<p><strong>The ‘Oligo-Miocene’ part</strong></p>

<p>The <a href="https://en.wikipedia.org/wiki/Oligocene" rel="noreferrer">Oligocene</a> and the <a href="https://en.wikipedia.org/wiki/Miocene" rel="noreferrer">Miocene</a> are epochs of geological time. The Oligocene lasted from ~33.9 million years ago to ~23 million years ago; the Miocene followed immediately after the Oligocene, and lasted until ~5 million years ago.</p>

<p><em>Oligo-Miocene</em> refers to events that happened around the boundary between the two epochs at ~23 million years, or that happened throughout the Oligocene and Miocene epochs.</p>

<p><strong>The ‘radiation’ part</strong></p>

<p>‘Radiation’ here is evolutionary radiation, a biological term usually referring to an increase in the number of species or in the differences between them. The Palaeontology Online glossary <a href="https://www.palaeontologyonline.com/glossary/e/evolutionary-radiation/" rel="noreferrer">defines</a> ‘evolutionary radiation’ as follows.</p>

<blockquote>
  <p>An evolutionary radiation is an increase in either taxonomic diversity (i.e. the number of species) or morphological disparity (how they differ in anatomy). This can result  from an adaptive change or the opening of ecospace.</p>
</blockquote>

<p><strong>The combination</strong></p>

<p>Putting the two parts back into the contexts where you found them: the first article mentions an increase in the diversity or marine mammals, and the second in the diversity of dry-adapted shrubs. Both these increases occurred between the start of the Oligocene and the end of the Miocene.</p>

CC BY-SA 3.0
2017-12-14T08:43:55.560Z
2017-12-14T08:43:55.560Z
Pont
<p>Radiation here has nothing to do with radioactivity. In this context it is refers to a diversification of marine mammals. It is a common term used in evolutionary biology.</p>

<blockquote>
  <p>Radiation: 'divergence out from a central point, in particular evolution from an ancestral animal or plant group into a variety of new forms.'</p>
</blockquote>

CC BY-SA 3.0
2017-12-14T08:42:06.563Z
2017-12-14T08:42:06.563Z
bon
<p>Some studies about Earth's fosilized plants/animals mention a "Oligo-Miocene radiation". </p>

<p>Examples:</p>

<blockquote>
  <p>Our study therefore strengthens previous suggestions that the absence
  of very large penguins today is likely due to the Oligo-Miocene
  radiation of marine mammals.</p>
</blockquote>

<p>from Mayr et al (2017), doi: <a href="http://dx.doi.org/10.1038/s41467-017-01959-6" rel="noreferrer">10.1038/s41467-017-01959-6</a> </p>

<blockquote>
  <p>Molecular phylogeny and dating reveals an Oligo-Miocene radiation of
  dry-adapted shrubs (former Tremandraceae) from rainforest tree
  progenitors (Elaeocarpaceae) in Australia</p>
</blockquote>

<p>from Crayn et al. (2006), doi: <a href="http://dx.doi.org/10.3732/ajb.93.9.1328" rel="noreferrer">10.3732/ajb.93.9.1328</a>, see also <a href="https://www.ncbi.nlm.nih.gov/pubmed/21642198" rel="noreferrer">www.ncbi.nlm.nih.gov/pubmed/21642198</a></p>

<p>So, what is this "Oligo-Miocene radiation" ?</p>

<terminology><paleontology><fossils>
What is Oligo-Miocene radiation?
Neel
# What is Oligo-Miocene radiation?

(Asked by: username_0 on 2017-12-14)

Some studies about Earth's fosilized plants/animals mention a "Oligo-Miocene radiation".

Examples:

> Our study therefore strengthens previous suggestions that the absence
> of very large penguins today is likely due to the Oligo-Miocene
> radiation of marine mammals.

from Mayr et al (2017), doi: [10.1038/s41467-017-01959-6](http://dx.doi.org/10.1038/s41467-017-01959-6)

> Molecular phylogeny and dating reveals an Oligo-Miocene radiation of
> dry-adapted shrubs (former Tremandraceae) from rainforest tree
> progenitors (Elaeocarpaceae) in Australia

from Crayn et al. (2006), doi: [10.3732/ajb.93.9.1328](http://dx.doi.org/10.3732/ajb.93.9.1328), see also [www.ncbi.nlm.nih.gov/pubmed/21642198](https://www.ncbi.nlm.nih.gov/pubmed/21642198)

So, what is this "Oligo-Miocene radiation" ?

**Tags:** terminology, paleontology, fossils


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## 2 answers

### Answer by username_1 on 2017-12-14. Score: 8 | Accepted answer

**The ‘Oligo-Miocene’ part**

The [Oligocene](https://en.wikipedia.org/wiki/Oligocene) and the [Miocene](https://en.wikipedia.org/wiki/Miocene) are epochs of geological time. The Oligocene lasted from ~33.9 million years ago to ~23 million years ago; the Miocene followed immediately after the Oligocene, and lasted until ~5 million years ago.

*Oligo-Miocene* refers to events that happened around the boundary between the two epochs at ~23 million years, or that happened throughout the Oligocene and Miocene epochs.

**The ‘radiation’ part**

‘Radiation’ here is evolutionary radiation, a biological term usually referring to an increase in the number of species or in the differences between them. The Palaeontology Online glossary [defines](https://www.palaeontologyonline.com/glossary/e/evolutionary-radiation/) ‘evolutionary radiation’ as follows.

> An evolutionary radiation is an increase in either taxonomic diversity (i.e. the number of species) or morphological disparity (how they differ in anatomy). This can result from an adaptive change or the opening of ecospace.

**The combination**

Putting the two parts back into the contexts where you found them: the first article mentions an increase in the diversity or marine mammals, and the second in the diversity of dry-adapted shrubs. Both these increases occurred between the start of the Oligocene and the end of the Miocene.


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### Answer by username_2 on 2017-12-14. Score: 3

Radiation here has nothing to do with radioactivity. In this context it is refers to a diversification of marine mammals. It is a common term used in evolutionary biology.

> Radiation: 'divergence out from a central point, in particular evolution from an ancestral animal or plant group into a variety of new forms.'


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