Princeton geologists solve fossil mystery by creating 3-D ‘virtual tour’ through rock
With an industrial grinder and a super-high-resolution camera, PEI associated faculty Adam Maloof, a Princeton associate professor of geosciences, and graduate student Akshay Mehra can deconstruct rock samples and create three-dimensional digital versions that scientists can look at from any angle. In addition, they have developed software that allows the computer to segment images and isolate objects without human bias.
Have you ever wished you could travel inside a rock? It may sound more like magic than science, but Princeton scientists have found a way to make it (almost) true.
With an industrial grinder and a super-high-resolution camera, PEI associated faculty Adam Maloof, a Princeton University associate professor of geosciences, and graduate student Akshay Mehra deconstruct rock samples and create three-dimensional digital versions that scientists can look at from any angle. In addition, they have developed software that allows the computer to segment images and isolate objects without human bias.
Using this technology in conjunction with detailed field observations, they examined a thin-shelled creature that lived over much of the world about 545 million years ago, Cloudina, generally agreed to be the first-ever “biomineralizer,” an organism that can create a shell or bones in addition to soft tissue.
While previous researchers had argued that Cloudina were reef builders, Maloof and Mehra were able to use their 3-D reconstruction of the creatures’ delicate tube-like structures to conclude that the fossils had been transported from other areas, suggesting that Cloudina played only a minor role in the earliest reef systems. Their work appears in the current issue of the Proceedings of the National Academy of Sciences.
“I thought going in we would learn all sorts about this amazing first biomineralizer and first reef builder, but Cloudina turned out to be more like a reef dweller,” said Maloof, an associate professor of geosciences. He has now turned his focus to the next-oldest potential reef builder, a sponge called Archaeocyathid that lived about 520 million years ago.
Cloudina had proven resistant to detailed study because its delicate casing is too fragile to extract physically from the surrounding limestone, and it could not be imaged remotely with traditional X-ray tomography techniques, which require density differences between the object of interest and the surrounding material. Because Cloudina is chemically identical to limestone, the fossils were effectively invisible to X-rays.