Paschatherium dolloi, (TEILHARD DE CHARDIN, 1927)

Hooker, Jerry J. & Russell, Donald E., 2012, Early Palaeogene Louisinidae (Macroscelidea, Mammalia), their relationships and north European diversity, Zoological Journal of the Linnean Society 164 (4), pp. 856-936 : 870

PASCHATHERIUM DOLLOI ( TEILHARD DE CHARDIN, 1927) ( FIGS 6I , 7B , 8A, B, D )

*vp 1927 Adapisorex Dolloi Teilhard de Chardin : pp. 7–11, figs 2–4, 5a, c–h, 6a–b, d, pl. 1, figs 5–22, 25–28, pl. 2, figs 1–13.

1927 Insectivore indéterminé; Teilhard de Chardin: p. 12, fig. 8a–d, pl. 2, figs 21–23 (DP 4 and DP 4).

1964 Paschatherium dolloi (Teilhard de Chardin) ; Russell, pp. 238–239, pl. 14, figs 1, 2.

vp 1964 Paschatherium ?; Russell: p. 240 (CRL-827).

vp 1964 Paschatherium petri Russell : p. 305 (CRL- 827).

p 1981 Paschatherium dolloi (Teilhard de Chardin) ; Denys & Russel [sic], pp. 37–44, pl. 1.

2006 Paschatherium dolloi (Teilhard de Chardin) ; López-Martínez, Smith, Peláez-Campomanes & Smith, pl. 1, figs 1–8.

Lectotype: R dentary fragment with P 3 –M 2 and part of ascending ramus, IRSNB.CtM1140, Tienen Formation, Dormaal [ Teilhard de Chardin, 1927: 9, fig. 4 (N.B. the M 3 is an addition, representing another specimen); pl. 2, fig. 4]. Lectotype selection is necessary because a second species of Paschatherium , Pa. yvettae , has been recognized at Dormaal ( López-Martínez et al., 2006). IRSNB.CtM1140 fits within the size range of Pa. dolloi as restricted by these authors and lacks the mesiobuccally curved premetacristid of Pa. yvettae .

Material: L dentary fragment with P 4 –M 3, MNHN.F.CRL-827; RM 1, MNHN.F.CR-5-Bn; both Cernay.

Age and distribution: Sables de Châlons-sur-Vesle supérieurs, late Thanetian, Late Palaeocene, Cernay, France; Tienen Formation, zone PE I, earliest Ypresian, Early Eocene, Dormaal, Belgium; Sables d’Erquelinnes, zone PE I, earliest Ypresian, Early Eocene, Erquelinnes, Belgium; Suffolk Pebble Beds, Zone PE I, earliest Ypresian, Early Eocene, Ferry Cliff, UK.

Emended diagnosis: Medium-sized Paschatherium , mean length of M 1 1.92 mm ( López-Martínez et al., 2006) ( Pa. russelli and Pa. levei are larger; Pa. yvettae , Pa. marianae , and Pa. plaziati are smaller). P 4 without postmetaconule crista (shared with Pa. yvettae and W. krumbiegeli ). M 1 pre-entocristid with concave edge (shared with Pa. yvettae and W. girardi ). M 1 paraconid sublingual in position (shared with Pa. yvettae and Pa. russelli ). Lacks the mesiobuccal curvature of the lower molar premetacristid that characterizes the otherwise morphologically similar Pa. yvettae . M 1–2 precingulid strong, extensive, shelf-like, bulging mesially (shared with Pa. yvettae ).

Description

The teeth in the dentary are fairly heavily worn, particularly M 1, and the P 4 is broken mesially. P 4 is 1.18 mm wide; M 1 is 1.95 mm long by 1.46 mm wide; M 2 is 2.00 mm long by 1.62 mm wide; and M 3 is 1.65 mm long by a minimum of 1.24 mm wide. The basic pattern is very similar to the lectotype from Dormaal. The paraconid is crestiform on all three molars, the cristid obliqua ascends the back of the trigonid a short distance and the M 3 is proportionately smaller compared to M 2 than in W. girardi ( Fig. 7B ). The back of the P 4 trigonid is steep and the talonid is narrower than the trigonid.

The M 1 is 1.77 mm long by 2.18 mm wide. It has equal height paracone and metacone, a distinct precingulum, a confluent postcingulum–metacingulum and a weak postmetaconule crista that does not join the postcingulum–metacingulum ( Fig. 6I ).

Discussion

The measurements of the teeth in the Cernay dentary show M 2 to be larger than M 1, typical of the species ( Fig. 7B ; López-Martínez et al., 2006: table 2). They also show M 1, M 1, and M 2 to fit well within the size range of the Dormaal type assemblage, in the case of M 1 and M 2 close to the mean ( Fig. 8 ). All the measurements lie outside those of the morphologically similar Pa. yvettae . Morphology and proportions are also different from similar-sized W. girardi ( Fig. 8 , Table 2). This is therefore the oldest recorded occurrence of Pa. dolloi , clearly very rare before its earliest Eocene acme in northern Europe. The first occurrence of Pa. yvettae is earlier, the middle Thanetian of Spain ( Gheerbrant et al., 1997; Pujalte et al., 2006).

Figures

Figure 6. Scanning electron micrographs of gold-palladium coated epoxy casts of teeth and jaw of Walbeckodon girardi gen. et sp. nov. (A–H) and Paschatherium dolloi (Teilhard de Chardin, 1927) (I), late Thanetian, Cernay, France. A, RP3 (reversed) (MNHN.F.CR-134-Ph). B, RP4 (reversed) (MNHN.F.CR-4412). C, LM1 (MNHN.F.CR-81-Pn). D, RM2 (reversed) (MNHN.F.CR-116-Ph). E, RM3 (reversed) (MNHN.F.CR-334-L). F, LP (MNHN.F.CR-1225). G, RP (reversed) 4 4 (MNHN.F.CR-168-Bn). H, holotype left dentary with M (MNHN.F.CR-330). I, RM1 (reversed) (MNHN.F.CR-5-Bn). Views 1–3 are: buccal (A1, B1, C1, D1, E1, G2, H2), occlusal (A2, B2, C2, D2, E2, F, G1, H1, I), and lingual (H3). Scale bar = 2 mm.

Figure 7. Scanning electron micrographs of gold-palladium coated epoxy casts of jaws of Walbeckodon girardi gen. et sp. nov., bed 4, Berru (A) and Paschatherium dolloi (Teilhard de Chardin, 1927), Cernay (B), both late Thanetian, France. A, right dentary with P4–M1 (reversed) (MNHN.F.BRL-17-G). B, left dentary with P4–M3 (MNHN.F.CRL-827). Views are: occlusal (A1, B), buccal (A2, A3), and lingual (A4). Scale bar = 2 mm for A1, A2, A4, B and 4 mm for A3.

Figure 8. Scatter diagrams of Ln length vs. Ln width in millimetres of cheek teeth of Walbeckodon, Paschatherium, and Berrulestes from Cernay, Berru and Châlons-sur-Vesle. A, M; B, M; C, P; D, M1. Hollow square = Cernay; hatched 1 2 4 square = Paschatherium dolloi, Cernay; hollow circle = bed 5, Berru; solid circle = bed 4, Berru; solid triangle = Berrulestes sp. 1, Châlons-sur-Vesle. The cross hairs in A, B, and D give the range of measurements of Pa. dolloi from the Dormaal type assemblage from López-Martínez et al. (2006: table 2).