Well -preserved fossils
Macri and his colleagues first learned about the McGrath site in 2017. Once this fossil was so important to them, they went there for three to four days in a row. They opened their hands to the rock like rocks as they tried to peek into the primeval forest.
As research progressed, they discovered how special this method of preservation was. All the fossils are trapped in a very thin layer of a mineral containing iron and oxygen called goethite. Fossils have been found in such rocks before, but the quality of the finds from McGraths Flat is remarkable.
“Little or no attention has been paid to this form of preservation,” said study co-leader Michael Freese, who is a virologist at Australia’s University of Canberra who also studies microfossils. “If you ask people if they really believe that iron rock contains beautiful fossils, they’ll probably say, ‘Don’t be silly!’”
Also read: Find fossils of ancient parasitic wasps in fossils
He explains that the findings from McGraths Flat can be well analyzed with a scanning electron microscope (SEM) because of its unusual petrification method. This is one of the most powerful microscopes out there. Researchers often have to coat the object they want with SEM with a thin layer of gold or platinum, which could limit future studies of these objects. The fossil from McGraths Flat already contains a lot of iron and is so conductive that it can be placed directly under an electron microscope, without any additional preparation.
“Fossils come out of SEM in the same way,” Freese said.
The smallest fossils have led to some great discoveries. In the only known feather fossil from the site, researchers were able to see an accumulation of the pigment melanin. The shape indicates that the fur is dark or colorful. Scientists have also looked at melanin in the eyes of fossil fish, and even found scales separated from the wings of a butterfly or moth that lived more than 11 million years ago.
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