Clapasorex alvarezae, Van den Hoek Ostende, 2003

Van Den Hoek Ostende, Lars W., Casanovas-Vilar, Isaac & Furió, Marc, 2020, Stuck in the middle. A geographical appraisal of the oldest insectivores - and a marsupial - from the Vallès-Penedès Basin (early Miocene, Catalonia, Spain), Comptes Rendus Palevol 19 (1), pp. 1-25 : 16

cf. Clapasorex alvarezae vel cf. Oligosorex thauensis

MATERIAL EXAMINED. — Spain. Sant Andreu de la Barca 1, 1 m2 sin. trigonid in ramus, IPS86187 .

DESCRIPTION

m1

In the m1 from Turó de les Forques, the trigonid and talonid are of similar length; the trigonid is only slightly narrower.The protoconid is rather massive; the metaconid lies close to the protoconid. The oblique cristid ends just lingually to the base of the protoconid. The hypolophid curves at just its lingual end, behind the entoconid, with little or no space for a post-entoconid valley. The entocristid slopes down before levelling, ending against the posterior flank of the metaconid. There is a well-developed cingulid on the anterior and posterior sides; the cingulum on the labial and lingual sides is narrow but continuous. The m1 from Can Martí Vell III has more slender cusps, the protoconid and metaconid further apart and a more open trigonid basin. Between the hypolophid and the entoconid, there is a narrow post-entoconid valley.

m2

The trigonid is just slightly narrower than the talonid and of similar length. The oblique cristid ends just a bit more lingually to the centre of the posterior wall of the trigonid.The hypolophid is relatively straight, with just a slight curve at the lingual end, rounding the entoconid and connecting to the lingual cingulum. The entocristid extends to the base of the metaconid.The cingulum is best developed on the anterior side, somewhat less on the labial and posterior sides and weak on the lingual side.

REMARKS

Van den Hoek Ostende (2003) commented on the difficulties in the taxonomy of the small shrews in the early Miocene and how these regularly led in literature to possible lumping of multiple species. In the material described in that paper, two of these small soricids were present as also testified by mandibles showing the alveoles of the antemolars. One of the species from the Ramblian type section was identified as Clapasorex alvarezae , the other as Oligosorex thauensis . Based on a change in the relative size of the m1 and m2, the younger assemblages of the latter were classified as O. aff. thauensis . Although the molar morphology of these two species, as indeed of most of the soricids of that period, is very close, Van den Hoek Ostende (2003) ventured to indicate some characters used to identify isolated molars. In the case of the lower molars, the cusps of Clapasorex had a more massive appearance, protoconid and metaconid of the m1 were situated close together and the hypolophid ran directly behind the entoconid without having a post-entoconid valley.

In the series from the early Miocene insectivore assemblages of the Vallès-Penedès, only a few isolated molars of small soricids have been found. Without the foreknowledge on the shrews from the Ramblian type section, these would almost certainly have been combined in one taxon.However, following the above-mentioned characteristics, both Clapasorex alvarezae and Oligosorex aff. thauensis appear to be represented in the Vallès-Penedès. Given the difficulties in identifying these isolated molars, we do take some caution in assigning the material to one or the other taxon, hence presenting them as cf. Clapasorex alvarezae and cf. Oligosorex thauensis , respectively. Despite these reservations, it is notable that cf. Clapasorex alvarezae was identified from the oldest assemblage in our series, Turó de les Forques. In the Ramblian type area, C. alvarezae has only been identified from older localities (zone Z).