparacrista disappears halfway between the bases of the parastyle and stylocone, and the protofossa is narrower than on M1.
The M3 ( Fig. 2C View Fig ) is similar to M 2 in size. The anteroposterior development of the tooth is less than that of M2, and the metacone is slightly reduced. The metastylar lobe is absent, while the parastylar lobe is well developed. The preparacrista is directed towards the parastyle and disappears just before reaching its base. One of the specimens identified as M3 has small pre− and postcingula.
The p4 ( Fig. 2D View Fig ) has a premolariform morphology. The trigonid is compressed labiolingually. The paraconid is very small and occupies an anterolingual position, and there is no precingulid. The metaconid occurs as a tiny cusp slightly posterior to the protoconid, while the postmetacristid is well marked and sharp. The talonid is short, lacks a basin, and carries only one cusp occupying the position of the hypoconulid. No crista obliqua is visible, and the hypoflexid occurs along the entire width of the talonid.
The m1 ( Fig. 2E View Fig ) is robust and marked by an anteroposteriorly long trigonid resembling the talonid in both height and width. The trigonid cusps are sharp and strong at their bases. The precingulid is moderately developed. The paraconid, though large, is the smallest cusp of the trigonid. The metaconid is slightly protruding lingually and lower than the protoconid. The protoconid is located slightly anterior to the metaconid, resulting in the posterior wall of the trigonid being somewhat oblique with respect to the anteroposterior axis of the tooth. The postmetacristid is well developed, giving the trigonid a markedly procline aspect. The talonid cusps are equidistant and of similar size. The talonid basin is moderately deep. The crista obliqua reaches the posterior wall of the trigonid halfway between the protoconid and the metaconid and extends up towards the tip of the latter. The hypoflexid is wide and relatively shallow.
The m2 ( Fig. 2F View Fig ) is very similar to m1. The trigonid is slightly wider than the talonid and more compressed anteroposteriorly, making m2 shorter than m1. The protoconid and metaconid are more widely spaced than on m1.
The m3 ( Fig. 2G View Fig ) is similar to m2. The metaconid is situated more anteriorly than on m1 and m2, and the posterior wall of the trigonid is consequently less oblique. The talonid is narrower than the trigonid. The hypoconulid is more developed than the hypoconid and entoconid, and shifted posteriorly. Discussion.— A. gheerbranti shares the following morpholog−
ical features with Adapisoriculidae : transversely elongated upper molars; stylar cusps well marked (at least parastyle and stylocone); wide stylar shelf with long prepara− and postmetacristae; paracone and metacone well separated down to their bases, with a rectilinear or dilambdodont centrocrista. Lower molars show little height difference between trigonid and talonid; well−developed talonid; crista obliqua extends up the posterior wall of the trigonid (see Gheerbrant and Russell 1989). Upper molar characters shared with the genus Afrodon include: rectilinear centrocrista; wide stylar shelf; stylar cusps little marked; strongly asymmetrical ectoflexus; large transverse development of the tooth; sharp internal crests of the conules; absence of precingulum and postcingulum. Lower molars share with the genus: massive cusps; metaconid posterior to the protoconid; submedial hypoconulid (see Gheerbrant and Russell 1989).
The upper molars of A. gheerbranti are morphologically similar to those of A. germanicus , but are 35% larger in size and proportionally less developed transversely. The upper molars of A. chleuhi are even more transversely developed than those of A. germanicus , and have a wider stylar shelf than those of either of the other two species. The upper molars of A. ivani are also very wide transversely, but the stylar shelf is narrower than in other species of Afrodon . A. tagourtensis is markedly smaller than A. gheerbranti , and characterised by an M1 with a more triangular aspect, a well developed paracingulum, and a less procline protocone. The M1 attributed here to Afrodon gheerbranti is rather large compared to M2, with a more anteroposteriorly developed protocone. This is unusual in adapisoriculids, but in line with the particularly long m1. The p4 with only one talonid cusp is closer to A. chleuhi and A. ivani than to A. germanicus or A. tagourtensis . Unlike A. chleuhi , the lower molars of A. gheerbranti have a talonid as wide as the trigonid.
http://dx.doi.org/10.4202/app.2010.0115
A. gheerbranti resembles A. ivani and A. germanicus in having sharp lower molar cusps, whereas the African species A. chleuhi and A. tagourtensis are marked by more massive cusps. The talonid of A. ivani has a more square aspect, with a relatively strong hypoconid, a feature it shares only with A. germanicus . A. gheerbranti is morphologically intermediate between A. germanicus and A. chleuhi , with a smaller stylar shelf and a smaller degree of transverse development of the upper molars than observed in A. chleuhi .
Stratigraphic and geographic range.—Known only from the early Palaeocene of the Mons Basin, Belgium.
| IRSNB |
Institut Royal des Sciences Naturelles de Belgique |
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