| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Devonian | Lower | Lochkovian | 419.2±3.2 | |
| Silurian | Pridoli |  423.0±2.3
| ||
| Ludlow | Ludfordian | 425.6±0.9
| ||
| Gorstian | 427.4±0.5
| |||
| Wenlock | Homerian | 430.5±0.7
| ||
| Sheinwoodian | 433.4±0.8
| |||
| Llandovery | Telychian | 438.5±1.1
| ||
| Aeronian | 440.8±1.2
| |||
| Rhuddanian | 443.8±1.5
| |||
| Ordovician | Upper | Hirnantian | older | |
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Pridoli is a fourth and upper series of the Silurian system, corresponding to the Pridoli epoch of the Silurian period. It began after the Ludfordian age of the Ludlow at 423.0 ± 2.3 Ma (million years ago) and lasted until the Lochkovian age of the Early Devonian, which began 419.2 ± 3.2 Ma (IUGS 2023). The oldest trigonotarbids are known from the Pridoli.
Definition[]
The Global Stratotype Section and Point (GSSP) of the Pridoli series was ratified in 1984. The type section is located in Reporyje, Prague, Czech Republic. The lower boundary related to the first appearance of the graptolite species Neocolonograptus parultimus about 2 m above the base of the Požáry Formation.[2]
Subdivisions[]
It is the only series that not divided into any stages in International Chronostratigraphic Chart. However, it corresponds to different regional stages. All listed from upper to lower:
- England:[3]
- Whitcliffe/Leintwardine
- Bringewood/Elton
- North America:[4]
- Cayugan
- Niagaran (uppermost)
- Baltic:[5]
- Ohesaare
- Kaugetuma
Climate[]
Pridoli was the warmest epoch of the Silurian period. Temperatures higher than in previous epochs facilitated the spread of land plants and terrestrialization in general.[6]
Pridoli life[]
In the coastal zone of warm seas, coral polyps such as Favosites continued to form large reefs. The main life was concentrated in these ecosystems. As in previous epochs, the seas were inhabited by numerous brachiopods. Pridoli genera include Dayia, Microsphaeridiorhynchus, Isorthis, Protochonetes, Leptaena and others. Bivalves like Goniophora, Rhytimya, Modiolopsis and Mytilus resembled brachiopods in appearance, but had right and left valves instead of upper and lower ones. Bivalves are included in the phylum of mollusks, as well as gastropods (Platyostoma, Mesocoelia, Loxonema, Poleumita) and cephalopods (Orthoceras, Dawsonoceras, Mitroceras, Gomphoceras, Phragmoceras), also abundant in the Pridoli sediments.
Pterobranchs, especially graptolites, remained an important component of the fauna. These animals led both an attached and a floating lifestyle, and fed on plankton, which they filtered with the help of cilia on their tentacles. Pridoli pterobranchs include dendroids (Dictyonema, Palaeodictyota), graptoloids (Monograptus, Pseudomonoclimacis, Orthograptus, Neocolonograptus, Climacograptus) and other groups.
Large Acutiramus and other eurypterids
Arthropods remained the dominant group in the Pridoli, although trilobite diversity never returned to Ordovician levels. Proetid (Proetus) and phacopid (Acaste, Calymene, Eophacops) trilobites lived in reef ecosystems in what is now Estonia. Shrimp-like malacostracan crustaceans (Ceratiocaris, Emmelezoe) swam in the water column. Ostracods (Dizygopleura, Leperditia, Kloedenia), another group of crustaceans, also flourished. Numerous eurypterids are known from this epoch. Small and large, they hunted at the bottom and in the water column, mainly in the seas. There are many families of these arthropods, which differ in physique, number and functionality of claws. Pridoli eurypterids include strobilopterids (Buffalopterus), eurypterids (Eurypterus), erieopterids (Erieopterus), carcinosomatids (Carcinosoma), pterygotids (Acutiramus, Pterygotus, Erettopterus), hughmilleriids (Hughmilleria), styloniruds (Stylonurus), dolichopterids (Dolichopterus), mixopterids (Mixopterus), rhenopterids (Brachyopterus), slimonids (Salteropterus) and other families.
Eurypterids preyed on other arthropods and numerous fish, among which jawless fish such as Thelodus, Gomphodus, Hemicyclaspis, Thyestes, Archegonaspis, Vernonaspis, and Corvaspis predominated. Among jawed fish, the number of cartilaginous fish like Nostolepis and Hanilepis gradually increased. Psarolepis, a possible sarcopterygian fish, was found in Pridoli and Lochkovian sediments of China.
Quite numerous but primitive terrestrial plants like Cooksonia and already foliar Baragwanathia, grew on sea coasts and along river banks. The spread of land plants contributed to an increase in the amount of atmospheric oxygen, and the Prilodi already saw a noticeable diversity of land animals, mainly arthropods. In addition to myriapods (Crussolum) and scorpions (Palaeophonus, Proscorpius), spider-like trigonotarbids (Palaeotarbus) have appeared. There is a high probability that primitive wingless insects lived at the same time, but their fossils of this epoch are unknown.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=77.
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Pridoli,Red%20Downtonian
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Pridoli,Cayugan
- ↑ https://paleobiodb.org/classic/displayTimescale?interval=Pridoli,Kaugetuma
- ↑ Bek, J.; Steemans, P.; Frýda, J.; Žárský, V. (2024). Silurian Climatic Zonation of Cryptospore, Trilete Spore and Plant Megafossils, with Emphasis on the Přídolí Epoch. Life (14): 258. DOI:10.3390/life14020258