Wednesday, August 19, 2015

URSP Student Tiffany A Wynn Conducts Foraminifera Photogrammetry by Enhancing 3D Modeling Methods From SEM Images

Going into my final year at George Mason University, thoughts of how I would apply my new knowledge to the working world quickly started to flood my mind. As a biology major with a passion for paleontology, I decided to dedicate my future to observing long and short term trends of the past to better understand our future. Some call this evolutionary biology and others call it conservation paleobiology. Regardless of its name, I quickly realized I needed to narrow my focus. To do so, I enrolled in a Paleontological Training Program (PTP) at the Smithsonian’s National Museum of Natural History (NMNH). During the course we had many speakers, one of which was Dr. Brian Huber (the chairman of the Department of Paleobiology). He gave a convincing argument as to why working with forams in the Department of Paleobiology would be the best place to spend my summer.

What are forams you may ask? Forams, formally known as foraminifera, are single celled organisms that spend their time floating in the ocean (planktics) or dwelling on the ocean floor (benthics). Most create their shell (tests) out of calcium carbonate and some are heavily ornamented with agglutinated materials. They also use spindly pseudopodia to wrangle their dinner, which can be as large as a small shrimp! Yum. These fascinating microfossils offer valuable insight into our past and can provide much needed information on current marine ecosystems.

At the end of the PTP course, I decided I wanted to work with these valuable creatures. Luckily for me, my current mentor, Miss Loren Petruny had been working with forams for her Master’s thesis and needed a helping hand. It was through working with her and Dr. Huber, that I developed a keen interest with forams. Fast forward to the current summer. With her approval, I decided to expand upon Miss Petruny’s research in hopes to help streamline the process.  I am intrigued by her research taking these tiny microfossils and rendering 3D printed models.

My journey this summer has been a broadening experience to say the least. As a volunteer at the National Zoo and camera trapper for the Smithsonian Conservation Biology Institute, it is safe to say I am not unfamiliar with the inner goings of the Smithsonian. However, my internship through URSP has afforded me experiences I wouldn’t have otherwise been privy to. Let’s look at some of what I’ve been working on!

As previously performed by my mentor, I had large shoes to fill and needed to learn many skills before I could consider broadening her research. In doing so I needed all the help I could get from various staff at the NMNH. This involved type specimen selection with the help of the Department of Paleobiology’s Jennifer Jett. I would also need help with imaging these fine fossils, enter the Scanning Electron Microscopy lab manager, Mr. Scott Whittaker. Together, Jennifer and I selected a total of fifteen forams, all with different shell types. I won’t go into detail of what is what, but we wanted to have enough variety in the event a particular type was not easily imaged in the scanning electron microscope.
So how does one image a microfossil the size of a pinhead in a scanning electron microscope? I’m glad you asked. First needles made of tungsten wire are carefully crafted using a dipping technique in sodium hydroxide. To expedite the process, an electrical charge is sent through the fluid. Using the meniscus of the fluid and repeated depressions in the center, the wire is transformed from having a blunt end to a fine needlepoint.

The needle is then used to drill a hole in the center of a carbon stub. I created a total of five needles and successfully made six stubs (these can be reused as needed).  Then using a straight cactus needle, some dental wax, Elmer’s glue and a lot of steady fingers, the end result is a mounted foram ready for imaging. Now that my hands are dirty it is time to take some images! As seen here each foram is imaged one at a time.

Using a series of images taken from a scanning electron microscope (SEM) at varying degrees, images are rendered in a photogrammetry program such as AgiSoft. Once complete, the type specimen will be 3D printed.

As expected, research comes with many expectations; some are met and some are altered. Currently this week, I am working to better understand AgiSoft so that I may align images taken at different depths from two different SEM sessions. Once this is mastered, the final step is 3D printing our microfossils. This will complete my summer research and will provide a truly tangible experience.