FossiLab Outreach at the Smithsonian

Andy here-

One of the most enjoyable activities I got involved with while at the Smithsonian Institution – National Museum of Natural History was FossiLab. FossiLab is a windowed room where volunteers and scientists go about doing work that needs to be done in the museum. Some of the volunteers there do is look through sediment samples for tiny fossils. That’s time consuming work, but it can be done, and done well, with a few afternoons of training. Most of what the volunteers engage in re-housing fossils. Besides research and education, the Smithsonian also very importantly stores lots of items. The NMNH stores over 40 million fossils, and the fossils are only one part of what that particular museum has. Some of these fossils need to be put in new boxes, since the old ones aren’t doing a good job storing them anymore. So, they spend hours cutting new styrofoam to cradle to fossils just so, making new custom ‘housing’ that will keep the fossil safe for decades to come. This means I’ve gotten to see many cool fossils, like Miocene aged dolphin ancestors collected by the scientist who found (though didn’t name) the first Triceratops.

The rare view from the other side of the glass in FossiLab with an empty museum.
An example of some of the measurements on a planktic foraminifer (image generated by Melanie Sorman)

I, as a scientist, was doing research while I was in FossiLab. I study planktic foraminifera. In particular I’m interested in how their history is changed by climate. Can we detect how their evolution was altered by changing climates in the past? While upstairs in FossiLab I spent lots of time measuring individual foraminifera to understand their shape. I was doing this with forams which lived about 100 million years ago in a warm interval, trying to understand the evolution of one particular aspect of their shape. Certain species of foraminifera develop a ‘keel’, a build-up of calcite on the outer-edge of the shell. Yes, if you look at it just right, it does look like the keel on a boat. The question that we’re attacking is ‘did the keel develop from one lineage, or did several independent lineages develop keels simultaneously?’. This is important for a few reasons. The keel is a key feature of the test (internal shells), and has been thought for years to indicate that the foram lived deeper (though that’s not always the case). Also, much evolutionary research in forams depends on understanding how different species are related. We know this really well for the Cenozoic (65 Million years ago to the present), but the Cretaceous has several really important ancestor-descendent relationships that we just haven’t figured out yet. This is one of those. There’s a sign in front of the microscope that I used explaining much of this, and a little slideshow that plays with more detail.

FossiLab also has a door that lets the volunteers or scientists walk out and talk to folks. If people watched for a while, then I’d usually get up and go talk to them. I have a little tray filled with objects to talk about what I do. First, I’d hand them a tray of microfossils (which to a naked eye, look like sand) and ask them to make observations about what they saw. Usually I’d get “It’s sand!”. I then put the tray under my WoodenScope and show them that each ‘grain of sand’ they saw was actually tiny shells. We’d talk about what forams are, and how we use a big boat called the R/V JOIDES Resolution with a drill on it to get them. Describing coring goes like this: 

“Have you ever stuck a straw through a cake?”

“Yes!” Oddly, 80% of the groups have somebody that’s done this.

“OK, so what happened? What’s in the straw?”

“Cake!”

“But what’s on top?”
“Icing!”

“Right, you get the cake layers. There’s icing on top, then cake, then if it’s a really good cake, there’s another layer of icing and more cake. The ocean is just like that, there are layers. The JOIDES is our straw, and we’re using the cores to sample the layers in the bottom of the ocean.”

Then we finish up by talking about what forams can tell us. We count up forams because if we have more of a kind that likes warm water, then we can tell the water was warmer at that time in that location, or more cold loving forams means colder water.

To finish the interaction, I let the kids or adults ask as many questions as they want. Usually it ends with the parents telling them they have to go.

How well do stable isotopes really work?

Defining uncertainty and error in planktic foraminiferal oxygen isotope measurements

Andrew Fraass and Christopher Lowery

Summary by Andy Fraass, website collaborator

Figure 1. Two different locations in the ocean. Temperature and salinity combine to give us the δ18O values. On the left are a few planktic foraminifera in their rough depth habitats (where each species likes to hang out in the water column) (Shiebel and Hemleben, 2005). Drawings are modified from Kennett and Srinivasan (1983) and Schiebel and Hemleben (2005).

Data: Chris and I developed a model to understand how good planktic foraminiferal isotopes actually are at recording temperature, and how important it is that a scientist uses a bunch of tests to measure the isotopes, rather than just a few. There’s actually no data in a traditional sense in this paper; we went back to theory, statistics, and math.

Methods: Chris and I wrote a theoretical model. Planktic foraminifera make their shells in a certain depth (or depths) in the water, and that depth has a certain chemistry. The model allows the scientist to say that the forams are mostly growing in a certain season and at a range of depths. Then the scientist has to decide to include how well the organism records the water chemistry (technically called ‘vital effects’), if the shell has its chemistry altered in the sediment (diagenesis), and a few other things including if there’s a chance that a different species (with a different ecology) got mixed in.

Results: Good results from stable isotope studies come from about 15 or so shells in an analysis, but it’s very dependent on the species and what the ocean structure is like.

Why is this study important? Given all the things that could go wrong, of which the parameters in the model are a part, it’s honestly a little surprising that planktic stable isotope records give the same results as the model. They do, which other folks have shown repeatedly. What Chris and I show here is that as long as you put in enough shells when you’re doing your analysis, then the record actually records what we think it does!

The big picture: Studying the ocean is tough, especially when we’re talking about the ocean from tens of millions of years ago. This paper helps show that despite statistical concerns some of us had with it, we’re doing a good job at recording the past.

Citation: Fraass, A. J., and C. M. Lowery (2017), Defining uncertainty and error in planktic foraminiferal oxygen isotope measurements, Paleoceanography, 32, 104–122, doi: 10.1002/2016PA003035.

References:

  • Kennett, J.P. and Srinivasan, M.S., 1983. Neogene planktonic foraminifera: a phylogenetic atlas. Hutchinson Ross.
  • Schiebel, R. and Hemleben, C., 2005. Modern planktic foraminifera. Paläontologische Zeitschrift, vol. 79(1), p.135-148.