Kollajen yiyen mikroplar fosil kaydındaki değişimi açıklayabilir

Soft-bodied animals from the late Ediacaran Period, 579 to 539 million years ago, were preserved surprisingly often despite lacking shells or bones, whereas comparable organisms later became scarce in the fossil record. Cambridge-led researchers propose that microbial evolution helped drive this change. They traced genes for collagenases—enzymes that break down the collagen supporting animal tissues—across 700 bacterial genomes and compared them with a dated tree of life. Collagenases existed before animals, but initially occurred in anaerobic microbes that could not thrive in oxygen-rich settings. Dead Ediacaran organisms could therefore retain collagen until surrounding sediments lost their oxygen, extending the time available for fossilisation. Around the Ediacaran-Cambrian transition, collagenase genes spread into aerobic bacteria, including groups responsible for modern decay. Soft tissue could then decompose in more environments before mineralisation recorded it. Exceptional rapid burial can still preserve younger organisms, but the findings offer a broad biological explanation for the later decline in both the abundance and quality of soft-tissue fossils.