The Triassic stem-turtles Pappochelys rosinae, Odontochelys semitestacea, and Proganochelys quenstedti. Proposed sequence of structural changes to the carapace and plastron in Eunotosaurus africanus and They may have been interconnected into a form of ‘protocarapace’. This includes the presence of strain-resisting fibres within the bone structure itself, an important step in the evolution of the turtle shell. In Pappochelys, the bone microstructure in the ribs was very close to the ‘turtle condition’, found in Odontochelys. What the researchers found were two main things. The carapaces for each species were not complete yet, but have different arrangements of their ribs and gastralia (underside body armour) that show different stages in the evolutionary sequence. In particular, these three species are important as together they illustrate the earliest evolutionary stages of the development of the plastron. ![]() Outline drawings of stem-turtles Pappochelys rosinae (A), Odontochelys semitestacea (B), and Histology works by carefully creating thin slices of bone and then looking at the texture and features under a microscope. For this, they used a technique called paleohistology, which is the study of the internal microstructure of bones. ![]() Researchers looked at three of the oldest species known from the Triassic, Pappochelys, Eorhynchochelys and Odontochelys, to try and see if they could trace the early evolution of the first shelled-turtles. The earliest known turtles stretch back in time to the Triassic period, around 240 million years ago, and perhaps even further.Ī new study has now tried to shed some light on this evolutionary conundrum. They have a history of repeatedly adapting to live on land or out at sea. The fossil record of turtles is quite incredible, covering dozens of now extinct species from a number of different. This means that in turtles, unlike crocodiles, the outer shell is actually integrated into the rest of the skeleton.īut just how did this strange evolutionary feature come about? How did it start? To answer this, we have to consult that ever-giving encyclopaedia of the history of life, the fossil record. In turtles, the ribs and vertebrae grow into the outer skin layers and connect together like tectonic plates, forming a solid shell. This is distinct from say, crocodiles, where their bony carapace is formed from growths within their skin known as osteoderms. Becoming heavily modified over millions of years, they joined together to form the tough, protective armour that we know and love so much about modern turtles. It has long been thought that the tough, bony shells of turtles and their ancestors are formed from their ribs. ![]() Anyone who has ever been lucky enough to see one swimming in the wild will know just how much of a heart-stopping sight they are to behold.įor scientists, one of the great and wonderful questions to ask is also one of the simplest: How did turtles get their shells? One of the most remarkable features about these graceful weirdos, we actually know very little about the evolutionary origins. Great folded from kami, Korean pattern paper, patterned duo, Grimmhobby Corona Harmony print, Aitoh Bokashi Chiyogami flower pattern print, Tuttle Rainbow Pattern print ().Turtles are a beautiful mystery in the animal kingdom. Special Requirements: Accurate pre-creasing and careful shaping is helpful for the model. ![]() The original diagram shows the major color on the front and a minor color on the back. I will share my variation that displays the major color on the front and back sides of the star. After precreasing an 8x8 grid, we will need to carefully form into a 3D shape and then twist-collapse the star. I will teach you my folding sequence to fold an 8x8 grid aligning cut edges and folded edges of the paper as a guide. You'll learn how to fold this versatile, fabulous 1-sheet model – no cutting, no gluing! A 6-inch square yields about a 3-inch star suitable for greeting cards, origami pins and holiday decoration.
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