Beauty, and by extension coloration, is only skin deep. It’s a frustrating fact for paleontologists, who can often only guess at what colors extinct creatures like dinosaurs may have been millions of years ago. Allowing for a few unusual exceptions, it’s just very unlikely for the color-producing pigments from an animal’s skin to be preserved as a fossil. Unless, apparently, that organism is so ancient and simple that there was never skin to worry about, in which case we can say with confidence that some of the world’s original organisms were all pink.
This conclusion is the result of oil drilling in the Sahara Desert. Some of the extracted shale was found to contain microscopic fossils from 1.1 billion years ago, well before any multi-cellular organism ever wriggled or swam across the Earth. When analyzed further, researchers realized that the fossilized cells were preserved well enough to carry molecules from the organisms’ pigmentation, and that that pigment would have given each cell a light pink hue. That pink was likely part of an early version of chlorophyll, which helped researchers identify exactly what kind of organism produced it.
Large numbers, tiny size
Cosmetic concerns aside, these fossils were identifiable as an ancient form of cyanobacteria. Their concentration was high enough to suggest that these tiny organisms likely dominated their ecosystem to such an extent that they may have been holding other forms of life in check. Until algae really spread throughout the oceans, an ecosystem flooded with minuscule cyanobacteria wouldn’t have provided much nutrition for larger, more predatory organisms. In fact, they’re so small many have been appropriated in to larger organisms’ cells, making up the chloroplasts found in plant cells today.
More complex organisms still had a long time to wait though. These tiny, pink cells would continue to dominate the planet for another 450 million years after this particular batch started becoming fossils.
My fourth-grader asked: What are cyanobacteria? What were they eating then?
Cyanobacteria were likely the first organisms on the planet, and they’re still alive today. They generally live in water, and produce their own food through photosynthesis, which is why some now live in plants as mentioned above. Thankfully for the rest of us, cyanobacteria’s primary waste product is oxygen, meaning their metabolism is actually the reason we have air to breath today.
Source: Scientists discover world's oldest colour – bright pink by Luke Henriques-Gomes, The Guardian