File talk:Fish evolution.png

Is there a way the creator could correct some minor errors here? Carboniferous is misspelled, and the Cenozoic is an era, not a period. Wilson44691 (talk) 22:23, 24 February 2013 (UTC)[reply]

Yes, I'll correct the typo in Carboniferous. I have a problem with your position on the Cenozoic. How else can the chart be labelled without introducing undue complications, such as subdividing the Cenozoic into component periods? Period is a flexible word in common usage. If you google "Cenozoic period" you will find it is not an uncommon term, even on Google Scholar. Even the short Wikipedia article on the Cenozoic refers to the Cenozoic as a period no less than three times:

The Cenozoic Era... covering the period from 65 millions years ago to the present.
the Cenozoic Era has been a period of long-term cooling.
mammals proliferated... giving this period its other name, the Age of Mammals

So I would suggest that the Cenozoic is not uncommonly referred to as a period, a period that happens also to be an "Era", and that no one is going to be mislead by the way the chart is currently labelled. Would it help if I relabelled Cenozoic as "Cenozoic era"?

On another issue, there is currently a discussion about whether any placoderms survived beyond the Devonian (which also affects this chart). Do you have a take on this? --Epipelagic (talk) 00:32, 25 February 2013 (UTC)[reply]

Hello Epipelagic. Thanks for such a quick reply. And thanks for your artistry and Wikipedia projects. This is all volunteer work and it is greatly appreciated (and useful). As for the Cenozoic, it really is an era, not a period. Both of those terms have informal uses, but their geological definitions are distinct. Since you have Cenozoic in the same column as actual periods, something needs to change. (This is why geologists rarely use "era" and "period" and "formation", for that matter, in casual ways!) I suggest dividing up that Cenozoic box into Paleogene and Neogene. As for placoderms in the Lower Carboniferous -- yes, I've long thought that based on what colleagues have told me, but I don't know the direct evidence. Thanks again! Wilson44691 (talk) 12:12, 25 February 2013 (UTC)[reply]