Roadian
Fifth stage of the Permian
title: "Roadian" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["roadian", "permian-geochronology", "permian-north-america", "permian-geology-of-texas"] description: "Fifth stage of the Permian" topic_path: "science/earth-science" source: "https://en.wikipedia.org/wiki/Roadian" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Fifth stage of the Permian ::
::data[format=table title="Infobox geologic timespan"]
| Field | Value |
|---|---|
| name | Roadian |
| color | Roadian |
| time_start | 274.4 |
| time_start_uncertainty | 0.4 |
| time_end | 266.9 |
| time_end_uncertainty | 0.4 |
| image_map | File:270Ma Mollweide.png |
| caption_map | Mollweide map of Earth 270 million years ago, with black outlines depicting countries in their locations |
| timeline | Permian |
| name_formality | Formal |
| celestial_body | earth |
| usage | Global (ICS) |
| timescales_used | ICS Time Scale |
| chrono_unit | Age |
| strat_unit | Stage |
| timespan_formality | Formal |
| lower_boundary_def | FAD of the Conodont Jinogondolella nanginkensis |
| lower_gssp_location | Stratotype Canyon, Guadalupe Mountains, Texas, USA |
| lower_gssp_coords | |
| lower_gssp_accept_date | 2001 |
| upper_boundary_def | FAD of the Conodont Jinogondolella aserrata |
| upper_gssp_location | Guadalupe Pass, Guadalupe Mountains, Texas, USA |
| upper_gssp_coords | |
| upper_gssp_accept_date | 2001 |
| :: |
| name = Roadian | color = Roadian | time_start = 274.4 | time_start_uncertainty = 0.4 | time_end = 266.9 | time_end_uncertainty = 0.4 | image_map =File:270Ma Mollweide.png | caption_map =Mollweide map of Earth 270 million years ago, with black outlines depicting countries in their locations | image_outcrop = | caption_outcrop = | image_art = | caption_art = | timeline = Permian | formerly_part_of = | partially_contained_in = | partially_contains = | name_formality = Formal | name_accept_date = | alternate_spellings = | synonym1 = | synonym1_coined = | synonym2 = | synonym2_coined = | synonym3 = | synonym3_coined = | nicknames = | former_names = | proposed_names = | celestial_body = earth | usage = Global (ICS) | timescales_used = ICS Time Scale | formerly_used_by = | not_used_by = | chrono_unit = Age | strat_unit = Stage | proposed_by = | type_section = | timespan_formality = Formal | lower_boundary_def = FAD of the Conodont Jinogondolella nanginkensis | lower_gssp_location = Stratotype Canyon, Guadalupe Mountains, Texas, USA | lower_gssp_coords = | lower_gssp_accept_date = 2001 | upper_boundary_def = FAD of the Conodont Jinogondolella aserrata | upper_gssp_location = Guadalupe Pass, Guadalupe Mountains, Texas, USA | upper_gssp_coords = | upper_gssp_accept_date = 2001 | o2 = | co2 = | temp = | sea_level =
In the geologic timescale, the Roadian is an age or stage of the Permian. It is the earliest or lower of three subdivisions of the Guadalupian Epoch or Series. The Roadian lasted between and million years ago (Ma). It was preceded by the Kungurian and followed by the Wordian.
Stratigraphy
In 1961, the regional timescale used for the southeastern US had the Wordian and Capitanian as subdivisions of the Guadalupian. Efforts to correlate the Permian stratigraphy of the southeastern US with that of Russia led to the conclusion that between the Wordian stage and the Russian Artinskian stage, another stage needed to be introduced. This stage, the Roadian Stage, was established in 1968 and took its name from the Road Canyon Formation in Brewster County, Texas, formerly considered the lower (oldest) part of the Word Formation. The stage was added to the internationally used IUGS timescale in 2001.
The base of the Roadian is defined as the place in the stratigraphic record where fossils of conodont species Jinogondolella nankingensis first appears. The global reference profile for the base (the GSSP) is located in Stratotype Canyon in the Guadalupe Mountains, Texas (). The top of the Roadian (the base of the Wordian Stage) is at the first appearance of fossils of conodont species Jinogondolella aserrata.
Life
Main article: :Category:Roadian life
::figure[src="https://upload.wikimedia.org/wikipedia/commons/9/92/Hercosestria040111.jpg" caption="''[[Hercosestria]] cribrosa'', a reef-forming Roadian [[brachiopod]] from the Glass Mountains of [[Texas"] ::
Some studies suggested that Olson's Extinction, a worldwide loss of terrestrial vertebrate life occurred during the Early Guadalupian (Roadian, Wordian), but the temporal resolution of most studies only indicates that this possible extinction event indicates around the Kungurian/Roadian boundary. Studies using higher-resolution stratigraphic data and the fossilized birth-death model suggest that this even is actually a slow decline over 20 Ma that started in the Sakmarian and that may have extended into the Roadian.
Notable formations
- Cherry Canyon Formation (New Mexico, Texas, USA)
- Road Canyon Formation (Texas, USA)
References
Literature
References
- "GSSP for Roadian Stage".
- {{aut. Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: ''A Geologic Time Scale 2004'', [[Cambridge University]] Press
- {{aut. Glenister, B.F. & Furnish, W.M.; '''1961''': ''The Permian ammonoids of Australia'', Journal of Paleontology '''35'''(4), pp 673–736.
- {{aut. Nassichuk, W.W.; '''1964''': ''Pennsylvanian and Permian rocks in the Parry Islands Group, Canadian Arctic Archipelago'', Report of activities, field
- Furnish & Glenister (1968)
- {{aut. Glenister, B.F.; Wardlaw, B.R.; Lambert, L.L.; Spinosa, C.; Bowring, S.A.; Erwin, D.H.; Menning, M. & Wilde, G.L.; '''1999''': ''Proposal of Guadalupian and Component Roadian, Wordian and Capitanian Stages as International Standards for the Middle Permian Series'', Permophiles '''34''': pp 3–11.
- (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B: Biological Sciences.
- (12 April 2017). "Olson's Extinction and the latitudinal biodiversity gradient of tetrapods in the Permian". Proceedings of the Royal Society B: Biological Sciences.
- (10 June 2020). "Olson's Gap or Olson's Extinction? A Bayesian tip-dating approach to resolving stratigraphic uncertainty". Proceedings of the Royal Society B: Biological Sciences.
- (9 December 2021). "Distributions of extinction times from fossil ages and tree topologies: the example of mid-Permian synapsid extinctions". PeerJ.
- (June 2024). "Testing extinction events and temporal shifts in diversification and fossilization rates through the skyline Fossilized Birth-Death (FBD) model: The example of some mid-Permian synapsid extinctions". Cladistics.
::callout[type=info title="Wikipedia Source"] This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page. ::