Teilhardimys brisswalteri, Hooker & Russell, 2012

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 : 912-914

TEILHARDIMYS BRISSWALTERI SP. NOV.

( FIGS 23 , 24 , 26A–I, 33D )

vp 1964 Louisina mirabilis Russell ; Russell, pp. 243–

245, pl. 15, figs 1a, 1b, 2c.

Etymology: After Monsieur G. Brisswalter for finding a key specimen of the species.

Holotype: LP 4 , MNHN.F.CR-4400, Cernay.

Paratypes: Two LP 4 s, MNHN.F.CR-11888, CR-38- Meniel; RP 4, MNHN.F.CR-4521; L maxilla, M 1–3, MNHN.F.CR-265-Bn; three RM 1 s, MNHN.F.CR-1281, CR-118-Pn, CR-33- MD; two LM 2 s, MNHN.F.CR- 568-Ph, CR-27- MD; LM 3 , MNHN.F.CR-538; RDP 4 , MNHN.F.CR-343-Ph; two RP 3 s, MNHN.F.CR-285-Bn, SLP.CR-352; three LP 4 s, MNHN.F.CR-1283, CR-4339, CR-546-Ph; two RP 4 s, MNHN.F.CR-238, CR-1264; five LM 1 s, MNHN.F.CR-234, CR-4324, CR-11891, CR-192- Ph, CR-690-Ph; five RM 1 s, MNHN.F.CR-358, CR- 191-Ph, CR-102-Pn, CR-358-Pn, SLP.CR-317; L dentary, M 2–3, MNHN.F.CR-3-Bw; four LM 2 s, MNHN.F. CR-4332, CR-6-F, UCMP.62009(CR-4327), 62016(CR-1157); seven RM 2 s, MNHN.F.CR-316, CR-4328, CR-1180, CR-367-Pn; CR-372-Pn, CR-1703- Pn, SLP.CR-320; six LM 3 s, MNHN.F.CR-11890, CR-15930(Collier 699), CR-1724-Pn, CR-273-Bn, CR-84- MD, UCMP.62023(CR-1104); 13 RM 3 s, MNHN. F.CR-236, CR-237, CR-1146, CR-1251, CR-1722, CR-1396-Pn, CR-1705-Pn, CR-1718-Pn, CR-203-Ph, CR-328-L, CR-309-Bn, CR-83- MD, CR-85- MD; all Cernay .

RP 4, MNHN.F.BRL-4-F; R dentary, P 4 –M 1, MNHN.F.BRL-198-P; LP 4, MNHN.F.BRL-23-G; two RM 1 s, MNHN.F.BRL-21-G, BRL-189-P; two RM 2 s, MNHN.F.BRL-196-P, BRL-17-Pn; R dentary fragment, M 3, MNHN.F.BRL-20-G; all bed 4, Berru.

RP 4, MNHN.F.I-124; RM 1, MNHN.F.I-712; two LM 2 s, MNHN.F.I-722, I-730; LP 3, MNHN.F.I-708; RM 1, MNHN.F.I-706; LM 2, MNHN.F.I-242; two RM 2 s, MNHN.F.I-244, I-716; LM 3, MNHN.F.I-715; two RM 3 s, MNHN.F.I-582, I-720; all bed 5, Berru.

Referred material: Two LP 4 s, MNHN.F.CR-207, CR-152-Bn; LM 2, MNHN.F.CR-17479; two RM 2 s, MNHN.F.CR-294, CR-4322; two LM 1 s, MNHN.F.CR- 545-Ph, UCMP.62019(CR-4326); RM 2, MNHN.F.CR- 619-Ph; RM 3, MNHN.F.CR-11977; Cernay.

LM 2, MNHN.F.I-726; LM 1, BR-39; bed 5, Berru.

Casts in MNHN.F: LM 1, MNHN.F.CR-1241-Mol; LDP 4, CR-86-Lx; LM 2, CR-125-Lx; three RM 2 s, CR-1176-Mol, CR-2-Gt, CR-242-Lx; two LM 3 s, CR-54- Mar, CR-10-Rob; all Cernay. LM 1, BLentille-233-CGH; bed 4, Berru.

Age and distribution: Sables de Châlons-sur-Vesle supérieurs, late Thanetian, Late Palaeocene, Cernay and Berru (beds 4, 5), France.

Diagnosis: P 4 with small metaconule and very small to absent paraconule, when present situated on preprotocrista (larger and more distal in Te. reisi and Te. musculus ). P 4 with metaconid and talonid basin (talonid without or almost without basin in Te. musculus and Te. reisi ). Molars relatively low-crowned (taller in Te. musculus ). Upper molars with postprotocrista and no metaloph (unlike the other two species), and distinct paraconule and metaconule (weak in Te. musculus ). M 1 metacone slightly lower than paracone (subequal in the other two species). Lower molars with distally bowed protocristid (instead of incipient protolophid in Te. musculus ). Precingulid joins paracristid to form mesiobuccal stylid on M 1–2 in some individuals (shared with Te. musculus ). Entoconulid strong on M 1, weak to absent on M 2 (shared with L. marci ).

Description

Maxilla and dentary: The maxilla, in addition to demonstrating the association of all three upper molars, shows the zygomatic arch originating at around the junction of M 2 and M 3 ( Fig. 26B). One dentary with P 4 –M 1 shows the association of these teeth ( Fig. 26H), whereas another shows M 2–3 in situ ( Fig. 26G).

P 4: The parastyle, paracone, metacone, and metastyle are consistently taller than those of L. marci , the species that the molars most closely resemble. In this respect, P 4 is like those of the other two species of Teilhardimys , although T. brisswalteri lacks the stronger cresting of T. reisi and T. musculus , which somewhat resembles an ectoloph. The holotype gives a good idea of the morphology ( Fig. 26A). The paracone and slightly smaller metacone are fairly close together. The hypocone is much smaller than the protocone. The postprotocrista leaves the protocone distally, then bends to a buccal direction for a short distance, unlike in L. marci , in which it extends to between the paracone and metacone. A crest joins it to the hypocone at the bend. A neoformed crest leaves the mesiodistal branch of the postprotocrista, near the protocone, in a buccal direction and swells into a large but low metaconule and continues as a thin crest ascending the shared lingual wall of the paracone and metacone between these two cusps. The preprotocrista plunges basally then curves buccally to a small worn paraconule, continuing as the paracingulum. There is a very short precingulum. The main wear begins as a buccal phase facet on the postparacrista, then continues as a transverse belt into the central valley, then swings up the buccal flank of the protocone as a lingual phase facet ( Fig. 33D ). There is much less wear on the cusp tips, contrasting with L. marci .

Other specimens show more widely spaced paracone and metacone, a hypocone that is closer to the protocone, no paraconule or buccal branch of the postprotocrista, and a more extensive precingulum ( Fig. 26C). No specimen is completely unworn, but the protocone appears to recurve buccally little if at all, in contrast to the state in Louisina . Length ranges from 2.39–2.72 mm (mean 2.51) and width from 2.95– 3.50 mm (mean 3.24).

M 1: This tooth type is very similar to that of L. marci in overall morphology and degree of exodaenodonty. It differs only in being smaller ( Figs 23 , 24A ), in having slightly longer and narrower outline proportions, and a more rounded, less squared lingual margin ( Fig. 26B 2 ). Degrees of variation for the ectocingulum and metaconule–hypocone crest resemble those of L. marci . In contrast to this species, the premetaconule crista is present in the majority of specimens.

M 2: This tooth is similar to that of L. marci but smaller ( Fig. 26B). It varies in terms of the development of the ectocingulum and metaconule–hypocone crest as on M 1 and as this tooth does in L. marci . However, like M 1, there is a greater incidence of a premetaconule crista than in L. marci . There is also more variation in outline shape, a substantial number being squarer and less trapeziform than M 2 s of L. marci . With their less oblique buccal margin and less acute mesiobuccal corner, these teeth are proportionally slightly longer and narrower than in the latter species. In only one (MNHN.F.CR-339-Bn) of the 12 observed specimens is there a low parastyle like L. marci . It is not in the apparent size overlap zone with L. marci , so is unlikely to belong to this species.

M 3: At 2.20 mm long by 2.33 mm wide, this tooth in the maxilla (MNHN.F.CR-265-Bn) is smaller but relatively longer than any attributed to L. marci , but morphologically very similar ( Fig. 26B). As all the M 3 s potentially attributable to L. marci are isolated, it is difficult to be sure that none of the smaller ones belong instead to Te. brisswalteri . However, MNHN.F.CR-538 at 1.73 mm long is small enough to be definitely attributable to Te. brisswalteri .

P 3: The tooth is similar to that of L. marci in general shape and degree of exodaenodonty, but smaller ( Fig. 26D). It differs in being relatively shorter and broader. SLP.CR-352 has a short distal protoconid crest representing the metaconid. In contrast, MNHN.F.CR-285-Bn has a distinct small metaconid cusp ( Fig. 26D 1 , D 3 ), whereas MNHN.F.I-708 has not even a crest in this position. Length ranges from 2.60–2.69 mm (mean 2.65) and width from 1.71– 1.85 mm (mean 1.77).

P 4: This tooth is very similar to that of L. marci , but smaller and with, in most cases, a slightly longer basined talonid ( Fig. 26E, H). Unlike the former, there is a cristid obliqua, which provides the important shearing companion for the postparacrista of P 4. The metaconid is a consistently distinct cusp that is smaller than the protoconid in all specimens. Length ranges from 2.63–2.89 mm (mean 2.79) and width from 1.84–2.28 mm (mean 2.11).

M 1: There is great similarity with this tooth type in L. marci , but it is smaller ( Figs 23 , 24A ). Crown height is also slightly lower, cusps are slightly less inflated, there is slightly less exodaenodonty, the metaconid is larger (like the state in Prolouisina ), and the paraconid is slightly larger and protrudes slightly more mesially ( Fig. 26F, H), although these differences are subtle. The small difference in exodaenodonty is probably more recognizable than in M 1–2, because the lower molars are relatively taller and narrower. More easily observed are sharper pre- and postmetacristids. This feature is fairly consistent, although it is affected by wear and postmortem abrasion. MNHN.F.BRL-189-P has a sharp premetacristid, but a blunt postmetacristid. There is also less incidence of an entoconulid, with fewer than half of the specimens observed bearing one (present in Fig. 26F, absent in Fig. 26H).

M 2: As for M 1, M 2 is very similar to that tooth type in L. marci ( Fig. 26G). However, the differences are less clear-cut, only a proportion of the Te. brisswalteri specimens having less inflated cusps, less exodaenodonty, and sharper pre- and postmetacristids. However, the metaconid is larger as on M 1. In only three out of 17 specimens does the precingulid join the paracristid to form a mesiobuccal stylid. This makes distinction between the two species difficult for this locus, apart from size and even here there is overlap ( Fig. 24A ). Only one of the observed specimens (MNHN.F.CR-367-Pn) has an entoconulid and only one [UCMP.62016 (CR-1157)] has a mesostylid.

M 3: There is likewise great similarity to L. marci ( Fig. 26G) and, because of much variation of form, distinction is really only possible on size. There is variation in relative length, width, and height of the trigonid and talonid and in the angle of the cristid obliqua. There may be a weak to strong precingulid or none at all. The three talonid cusps may be distinct or almost completely subsumed into a distally encircling crest. There is a tendency for sharp pre- and postmetacristids, but the distinction from L. marci at this locus is not consistent. Three specimens show a small cusp in the talonid notch, which may be construed as an entoconulid or a mesostylid. Another (MNHN.F.CR- 1718-Pn) has a small mesoconid. MNHN.F.I-715 has the protocristid broken, the buccal branch joining the cristid obliqua. Length ranges from 2.21–2.78 mm (mean 2.53) and trigonid width from 1.62–2.40 mm (mean 2.00).

DP 4: Two teeth are very similar to that of L. marci but smaller with more widely spaced paracone and metacone and a more rounded lingual margin like M 1 ( Fig. 26I). The paracone–metacone spacing is thus more like Te. musculus . Length ranges from 2.59–2.70 mm and the only width measurement is 2.55 mm.

Figures

Figure 1. Dental terminology. A, B, upper molar; C, D, lower molar, all shown as from left side in occlusal view. Mesial is to left; distal is to right; buccal in uppers is above and in lowers below; lingual in uppers is below and in lowers above. A, C, primitive morphotype; B, D, derived morphotype. Some cusps and crests shown in A and C are assumed for B and D, respectively. Some taxa combine some features of the different morphotypes. Abbreviations: co, cristid obliqua; dclm, distal cingulum; ecf, ectoflexus; ecfd, ectoflexid; eclm, ectocingulum; ectsd, ectostylid; entd, entoconid; entf, entoflexus; entld, entoconulid; ents, entostyle; hyd, hypoconid; hyfd, hypoflexid; hyld, hypoconulid; hyp, hypocone; hyphd, hypolophid; mbstd, mesiobuccal stylid; mclm, mesial cingulum; mes, mesostyle; mesd, mesoconid; mestd, mesostylid; met, metacone; metclm, metacingulum; metd, metaconid; metle, metaconule; metph, metaloph; mets, metastyle; pacd, paracristid; paclm, paracingulum; pad, paraconid; par, paracone; parle, paraconule; pas, parastyle; pocld, postcingulid; poclm, postcingulum; pof, postflexus; poentcd, postentocristid; pohycd, posthypocristid; pomec, postmetacrista; pometcd, postmetacristid; pometlc, postmetaconule crista; popac, postparacrista; poparlc, postparaconule crista; poprc, postprotocrista; precld, precingulid; preclm, precingulum; preentcd, pre-entocristid; pref, preflexus; premec, premetacrista; premetcd, premetacristid; premetlc, premetaconule crista; prepac, preparacrista; preparlc, preparaconule crista; preprc, preprotocrista; procd, protocristid; prot, protocone; protd, protoconid; prs, protostyle; prtph, protoloph; prtphd, protolophid; tb, trigon basin; tgb, trigonid basin; tlb, talonid basin. Tooth abbreviations in text: I, incisor; C, canine; P, premolar; M, molar; DP, deciduous premolar.

Figure 2. Scanning electron micrographs of gold-palladium coated epoxy casts of teeth and jaw of Walbeckodon krumbiegeli gen. et sp. nov., Palaeocene, Walbeck, Germany. A, paratype LP3 (MLU.Wa/363). B, paratype composite dentition, LP4, LM1, LM2, LM3 (MLU.Wa/386). C, holotype left dentary with P –M (MLU.Wa104.2011). Views are: buccal 4 3 (A1, B1, C2), occlusal (A2, B2, C1), and lingual (C3). Scale bar = 2 mm.

Figure 3. Scanning electron micrographs of gold-palladium coated epoxy casts of jaws of Walbeckodon krumbiegeli gen. et sp. nov., Palaeocene, Walbeck, Germany. A, paratype left dentary with P4–M2 (MLU.Wa/387). B, paratype left dentary with P3–4 (MLU.Wa/417). Views are: buccal (A1, B1), occlusal (A2, B2), and lingual (B3). Scale bar = 2 mm.

Figure 23. Scatter diagrams of Ln length vs. Ln width in millimetres of molars of Louisina spp. and Teilhardimys brisswalteri sp. nov. For explanation of symbols see Figure 8. A, M1; B, M2; C, M; D, M.

Figure 24. Histograms of Ln length ¥ width in millimetres (A) and the distance between M1 paracone and protocone and between M1 hypoconid and entoconid, each as a percentage of tooth width (B), of Louisina spp. and Teilhardimys brisswalteri sp. nov. Lined boxes in A indicate Louisina mirabilis. Arrowed names indicate holotypes of species. See text for further explanation.

Figure 33. Occlusal diagrams of P4, P, and (except Teilhardimys musculus) M trigonid of Prolouisina atavella (A), 4 1 Louisina marci (B), Louisina mirabilis (C), Teilhardimys brisswalteri (D), and Te. musculus (E). Facets are numbered following Butler (1952a, b). Uppers are shown as from left side, lowers from right side. Diagrams are partly schematic, drawn from the maximum number of informative specimens. C is based on MNHN.F.CR-248-Bn, MNHN.F.BRL-3-Pn, and MNHN.F.BR-143. E is based mainly on NHMUK.M29708 and M50379. Taxa not shown to scale.