Transmission X-ray microscopy used to uncover inner details and composition of fossils
Just because an organism died millions of years ago doesn’t mean it can’t be studied. Fossils preserve the remains of ancient organisms and reveal when, how, and where it lived. Fossils of an ancient shrimp have now been studied with an emerging technology to reveal their morphological structure, evolutionary origins and the kind of environment in which they lived.
Fossils of marine organisms form through a number of chemical processes after they become buried in sediments. Over time, these organisms’ remains accumulate minerals and harden. The composition of a fossil is critical in understanding when and where it lived; poorly preserved materials can lead to incorrect identification.
In a report published in the journal Analytical Chemistry in September, a team of scientists, led by Niara Oliveria from the Federal University of Ceara, Brazil, analyzed fossils of an unknown shrimp species to determine their composition and physical characteristics. The shrimps lived during the Cretaceous period, 65 million years ago, and were discovered in a region in northeastern Brazil known as the Araripe Basin. Fossils of dinosaurs, fish, turtles and other aquatic organisms have been discovered in this area as well.
The study found large quantities of metal zinc in the fossil, a compound not observed in modern shrimp due to its high toxicity. Its authors hypothesized that these shrimp accumulated zinc throughout their lives, some of which was released into their environment after death and formed zinc sulphide. In marine environments, sulphide dissolves and forms hydrogen sulphide, a gas mainly found in deep-sea hot springs and volcanic ridges where the temperatures and pressures are extreme. This suggests the shrimp may have lived in such environments.
The study’s authors used scanning electron microscopy (SEM) and scanning transmission X-ray microscopy to examine the shrimp fossil. SEM was used to analyze the physical characteristics of the shrimp in high definition, allowing insights into the lifestyle, diet, distribution and geological information of the fossil. Transmission X-ray microscopy revealed morphological details at deeper layers of the fossil which could not be observed through light microscopy.
Unique fractals were also discovered in the fossils, which are complex repeating patterns seen in snowflakes, flowers and even galaxies. The study hypothesized that these patterns were formed by the deposition of calcium apatite during the fossils’ formation, which also indicates they lived in a warm environment.