Proganochelys quenstedtii is the second oldest turtle Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield. "Turtle" may either refer to the Testudines as a whole, or to particular Testudines which make up a form taxon that is not monophyletic—see also sea turtle, terrapin, tortoise, and the species discovered to date, known only from fossils found in Germany A region named Germania, inhabited by several Germanic peoples, has been known and documented before AD 100. Beginning in the 10th century, German territories formed a central part of the Holy Roman Empire, which lasted until 1806. During the 16th century, northern Germany became the centre of the Protestant Reformation. As a modern nation-state, and Thailand Thailand (pronounced /ˈtaɪlænd/ TYE-land or /ˈtaɪlənd/; Thai: ราชอาณาจักรไทย Ratcha Anachak Thai, IPA: [râːtɕʰa ʔaːnaːtɕɑ̀k tʰɑj]) (formerly Siam Thai: สยาม) is an independent country that lies in the heart of Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos in strata from the late Triassic The Triassic is a geologic period that extended from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events. The extinction event that closed the Triassic Period has recently been more accurately, dating to approximately 210 million years ago. It has several synonyms, including Chelytherium ("Turtle Beast"), Psammochelys ("Sand Turtle"), Stegochelys ("Roof Turtle") and Triassochelys ("Triassic Turtle"). Until relatively recently, it was popularly known by the last name.
Until 2008, when the 220 million year old Odontochelys was discovered, Proganochelys was the oldest known turtle species.
Palaeobiology
Skeleton of Proganochelys quenstedti, American Museum of Natural HistoryIn life it was about 1 metre (3.3 ft) long, its overall appearance resembling modern turtles in many respects: it lacked teeth, likely had a beak, and had the characteristic heavily armored shell formed from bony plates and ribs which fused together into a solid cage around the internal organs. The plates comprising the carapace A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron and plastron The plastron is the nearly flat part of the shell structure of a turtle or tortoise, what one would call the belly, similar in composition to the carapace; with an external layer of horny material divided into plates called scutes and an underlying layer of interlocking bones were already in the modern form, although there were additional plates along the margins of the shell, that would have served to protect the legs. Also unlike any modern species of turtle, its long tail had spikes and terminated in a club, its head could not be retracted under the shell, and its neck was protected by small spines. While it had no teeth in its jaws, it did have small denticles on the palate The palate is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior bony hard palate, and the posterior fleshy soft.[1]
References
- ^ Palmer, D., ed (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. pp. 66-67. ISBN 1-84028-152-9.
External links
- American Museum of Natural History: Proganochelys
- Enchanted Learning Paleontology and Geology Glossary
- belated questions about beaks
- Animal Diversity Web: Order Testudines
Categories: Prehistoric reptiles of Europe | Triassic turtles
