Butselia biveri Quinet and Misonne, 1965
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publication ID |
https://doi.org/ 10.4202/app.2008.0061 |
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persistent identifier |
https://treatment.plazi.org/id/03F587D4-FFCF-FFC9-FC89-B816FDFCFC1F |
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treatment provided by |
Felipe |
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scientific name |
Butselia biveri Quinet and Misonne, 1965 |
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Butselia biveri Quinet and Misonne, 1965
Fig. 2 View Fig .
Material.—Left dentary fragment with alveoli of i2−c and p2, p1 and p3–m3 (BSP 1971 XXX 60, Möhren 12). Two right edentulous dentary fragments, left dentary fragment with p3– p4, left dentary fragment with m1, and 24 isolated teeth (BSP 1972 XI 217–243, 5599–5605, 5908–5909, Möhren 13). See Table 2 for specimens and measurements.
Description
Dentary.—Only fragments of the horizontal ramus are preserved. The most complete specimen from Möhren 12 includes the lowermost part of the ascending ramus with the cylindrical condyle high above the level of the tooth row and a strong, ledge−shaped mylohyoid ridge. Directly below this ridge the mandibular foramen opens posteriorly. The mental foramina lie under the anterior roots of p4 and p2, respectively. In one edentulous fragment from Möhren 13, there are three mental foramina: under the posterior root of p4, and un− der each of the roots of p3. Another fragment, which is broken anterior to p3, preserves one mental foramen under the posterior root of p4.
Lower dentition.—Based on the alveoli, there are at least three single−rooted teeth anterior to the p1. One small alveolus is for the obliquely implanted canine, another small alveolus housed a more obliquely implanted i3, and a procumbently oriented alveolus housed a large i2. The possible presence of i1 is suggested by the remnant of what appears to have been a very small alveolus. The single−rooted p1, which is preserved in the Möhren 12 dentary, is heavily worn. It has a lingual cingulid, a posterior cuspule and a straight posterior margin. The p2 has two perpendicular roots, a crested main cusp, a tiny anterior cuspule, a somewhat larger posterior cuspule, and a broad postero−lingual cingulum. The p3 differs from the p 2 in its larger size and a more anteriorly directed taper. The p4 has a blade−like paraconid, a metaconid attached to the lingual face of the protoconid, a posterior cuspule and marked precingulid. The lower molars are strongly graded in size. Morphologically all are rather similar in the trigonid, being distinctly wider than the talonid. Anterior to the paraconid is a vertical bar. The paraconid is blade−like, at best a slightly pointed extremity of the paralophid, which is notched. All lower molars have a well−developed precingulid. The protolophid is also deeply notched. The talonid is reduced in size, with an entoconid more or less fused in the entocristid.
Upper dentition.—All upper teeth are isolated. One double−rooted tooth (no. 5603) with an ovoid occlusal outline, a crested main cusp and a posterior cuspule, is probably a P2. The P3 (no. 217; Fig. 2J View Fig ) is triple−rooted with a lingual talon. The paracone is crested and the parastyle is only an anterior cingular projection. The protocone is a small cusp. The ectocingulum is interrupted above the paracone. The lingual part of this tooth, from the parastyle to the metastyle, is bordered by a cingulum. In the triple−rooted P4 the parastyle is a small, anterior and slightly cuspidate projection. There is a large talon with an anteriorly situated protocone and without a hypocone. Though the posterior part of the talon is broken the missing part is too small to have housed a hypocone. A cingular swelling may be interpreted as a vestigial (or incipient) hypocone. The most conspicuous feature of the P4 is the expanded, postero−labially directed metastylar blade. The crown base is surrounded by a lingually interrupted cingulum. The M1 and M2 are morphologically indistinguishable. An upper molar from the type locality was determined as M1/2 by Quinet and Misonne (1965). The new material—a dentary fragment with p4–m1, a maxillary fragment with P3–P4 and 32 isolated teeth—was included in Smith (2004) but were not described in detail. There are no upper molars in situ but in the Möhren 13 sample there are two size classes of morphologically identical teeth. The larger ones are considered to be the M1, the smaller ones the M2. The upper molars are extremely short with respect to their width. The paracone is the highest cusp, followed by the protocone. The metacone is adjacent and posterior to the paracone and is distinctly smaller. On the labial side there is an expanded stylar shelf.
Saturninia gracilis Butselia biveri Plesiosorex soricinoides Plesiosorex germanicus Plesiosorex schaffneri Plesiosorex coloradensis Plesiosorex donroosai Plesiosorex latidens Plesiosorex aydarlensis Plesiosorex evolutus Plesiosorex greeni
The stylar cusps labial to the paracone and metacone are well developed but distinctly lower than the paracone and metacone, respectively. The parastyle and hypocone are the lowest cusps. The preprotocrista is continuous with the paracingulum; the postprotocrista joins the metacingulum. These crests converge at an acute angle towards the protocone. Slight constrictions on the preprotocrista and postprotocrista, respectively may indicate a vestigial paraconule or metaconule. The precingulum and postcingulum are also well−developed. The hypocone is either an inconspicuous swelling of the postcingulum (as on M3) or is slightly cuspidate (on M1 and M2). The M3 differs from the M 2 in its smaller size and in its reduced postero−labial part, which results in an oblique labial margin.
Discussion.—Without doubt the specimens under study belong to Butselia . The characteristic morphology of the short upper molars, with their reduced posterior heel and poorly developed hypocone, differentiates them from any other plesiosoricid known by upper molars. The specimens herein compare well with Butselia biveri from the type locality, Hoogbutsel, Belgium, in the extremely short upper molars, in the absence of a marked hypocone, the size of the stylar cusps, in their degree of zalambdodonty and in the reduced talonid of the lower molars. The size differences are expected to lie within the normal size range of a population.
Quinet and Misonne (1965) placed Butselia in its own family, Butselidae , in the insectivoran suborder Zalambdodonta because of its semi−zalambdodont molars. Butler (1972) was the first to include it in the family Plesiosoricidae . Recently the plesiosoricid affinities of Butselia were questioned by Hooker (2005). He identified an isolated astragalus from the Isle of Wight as that of Butselia , which is unlike that of any lipotyphlan, but he did not publish further details. So far postcranials of plesiosoricids are unknown. Hooker (2005) presented two alternatives: either the Plesiosoricidae are not lipotyphlans or Butselia is not a plesiosoricid. Given the poor record, another alternative seems to be more probable (i.e., that the astragalus does not belong to Butselia ). At present, there is no reason to exclude Butselia from the Plesiosoricidae .
Hooker (1987) and Hooker et al. (2004) also reported on the first pre−Grande Coupure record of Butselia , again from the Isle of Wight. This extended the range of the genus to the late Eocene. To date, all other pre−Oligocene plesiosoricids are Asian. However, as discussed earlier, the Chinese Ernosorex is not a plesiosoricid, and the familial allocation of the Pakistan Pakilestes is somewhat questionable. Hence Ordolestes ordinatus from the early Eocene of Mongolia is the only record which, though being sparse, may be attributed with some certainty to the plesiosoricids. Ordolestes is only known from some lower molars. They share with Butselia the narrow talonid, but differ from it in the strong ectocingulid below the hypoconid, and in the smaller entoconid. Given their sparse pre−Oligocene record, the origin of the plesiosoricids remains obscure.
Stratigraphic and geographic range.— Butselia biveri is recorded from England (Isle of White), from Belgium, and from Möhren in South Germany. The sites correlate with the late Eocene and the the early Oligocene.
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