After the dinosaurs died out in front of 66 million, crocodiles conquered many free niches and dominated many habitats. Only the Pleistocene ensured that her rule also ended through the onset of cold. Today only 23 types of crocodile live. They are the last rest of an animal group, the history of which began 200 million years ago. A new fossil from Wyoming now provides knowledge of how these living things once conquered water as a habitat. This is reported by a working group around Junki Yoshida from the Gunma Museum of Natural History in Tomioka in "Royal Society Open Science".
The very well -preserved fossil of a kind of called amphicotylus Milesi has some properties in his skeleton, which speak for a newly acquired adaptation to a semiac -quatic life. The skull, for example, has a throat flap with which the animal could close its throat so that no water penetrates. Today's crocodiles also have this closure, while the oldest known fossils of the tribal line do not have them.
Amphicotylus also had a backward-facing, arched extension of the air duct leading from the nostrils to the posterior part of the throat, and a short, curved hyoid bone similar to that of modern crocodiles. Because the nostrils at the end of the snout could remain above the surface of the water, the animals were able to breathe underwater while holding their prey in their mouths to drown them – much like crocodiles do today. The throat valve ensured that no water got into the throat and respiratory tract.
This allowed the species to conquer a new ecological niche. Until then, all known crocodiles lived on land, although among them there were also species that ate plants or carrion. Today, on the other hand, all crocodilians feed on meat and fish. The separation of the mouth and nose by the laryngeal cap allows you to lurk motionless with your mouth open underwater, while the nostrils in the air continue to allow breathing.
Since the valve is a cartilage tissue, it petrifies worse than the bones. With Amphicotylus Milesi, however, the completely animal was well preserved. Compared to giants such as the extinct Sarcosuchus or today's groin crocodiles with lengths from 7 to over 10 meters, Amphicotylus Milesi with a length of only 2.3 meters was relatively small. Small dinosaurs could still surprise the species while drinking, drown and then tear their meat off the body with the so -called death role.
