2015-09-16 11:33:28
About 80 million years ago, at the end of the Cretaceous, sea levels were higher than they are today, and an arm of the sea cut through the lowlands of central North America. It was the Niobrara Sea, or Western Interior Sea, which at its greatest extent was about 1,000 kilometers wide, 750 meters deep, and more than 3,000 kilometers long, from northwestern Canada to eastern Mexico. .
While dinosaurs and mammals lived on land, in the sea we found sharks and bony fish, already very similar to modern ones, diving birds with strong legs and short wings that serve as underwater rudders, and various types of reptiles now extinct, such as long-necked plesiosaurs, and mosasaurs, large predators related to lizards or snakes. Among the invertebrates there are crinoids or sea lilies, sea urchins, crustaceans, molluscs… There are also turtles, and among them Archelon stands out, the largest sea turtle we know of. Of all the known turtles, it is only surpassed in size by Stupendemys, the freshwater turtle that we already referred to when we talked about the giants of the Amazon sea.
Archelon is related to the modern leatherback turtle, but is much larger. It reaches a length of more than 4.5 meters, almost 5 meters wide including the fins, and a weight of more than two tons. As in the leatherback, Archelon’s carapace is domed, and the carapace lacks bony plates. A structure of bone struts made up of the ribs and the perimeter of the carapace is covered in thick leathery skin. The breastplate or plastron, the lower part of the carapace, is made up of four star-shaped plates that leave a hole in the center.
Archelon’s head is relatively small and narrow, and the tail is long and pointed. Although it lacks teeth, its mouth has a strong hooked beak, with which it catches and crushes the animals that serve as food: jellyfish, squid, fish… The front fins are more developed than the rear ones. The huge turtle moves majestically underwater, with movements reminiscent of the underwater flight of penguins. With their size, adult turtles have nothing to fear from the large marine predators of the time. On land, however, where the females must go out to lay their eggs, they are very clumsy animals.
Archelon’s first fossil, discovered in 1895 in South Dakota, has been on display at Yale University’s Peabody Museum of Natural History since 1907. Other remains have been found in Kansas and Nebraska, but the largest and most complete specimen It was also discovered in South Dakota in the mid-1970s, and since 1982 it can be seen at the Natural History Museum in Vienna. This individual must have been close to a century in age, and probably died during the brumation, partially buried in the mud at the bottom of the sea. That is why it has been preserved so well. Brumation is a period of winter inactivity for some reptiles, similar to mammalian hibernation. A replica of this skeleton can be seen at Reptile Gardens, a zoo in Rapid City, South Dakota, very close to the site of its discovery.
During the Cretaceous, North Africa was also partially submerged, in this case under the Tethys Sea, ancestor of the Mediterranean Sea. Closer to the end of the period, 67 million years ago, another giant sea turtle, Ocepechelon, lived there, of which we only know the skull. A skull measuring 70 centimeters in length, which in addition to its enormous size presents unique characteristics among tetrapods. The skull was discovered by Moroccan geologist Baâdi Bouya in the Ouled Abdoun phosphate deposits near the city of Khouribga in central Morocco. Like Archelon, Ocepechelon is a relative, in this case more distant, of the leatherback.
The Ocepechelon’s skull is highly flattened, with a long, narrow snout. The nostrils are located at the base of the snout, between the eyes. The jaw bones have been transformed into a long tube of bone, similar to that of seahorses and needlefish. No other tetrapod, extinct or living, has such a mouthpart; the closest thing is the long snout of the beaked whales, relatives of dolphins, which live in deep waters and which, with the rapid retraction of the tongue, create a vacuum that sucks in the water and drags small prey into the mouth with it. . Surely Ocepechelon fed in the same way.
CONSTRUCTION OF GERMAN FERNÁNDEZ:
reticular infiltrate
Reticular Infiltrator is the first novel in the trilogy The Saga of the Borelians. Do you want to see how it starts? Here you can read the first two chapters.
The Karnak file. Ed.Rubeo
The hanged man and other fantastic tales. Ed.Rubeo
#Cienciaes.com #Giant #Cretaceous #Tortoises