Pridoli epoch

In the geologic timescale, the Pridoli epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon is comprehended between 423 ± 1.5 and 419.2 ± 2.8 mya (million years ago), approximately. The Pridoli epoch succeeds the Ludfordian age and precedes the Lochkovian age of the Devonian. It is named after one locality at the Homolka a Přídolí nature reserve near the Prague suburb Slivenec in the Czech Republic.[3] Přídolí is the old name of a cadastral field area.[4]



Arthropods of the Gorstian
Taxa Presence Location Description Images
Gorstian-Pridoli Trimpley, Worcestershire, UK


  1. ^ Jeppsson, L.; Calner, M. (2007). "The Silurian Mulde Event and a scenario for secundo—secundo events". Earth and Environmental Science Transactions of the Royal Society of Edinburgh. 93 (02): 135–154. doi:10.1017/S0263593300000377.
  2. ^ Munnecke, A.; Samtleben, C.; Bickert, T. (2003). "The Ireviken Event in the lower Silurian of Gotland, Sweden-relation to similar Palaeozoic and Proterozoic events". Palaeogeography, Palaeoclimatology, Palaeoecology. 195 (1): 99–124. doi:10.1016/S0031-0182(03)00304-3.
  3. ^ Gradstein, Felix M.; Ogg, James G.; Smith, Alan G. (2004). A Geologic Time Scale 2004. ISBN 9780521786737.
  4. ^ Manda, Štěpán; Frýda, Jiří (2010). "Silurian-Devonian boundary events and their influence on cephalopod evolution: evolutionary significance of cephalopod egg size during mass extinctions". Bulletin of Geosciences. 85 (3): 513–40. doi:10.3140/bull.geosci.1174.

In the geologic timescale, the Aeronian is the age of the Llandovery epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that began 440.8 ± 1.2 Ma and ended 438.5 ± 1.1 Ma (million years ago). The Aeronian age succeeds the Rhuddanian age and precedes the Telychian age, all in the same epoch.


Carcinosoma (meaning "crab body") is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of Carcinosoma are restricted to deposits of late Silurian (Late Llandovery to Early Pridoli) age. Classified as part of the family Carcinosomatidae, which the genus lends its name to, Carcinosoma contains seven species from North America and Great Britain.

Carcinosomatid eurypterids had unusual proportions and features compared to other eurypterids, with a broad abdomen, thin and long tail and spined and forward-facing walking appendages. They were not as streamlined as other groups but had considerably more robust and well developed walking appendages. In Carcinosoma, these spined walking appendages are thought to have been used to create a trap to capture prey in. The telson (final segment of the body) of Carcinosoma appears to have possessed distinct segmentation, Carcinosoma is the only known eurypterid to possess this feature.

At 2.2 meters (7.2 ft) in length, the species C. punctatum is the largest carcinosomatoid eurypterid by far and is among the largest eurypterids overall, rivalling the large pterygotid eurypterids (such as Jaekelopterus) in size. Other species of the genus were considerably smaller, with most ranging from 70 centimeters (2.3 ft) to 100 centimeters (3.3 ft) in length.


Eurypterids, often informally called sea scorpions, are a group of extinct arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period 467.3 million years ago. The group is likely to have appeared first either during the Early Ordovician or Late Cambrian period. With approximately 250 species, the Eurypterida is the most diverse Paleozoic chelicerate order. Following their appearance during the Ordovician, eurypterids became major components of marine faunas during the Silurian, from which the majority of eurypterid species have been described. The Silurian genus Eurypterus accounts for more than 90% of all known eurypterid specimens. Though the group continued to diversify during the subsequent Devonian period, the eurypterids were heavily affected by the Late Devonian extinction event. They declined in numbers and diversity until becoming extinct during the Permian–Triassic extinction event (or sometime shortly before) 251.9 million years ago.

Although popularly called "sea scorpions", only the earliest eurypterids were marine; many later forms lived in brackish or fresh water, and they were not true scorpions. Some studies suggest that a dual respiratory system was present, which would have allowed for short periods of time in terrestrial environments. The name Eurypterida comes from the Ancient Greek words εὐρύς (eurús), meaning "broad" or "wide", and πτερόν (pteron), meaning "wing", referring to the pair of wide swimming appendages present in many members of the group.

The eurypterids include the largest known arthropods ever to have lived. The largest, Jaekelopterus, reached 2.5 meters (8.2 ft) in length. Eurypterids were not uniformly large and most species were less than 20 centimeters (8 in) long; the smallest eurypterid, Alkenopterus, was only 2.03 centimeters (0.80 in) long. Eurypterid fossils have been recovered from every continent. A majority of fossils are from fossil sites in North America and Europe because the group lived primarily in the waters around and within the ancient supercontinent of Euramerica. Only a handful of eurypterid groups spread beyond the confines of Euramerica and a few genera, such as Adelophthalmus and Pterygotus, achieved a cosmopolitan distribution with fossils being found worldwide.


Eurypterus ( yoo-RIP-tər-əs) is an extinct genus of eurypterid, a group of organisms commonly called "sea scorpions". The genus lived during the Silurian period, from around 432 to 418 million years ago. Eurypterus is by far the most well-studied and well-known eurypterid and its fossil specimens probably represent more than 90% of all known eurypterid specimens.There are fifteen species belonging to the genus Eurypterus, the most common of which is Eurypterus remipes, the first eurypterid fossil discovered and the state fossil of New York.

Members of Eurypterus averaged at about 13 to 23 cm (5 to 9 in) in length, but the largest individual discovered was 1.3 m (4.3 ft) long. They all possessed spine-bearing appendages and a large paddle they used for swimming. They were generalist species, equally likely to engage in predation or scavenging.


Gateholm or Gateholm Island is a small tidal island off the south west coast of Pembrokeshire, in the community of Marloes and St Brides, in the south west side of Wales, in the west of the UK, and about 8 miles (13km) west of the port of Milford Haven. It is known for its Romano-British remains.


In the geologic timescale, the Gorstian is the age of the Ludlow epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that is comprehended between 422.9 ± 2.5 Ma and 421.3 ± 2.6 Ma (million years ago), approximately. The Gorstian age succeeds the Homerian age and precedes the Ludfordian age.


In the geologic timescale, the Homerian is the age of the Wenlock epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that is comprehended between 426.2 ± 2.4 Ma and 422.9 ± 2.5 Ma (million years ago), approximately. The Homerian age succeeds the Sheinwoodian age and precedes the Gorstian age.

The name comes from the small village of Homer, Shropshire near Much Wenlock.

Llandovery epoch

In the geological timescale, the Llandovery epoch (from 443.7 ± 1.5 million years ago to 428.2 ± 2.3 million years ago) occurred at the beginning of the Silurian period. The Llandoverian epoch follows the massive Ordovician-Silurian extinction events, which led to a large decrease in biodiversity and an opening up of ecosystems.

Widespread reef building started in this period and continued into the Devonian period when rising water temperatures are thought to have bleached out the coral by killing their photo symbionts.

The Llandoverian epoch ended with the Ireviken event which killed off 50% of trilobite species, and 80% of the global conodont species.


In the geologic timescale, the Ludfordian is the age of the Ludlow epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that occurred between 421.3 ± 2.6Ma and 418.7 ± 2.7 Ma (million years ago). The Ludfordian age succeeds the Gorstian age and precedes the Pridoli epoch. It is named for the town of Ludford in Shropshire, England.

The Lau event is a rapid pulse of cooling during the Ludfordian, about 420 million years ago; it is identified by a pulse of extinctions and oceanic changes. It is one of the series of fast sea-level and excursions in oxygen isotope ratios that signal fast switches between warm and cold climate states, characteristic of the Silurian climatic instability. The Lau Event occurred during an extended period of elevated seawater saturation state, explained by reservoirs of the planet's fresh water being locked up in massive polar ice caps. The sudden reappearance in normally saline marine environments of stromatolites and a mass occurrence of oncoids during the event suggested that minor extinction events like the Lau Event also resulted in periods of reduced grazing pressures on surviving "disaster biota", which can be compared to the aftermath of the more catastrophic end-Ordovician and end-Permian mass extinctions.


Monograptus is a genus of graptolites in the Order Graptoloidea. This particular genus is the last stage of the graptoloid evolution before its extinction in the early Devonian. A characteristic of the genus includes one uniserial stipe with very elaborate thecae. This particular genus contains large number of graptolite species and may not be monophyletic.

New Zealand geologic time scale

While also using the international geologic time scale, many nations - especially those with isolated and therefore non-standard prehistories - use their own system of dividing geologic time into epochs and faunal stages.

In New Zealand, these epochs and stages use local place names (mainly Maori in origin) back to the Permian. Prior to this time, they largely use the same terms as used in the Australian geologic time scale, and are not divided into epochs. In practice, these early terms are rarely used, as most New Zealand geology is of more recent origin. In all cases, New Zealand uses the same periods as used internationally; it is only the subdivisions of these periods that have been renamed. Very few epochs and stages cross international period boundaries. Of those that do, almost all are within the Cenozoic Era.

Though the New Zealand geologic time scale has not been formally adopted, it has become widely used by New Zealand earth scientists, geologists and palaeontologists since its proposal by J. S. Crampton in 1995.

A standard abbreviation is also used for these epochs and stages, mostly in the form Xx where the first letter is the initial letter of the epoch and the second (lower-case) letter is the initial letter of the stage. These are listed alongside the stage names in the list below.

Currently, we are in the Haweran stage of the Wanganui epoch. The Haweran, which started some 340,000 years ago, is named after the North Island town of Hawera.


Onychopterella ( ON-ə-kop-tə-REL-ə, from Ancient Greek: ὄνῠξ (ónux), "claw", and πτερόν (pteron), "wing") is a genus of predatory eurypterid ("sea scorpion"), an extinct group of aquatic arthropods. Fossils of Onychopterella have been discovered in deposits from the Late Ordovician to the Late Silurian. The genus contains three species: O. kokomoensis, the type species, from the Early Pridoli epoch of Indiana; O. pumilus, from the Early Llandovery epoch of Illinois, both from the United States; and O. augusti, from the Late Hirnantian to Early Rhuddanian stages of South Africa.

Its prosoma (head) could be subquadrate (almost square) or subrectangular (almost rectangular), with reniform (bean-shaped) eyes. The appendages (limbs) were generally long and narrow with a spine on their tip. The abdomen and telson ("tail") had different shapes and sizes depending on the species. The ornamentation of the body consisted of small, pointed scales. The largest species of the genus was O. kokomoensis with a total length of 16 centimetres (6.3 inches) long, followed by O. augusti (14.3 cm, 5.6 in) and O. pumilus (4 cm, 1.6 in).

The first Onychopterella fossils, belonging to O. kokomoensis, were discovered in 1896 at the Waterlime Group of Kokomo, Indiana. It has received attention from eurypterid researchers for its terminal claw in the sixth pair of appendages or swimming legs. Onychopterella is also the type genus of the basal ("primitive") family of eurypterines Onychopterellidae together with Alkenopterus and Tylopterella, characterized by the presence of spines on the second to fourth pair of appendages and a lack of them on the fifth and sixth pair of appendages (except occasionally one on the distal end of the swimming leg), as well as the lanceolate (lance-shaped) or styliform (pen-shaped) form of the telson and other characteristics.

The exceptional preservation of the fossils of O. augusti has permitted scientists to describe part of the alimentary canal that has only been observed in a few species of eurypterids, as well as the internal muscular structure of its limbs and even part of the external branchial respiratory system. This turned out to be highly similar to that of the scorpions of today, supporting a eurypterid-scorpion relationship. Onychopterella was a genus that was able to swim. Most of the time it was likely in the stratum, probably using its spines to walk and its head to dig in the ground.

Prague 5

Prague 5, formally the Prague Municipal District (Městská čast Praha 5), is a second-tier municipality in Prague. The administrative district (správní obvod) of the same name consists of municipal districts Prague 5 and Slivenec.

Prague 5 is one of the largest districts of Prague located at the west side of the Vltava river.

It comprises Smíchov, Radlice, Košíře, Barrandov, Zlíchov, Zličín, Jinonice, Hlubočepy, Motol, Slivenec, Butovice, Chuchle, and Klukovice, as well as a very small part of Malá Strana.

The district was the first one in Prague that offered free wireless internet connection to its citizens.

Prague 5 is growing more important since the reconstruction of Anděl on Smíchov. Now, Anděl is the heart of Prague 5, with thousands of offices and one big shopping mall. Also, the underground garages in Anděl are the biggest in Prague. Prague 5 is very easily accessible by public transport: Metro line B, dozens of tram lines and buses.


Pridoli (Přídolí) may refer to:

Pridoli epoch, part of the Silurian period

Přídolí, a small town in the southern Czech Republic

Pridoli (Bajina Bašta)


In the geologic timescale, the Sheinwoodian is the age of the Wenlock epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that is comprehended between 428.2 ± 2.3 Ma and 426.2 ± 2.4 Ma (million years ago), approximately. The Sheinwoodian age succeeds the Telychian age and precedes the Homerian age.


The Silurian ( sy-LUURR-ee-ən) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya. The Silurian is the shortest period of the Paleozoic Era. As with other geologic periods, the rock beds that define the period's start and end are well identified, but the exact dates are uncertain by several million years. The base of the Silurian is set at a series of major Ordovician–Silurian extinction events when up to 60% of marine genera were wiped out.

A significant evolutionary milestone during the Silurian was the diversification of jawed fish and bony fish. Multi-cellular life also began to appear on land in the form of small, bryophyte-like and vascular plants that grew beside lakes, streams, and coastlines, and terrestrial arthropods are also first found on land during the Silurian. However, terrestrial life would not greatly diversify and affect the landscape until the Devonian.


In the geologic timescale, the Telychian is the age of the Llandovery epoch of the Silurian period of the Paleozoic era of the Phanerozoic eon that is comprehended between 436.0 ± 1.9 Ma and 428.2 ± 2.3 Ma (million years ago), approximately. The Telychian age succeeds the Aeronian age and precedes the Sheinwoodian age.It ended with the Ireviken event.

Yulongsi Formation

The Yulongsi Formation is a palaeontological geological formation located at Qujing, in Yunnan Province of Southern China.


Řeporyje is a cadastral area of Prague. Most of it belongs to the municipal district of the same name, the rest belonging to Prague 13. Řeporyje became part of Prague in 1974, before which it was recorded as a městys.

The district is situated on Dalejský potok and borders Prokopské údolí to the east. The western part of Řeporyje is an industrial area, marked by the visually prominent silo belonging to Soufflet Agro a.s. The district is served by Praha-Řeporyje railway station, a passing point on the Praha - Rudná - Beroun railway line.

Cenozoic era
(present–66.0 Mya)
Mesozoic era
(66.0–251.902 Mya)
Paleozoic era
(251.902–541.0 Mya)
Proterozoic eon
(541.0 Mya–2.5 Gya)
Archean eon (2.5–4 Gya)
Hadean eon (4–4.6 Gya)


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