Over time, this is likely to have helped the reptiles specialise as the ambush predators they are today. These features are similar to modern crocodiles, which suggests Amphicotylus milesi would also have possessed a gular valve-like structure. The specimen was uncovered in the Morrison Formation in Wyoming, from which many dinosaur species have been uncovered, including Dippy the Diplodocus unearthed in 1899.Īmphicotylus milesi is separated from its closest relatives through its large snout, a backward extension of its nose duct and a short, curved tongue bone. This flap, however, contains cartilaginous structures that don't fossilise well, making it harder to work out when the gular valve first evolved.Īs one of the most well-preserved specimens of the goniopholididae, Amphicotylus milesi has one of these cartilaginous elements preserved. 'The valve is a fundamental thing to the way crocodiles live and hunt nowadays, allowing them to sit in the water with their mouth open.' However, crocodiles have the gular valve behind the mouth which can separate it from the nose, allowing them to breathe even if their mouth is underwater. 'It keeps the nasal cavity and mouth separate, with an opening at the back of the throat instead. 'We as humans have a secondary palate, but crocodiles are rare among reptiles in having one,' Stephan explains. This allows the reptile to continue to breathe through its nostrils while the rest of its head is underwater. Their semi-aquatic lifestyle is further supported by the possession of the gular valve, which seals off the mouth from the throat using a flap. They possessed many of the features that are common to modern crocodilians, including a similar body plan from which a semi-aquatic lifestyle has been suggested. The goniopholididae were one group of these reptiles which arose during the Jurassic Period. These diverse species and their descendants subsequently died out as carnivorous crocodyliformes became the dominant form. Some like Sarcosuchuswere enormous predators, while others were herbivores and omnivores.' 'They started out living on land where they were generally smaller and a lot more active. 'Nowadays, they are all semi-aquatic and predators of fish and other prey, but they have a very interesting evolutionary history. 'Crocodiles are known as living fossils, so you might have the idea that they have looked the same for millions of years,' Stephan says. While crocodilians tend towards similar lifestyles now, many of their ancient relatives were very different from one another. However, they did possess a secondary bony palate which separated the passage between their internal and external nostrils which all of their descendants also had. These ancestors were smaller than most living crocodilians, with a shorter snout. The earliest ancestors of the crocodiles evolved around 200 million years ago during the Late Triassic and Early Jurassic. The findings, led by researchers at Japan's Hokkaido University, were published in Royal Society Open Science. They're one of the earliest branching lineages in a group called neosuchia, which includes all modern crocodilians and their closest ancestors.' 'It was a member of the goniopholididae, which have a similar semi-aquatic lifestyle and a generally similar skull shape and skeleton to modern crocodiles. This would have enabled the predator to tackle prey in the water without the risk of drowning.ĭr Stephan Spiekman, who researches ancient crocodiles at the Museum and was not involved with the study, says, ' Amphicotylus milesi is a fantastic specimen, and seeing it as a mounted specimen is unbelievable as it almost looks like a modern crocodile. A well-preserved ancestor of the crocodiles has shown how the group of reptiles became the feared aquatic predators of today.ĭescribed as the 'uncle' of modern crocodilians, Amphicotylus milesi had a similar skull to its later relatives that is believed to have allowed it to seal its throat.
0 kommentar(er)
