The appearance of scutes correlates to the transition from aquatic to terrestrial mode of life in tetrapods during the Carboniferous period (340 Ma). [28] In the evolution from amphibians to terrestrial amniotes, transition in a wide variety of skin structures occurred. Ancestors of turtles likely diverged from amphibians to develop a horny cover in their early terrestrial ancestral forms. [29] Ontogeny [ edit ] Development of the shell: seen in the egg at stage 16/17, the carapace is developing. In section, the ribs are growing sideways not downwards, into the carapacial ridge, seen here as a bud, to support the carapace. [30] On top of this is a covering of keratin, which is the same material that makes up our fingernails. This is laid down in a distinctive pattern, with the individual segments of the shell known as scutes. Tortoises are generally considered to be strict herbivores, feeding on grasses, weeds, leafy greens, flowers, and some fruits. However, hunting and eating of birds has been observed on occasion. [28] Pet tortoises typically require diets based on wild grasses, weeds, leafy greens and certain flowers. Certain species consume worms or insects and carrion in their normal habitats. Too much protein is detrimental in herbivorous species, and has been associated with shell deformities and other medical problems. Different tortoise species vary greatly in their nutritional requirements. C.H. Ernst; R.G.M. Altenburg; R.W. Barbour. "Terrapene carolina". Netherlands Biodiversity Information Facility. Archived from the original on 24 July 2011 . Retrieved 12 February 2011. Running through your management and identifying any problems at this early stage is the best way to combat this disfiguring condition.

The signs can vary from mild to very disfiguring, affecting the tortoise’s mobility and its ability to mate successfully in extreme cases. Schoch, Rainer R.; Sues, Hans-Dieter (2015). "A Middle Triassic stem-turtle and the evolution of the turtle body plan". Nature. 523 (7562): 584–587. Bibcode: 2015Natur.523..584S. doi: 10.1038/nature14472. PMID 26106865. S2CID 205243837. Pyramiding affects the scutes on the top part of the tortoise’s shell, known as the carapace, causing them to grow abnormally, often in a shape rather like that of a mini-pyramid which explains the name of this condition.Young tortoises, such as Hermann’s and Horsfield’s (Agrionemys horsfieldii) which are being reared indoors are especially susceptible to MBD because they will be growing relatively fast, and therefore have a higher dietary calcium requirement to support their growth, compared with non-breeding adults. To visualize these contrasts effectively, refer to the following table highlighting various aspects of turtle and tortoise skeletons: Characteristic

Auffenberg, Walter (1977-02-01). "Display Behavior in Tortoises". American Zoologist. 17 (1): 241–250. doi: 10.1093/icb/17.1.241. ISSN 0003-1569. Through countless years of evolution, turtles and tortoises have developed remarkable adaptations that allow them to thrive in a wide range of environments. These skeletal modifications enable these creatures to navigate various terrains, protect themselves from predators, and efficiently carry out their vital functions. Lyson, T. R.; etal. (2016). B. S. Rubidge, T. M. Scheyer, K. De Queiroz, E. R. Schachner, R. M. Smith, J. Botha-Brink. "Fossorial Origin of the Turtle Shell" (PDF). Current Biology. 26 (14): 1887–1894. doi: 10.1016/j.cub.2016.05.020. PMID 27426515. S2CID 3935231. And these shells are not just fused bones. As a matter of fact, a turtle’s shell also has a blood and nerve supply. Therefore, if the shell is injured or damaged, it can bleed and cause a turtle pain. Chen, Z.-Q.; Benton, M. J. (2012). "The timing and pattern of biotic recovery following the end-Permian mass extinction". Nature Geoscience. 5 (6): 375–383. Bibcode: 2012NatGe...5..375C. doi: 10.1038/ngeo1475.

The turtle's shell is an important study, not just because of the apparent protection it provides for the animal but also as an identification tool, in particular with fossils, as the shell is one of the likely parts of a turtle to survive fossilization. Hence understanding the shell structure in living species provides comparable material with fossils. Turtles are related to dinosaurs, and the latest genetic studies suggest turtles share the same ancestor. The earliest turtles existed together with the dinosaurs millions of years ago. Descendants of ancient turtles are still present today, with most of them being species of sea turtles. Do butterflies have hearts?

Conservation efforts: A thorough understanding of their skeletal system aids conservationists in identifying potential threats to these species’ survival due to environmental changes or human activities. Jonathan, a Seychelles giant tortoise living on the island of St Helena, may be as old as 191 years. [19] Dimorphism [ edit ] Nagashima, H.; Sugahara, F.; Takechi, M.; Ericsson, R.; Kawashima-Ohya, Y.; Narita, Y.; Kuratani, S. (2009). "Evolution of the turtle body plan by the folding and creation of new muscle connections". Science. 325 (5937): 193–196. Bibcode: 2009Sci...325..193N. doi: 10.1126/science.1173826. PMID 19590000. S2CID 206519888. To better understand the skeletal composition, here are some key bones commonly found in both turtles and tortoises: One interesting example that showcases these differences is the case of the green sea turtle (Chelonia mydas) and the Galapagos giant tortoise (Chelonoidis nigra). The green sea turtle has a more streamlined body for efficient swimming in water, with its limbs adapted as flippers. In contrast, the Galapagos giant tortoise has sturdy limbs designed for walking on land.Shells: Anatomy and Diseases of Turtle and Tortoise Shells". PetEducation.com. Drs. Foster & Smith. Archived from the original on 2013-10-23 . Retrieved 2013-10-22. This acts as a hinge, allowing the turtle to pull its carapace and plastron together tightly. This usually happens when the turtle reacts to something and retracts its body into its shell. i) Neural 1, (ii) Neural 2, (iii) Neural 3, (iv) Neural 4, (v) Neural 5, (vi) Neural 6, (vii) Neural 7, (viii) Neural 8, (ix) extra neural, divided, (x) suprapygal, (xi) nuchal, (xii) right peripheral 1, (xiii) right peripheral 2, (xiv) right peripheral 3, (xv) right peripheral 4, (xvi) right peripheral 5, (xvii) right peripheral 6, (xviii) right peripheral 7, (xix) right peripheral 8, (xx) right peripheral 9, (xxi) right peripheral 10, (xxii) right peripheral 11, (xxiii) pygal, (xxiv) left peripheral 11, (xxv) left peripheral 10, (xxvi) left peripheral 9, (xxvii) left peripheral 8, (xxviii) left peripheral 7, (xxix) left peripheral 6, xxx left peripheral 5, xxxi left peripheral 4, (xxxii) left peripheral 3, (xxxiii) left peripheral 2, (xxxiv) left peripheral 1, (xxxv) right 1st rib, (xxxvi) right pleural 1, (xxxvii) right pleural 2, (xxxviii) right pleural 3, (xxxix) right pleural 4, (xl) right pleural 5, (xli) right pleural 6, (xlii) right pleural 7, (xliii) right pleural 8, (xliv) right 10th rib, (xlv) left 1st rib, (xlvi) left pleural 1, (xlvii) left pleural 2, (xlviii) left pleural 3, (xlix) left pleural 4, (l) left pleural 5, (li) left pleural 6, (lii) left pleural 7, (liii) left pleural 8, (liv) left 10th rib, (9-18) centrums. Today there are only two living species of giant tortoises, the Aldabra giant tortoise on Aldabra Atoll and the dozen subspecies of Galapagos giant tortoise found on the Galapagos Islands. However, until recently giant tortoises could be found on nearly every major island group, including the Bahamas, the Greater Antilles (including Cuba and Hispaniola), the Lesser Antilles, the Canary Islands, Malta, the Seychelles, the Mascarene Islands (including Mauritius and Reunion), and Madagascar. Most of these tortoises were wiped out by human arrival. Many of these giant tortoises are not closely related (belonging to different genera such as Megalochelys, Chelonoidis, Centrochelys, Aldabrachelys, Cylindraspis, and Hesperotestudo), but are thought to have independently evolved large body size through convergent evolution. Giant tortoises are notably absent from Australasia and many south Pacific islands, but the distantly related meiolaniid turtles are thought to have filled the same niche. Giant tortoises are also known from the Oligocene- Pliocene of mainland North America, South America, Europe, Asia, and Africa, but are all now extinct, which is also attributed to human activity. [27] Diet [ edit ] Baby tortoise feeding on lettuce Tortoise feeding on a cactus Duméril, André Marie Constant and Bibron, Gab riel. 1834. Erpétologie Générale ou Histoire Naturelle Complète des Reptiles. Tome Premier. Paris: Roret, 439 pp.

This is typically an indication that environmental conditions may be dirty and possibly too damp, facilitating a build-up in bacterial numbers. It can be a problem in red-footed tortoises for example. The Alipore Zoo in India was the home to Adwaita, which zoo officials claimed was the oldest living animal until its death on March 23, 2006. Adwaita (also spelled Addwaita) was an Aldabra giant tortoise brought to India by Lord Wellesley, who handed it over to the Alipur Zoological Gardens in 1875 when the zoo was set up. West Bengal officials said records showed Adwaita was at least 150 years old, but other evidence pointed to 250. Adwaita was said to be the pet of Robert Clive. [16]Buoyancy Control: Certain species possess hollowed-out bones within their limbs that aid in buoyancy control while swimming. Unlike other turtles, tortoises can't swim, but they can hold their breaths for a very long time - about 30 minutes! Turtles can hold theirs much longer, but considering a human can't do it for more than a couple of minutes, that's very impressive! 10. They Can Travel Up To Four Miles A Day The skeletal elements of the plastron are also largely in pairs. Anteriorly there are two epiplastra, with the hyoplastra behind them. These enclose the singular entoplastron. These make up the front half of the plastron and the hyoplastron contains the anterior bridge strut. The posterior half is made up of two hypoplastra (containing the posterior bridge strut) and the rear is a pair of xiphiplastra. [3] [4] Particular care needs to be taken with female sulcatas, because of the relatively large clutches of eggs that they produce. As a consequence, any calcium deficiency is then more likely to become apparent.