''Pachycondyla petrosa'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species of ant in the formicid subfamily Ponerinae described from a fossil found in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. ''P. petrosa'' is one of six Lutetian ''

Pachycondyla ''Pachycondyla'' is a ponerine genus of ants found in the Neotropics. Distribution ''Pachycondyla'' is currently distributed from southern United States to northern Argentina, but some fossil species (e.g. '' P. eocenica'' and '' P. lutzi'') a ...

'' species.

History and classification

When described ''Pachycondyla petrosa'' was known from a single fossil insect which is a compression-impression fossil preserved in layers of soft

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

rock. Along with other well preserved insect fossils, the ''P. petrosa'' specimen was collected from layers of

Lutetian The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Midd ...

Messel Formation The Messel Formation is a geologic formation in Hesse, central Germany, dating back to the Eocene epoch (about 47 MaJens Lorenz Franzen (2005). "The implications of the numerical dating of the Messel fossil deposit (Eocene, Germany) for mamma ...

rock in the Messel pit

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

. The Messel formation is composed of brown coals, oil shales, and

bituminous shale Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen (a solid mixture of organic chemical compounds) from which liquid hydrocarbons can be produced. In addition to kerogen, general composition of oil shales constitute ...

, which preserved numerous insects, fish, birds, reptiles, and terrestrial mammals as a notable lagerstätten. The area is a preserved

maar lake A maar is a broad, low-relief volcanic crater caused by a phreatomagmatic eruption (an explosion which occurs when groundwater comes into contact with hot lava or magma). A maar characteristically fills with water to form a relatively shallow ...

which initially formed approximately 47 million years ago as the result of volcanic explosions. At the time of description, the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

specimen, number SMF MeI 12273 was preserved in the Senckenberg Research Station Messel fossil collections. The fossil was first described by Gennady Dlussky and Sonja Wedmann in a 2012 paper on the poneromorph ants of Messel. In the type description, Dlussky and Wedmann named the species ''P. petrosa'', with the

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

derived from the Greek "petros", which means stone. The species is one of six ''Pachycondyla'' which have been described from Messel Formation fossils. All six of the species were described by Dlussky and Wedmann in the same 2012 paper, the other five being '' P. eocenica'', '' P. lutzi'', '' P.? messeliana'', '' P. parvula'', and '' P. petiolosa''. Another eight fossil species have been described from fossils in North America, Europe, and Asia.

Description

The ''Pachycondyla petrosa'' fossil is possibly either a

queen Queen or QUEEN may refer to: Monarchy * Queen regnant, a female monarch of a Kingdom ** List of queens regnant * Queen consort, the wife of a reigning king * Queen dowager, the widow of a king * Queen mother, a queen dowager who is the mother ...

or worker and preserved in lateral positioning. The ant has a body length of approximately and the head is . The alitrunk is long, with the ant being described as being very similar to members of the genus ''

Mesoponera ''Mesoponera'' is an Old World genus of ants in the subfamily Ponerinae Ponerinae is a subfamily of ants in the Poneromorph subfamilies group, with about 1,600 species in 47 extant genera, including '' Dinoponera gigantea'' - one of the ...

'', formerly considered a subgenus of ''Pachycondyla''. Where preserved the generally triangular mandibles have large blocky teeth and comprise less than half the length of the head. The petiole is a triangle in side view, with a high scale, and a rounded apex.

References

External links

* * {{Taxonbar, from=Q21279557 †Pachycondyla petrosa Fossil taxa described in 2012 Hymenoptera of Europe Fossil ant taxa Prehistoric life of Europe Ant genera Insects described in 2012