Galerix Kostakii

''Galerix kostakii'' is a fossil erinaceid mammal from the early Miocene of Greece. It is known from the site of Karydia, assigned to the biostratigraphical zone MN 4; similar fossils have been found at an approximately contemporary Czech site and a slightly younger Greek site. With characters like the presence of a hypocone (fourth cusp) on the upper third premolar, the presence of a connection between the protocone and metaconule cusps on the second upper molar in only a few specimens, this species is intermediate between the slightly older ''Galerix symeonidisi'' and the slightly younger '' Parasorex pristinus''. It may form part of the lineage leading from the genus ''Galerix'' to the younger genus '' Parasorex''.

Taxonomy and range

''Galerix kostakii'' was first described in 2006 by Greek and Dutch paleontologists Constantin Doukas and Lars van den Hoek Ostende from the Greek paleontological site of Karydia. The specific name, ''kostakii'', honors Constantin "Kostaki" Theocharopoulos, who studied the cricetid rodents found at Karydia. Karydia is dated to the mammal zone MN 4 (late early Miocene). ''Galerix kostakii'' dominates the insectivore fauna of Karydia, forming 60% of the total fauna. In contrast, at Aliveri, a slightly older Greek site also assigned to MN 4, ''Galerix'' (represented by the related species ''Galerix symeonidisi'') forms only about 25% of the insectivore fauna. The reason for this difference is unknown. In Komotini, a slightly younger site (assigned to zone MN 5) near Karydia, a single first upper molar (M1) of an unidentified ''Galerix'' species similar to ''G. kostakii'' has been found. In the Czech region of Mokrá, at a site known as "Mokrá – 1/2001 Turtle Joint" (MN 4), a few fossils of a ''Galerix'' very similar to ''G. kostakii'' have been found.

Description and relationships

Unlike most species of the genus ''Galerix'', ''G. kostakii'' has a fourth cusp, the hypocone, on its upper third premolar (P3). ''Galerix symeonidisi'' and '' Galerix iliensis'' also have this cusp, but are smaller and larger, respectively, than ''G. kostakii''. In addition, ''G. kostakii'' differs from ''G. symeonidisi'' in that a connection between the protocone and metaconule cusps of M2 is more rarely present and the back arm of the metaconule always reaches the back corner of the tooth. Members of the related genus '' Parasorex'' are similar, but never have a protocone-metaconule connection, which is still occasionally present in ''G. kostakii''. The primitive ''Parasorex'' species '' Parasorex pristinus'' is about as large as ''G. kostakii'', but its molars are narrower, the first lower premolar (p4) is smaller, and the metacone cusp on M2 has a straight anterior arm. Furthermore, ''Galerix kostakii'' lacks the paralophid on p4, a crest that connects the paraconid and protoconid cusps.

''Galerix kostakii'' shares some of the features present in ''Parasorex'' and '' Schizogalerix'', both derived descendants of ''Galerix'', including the presence of a hypocone on P3, a partitioned posterior cingulum on m1 and m2, and the absence of the protocone-metaconule connection in most M1 and M2. However, it also retains primitive, ''Galerix''-like features, including the condition of p4 and the presence of a protocone-metaconule connection in some specimens. ''Galerix kostakii'' may be part of a lineage that led from the slightly more primitive ''G. symeonidisi'' through ''G. kostakii'' to ''Parasorex pristinus'', the oldest species of its genus, and then to the other ''Parasorex'' species. This lineage may have evolved these traits, which may be adaptations to a herbivorous diet, convergently with ''Schizogalerix'', which appears earlier in the fossil record.

References

Literature cited

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Gymnures
Prehistoric Eulipotyphla
Miocene mammals of Europe