López-Torres and Silcox—European Paromomyidae
927
Materials.—AV 1092-BN, right M2; CB 232-BN, left P4;AV 7707, rightM2; AV7714, right I1; AV7716, rightM1; CB 3583, rightM3; CB4162, left P4; CBX2-Ph, I1;AV1306-Ph, rightM1.
Remarks.—Along with A. fuscus, A. lapparenti is one of the most common species of this European genus. While Russell et al. (1967) described A. fuscus as appearing at Mutigny, A. lapparenti was argued by the same authors to have been present in Avenay, very close geographically to Mutigny. When Aumont (2003, 2004) suggested the sympatry of
these two species, she also reported that the samples from the type localities of both species were mixed. In addition, the molariform morphology of Arcius fourth upper premolars led to misidentification in the original Russell et al. (1967) paper. AV 5775, reported in Russell et al. (1967) as anM1 of A. lapparenti, is interpreted here to be a P4 based on its poorly developed postprotocrista, a feature of P4 in other species of Arcius. These two teeth can be distinguished mainly by the lack of a postprotocrista and by the slightly convex mesial aspect of the tooth on P4. Whereas relative size of the metacone to the paracone is often used to discriminate between M1 and P4 in primate species, the paracone of the P4 is so close in size to the metacone in A. lapparenti that it is quite challenging to see a size difference between these two cusps.
Figure 7. Micro-CT scan images of three paromomyid P4s. (1, 2, 4, 5) The ‘prehypoflexid cristid’ (white arrow) as seen on the P4 of (1, 4) Paromomys maturus Gidley, 1923 and (2, 5) Arcius fuscus Russell et al., 1967. (3, 6)
Arcius lapparenti Russell et al., 1967 is shown as an example of a paromomyid with no prehypoflexid cristid. When the prehypoflexid cristid is present, the postprotocristid (black arrow) is shifted to a central position across the postvallid. The main difference between the prehypoflexid cristid of Paromomys maturus and that of A. fuscus is that in (4) Paromomys maturus it is located more mesially, contrary to (5) A. fuscus, in which the three cristids are in the same plane on the postvallid. Scale bar=1mm.
Emended diagnosis (modified from Russell et al., 1967 and Aumont, 2003).—Largest species of Arcius. Further differs from A. rougieri in having a more apically extended (taller) medio- cone than anterocone on I1, no expansion of the parastylar area of M3, and stronger mesial inflection of molar trigonids and lacking a stepped postvallid on M1. Further differs from A. fuscus in lacking a ‘prehypoflexid cristid.’ Well-developed paraconid on M1, but proportionally smaller relative to the metaconid than in A. fuscus. Further differs from A. zbyszewskii and A. ilerdensis n. sp. in having a cingulid on the buccal half of the distal aspect of M1 that runs up to the hypoconulid. Further differs from A. zbyszewskii in not having a paraconid on M3.
Occurrence.—Avenay (type locality, PE V; Marandat et al., 2012), Marne, France; Fournes (PE II; Marandat et al., 2012), Hérault, France; Meudon (PE II; Hooker, 2015), Hauts-de- Seine, France; Pourcy (PE III [55.12 mya]; Hooker, 2010), Marne, France; Mutigny (PE IV; Marandat et al., 2012), Marne, France; Gland (PE V; Aumont, 2003), Aisne, France; Sézanne (PE V; Aumont, 2003), Aisne, France; Condé-en-Brie (PE V; Hooker and Russell, 2012), Aisne, France; Venteuil (MP10; Aumont, 2003), Marne, France; St. Agnan (MP10; Hooker, 1996), Aisne, France; Prémontré (MP10 [48.4 mya]; Franzen, 2005), Aisne, France.
Arcius zbyszewskii Estravís, 2000 Figures 2.8, 4
1981 Phenacolemur sp. Antunes, p. 257.
1981 Phenacolemur cf. P. fuscus Antunes and Russell, p. 1101.
2000 Arcius zbyszewskii Estravís, p. 283. 2003 Arcius zbyszewskii; Aumont, pl. 24. 2011 Arcius sp.; Smith et al., fig. 19A, B.
Holotype.—SV1-29, right M2.
Emended diagnosis (modified from Estravís, 2000).—Smallest species of Arcius, approaching the size of A. rougieri. Distolingual basin of M3 somewhat expanded distally, more than in A. rougieri but less than in A. fuscus. Small but patent paraconid onM1, stronger paraconid onM3 than in other species of Arcius. The hypoconulid lobe onM3 is enlarged, as typical of paromomyids, but is the smallest lobe in proportion to the rest of the tooth relative to any other paromomyid, with the exception of Paromomys farrandi.
Horizon and locality.—.— Silveirinha (type locality, PE II; see
Biostratigraphy), Baixo Mondego, Portugal; Sotteville-sur-Mer (PE II; Hooker, 2015), Normandy, France.
Biostratigraphy.—Silveirinha has been considered to belong to MP 7 (PE I) (Estravís, 1992; López-Martínez et al., 2006; Badiola et al., 2009; Smith et al., 2011; Marandat et al., 2012), but also to be very close in age to Sotteville-sur-Mer, probably slightly younger (Smith et al., 2011; Marandat et al., 2012). Recently, Hooker (2015) assigned Sotteville-sur-Mer to PE II, so Silveirinha is here considered to be PE II in age following his temporal framework.
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