Trogontherium Fischer de Waldheim, 1809

Fostowicz-Frelik, Łucja, 2008, First record of Trogontherium cuvieri (Mammalia, Rodentia) from the middle Pleistocene of Poland and review of the species, Geodiversitas 30 (4), pp. 765-778 : 767-770

Genus Trogontherium Fischer de Waldheim, 1809

Trogontherium cuvieri Fischer de Waldheim, 1809

Castor trogontherium Cuvier, 1812 : pt. IV, chap. V, a. I: 4.

“ Diabroticus schmerlingi ” Pomel, 1848: 167 , nomen nudum.

Conodontes boisvilletti Laugel, 1862: 715-717 .

Dipoides lydekkeri Schlosser, 1902: 117 .

Trogontherium Soergeli Rüger, 1928: 224 , pl. 11, figs 5, 6.

Sinocastor andersoni Teilhard de Chardin, 1942: 5 , fig. 7.

HOLOTYPE. — PIN 2422 /1, an incomplete skull ( Fischer de Waldheim 1809a: pl. I).

TYPE LOCALITY. — Taganrog, Azov seashore, Russia; the horizon unknown.

DISTRIBUTION. — Late Pliocene to middle Pleistocene in Europe, and late Pliocene to Pleistocene in Asia.

MATERIAL EXAMINED. — ISEZ MF/2314, a right P4.

LOCALITY AND HORIZON OF THE REFERRED SPECIMEN. — Unit 2, layers 2a-c, of a partly destroyed cave etched

in a Devonian limestone hill, Kozi Grzbiet, 50°51’N,

Trogontherium cuvieri ( Mammalia, Rodentia ) from Poland

20°21’E, at Zajączków near Kielce, Świętokrzyskie Mts, southeastern Poland ( Głazek et al. 1976, 1977a, b). Unit 2 is composed principally of yellowish-brown to dark brown sandy loams and contains abundant fossils. These represent more than 100 species of mammals, including lipotyphlans (Rzebik-Kowalska 1994), bats ( Wołoszyn 1988), lagomorphs ( Sych 1980; Fostowicz- Frelik 2008), rodents ( Kowalski 2001, and references therein), carnivorans ( Wiszniowska 1989), and artiodactyls ( Stefaniak 2007).

The deposition period of the bone bearing layers of Kozi Grzbiet ( Fig. 1) was established on the basis of the fluorochloro-apatite ( FCL /P) and collagene methods at c. 700- 550 ka ( Głazek et al. 1976). It is assigned to an interstadial warming, correlated with the Cromerian II (Małopolanian Interglacial according to Ber 2005). Paleomagnetic investigation of the sediment revealed positive magnetic polarity referred to Brunhes normal magnetic epoch ( Głazek et al. 1977b; Lindner 1982).The composition of the rodent fauna indicatestheuppermostBiharianoftheTemplomhegyphase ( Nadachowski 1990). Mimomys savini Hinton, 1910 , the index species for the upper Biharian in Central Europe, is quite abundant and shows some advanced morphological features similar to Arvicola Lacépède, 1799 , believed to be its descendant ( Nadachowski 1985). The presence of the other Biharian species, such as Pliomys episcopalis Méhely, 1914 , P. lenki (Heller, 1930) , Allocricetus bursae Schaub, 1930 , and A. ehiki Schaub, 1930 , as well as the late Villanyian and Biharian glirid species, Glis cf. sackdillingensis and, on the other hand, the lack of Allophaiomys Kormos, 1933 , confirm the late Biharian dating. Presence of Microtus (Pitymys) arvalidens Kretzoi, 1958 , M. (Stenocranius) gregaloides (Schrank, 1798) , and Clethrionomys glareolus (Schreber, 1780) narrows this period to the latest part of the Biharian ( Nadachowski 1990).

The composition of the vertebrate fauna suggests a moist and sylvan environment ( Lindner 1982), at least for the greater part of the time of deposition. The presence of typical forest rodents such as Petauria sp., Clethrionomys glareolus , Eliomys cf. quercinus , Sicista praeloliger Kormos, 1930 , and Glis cf. sackdillingensis, as well as birds such as Tetrao sp. and Tetrastes sp., indicates a woodland habitat of taiga type (Bocheński 1984).

REVISED DIAGNOSIS. — Large beaver but smaller than Castoroides and Youngofiber , maximal skull length 210 mm; sagittal suture of skull distinct, flanked by two deep depressions. Incisors with convex enamel face, lower pair pear-shaped in cross section. The enamel surface of the incisors covered with subtle longitudinal grooves.

Cheek teeth high-crowned with weak roots. P4 larger than any other upper cheek tooth. M1 and M2 about equal in size, each shorter than M3. M3 considerably elongated anteroposteriorly. Shallow striae of upper cheek teeth, reaching no further than a half of the crown height

(hypostria is the deepest one), differentiate Trogontherium

Fostowicz-Frelik Ł.

General Mammal Local division stratigraphy correlations 400 1 Layer 1/2a glacistadial Climate warm Age 587 568 547 (ka) 500 Pleistocene middle Steinheimian Mauer Mosbach 2a cool 600 Brunhes KG 2 2 C C 3 1 2 2 C b 2 cool warm warm glacistadial 615 629 620 610 652 700 Templomhegy Voigtstedt 800 lower Pleistocene Biharian upper Nagyhársányhegy Untermassfeld 900. Jar

cuvieri from Castor Linnaeus, 1758 , which has very deep striae and striids (sometimes covered by cement), reaching the base of the tooth. Early wear stages of P4 and M3 with small flexus or fossette posterior to metaflexus. Metaflexus closes early in ontogeny, T. cuvieri differs from Castor which has most of the folds open even in strongly worn teeth. Lower cheek teeth with hypoflexid extending between mesoflexid and metaflexid, nearly straight (in occlusal view) flexids, and striids reaching half of crown height. Differs from Euroxenomys in larger size, ridged incisor enamel, lower-crowned cheek teeth, and M3 longer anteroposteriorly relative to length of either M1 or M2.

DESCRIPTION OF THE REFERRED SPECIMEN Isolated, right P4 of an adult but relatively young animal. The crown is 12.4 mm wide and 10.0 mm long (Fig. 2). The wear surface shows only one closed fold, transformed into isolated fosset (here metafosset, 5.0 mm width), which indicates age class 2 ( Mayhew 1978). There are two open folds on the buccal side, paraflexus (5.2 mm width) and mesoflexus (8.7 mm width), and one on the lingual

side, hypoflexus, 4.6 mm width. Hypoflexus does not significantly overlap paraflexus anteriorly, but at its most lingual end it delicately bends anteriorward. Mesoflexus is very deep and cut across the whole width of the tooth, ending at the lingual layer of enamel surrounding the tooth. The vertical depth of hypostria and mesostria is 5.7 and 1.7 mm respectively, measured at the buccal side. The wear stage of the tooth almost reached the bottom of the buccal incision of the paraflexus but a fault is still open. The tooth exhibits the partial hypsodonty revealed by the presence of an elongated, broad main root, placed anteriorly and in equal breadth with the crown of the tooth, and a small posterior rootlet. Consequently, the enamel margin is reaching deeper into tooth base at the anterior margin. Both roots are compressed anteroposteriorly, beginning to close, which is a characteristic feature in mature beavers ( Xu 1994).

REMARKS

The tooth of Trogontherium cuvieri from Kozi

Grzbiet is the first and only Polish discovery of

Trogontherium cuvieri ( Mammalia, Rodentia ) from Poland

distal metafossette

FIG. 2. — Right P4 of Trogontherium cuvieri Fischer de Waldheim,1809 from the early middle Pleistocene of Kozi Grzbiet (ISEZ MF/2314): A, lingual view; B, mesial view; C, distal view; D, buccal view; E, occlusal view. Scale bars: 10 mm.

this species. It is the most northern occurrence of T. cuvieri in Central Europe and one of the few specimens found in cave sediments. The specimen ISEZ MF/2314 was previously ascribed to Castor fiber ( Bartolomei et al. 1975: 423; Głazek et al. 1976, 1977a, b) and subsequently recognized as T. cuvieri by Mieczysław Wolsan; however, it was listed only (e.g., Nadachowski1990; Kowalski 2001), and presented briefly in the volume of abstracts by Fostowicz-Frelik & Wolsan (2004).

The morphology of the specimen is typical for T. cuvieri . The striae are relatively shallow and presumably reached about one-third of the crown depth in the unworn stage; certainly not exceeding half of it, as noticed for this species ( Xu 1994). This

feature distinguishes the specimen ISEZ MF/2314

from Castor which has definitely deeper striae, with hypostriae reaching nearly the base of the crown ( Xu 1994). Furthermore, the well separated rootlet (Fig. 2) differentiates this specimen from Castor , which has a higher ratio of hypsodonty and the radical part decreases in diameter, but no separate roots are observed.The described tooth differs from the holotype (PIN 2422/1) in still open paraflexus, although the tooth wear almost reaches the base of the fold (Fig. 2). In the studied specimen the metaflexus is already closed into a metafossette, while in Castor even heavily worn teeth have this fold still open. Morphology of all flexi is simple, they lack crenulation and do not show any kind of splitting or widening at the end. The hypoflexus does not

significantly overlap the paraflexus anteriorly.

Fostowicz-Frelik Ł.