| Itagnostus Temporal range: | |
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![Itagnostus interstrictus - Wheeler Schale, Utah, USA - Cambrian period ([?] -507 MA) - 39.25degN 113.33degW .jpg](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Itagnostus_interstrictus_-_Wheeler_Shale%2C_Utah%2C_USA_-_Cambrian_period_%28%E2%89%88_-507_MA%29_-_39.25%C2%B0N_113.33%C2%B0W.jpg/220px-Itagnostus_interstrictus_-_Wheeler_Shale%2C_Utah%2C_USA_-_Cambrian_period_%28%E2%89%88_-507_MA%29_-_39.25%C2%B0N_113.33%C2%B0W.jpg) | |
| Itagnostus interstrictus, until recently known as Peronopsis interstricta, from the Wheeler Shale, Utah | |
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| Genus: | Itagnostus Öpik, 1979 |
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Itagnostus is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America. [1]
Agnostus is a genus of agnostid trilobites, belonging to the family Agnostidae, that lived during the late Middle Cambrian – early Upper Cambrian. It is the type genus of the family Agnostidae and is subdivided into two subgenera, Agnostus and Homagnostus.
Agraulos is a genus of Solenopleuridae trilobites that lived during the Middle Cambrian in North America and Europe, particularly the Czech Republic. The genus was named by Hawle & Corda in 1847.
Xystridura Whitehouse, 1936 is a genus of Redlichiid trilobite described originally from the Middle Cambrian (Miaolingian) strata of Queensland, Australia. The genus ranges upwards from Ordian into Florian Stages in terms of Australian Cambrian stratigraphic nomenclature.
Peronopsis is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America.
The Wheeler Shale is a Cambrian (c. 507 Ma) fossil locality world-famous for prolific agnostid and Elrathia kingii trilobite remains and represents a Konzentrat-Lagerstätte. Varied soft bodied organisms are locally preserved, a fauna and preservation style normally associated with the more famous Burgess Shale. As such, the Wheeler Shale also represents a Konservat-Lagerstätten.
Caerfai Bay is a rocky cove on the north coast of St Brides Bay near St Davids in Pembrokeshire, West Wales. It is enclosed by steep varicoloured cliffs and has a sandy beach at low tide accessed by pathway and steps. The beach is situated in the Pembrokeshire Coast National Park and on the Pembrokeshire Coast Path. There is free parking above the beach with picnic benches and views of the islands of Penpleidiau, Skomer and Skokholm.
Trilobites are used as index fossils to subdivide the Cambrian period. Assemblages of trilobites define trilobite zones. The Olenellus-zone has traditionally marked the top of the Lower Cambrian, and is followed by the Eokochaspis zone.
Ptychagnostus is a member of the agnostida that lived during the Cambrian period. Ptychagnostidae generally do not exceed one centimetre in length. Their remains are rarely found in empty tubes of the polychaete worm Selkirkia. The genus probably ranged throughout the water column. It has two glabellar lobes, and three pygidial lobes.
Bolbolenellus is an extinct genus of trilobites, fossil marine arthropods, with five species attributed to it currently. It can be easily distinguished from all other trilobites by the combination of the absence of dorsal sutures in the head shield like all Olenellina, and a distinctly bulbous frontal lobe (L4) of the raised axial area in the head called glabella. The species lived at the end of the Lower Cambrian.
The Drumian is a stage of the Miaolingian Series of the Cambrian. It succeeds the Wuliuan and precedes the Guzhangian. The base is defined as the first appearance of the trilobite Ptychagnostus atavus around 504.5 million years ago. The top is defined as the first appearance of another trilobite Lejopyge laevigata around 500.5 million years ago.
The Wuliuan stage is the fifth stage of the Cambrian, and the first stage of the Miaolingian Series of the Cambrian. It was formally defined by the International Commission on Stratigraphy in 2018. Its base is defined by the first appearance of the trilobite species Oryctocephalus indicus; it ends with the beginning of the Drumian Stage, marked by the first appearance of the trilobite Ptychagnostus atavus around 504.5 million years ago.
The Peronopsidae comprise the earliest family of the Agnostina suborder. Species of this family occurred on all paleocontinents. The earliest representatives of this family first occur just before the start of the Middle Cambrian, and the last disappeared just after the start of the Upper Cambrian.
Pleuroctenium Hawle & Corda (1847) is an agnostid trilobite belonging to the family Condylopygidae Raymond (1913). The genus occurs in Middle Cambrian (Drumian) strata of Canada, the Czech Republic, England and Wales, France, and Sweden.
Diplorrhina Hawle and Corda (1847) is a genus of trilobite belonging to Order Agnostida. It lived during the early Middle Cambrian in what are now the Czech Republic and the North Siberian plateau. as in members of the family Peronopsidae it lacks a preglabellar furrow. Both cephalon and pygidium lack spines. It is difficult to distinguish Diplorrhina from many other peronopsids.
Condylopyge Hawle and Corda (1847) is a genus of agnostid trilobite that lived during the late Lower and early Middle Cambrian, in what are today Canada, the Czech Republic, England and Wales, France, Germany, Italy, Morocco, the Russian Federation, Spain, Turkey and Sweden. It can easily be distinguished from all other Agnostida because the frontal glabellar lobe is notably wider than the rear lobe. It belongs to the same family as Pleuroctenium but the frontal glabellar lobe does not fold around the rear lobe, as it does in that genus. Condylopyge is long ranging, possibly spanning the early Cambrian Terreneuvian Series in Nuneaton, central England into at least Drumian strata at various locations elsewhere.
Ovatoryctocara is a genus of small corynexochid trilobites from the Cambrian, that lived in what now are Siberia, China, Greenland and Canada (Newfoundland). Ovatoryctocara can be recognised by the combination of the following characters: the central raised area of the cephalon is approximately cylindrical and has two rows of four triangular or round pits. The thorax only has 5 or 6 segments. The tailshield has an axis of 6 to 12 rings, the pleural furrows are well developed and the border is absent or narrow as a hair.
Schmalenseeia is genus of trilobites of uncertain affinity, that lived during the middle Middle to earliest Upper Cambrian. Species assigned to Schmalenseeia have been found in Norway, Sweden, Northern Siberia, Eastern China, Australia (Tasmania), India (Himalayas) and the United Kingdom.
Serrodiscus Richter and Richter 1941. is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida. It lived during the late Lower Cambrian, with remains found in Canada, China (Gansu), The United Kingdom (England), Germany (Silesia), Poland, the Russian Federation, and the United States. It is named for the spines on the ventral side of the pygidium, which give it a serrated impression.
Bailiaspis Resser, 1936, is a Middle Cambrian (Miaolingian) trilobite genus belonging to the Family Conocoryphidae Angelin, 1854. Within the Acado-Baltic region, the genus ranges from Wuliuan into Guzhangian age strata.