''Afromyrma'' 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 ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

ant Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of 22 ...

in the formicid subfamily

Myrmicinae Myrmicinae is a subfamily of ants, with about 140 extant genera; their distribution is cosmopolitan. The pupae lack cocoons. Some species retain a functional sting. The petioles of Myrmicinae consist of two nodes. The nests are permanent and ...

, and is currently unplaced in any of the tribes of that subfamily. The genus contains a single described species, ''Afromyrma petrosa''. ''Afromyrma'' is known from a single

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...

fossil, which was found in

Orapa Orapa is a town located in the Central District of Botswana. It is the site of the Orapa diamond mine, the largest diamond-producing mine in the world, and is considered to be the diamond capital of the country. Nearby is another kimberlite min ...

in the Central District of

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...

History and classification

''Afromyrma'' is known from a solitary fossil from Orapa, 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 BP/2/26501 tentatively identified as a female, though there is a possibility this is incorrect. The holotype specimen is mostly complete but is rather poor in details, and is preserved as a compression fossil in shale. The shales and mudstones of the Orapa site were rapidly deposited in a

crater lake Crater Lake (Klamath language, Klamath: ''Giiwas'') is a volcanic crater lake in south-central Oregon in the western United States. It is the main feature of Crater Lake National Park and is famous for its deep blue color and water clarity. The ...

formed as the result of a large volcanic eruption in the Cretaceous. The sediment originated as an epiclastic

kimberlite Kimberlite is an igneous rock and a rare variant of peridotite. It is most commonly known to be the main host matrix for diamonds. It is named after the town of Kimberley in South Africa, where the discovery of an diamond called the Star of ...

and derives from rapid weathering and decomposition of the sides of the kimberlite crater. Of the four major sedimentation types that have been observe at Orapa, fossils are found in only two, the granular mass flows and the fine-grained sediments: woody debris fossils are found in the granular mass flows, but well-preserved fossils are only recovered in the fine-grained sediments. The fossil-bearing stratum was uncovered during mining of the underlying diamond-bearing rocks at the site.

radiometric dating Radiometric dating, radioactive dating or radioisotope dating is a technique which is used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. The method compares t ...

of the kimberlite pipe reported on in 1977 gave a general age between . Further dating utilizing zircon crystals reported on in 2004 gave more defined age of approximately placing the date in the Turonian age of the late Cretaceous. The fossil was first studied by Russian paleontologists Gennady M. Dlussky and

Alexandr Rasnitsyn Alexandr Pavlovich Rasnitsyn (Russian: Александр Павлович Расницын) is a Russian entomologist, expert in palaeoentomology, and Honored Scientist of the Russian Federation (2001). His scientific interests are centered on ...

with South African paleontologist Denis Brothers. Their 2004

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

of the new genus and species was published in the journal '' Insect Systematics and Evolution''. The genus name ''Afromyrma'' is a combination of Africa, where the fossil was found, and the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

'' myrmex'' which means "ant". 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 ...

''petrosa'', a derivation of the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

word ''petra'' meaning ''rock'' is a reference to the fossil status of the species.

Description

The solitary ''Afromyrma'' specimen is incomplete and shows poor preservation in general with portions of the legs and antennae missing or very indistinct. Overall it is estimated the full body would have been around long. Overall the shape of the head capsule is shorter than it is wide, with eyes located slightly to the rear of the heads midpoint and having an oval shape. The mandibles are triangular in outline with distinct teeth on the chewing margin. The specimen has a waist divided into two segments and the petiole shows a weakly developed node. The abdomen segmentation and general form of the abdominal apex are suggestive of a male ant, but the soft nature of the abdominal tissue makes this interpretation problematic, in contrast the harder head capsule is more reminiscent of a female and thus the fossil is interpreted as such.

References

{{Taxonbar, from=Q15514311 Monotypic fossil ant genera Late Cretaceous insects Fossil taxa described in 2004 Prehistoric insects of Africa Myrmicinae