''Omma'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

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. Howev ...

. ''Omma'' is an example of a

living fossil A living fossil is a Deprecation, deprecated term for an extant taxon that phenotypically 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 or ...

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

Rhaetian The Rhaetian is the latest age (geology), age of the Triassic period (geology), Period (in geochronology) or the uppermost stage (stratigraphy), stage of the Triassic system (stratigraphy), System (in chronostratigraphy). It was preceded by the N ...

), 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 The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately 143.1 Mya. ...

and

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

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

endemic Endemism is the state of a species being found only 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 foun ...

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 more than 700 species of flowering plants in the family Myrtaceae. Most species of ''Eucalyptus'' are trees, often Mallee (habit), mallees, and a few are shrubs. Along with several other genera in the tribe Eucalyp ...

'' bark and exhibiting thanatosis 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: * Queen Victoria (1819–1901), Queen of the United Kingdom and Empress of India * Victoria (state), a state of Australia * Victoria, British Columbia, Canada, a provincial capital * Victoria, Seychelles, the capi ...

Central Queensland Central Queensland is an imprecisely-defined geographical division of Queensland ( a state in Australia) that centres on the eastern coast, around the Tropic of Capricorn. Its major regional centre is Rockhampton. The region extends from the Cap ...

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 an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

and

extant Extant or Least-concern species, least concern 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 * Exta ...

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

Fossil species

* Middle-Late Jurassic,

Jiulongshan Formation The Haifanggou Formation (), also known as the Jiulongshan Formation (), is a fossil-bearing rock deposit located near Daohugou () village of Ningcheng County, in Inner Mongolia, northeastern China. The formation consists of coarse Conglomerate ( ...

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 (stage), Oxfordian stages). It is known for its Lagerstätte, exceptionally preser ...

, 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 154.8 ±0.8 Ma and 149.2 ±0.7 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...

)

Karabastau Formation The Karabastau Formation () is a geological formation and lagerstätte in the Karatau Mountains of southern Kazakhstan whose strata date to the Middle to Late Jurassic. It is an important locality for insect fossils that has been studied since ...

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

Tithonian In the geological timescale, the Tithonian is the latest age (geology), age of the Late Jurassic Epoch and the uppermost stage (stratigraphy), stage of the Upper Jurassic Series. It spans the time between 149.2 ±0.7 annum, Ma and 143.1 ±0.6 (mi ...

Solnhofen Limestone The Solnhofen Limestone or Solnhofen Plattenkalk, formally known as the Altmühltal Formation, is a Jurassic Konservat-Lagerstätte that preserves a rare assemblage of fossilized organisms, including highly detailed imprints of soft bodied organi ...

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

Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...

), 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 International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

)

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...

, 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 The Hettangian is the earliest age and lowest stage of the Jurassic Period of the geologic timescale. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). The Hettangian follows the Rhaetian (part of the Triass ...

), 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 143.1 ±0.6 Ma and 137.05 ± 0.2 (million years ago) ...

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

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 132.6 ± 2 Ma and 125.77 (million years ago). The Hauterivian is preceded by the Valangi ...

Weald Clay Weald Clay or the Weald Clay Formation is a Lower Cretaceous sedimentary rock unit underlying areas of South East England, between the North and South Downs, in an area called the Weald Basin. It is the uppermost unit of the Wealden Group of ...

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

Lilstock Formation The Lilstock Formation is a geologic formation in England. It preserves bivalve, insect and other invertebrate fossils, as well as fossil fish of '' Agkistracanthus mitgelensis'' and the basal theropod dinosaur '' Newtonsaurus cambrensis'' datin ...

, Brown's wood, Warwickshire, Lower Jurassic (

Blue Lias The Blue Lias is a formation (stratigraphy), 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 ...

, Binton, Warwickshire, Lower Jurassic (Sinemurian), Charmouth Mudstone, 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 137.05 ± 0.2 Ma and 132.6 ± 0.2 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. The age of the formation is disputed, and is considered likely to be Valanginian-Hauterivian, or Aptian in age. It comprises sandstones, ...

, 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 Taxa named by Edward Newman