In a groundbreaking study published in Science Advances, Professor Zhu Maoyan, leading a team from the Nanjing Institute of Geology and Palaeontology at the Chinese Academy of Sciences, has unveiled a remarkable discovery of multicellular fossils dating back 1.63 billion years in North China.
These exquisitely preserved microfossils represent the earliest evidence of multicellular eukaryotes, marking a significant leap in our understanding of the emergence of complex life. This discovery builds upon the researchers’ previous breakthrough of finding decimeter-sized eukaryotic fossils in North China’s Yanshan area, pushing back the timeline of multicellularity in eukaryotes by approximately 70 million years.
Multicellularity is a fundamental characteristic of complex life forms on Earth, encompassing diverse organisms such as animals, land plants, fungi, and seaweeds. It represents a pivotal transition in the evolutionary history of life, contributing to the development of organismal complexity and large size.
While earlier fossil records hinted at the existence of multicellular eukaryotes around 1.05 billion years ago, the authenticity of those findings has been a subject of debate due to their simple morphology and lack of cellular structure.
The newfound multicellular fossils derive from the late Paleoproterozoic Chuanlinggou Formation, dating back 1,635 million years. These fossils present as unbranched, uniseriate filaments composed of two to more than 20 large cylindrical or barrel-shaped cells. Ranging in diameters from 20 to 194 μm and incomplete lengths up to 860 μm, these filaments showcase a degree of complexity through morphological variation.
Named Qingshania magnifica, these fossils exhibit a remarkable feature—an intracellular structure with a diameter of 15–20 μm in some cells. Comparable to asexual spores found in many eukaryotic algae, this suggests that Qingshania likely reproduced through spores.
Uniseriate filaments are common in both prokaryotes (bacteria and archaea) and eukaryotes in modern life. Qingshania’s large cell size, wide filament diameter range, morphological diversity, and intracellular spores all point to its eukaryotic affinity, distinguishing it from known prokaryotes.
While filamentous prokaryotes are typically small and simple, with diameters of 1–3 μm, Qingshania’s complexity aligns more with modern eukaryotic algae, particularly some green algae. This discovery offers valuable insights into the early stages of multicellular life, highlighting the intricate evolutionary processes that paved the way for the diverse array of complex organisms we see today.
Source: Chinese Academy of Sciences