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Ma vs. mya[edit]

In these era pages I have seen "million years ago" abbreviated as Ma and as mya. Which one is the standard?

If the Mya (unit) article is to be believed, Ma has replaced the older Mya in scientific literature. Because of that I think we should use only Ma.--Jyril 20:23, 26 February 2006 (UTC)
There should be an agreed on convention regarding this notation somewhere, as I know it's been brought up before. I'd like to know as well, so if I find it, I'll leave a note here. --DanielCD 22:08, 26 February 2006 (UTC)
Ma is certainly the standard in professional geologic circles. Cheers Geologyguy 23:54, 10 March 2007 (UTC)
I vote we go with that then. --DanielCD 01:46, 11 March 2007 (UTC)

Adaptive radiation[edit]

Added information on Ordovician adaptive radiation.Erimus 23:11, 10 March 2007 (UTC) [1]


Volcanic eruption[edit]

[1] Notable enough? --Artman40 (talk) 12:08, 26 March 2009 (UTC)


Is it OK to start a questions tab here? Bill Newbold (talk) 14:24, 16 September 2009 (UTC)

Are there any more details that we know?

How classifiable and reliable are the descriptions from this time?

Needs Separate Pages[edit]

Lower or Early Ordovician, Middle Ordovician, and Upper or Late Ordovician each could well have a page of its own covering the respective science including paleontology. General historic and summary information could be retained in a general article titled simply Ordovician. Biota sections in the Arenig/Floian page could sensibly be transferred to "Ordovician" or to a specific page covering that particular taxon.J.H.McDonnell (talk) 01:48, 10 November 2009 (UTC)

Capital P?[edit]

Shouldnt it be spelled Ordovician Period rather than Ordovician period? —Preceding unsigned comment added by (talk) 14:47, 12 November 2009 (UTC)

CO2 levels 440 Ma[edit]

Could someone with access please check these papers out, with a view to reducing the stated CO2 level before the late Ordovician glaciation to 3000ppm? I found them being referenced here; but dont want to change the wiki without reading the papers.

Did changes in atmospheric CO2 coincide with latest Ordovician glacial-interglacial cycles?

According to new research the CO2 level did not correspond to the temperatur at this period of time. See link —Preceding unsigned comment added by Chriscross72 (talkcontribs) 08:32, 15 July 2010 (UTC)

cheers. --Littlerobbergirl (talk) 01:20, 13 March 2010 (UTC)

In the upper right table of the Wikipedia page on the Ordovician, the end of the Ordovician should be changed from 443.4 to 443.8 according to the 2015 Geologic Time Scale published by the ICS ( — Preceding unsigned comment added by (talk) 07:14, 2 June 2015 (UTC)

C/E Notes[edit]

These edits actually changed the meanings intended and I've reverted to the previous terms used:

  • ... is a geologic period and system... -> a geologic period (system)...
A geologic period is not a system. Though the latter is what delineates the former (and thus have the same names); the former is a specific measure of a length of time within Earth's history (geochronology), while the latter is a specific series of rock layers (chronostratigraphy).
  • Biogenic aragonite, like that composing the shells of most mollusks... -> Biogenic calcium carbonate, like that composing the shells of most mollusks...
Aragonite is not synonymous to calcium carbonate. It is a specific type of crystal of calcium carbonate (the other two being calcite and vaterite). Notice how the paragraph differentiates inorganic calcite with biogenic aragonite.

Restored these sentences for clarity:

  • Life continued to flourish during the Ordovician as it did in the Cambrian, although the end of the period...
The wording of your new sentence makes it confusing as to whether you are referring to the end of the Ordovician or the Cambrian.
The new wording makes it seem like Gondwana spontaneously appeared in the equatorial latitudes.
  • ...for ~30 million years leading up to the Hirnantian glaciation.
It culminated with the Hirnantian glaciation, i.e. it happened from the Dapingian to the Katian stages, not within Hirnantian proper (which only lasted for ~2 million years).
  • But over time, the climate became cooler, and around 460 million...
New wording implies the cooling happened at the start of the Ordovician, instead of happening during the Ordovician.

-- OBSIDIANSOUL 16:59, 18 September 2016 (UTC)

Succinct abbreviation[edit]

geologic period and system = geoperiosystem — Preceding unsigned comment added by 2A02:2149:8409:B00:2175:F455:1730:158E (talk) 08:04, 29 November 2017 (UTC)

External links modified (January 2018)[edit]

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