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The study was led by Dr. Alexandre Siqueira, a research fellow at Edith Cowan University (ECU<\/a>).<\/p>\n The researchers found that during the Miocene<\/a>, roughly 20 to 10 million years ago, reefs expanded on a scale not seen in 100 million years.<\/p>\n Reefs hold about a quarter of all marine species but cover less than one percent of the ocean. How did that happen in the first place?<\/p>\n Three lines of evidence<\/p>\n Dr. Siqueira and his colleagues drew on three independent records: geological maps of ancient reefs, fossils, and the genetic family trees of living reef species.<\/p>\n Each record alone is partial. Geology shows where ancient reefs once rose from the seafloor. Fossils preserve species in patches. Genetic trees show when lineages split but not where.<\/p>\n \u201cThis study uncovers a turning point deep in Earth\u2019s history \u2013 a time when reefs didn\u2019t just grow, but magnified on a scale far beyond anything we see today,\u201d Siqueira said.<\/p>\n All three lines aligned on a single window roughly 20 million years ago, when reefs across what is now the Coral Triangle<\/a> grew on a scale the ocean hasn\u2019t matched since.<\/p>\n A recent study<\/a> tracking the region\u2019s biodiversity over 40 million years captured the rise in species but never asked how large those reefs actually were.<\/p>\n The west coast surprise<\/p>\n What surprised the researchers most was the location. The largest reefs in this ancient network were not near Indonesia or the Philippines, but off Australia\u2019s northwest coast.<\/p>\n What\u2019s left today is a scattering of small, remote reefs \u2013 modest by Great Barrier Reef<\/a> standards. <\/p>\n Dr. Siqueira\u2019s team calls them worn-down survivors of what they\u2019ve named the Great Indo-Australian Miocene Reef System.<\/p>\n Geologists have known for decades that a barrier reef once tracked Australia\u2019s northwest coast, roughly matching the Great Barrier Reef in extent. <\/p>\n What no one had measured was how big the individual reefs within it grew.<\/p>\n \u201cThe new findings go further, suggesting individual reefs within this system may have been far larger than any modern reef,\u201d Siqueira said.<\/p>\n The role of tectonic plates<\/p>\n The timing raises an obvious question: why did reefs expand so dramatically 20 million years ago? The researchers trace the answer to shifting tectonic plates.<\/p>\n By then, Australia\u2019s tectonic plate was pushing north into the Southeast Asian margin, opening vast shallow, warm seas \u2013 exactly what coral needs.<\/p>\n An earlier paper<\/a> reached the same conclusion, simulating 140 million years of plate motion to map where shallow tropical seas opened up.<\/p>\n What modeling alone couldn\u2019t supply was fossil and genetic evidence. The current study reveals that the reefs in those new seas didn\u2019t just exist \u2013 they flourished on a scale the modern ocean doesn\u2019t match.<\/p>\n When fish lineages exploded<\/p>\n Reefs aren\u2019t just rock and coral. They\u2019re scaffolding for everything that lives on them. As the Indo-Australian system grew, fish family trees were branching fast.<\/p>\n Parrotfishes<\/a> are one of the clearest examples. A separate genetic study<\/a> on wrasses and parrotfish found that reef lineages diversified rapidly between 20 and 15 million years ago. Non-reef branches didn\u2019t.<\/p>\n Dr. Siqueira\u2019s analysis suggests the timing wasn\u2019t coincidence. Larger reefs likely created more habitat types, opening ecological space that new species moved into. <\/p>\n Many questions still remain. Whether reefs grew first and pulled in new species, or whether it worked the other way around, is still debated. <\/p>\n The weight of climate, tectonics, and biology in driving the expansion isn\u2019t settled.<\/p>\n \u201cIt adds one more piece of evidence to the puzzle on how coral reef systems as a whole evolved,\u201d said Dr. Siqueira.<\/p>\n Living artifacts of an ancient reef<\/p>\n The search for marine biodiversity\u2019s origins has changed. For decades, the question was why the Coral Triangle is so rich. It inherited its riches from a vanished neighbor.<\/p>\n That changes the conversation about conservation. Australia\u2019s northwest reefs \u2013 Ashmore, Scott, and Rowley \u2013 have been treated as remote outposts. <\/p>\n They may be living artifacts of a system that seeded today\u2019s tropical oceans.<\/p>\n This vast ancient reef network had never been formally unified under a single name. The new study gives researchers a framework to map the Great Indo-Australian Miocene Reef System and trace what remains of it today.<\/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.<\/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":"Australia\u2019s northwest coast has never ranked high on the list of places reef scientists study first. The reefs…\n","protected":false},"author":2,"featured_media":453634,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[61,60,82],"class_list":["post-453633","post","type-post","status-publish","format-standard","has-post-thumbnail","category-science","tag-ie","tag-ireland","tag-science"],"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/453633","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=453633"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/posts\/453633\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media\/453634"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/media?parent=453633"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/categories?post=453633"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/ie\/wp-json\/wp\/v2\/tags?post=453633"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}