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The study was led by Dr. Maria Eleonora Rossi, Honorary Research Associate, at the University of Bristol<\/a> School of Biological Sciences.<\/p>\n The research suggests that the earliest sponges were soft-bodied, lacking mineral skeletons.<\/p>\n Skeletons that survive decay<\/p>\n Mineral fragments can survive long after an organism decays, so sponge skeletal pieces carry outsized weight in deep time.<\/p>\n Spicules<\/a>, tiny mineral needles that stiffen sponge tissue, drop into seafloor mud and can persist for ages.<\/p>\n When early sponges lacked these needles, the fossil record would mainly show empty space and a few ambiguous chemical traces.<\/p>\n Many of the rocks that capture early animal life formed during the quiet stretch just before the Cambrian explosion.<\/p>\n Geologists call this interval the Ediacaran, the last Precambrian period with large, soft animals, and they mark it on official time charts<\/a>.<\/p>\n In those layers, sponge bodies are hard to spot, so the debate has leaned heavily on genetics and chemistry.<\/p>\n Timing evolution accurately<\/p>\n Instead of choosing sides, the team built a timescale that let fossils and gene sequences constrain each other.<\/p>\n They first assembled a phylogeny, a family tree of species from shared data, then pinned key branches to fossils.<\/p>\n That pairing narrows the space for wildly different dates, but it still depends on how fossils are interpreted.<\/p>\n Time estimates from genes work best when researchers anchor them to real rock layers, not just assumptions.<\/p>\n A molecular clock<\/a>, a dating method using genetic change over time, can drift unless fossils set bounds.<\/p>\n In this case, the new clock pulls sponge origins closer to their known hard parts, trimming decades of disagreement.<\/p>\n Similar shapes, different genes<\/p>\n Mineral skeletons can look similar across sponge groups, yet the genes behind them do not always match.<\/p>\n The results point to biomineralization<\/a>, cells turning dissolved minerals into hard body parts, arising more than once in sponges.<\/p>\n Independent origins mean shared shapes do not guarantee shared ancestry, which changes how scientists read ancient fragments.<\/p>\n Soft-bodied animals usually rot or get squashed, so their early history often hides outside the fossil record.<\/p>\n \u201cOur results show that the first sponges were soft-bodied and lacked mineralized skeletons,\u201d said Rossi.<\/p>\n Without sturdy skeleton pieces, earlier sponges could pass through deep time unnoticed, even if they lived in large numbers.<\/p>\n Modeling changes in early skeletons<\/p>\n To test ancient skeleton types, the team treated each lineage like a set of states that can change over time.<\/p>\n A Markov process<\/a>, a statistical method that tracks stepwise changes between states, let the model compare soft and mineralized forms.<\/p>\n Most reasonable settings favored soft ancestors, showing that the answer hinges on allowing different minerals to count as different.<\/p>\n Different minerals resist decay in different ways, and that matters when a fossil record depends on microscopic fragments.<\/p>\n Siliceous spicules can survive heat and pressure better than many soft tissues, so they leave clear trails in mud.<\/p>\n A model that treats silica and carbonate as interchangeable can blur real biological differences, so the team judged that approach unrealistic.<\/p>\n Sponges shape modern seas<\/p>\n Modern reefs and seafloors still rely on sponges as ecosystem engineers<\/a>, organisms that reshape habitats for other species.<\/p>\n By pumping huge volumes of water through their bodies, sponges<\/a> capture food and recycle carbon and nutrients in seawater.<\/p>\n That day-to-day work helps explain why scientists care about sponge origins, since early changes could ripple through ocean chemistry.<\/p>\n In the ocean, sponges also participate in the silicon cycle, movement of dissolved silicon through seawater, organisms, and sediments.<\/p>\n Siliceous species lock silicon into tough skeletons, then return it to seawater as fragments<\/a> dissolve.<\/p>\n Because skeleton chemistry changes over time, understanding early sponge materials may also refine how researchers model long-term nutrient budgets.<\/p>\n Chemical traces and controversy<\/p>\n Some researchers have pointed to biomarkers in rocks older than 635 million years. These chemical leftovers can hint at past life.<\/p>\n One influential report<\/a> tied certain fossil sterols to early demosponges, pushing their origin far earlier than most body fossil evidence.<\/p>\n The new work does not settle that debate outright, but it reduces the size of the mismatch that fueled it.<\/p>\n Limits of the current evidence<\/p>\n The team also tested diversification, the rate at which lineages split into new species, against the appearance of spicules.<\/p>\n Their statistical checks found little sign that mineral needles alone triggered big branching events, hinting at other pressures.<\/p>\n That uncertainty is a clear limit of the current evidence, since soft-body traits and environments rarely fossilize together.<\/p>\n Taken together, the dates, genes, and skeleton reconstructions suggest sponge history began later than some chemical hints implied.<\/p>\n Future fossil finds and wider genome sampling could still move the timeline, but the study offers a clearer target for searches.<\/p>\n The study is published in the journal Science Advances<\/a>.<\/p>\n \u2014\u2013<\/p>\n Like what you read? Subscribe to our newsletter<\/a> for engaging articles, exclusive content, and the latest updates.\u00a0<\/p>\n Check us out on EarthSnap<\/a>, a free app brought to you by Eric Ralls<\/a> and Earth.com.<\/p>\n \u2014\u2013<\/p>\n","protected":false},"excerpt":{"rendered":"For decades, sponges have sat at the center of a timeline dispute, because genes and fossils have told…\n","protected":false},"author":2,"featured_media":238565,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[264,61,60,82],"class_list":["post-238564","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-animals","tag-ie","tag-ireland","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/238564","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/comments?post=238564"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/238564\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/238565"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=238564"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=238564"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=238564"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}