His colleague Dr. Mahdieh Malekhosseini has been studying calcium oxalate in fossilized plant remains, including finds that are up to 370 million years old. Malekhosseini was the first to notice that the fossil leaves exhibit characteristic patterns of distinct cavities. The team of researchers then examined these “ghost crystals” under a range of microscopes. During the lengthy fossilization process, the calcium oxalate is dissolved away and, in some cases, replaced by other substances.
After studying over 1,000 samples, the researchers were faintly astonished to discover that calcium oxalate was present in over 90 percent of plant species, from early lineages through to modern-day groups. “This underlines its role as one of the most important biominerals in both plants and other creatures on the planet,” Malekhosseini explains. The appearance and distribution patterns of the crystals in fossil leaves largely match those in modern plants. “This suggests that evolution has been following a stable trend.” The researchers’ findings have been published in the international journal “Plos One”.