The puzzle surrounding the identity of the first animal on Earth has\nfinally been solved. A team of geochemistry researchers at the\nMassachusetts Institute of Technology (MIT) has found strong evidence\nthat the ancestors of modern sea sponges were pioneers of multicellular\nlife in ancient oceans.<\/p>\n
The study, led by MIT Emeritus Professor of Geobiology Roger Summons,\ntogether with researcher Lubna Shawar, revealed the presence of\n\u2018chemical fossils\u2019 in ancient rocks more than 541 million years old. The\nfinding offers a new perspective that animal evolution began far earlier\nthan previously estimated.<\/p>\n
Unlike dinosaur fossils, which are bones, the first animals had very\nsoft bodies leaving no clear physical traces. Instead, they left\n\u2018molecular footprints\u2019 known as chemical fossils.<\/p>\n
The MIT team identified compounds called steranes, stable forms of\nsterols (such as cholesterol) found in membranes of complex organisms.\nThese steranes were abundant in rocks from the Ediacaran Period\n(approximately 541-635 million years ago) collected from Oman, India,\nand Siberia.<\/p>\n
Researchers found that sea sponges of the class Demospongiae possess\na unique genetic capacity to produce a sterol with 31 carbon atoms\n(C31). In comparison, the rarity of the C31 molecule acts as a\nbiological fingerprint, ensuring the compound in ancient rocks derives\nfrom living organisms rather than incidental geological processes.<\/p>\n
Roger Summons explained that although we do not know precisely what\nthe organism looked like, they certainly lived in the oceans and had\nvery simple bodies. \u201cThey must have been soft-bodied, and we suspect\nthey did not yet possess silica skeletons (spicules) as modern sponges\ndo,\u201d Summons said.<\/p>\n
This explains why paleontologists rarely find intact sponge fossils\nfrom the pre-Cambrian era. Without hard body parts, the fatty molecules\nin cell membranes are the only evidence preserved for hundreds of\nmillions of years.<\/p>\n
To ensure the accuracy of the findings, the team used a three-pronged\napproach. The results showed that only two compounds precisely matched\nthe C31 sterane found in the ancient rocks, all pointing to a lineage of\nsea sponges.<\/p>\n
The findings prove that sea sponges existed on Earth at least 60\nmillion years before the emergence of other major animal groups. Their\npresence in ancient oceans likely played a crucial role in altering\nocean chemistry, making it richer in oxygen and more habitable for more\ncomplex life in the future.<\/p>\n
Currently, the researchers plan to widen the search for chemical\nfossils in other regions to tighten the timeline of when exactly these\nfirst animals formed and how they endured past extreme climate\nchanges.<\/p>\n
(MIT News \/ Proceedings of the National Academy of Sciences (PNAS) \/\nH-3)<\/p>\n
The research was partly funded by the MIT Crosby Fund, the\nDistinguished Postdoctoral Fellowship Program, the Simons Foundation\nCollaboration on the Origins of Life, and NASA\u2019s Exobiology Program.<\/p>", "url": "https:\/\/jawawa.id\/newsitem\/the-first-animals-on-earth-were-sea-sponges-mit-researchers-present-evidence-1772639969", "image": "" }, "sponsor": "Okusi Associates", "sponsor_url": "https:\/\/okusiassociates.com" }