A brand new examine exhibits that the physique measurement of the iconic gigantic Megalodon or megatooth shark, about 50 toes (15 meters) in size, is certainly anomalously massive in comparison with physique sizes of its relations. Formally known as Otodus megalodon, the fossil shark that lived almost worldwide roughly 15-3.6 million years in the past is receiving a renewed have a look at the significance of its physique measurement in the shark world, based mostly on a brand new examine showing in the worldwide journal Historic Biology.
Otodus megalodon is usually portrayed as a super-sized, monstrous shark, in novels and movies equivalent to the 2018 sci-fi thriller “The Meg,” however it’s identified that the scientifically justifiable most doable physique measurement for the species is about 50 toes at current (15 meters; not 16 meters or bigger in some earlier research). Nonetheless, it’s nonetheless an impressively massive shark, and the new examine illuminates precisely how uniquely gigantic the shark was relative to different sharks, famous Kenshu Shimada, a paleobiologist at DePaul College in Chicago and lead writer of the examine.
Otodus megalodon belongs to the shark group known as lamniforms with a wealthy fossil report, however the biology of extinct varieties is poorly understood as a result of these cartilaginous fishes are principally identified solely from their enamel. The examine used measurements taken from specimens of all 13 species of present-day macrophagous (non-planktivorous) lamniforms to generate capabilities that will permit estimations of physique, jaw and dentition lengths of extinct macrophagous lamniforms from their enamel. These quantitative capabilities enabled the researchers to look at the physique measurement distribution of all identified macrophagous lamniform genera over geologic time.
The examine demonstrates that O. megalodon reaching no less than 46 toes (14.1 meters) is really an outlier as a result of virtually all different macrophagous sharks, together with extinct varieties, have a basic measurement restrict of 23 toes (7 meters); and just a few plankton-eating sharks, equivalent to the whale shark and basking shark, have been equal or got here near the measurement. The examine additionally reveals that the Cenozoic Period (after the age of dinosaurs, together with in the present day) noticed extra lamniform lineages attaining bigger sizes than the Mesozoic Period (age of dinosaurs).
Heat-bloodedness has beforehand been proposed to have led to the gigantism (20 toes, or over 6 meters) in a number of lamniform lineages. The brand new examine proposes their live-bearing reproductive technique with a novel cannibalistic egg-eating habits to nourish early-hatched embryos to massive sizes inside their mom to be one other doable trigger for the frequent evolution of gigantism achieved by lamniform sharks.
Understanding physique sizes of extinct organisms is necessary in the context of ecology and evolution. “Lamniform sharks have represented main carnivores in oceans since the age of dinosaurs, so it’s affordable to claim that they should have performed an necessary function in shaping the marine ecosystems we all know in the present day,” mentioned Shimada.
“That is compelling proof for the really distinctive measurement of megalodon,” famous co-author Michael Griffiths, a professor of environmental science at William Paterson College in Wayne, New Jersey. Co-author Martin Becker, additionally a professor of environmental science at William Paterson College, added, “This work represents a vital development in our understanding of the evolution of this ocean large.”
The brand new examine, “Body, jaw, and dentition lengths of macrophagous lamniform sharks, and physique measurement evolution in Lamniformes with particular reference to ‘off-the-scale’ gigantism of the megatooth shark, Otodus megalodon,” will seem in the forthcoming concern of Historic Biology.
Reference: “Body, jaw, and dentition lengths of macrophagous lamniform sharks, and physique measurement evolution in Lamniformes with particular reference to ‘off-the-scale’ gigantism of the megatooth shark, Otodus megalodon” by Kenshu Shimada, Martin A. Becker and Michael L. Griffiths, 4 October 2020, Historic Biology.