926


Journal of Paleontology 92(5):920–937


missing the hypoconulid lobe, which is particularly relevant in determining which species of Arcius it belongs to. Aumont (2003) suggested that the only way to know the correct ascription of FDN28 is to find an M3 from the type locality for A. rougieri (Palette), but the size, the metric proportions, and the fact that other A. rougieri fossils have been found in Fordones support the inference that FDN28 is the first M3 known of A. rougieri (Marandat, 1991; Aumont, 2003).


Arcius fuscus Russell, Louis, and Savage, 1967 Figures 2.6, 3.1–3.4, 3.9, 3.10, 3.13–3.16, 7.2, 7.5


1962 ‘Phenacolemuridae’ gen. indet. sp. indet. Louis and Michaux, p. 171.


1966 Phenacolemur sp. Louis, p. 51.


1967 Phenacolemur fuscus (in part) Russell et al., figs. 2a–j, l, 3d, g.


1981 Phenacolemur cf. P. fuscus Godinot, p. 77. 1984 Arcius fuscus Godinot, fig. 2b. 1991 Phenacolemur cf. P. fuscus Marandat, p. 92.


2003 Arcius fuscus; Aumont, pl. 1, figs. 3, 4, 8, pl. 2, figs. 9– 12, pl. 4, figs. 4, 5, pl. 5, figs. 5, 6, 10, pl. 7, figs. 8–15, pl. 8, figs. 3, 8, 9, 13, 14, pl. 10, figs. 6–8, pl. 11, fig. 2, pl. 12, figs. 4, 6, pl. 13, figs. 3–5, 10, pl. 14, fig. 3.


2004 Arcius fuscus; Aumont, fig. 3.5–3.9, 3.14–3.16. Holotype.—MU 6507, left M3.


Emended diagnosis (modified from Russell et al., 1967 and Aumont, 2003).—Smaller M2 than those of Arcius lapparenti, A. hookeri n. sp., and A. ilerdensis n. sp. but larger M1 than those of A. rougieri and A. zbyszewskii. Further differs from A. rougieri in having a more apically extended (taller) mediocone than anterocone on I1, no expansion of the parastylar area of M3, presence of ‘prehypoflexid cristid’ on the P4,a concave mesial border of P4 in lateral view, stronger mesial inflection of molar trigonids, and lacking a stepped postvallid on M1. 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.—Mutigny (type locality, PE IV; Marandat et al., 2012), Marne, France; Fournes (PE II; Marandat et al., 2012), Hérault, France; Var, France; Gland (PE V; Aumont, 2003), Aisne, France; Avenay (PE V; Marandat et al., 2012), Marne, France; Sézanne (PE V; Aumont, 2003), Aisne, France; Condé- en-Brie (PE V; Hooker and Russell, 2012), Aisne, France; St. Agnan (MP10; Hooker, 1996), Aisne, France.


Materials.—AV 422-L, left M2; AV 610-BN, left M2;AV 6838, left I1; CB 1914-L, left P4; CB 2560, left P4; MU 6458, right M1; UCMP 71976, left M1; UCMP 71982, left M3.


Remarks.—Arcius fuscus, along with A. lapparenti, is one of the most common species of the genus found in Europe. When it was first described by Russell et al. (1967), A. fuscus was thought to come just from its type locality, Mutigny (Marne,


France). Arcius lapparenti was also described for the first time by Russell et al. (1967) and at that time was thought to come only from its type locality, Avenay (Marne, France). However, Aumont (2003, 2004) argued these two species were sympatric across many sites in France. Aumont (2003) also interpreted the Arcius fuscus sample from Russell et al. (1967) to be a mixture of both A. fuscus and A. lapparenti and considered the only two P4 specimens (MU5627 and MU6294) found at Mutigny to belong to A. lapparenti, which is significant since P4 is generally the most diagnostic tooth for paromomyids. Aumont (2003) came to that conclusion after studying the large sample from Condé-en-Brie (Aisne, France), where there are two distinct P4 sizes and morphs. Russell et al. (1967) did not choose a P4 as the holotype for


Arcius fuscus but instead selected anM3. They used differences in the inclination of the M3 postvallid, and in the degree of lateral projection of the entoconid, to differentiate A. fuscus from A. lapparenti. However, after the study of the large collection from Condé-en-Brie, it seems as though there is too much variability in these characters for them to be considered diagnostic of species of Arcius. Although form of the M3 hypoconulid is diagnostic for the genus as a whole, variability in this tooth position implies that distinguishing among species in the genus Arcius also requires consideration of characters from the premolars and other molars. There are two genera of paromomyids that have three


distinct crests on the postvallid of the P4 of some species: Arcius and Paromomys. These crests are interpreted here as ametacristid (this term used in preference to premetacristid or postmetacristid because of the absence of a metaconid; in this case, ‘metacristid’ is used for a crest in the metaconid position), a postprotocristid, and a third crest that we are referring to here as a ‘prehypoflexid cristid.’ These crests can be distinguished in the following way: (1) the metacristid runs lingually from the protoconid to the entocristid or to the lingual aspect of the bottom of the postvallid (if no entocristid is present); (2) the postprotocristid runs buccally or centrally fromthe protoconid to the cristid obliqua; and (3) the ‘prehypoflexid cristid’ runs buccally from the protoconid to the hypoflexid. Themain difference between these two taxa is that all three crests are in the same plane in Arcius fuscus, but the ‘prehypoflexid cristid’ is less well defined and more distally located in Paromomys (Fig. 7). Only two crests are visible on the postvallid in all other known paromomyid species.


Arcius lapparenti Russell, Louis, and Savage, 1967 Figures 2.7, 3.5–3.8, 3.11, 3.12, 3.17–3.19, 6, 7.3, 7.6


1967 Phenacolemur lapparenti (in part) Russell et al., figs. 2k, 3a–c, e, f.


1984 Arcius lapparenti Godinot, fig. 2c–f.


2003 Arcius lapparenti; Aumont, pl. 1, figs. 1, 2, 5–7, pl. 2, figs. 1–8, pl. 3, figs. 1–3, pl. 4, figs. 1–3, 6–8, pl. 5, figs. 1, 2, 7–9, pl. 6, figs. 1–4, pl. 7, figs. 1–7, pl. 8, figs. 1, 2, pl. 9, pl. 10, figs. 1–5, pl. 11, figs. 1, 9, pl. 12, figs. 1–3, 5, 7–12, pl. 13, figs. 1, 2, 6–9, 11–13, pl. 14, figs. 1, 2, 4–8, pl. 15, figs. 1, 2, pl. 16, 17, pl. 18, figs. 3, 4.


2004 Arcius lapparenti; Aumont, fig. 3.1–3.4, 3.10–3.13. Holotype.—AV 5849, left M3.


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