''Omma'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial no ...

beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

s in the family

Ommatidae The Ommatidae are a family of beetles in the suborder Archostemata. The Ommatidae are considered the extant beetle family that has most ancestral characteristics. There are only seven extant species, confined to Australia and South America. Howe ...

. ''Omma'' is an example of a

living fossil A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living fossi ...

. The oldest species known, ''O. liassicum'', lived during the final stage of the Triassic (

Rhaetian The Rhaetian is the latest age of the Triassic Period (in geochronology) or the uppermost stage of the Triassic System (in chronostratigraphy). It was preceded by the Norian and succeeded by the Hettangian (the lowermost stage or earliest age ...

), over 200 million years ago, though the placement of this species in ''Omma'' has been questioned. Numerous other fossil species are known from the Jurassic and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

of Europe and Asia. The only living species is '' Omma stanleyi'', which is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to Australia. Three other extant species endemic to Australia that were formerly part of this genus were moved to the separate genus '' Beutelius'' in 2020''.'' ''Omma stanleyi'' is strongly associated with wood, being found under ''

Eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including ''Corymbia'', they are commonly known as euca ...

'' bark and exhibiting

thanatosis Apparent death, colloquially known as playing dead, feigning death, or playing possum, is a behavior in which animals take on the appearance of being dead. It is an immobile state most often triggered by a predatory attack and can be found in a ...

when disturbed. Its larval stage and many other life details are unknown due to its rarity. Males are typically 14–20 mm in length, while females are 14.4-27.5 mm. ''Omma stanleyi'' occurs throughout eastern Australia from

Victoria Victoria most commonly refers to: * Victoria (Australia), a state of the Commonwealth of Australia * Victoria, British Columbia, provincial capital of British Columbia, Canada * Victoria (mythology), Roman goddess of Victory * Victoria, Seyche ...

Central Queensland Central Queensland is an ambiguous geography, geographical division of Queensland (States and territories of Australia, a state in Australia) that centres on the eastern coast, around the Tropic of Capricorn. Its major regional centre is Rockhamp ...

Description

According to Li, Huang & Cai, 2021, ''Omma'' is distinguished from other ommatid beetles by the following characters:

Species, temporal and spatial distribution

The following

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 ...

and

extant Extant is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Extant taxon, a taxon which is not extin ...

species have been described. Taxa labelled (?) are considered questionable by Kirejtshuk, 2020 '' Omma stanleyi'' , recent, Australia

Fossil species

* Middle-Late Jurassic, Jiulongshan Formation and

Tiaojishan Formation The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period ( Bathonian- Oxfordian stages). It is known for its exceptionally preserved fossils, including those o ...

, Inner Mongolia, China, ** ''Omma ancistrodontum'' (Callovian-Oxfordian), Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China ** (?)''Omma daxishanense'' Upper Jurassic ( Oxfordian), China ** ''Omma delicatum'' * Late Jurassic ( Oxfordian and

Kimmeridgian In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxford ...

) Karabastau Formation, Karatau, Kazakhstan **''Omma aberratum'' **(?)''Omma grande'' **''Omma jurassicum'' **''Omma pilosum'' *Upper Jurassic (

Tithonian In the geological timescale, the Tithonian is the latest age of the Late Jurassic Epoch and the uppermost stage of the Upper Jurassic Series. It spans the time between 152.1 ± 4 Ma and 145.0 ± 4 Ma (million years ago). It is preceded by the ...

), Solnhofen Limestone, Bavaria, Germany **''Omma brevipes'' **(?)''Omma zitteli'' *Lower Cretaceous (

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago) ...

), Dzun-Bain Formation, Bon-Tsagan, Mongolia **(?)''Omma antennatum'' **''Omma longicolle'' *Mid Cretaceous (

Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in ...

) Burmese amber, Myanmar **''Omma davidbatteni'' **''Omma forte'' Li, Huang & Cai, 2021 **''Omma janetae'' **''Omma lii'' **''Omma manukyani'' (Kirejtshuk, 2020) formerly placed in separate genus '' Cionocups''. **''Omma'' (''Coronomma'') ''axsmithi'' Jarzembowski, Zheng & Zhao, 2022 *Other Species: * (?)''Omma altajense'' , Middle to Late Jurassic, Togo-Khuduk Formation, Bakhar, Mongolia *''Omma avus'' , Lower Jurassic ( Hettangian), Dzhil Formation, Issyk-Kul’, Kyrgyzstan * (?)''Omma elongatum'' , Lower Cretaceous (

Berriasian In the geological timescale, the Berriasian is an age/ stage of the Early/Lower Cretaceous. It is the oldest subdivision in the entire Cretaceous. It has been taken to span the time between 145.0 ± 4.0 Ma and 139.8 ± 3.0 Ma (million years ag ...

Purbeck Group The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) in south-east England. The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed in t ...

Lower Cretaceous (

Hauterivian The Hauterivian is, in the geologic timescale, an age in the Early Cretaceous Epoch or a stage in the Lower Cretaceous Series. It spans the time between 132.9 ± 2 Ma and 129.4 ± 1.5 Ma (million years ago). The Hauterivian is preceded by the ...

), Weald Clay, United Kingdom *(?)''Omma gobiense'' , Upper Jurassic (Tithonian), Ulan-Ereg Formation, Khoutiin-Khotgor, Mongolia *''Omma liassicum'' , Late Triassic (

), Lilstock Formation, Brown's wood, Warwickshire, Lower Jurassic ( Hettangian),

Blue Lias The Blue Lias is a geological formation in southern, eastern and western England and parts of South Wales, part of the Lias Group. The Blue Lias consists of a sequence of limestone and shale layers, laid down in latest Triassic and early Jurassi ...

, Binton, Warwickshire, Lower Jurassic (Sinemurian),

Charmouth Mudstone The Charmouth Mudstone Formation is a geological formation in England. It preserves fossils dating back to the early part of the Jurassic period ( Sinemurian–Pliensbachian). It forms part of the lower Lias Group. It is most prominently exposed ...

, Charmouth, England *''Omma sibiricum'' , Lower Cretaceous (

Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretac ...

Zaza Formation The Zaza Formation is a geological formation located in Buryatia ( Russia). It dates to the Lower Cretaceous period. It is Aptian in age and consists of sandstones, siltstones, marls and bituminous shales, deposited in a stratified lake. It is s ...

, Baissa, West Transbaikalia Russia

References

{{Taxonbar, from=Q7090278 Ommatidae Endemic fauna of Australia Insects of Australia Jurassic insects Cretaceous insects Mesozoic life of Asia Rhaetian first appearances Extant Late Triassic first appearances Archostemata genera