When and where did sharks first become so massive? The discovery of enormous shark remains from northern Australia has just changed everything we thought we knew about these supersized predators.<\/p>\n
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We\u2019ve long thought that gigantic lamniform sharks \u2013 which today are represented by comparatively smaller species like the great white<\/a> \u2013 first evolved around 100 million years ago in the mid-Cretaceous seas of North America and Europe. Now, new research has pushed that origin back to around 115 million years ago and into the Southern Hemisphere.<\/p>\n Sorry, Australia. We really should\u2019ve known.<\/p>\n Today some of the oceans\u2019 greatest predators are lamniform sharks. Their evolutionary history is thought to span around 135 million years, in which time it\u2019s churned out \u201cThe Meg<\/a>\u201d, Otodus megalodon<\/a>, one of the most formidable predators<\/a> in Earth\u2019s history, and the \u201cGinsu Shark\u201d Cretoxyrhina mantelli that \u2013 though smaller than the megalodon \u2013 was larger than any shark alive today.<\/p>\n Measuring living sharks is easy enough (provided you keep a safe distance from the business end) but figuring out how large extinct sharks were<\/a> is a bit trickier. That\u2019s because, as cartilaginous fish<\/a>, they don\u2019t leave much behind in the fossil record.<\/p>\n \u00a0\u00a0<\/p>\n Teeth are common, but another thing we find is vertebrae and these can be used to estimate size. Of course, that depends on us finding the fossils to begin with.<\/p>\n Historic fossil finds have pointed towards North America and Europe as the waters of origin for large size in lamniform sharks, but the discovery of five fossil vertebrae from Australia says otherwise. The largest of the fossils is 12.6 centimeters (5 inches) in diameter, thought to be the vertebra of a massive Cardabiodontid shark.<\/p>\n The fossils were found in the Darwin Formation that dates back to the Upper Aptian of the Early Cretaceous, approximately 115 million years ago. Today that translates to the waters off Casuarina Beach near Darwin, Australia, and an entirely new timeline for gigantic lamniform sharks.<\/p>\n \u201cOur results show that mega-body size is an ancient lamniform trait, with the Australian cardabiodontid being around 6\u20138\u2009m [19.7-26.2 feet] and over 3 tons,\u201d write the authors. \u201cThis rivalled some of the largest coeval marine reptiles and suggests that lamniforms invaded top-predator niches from an early stage in their adaptive evolution.\u201d<\/p>\n Evidently, these sharks meant business. They likely filled the same ecological role as today\u2019s great white and may have rivalled giant marine reptiles like Kronosaurus<\/a>.<\/p>\n Curiously, fossils from the Darwin Formation so far include only mid-level predatory marine reptiles, suggesting these massive sharks may have hunted in different waters from the true sea monsters. If their paths ever did cross? Well, it would\u2019ve been one hell of a fight.<\/p>\n