Extinction

So you've survived the Mayan apocalypse this week - what better time to start talking about something that didn't survive its doom:

What could this little benthic foram tell you?

Orbina universa

Photo: Dr Howard Spero, University of California, Davis

He probably wont be able to tell you the future, remind you of that last item on your shopping list or tell you what to buy this Christmas, but he, and all his friends can tell you alot about climate change in the past. 

He’s a benthic foram and has the biggest habitat in the world - the deep ocean floor. It used to be thought to be a low-diversity and desolate place, but since the 1960s, it has revealed itself to be an incredible diverse habitat. In the deeper depths (>2000m) forams are thought to be the most diverse and constitute over 90% of the biomass. So, in short, they’re well adapted and successful in their habitat!

But 55.5Ma, these little forams experienced their biggest extinction for over 100Ma where 37% of species died out. In some instances this range has expanded to 50%. To put this into a wider perspective, the benthic forams survived the KT extinction relatively unscathed, whereas terrestrially there was huge biological shifts, where the dinosaurs gave way to mammals. Benthic forams have one of the most complete fossil records of marine species and so are used in a variety of paleoclimate reconstructions.

From Thomas, 2007, this figure shows the benthic foram turnover since the Cretaceous.

Note the P/E boundary shows the most significant change in δ¹³C and δ¹⁸O.

The observations across the PETM are unclear, it doesn’t help that the deep sea is still one of the least well known ecosystems on Earth. Many deep-sea species that survived the KT extinction suddenly became extinct at the KT and were replaced by varying taxa with no clear pattern of succession. Other, planktic foraminifera, genera of the dinoflagellates, Apectodinium, appeared to migrate to higher latitudes. There were similar migrations in terrestrial migrations in plants, but more peculiarly, there is a rapid diversification of mammals in this time. It a confusing picture......

So what could affect this, the largest habitat on Earth? 

Ocean Circulation. 

If you’d like to delve more into extinction, and discover more about extinction of other species and its effects on biodiversity today, I recommend this blog here. It provides a particularly detailed insight into a few select species that are at risk of extinction and even what you can do to help!