{"id":167034,"date":"2025-12-04T02:24:15","date_gmt":"2025-12-04T02:24:15","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/167034\/"},"modified":"2025-12-04T02:24:15","modified_gmt":"2025-12-04T02:24:15","slug":"fossils-reveal-the-green-anaconda-has-been-a-giant-for-12-million-years","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/167034\/","title":{"rendered":"Fossils Reveal the Green Anaconda Has Been a Giant For 12 Million Years"},"content":{"rendered":"

\"Anaconda <\/a>Nowadays, anacondas are usually four to five meters long, but they can reach seven meters. Credit: Andres Alfonso-Rojas<\/p>\n

The Green Anaconda is the heaviest snake on Earth<\/a> today. For decades, many paleontologists suspected that the snake started out smaller and grew over the years. A new Cambridge study says otherwise.<\/p>\n

The team of paleontologists has unearthed fossils from the Urumaco and Socorro formations in Venezuela that tell a different story: Anacondas were giants over 12 million year ago. <\/p>\n

A Trip to the Miocene<\/p>\n

The Amazon may be a biodiversity hotspot<\/a> today, but 12 million years ago, it was quite different. During the Miocene, a period that lasted from around 20 to 5 million years ago, western Amazonia wasn\u2019t a river system<\/a> flowing east to the Atlantic. It was the \u201cPebas system\u201d \u2014 a colossal, sprawling landscape of mega-wetlands, shallow lakes, and swamps that covered a vast portion of the continent. It was a biological factory designed to produce giants.<\/p>\n

This era, specifically the Middle Miocene Climatic Optimum, was warmer than today. The heat and the boundless aquatic real estate<\/a> allowed reptiles to scale up. The fossil record<\/a> from this time is littered with the remains of titans. We have seen Purussaurus, a caiman that could crush a car, Stupendemys, a freshwater turtle the size of a sedan, and Mourasuchus, a bizarre crocodilian with a mouth like a duck\u2019s bill.<\/p>\n

These animals were specialists of their time, growing huge to exploit the rich resources of the Pebas wetland. But as the Andes Mountains<\/a> continued their slow, grinding uplift, they changed the continent\u2019s drainage. The massive wetlands drained, eventually forming the modern Amazon and Orinoco river basins<\/a>.<\/p>\n

This transition was catastrophic for the giants. As the Pebas system vanished, so did the mega-caimans and the colossal turtles. They peaked, they faced a changing world, and they went extinct, replaced by smaller relatives.<\/p>\n

But the anaconda refused to follow the script.<\/p>\n

Reading the Bones<\/p>\n

\"Fossilized<\/a>Anacondas can have more than 300 vertebrae in their backbones, and measurements of the size of individual fossilized vertebrae can provide a reliable indication of how long a snake was. Credit: Jorge Carrillo-Brice\u00f1o.<\/p>\n

\u201cOther species like giant crocodiles and giant turtles have gone extinct since the Miocene, probably due to cooling global temperatures and shrinking habitats, but the giant anacondas have survived \u2014 they are super-resilient,\u201d said Andr\u00e9s Alfonso-Rojas, a Ph.D. student and Gates Cambridge Scholar in the Department of Zoology at the University of Cambridge, lead author of the research.<\/p>\n

Alfonso-Rojas and colleagues analyzed ancient vertebrae of the genus Eunectes (anacondas), calculating that they had already reached body lengths of nearly 5.2 meters (about 17 feet) by 12.4 million years ago. <\/p>\n

But they didn\u2019t find out why the anacondas stayed big.<\/p>\n

For a long time, scientists believed that \u201cabiotic\u201d factors (things like temperature and habitat size) were the main drivers of size. The logic was simple: a warmer world in the Miocene and a bigger home (the Pebas wetland) equals bigger snakes. But here is the snag: the world cooled down. The massive wetlands shrank, and if temperature and habitat size were the only things keeping anacondas big, they should have shrunk like the caimans. But they didn\u2019t.<\/p>\n

The researchers suggest that perhaps the answer lies in what these snakes ate. Anacondas are generalist hypercarnivores. They\u2019ll eat pretty much anything. Fish, turtles, birds, mammals, other reptiles \u2014 if it fits in the mouth, it\u2019s dinner. The fossil record shows that the Urumaco region was teeming with potential prey: giant rodents, huge fish, freshwater turtles, and crocodilians. Perhaps they needed to stay big so that they could ambush and eat big food.<\/p>\n

However, even this theory has holes. The study notes that later in the timeline (Pliocene and Pleistocene), new predators (carnivorous mammals) entered South America, which should have increased competition. Yet, the anaconda didn\u2019t flinch.<\/p>\n

The researchers candidly admit that while the environment likely helped start the gigantism, the specific driver that maintained it through millions of years of change remains elusive. <\/p>\n

Journal Reference: An early origin of gigantism in anacondas (Serpentes: Eunectes) revealed by the fossil record, Journal of Vertebrate Paleontology (2025). DOI: 10.1080\/02724634.2025.2572967<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Nowadays, anacondas are usually four to five meters long, but they can reach seven meters. Credit: Andres Alfonso-Rojas…\n","protected":false},"author":2,"featured_media":167035,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[26],"tags":[26077,108042,4590,84275,108908,25081,111,139,69,6581,147,108909,41812,406],"class_list":{"0":"post-167034","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-wildlife","8":"tag-amazon-rainforest","9":"tag-eunectes","10":"tag-evolutionary-biology","11":"tag-green-anaconda","12":"tag-megafauna","13":"tag-miocene","14":"tag-new-zealand","15":"tag-newzealand","16":"tag-nz","17":"tag-paleontology","18":"tag-science","19":"tag-snake-evolution","20":"tag-venezuela","21":"tag-wildlife"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/167034","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=167034"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/167034\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/167035"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=167034"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=167034"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=167034"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}