Galerix kostakii
Encyclopedia
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.
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.
, 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.
Erinaceidae
Erinaceidae is the only living family in the order Erinaceomorpha, which has recently been subsumed with Soricomorpha into the order Eulipotyphla...
mammal from the early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
of Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
. It is known from the site of Karydia, assigned to the biostratigraphical
Biostratigraphy
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. Usually the aim is correlation, demonstrating that a particular horizon in one geological section represents the same period...
zone MN 4; similar fossils have been found at an approximately contemporary Czech
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
site and a slightly younger Greek site. With characters like the presence of a hypocone
Hypocone
The hypocone is the name for a main cusp found on the molars of the upper dentition of hominids. It is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an adaptation for the overall grinding and tearing of foods using the occlusal of the tooth...
(fourth cusp
Cusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
) on the upper third premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
, the presence of a connection between the protocone
Protocone
thumb|500px|right|Right upper molar showing the four main upper molars cusps.The protocone is a cusp of the molars of the upper dentition in Placental and Marsupial vertebrates .It is found at the mesiolingual area of the tooth...
and metaconule cusps on the second upper molar
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
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
Galerix
Galerix is a prehistoric genus of gymnures. Fossils of these hedgehog-like creatures are found in Europe, Africa, and Asia.-Taxonomy:Nine species are considered as members of the genus:*Galerix aurelianensis*Galerix exilis...
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 cricetidCricetidae
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, and New World rats and mice...
rodents found at Karydia. Karydia is dated to the mammal zone MN 4
MN 4 (biostratigraphy)
In biostratigraphy, MN 4 is one of the MN zones used to characterize the fossil mammal faunas of the Neogene of Europe. It is preceded by MN 3 and followed by MN 5; together, these three zones form the Orleanian age of the middle Miocene...
(late early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
). Galerix kostakii dominates the insectivore fauna of Karydia, forming 60% of the total fauna. In contrast, at Aliveri
Aliveri
Aliveri , is a town in the Greek island of Euboea. It is part of the municipal unit Taminaioi, and the seat of the municipality Kymi-Aliveri. Aliveri is linked by the GR-44 . Aliveri lies next to the South Euboic Gulf...
, 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
Komotini
Komotini is a city in Thrace, northeastern Greece. It is the capital of the region of East Macedonia and Thrace and of the Rhodope regional unit. It is also the administrative center of the Rhodope-Evros super-prefecture. The city is home to the Democritus University of Thrace, founded in 1973...
, 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
Czech Republic
The Czech Republic is a landlocked country in Central Europe. The country is bordered by Poland to the northeast, Slovakia to the east, Austria to the south, and Germany to the west and northwest....
region of Mokrá
Mokra
Mokra is a village in the administrative district of Gmina Miedźno, within Kłobuck County, Silesian Voivodeship, in southern Poland. It lies approximately north of Kłobuck and north of the regional capital Katowice. The village has a population of 796....
, 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 cuspCusp (dentistry)
A cusp is an occlusal or incisal eminence on a tooth.Canine teeth, otherwise known as cuspids, each possess a single cusp, while premolars, otherwise known as bicuspids, possess two each. Molars normally possess either four or five cusps...
, the hypocone
Hypocone
The hypocone is the name for a main cusp found on the molars of the upper dentition of hominids. It is found on the distal lingual side of the tooth. It fits into the grooves of the lower dentition and is an adaptation for the overall grinding and tearing of foods using the occlusal of the tooth...
, on its upper third premolar
Premolar
The premolar teeth or bicuspids are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant, making eight premolars total in the mouth. They have at least two cusps. Premolars can be considered as a 'transitional tooth' during chewing, or...
(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
Protocone
thumb|500px|right|Right upper molar showing the four main upper molars cusps.The protocone is a cusp of the molars of the upper dentition in Placental and Marsupial vertebrates .It is found at the mesiolingual area of the tooth...
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
Metacone
thumb|500px|left|Right upper molar showing the four main upper molars cusps.The metacone is a cusp on the molars of the upper dentition in hominids. It is found at the buccal distal area of the tooth...
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
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
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
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
with Schizogalerix, which appears earlier in the fossil record.