Reptiles, as most commonly defined, are the animals in the class Reptilia, a paraphyletic grouping comprising all amniotes except synapsids and Aves (birds). The class comprises turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. In the traditional Linnaean classification system, birds are considered a separate class to reptiles. However, crocodilians are more closely related to birds than they are to other living reptiles, and so modern cladistic classification systems include birds within Reptilia, redefining the term as a clade. Other cladistic definitions abandon the term reptile altogether in favor of the clade Sauropsida, which refers to all animals more closely related to modern reptiles than to mammals. The study of the traditional reptile orders, historically combined with that of modern amphibians, is called herpetology.
Turtles are an order of reptiles known as Testudines; characterized by a shell developed from their skeleton. Turtles were historically considered part of a group of reptiles known as Anapsida but more recent studies place them with other modern reptiles and birds in Diapsida, usually closer to Archosauria than Lepidosauria. Modern turtles are divided into two major groups, the Pleurodira and Cryptodira which differ in the way the head is retracted. There are 360 recent species of turtles and include tortoises and terrapins; which are widely distributed across the world's continents and oceans..
Sea turtles, sometimes called marine turtles, are reptiles of the order Testudines and of the suborder Cryptodira. The seven existing species of sea turtles are the green sea turtle, loggerhead sea turtle, Kemp's ridley sea turtle, olive ridley sea turtle, hawksbill sea turtle, flatback sea turtle, and leatherback sea turtle. All six of the sea turtle species present in US waters are listed as endangered and/or threatened under the Endangered Species Act. The seventh sea turtle species is the Flatback, which exists in the waters of Australia, Papua New Guinea and Indonesia. Sea turtles can be separated into the categories of hard-shelled (cheloniid) and leathery-shelled (dermochelyid). There is only one dermochelyid species which is the leatherback sea turtle.
Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families, all in the order Alismatales. Seagrasses evolved from terrestrial plants which recolonised the ocean 70 to 100 million years ago.
Diapsids are a group of amniote tetrapods that developed two holes in each side of their skulls about 300 million years ago during the late Carboniferous period. The diapsids are extremely diverse, and include all crocodilians, lizards, snakes, tuatara, turtles, and birds. Although some diapsids have lost either one hole (lizards), or both holes, or have a heavily restructured skull, they are still classified as diapsids based on their ancestry. At least 17,084 species of diapsid animals are extant: 9,159 birds, and 7,925 snakes, lizards, tautara, turtles, and crocodiles.
A cold seep is an area of the ocean floor where hydrogen sulfide, methane and other hydrocarbon-rich fluid seepage occurs, often in the form of a brine pool. Cold does not mean that the temperature of the seepage is lower than that of the surrounding sea water. On the contrary, its temperature is often slightly higher. The "cold" is relative to the very warm conditions of a hydrothermal vent. Cold seeps constitute a biome supporting several endemic species.
Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semiaquatic life in a marine environment.
Mosasaurs comprise a group of extinct, large marine reptiles from the Late Cretaceous.Their first fossil remains were discovered in a limestone quarry at Maastricht on the Meuse in 1764. They belong to the order Squamata, which includes lizards and snakes.
The South Polar region of the Cretaceous comprised the continent of East Gondwana–modern day Australia and Antarctica–a product of the break-up of Gondwana. The southern region, during this time, was much warmer than it is today, ranging from perhaps 4–8 °C (39–46 °F) in the latest Cretaceous Maastrichtian in what is now southeastern Australia. This prevented permanent ice sheets from developing and fostered polar forests, which were largely dominated by conifers, cycads, and ferns, and relied on a temperate climate and heavy rainfall. Major fossil-bearing geological formations that record this area are: the Santa Marta and Sobral Formations of Seymour Island off the Antarctic Peninsula; the Snow Hill Island, Lopez de Bertodano, and the Hidden Lake Formations on James Ross Island also off the Antarctic Peninsula; and the Eumeralla and Wonthaggi Formations in Australia.
The loggerhead sea turtle, is a species of oceanic turtle distributed throughout the world. It is a marine reptile, belonging to the family Cheloniidae. The average loggerhead measures around 90 cm (35 in) in carapace length when fully grown. The adult loggerhead sea turtle weighs approximately 135 kg (298 lb), with the largest specimens weighing in at more than 450 kg (1,000 lb). The skin ranges from yellow to brown in color, and the shell is typically reddish brown. No external differences in sex are seen until the turtle becomes an adult, the most obvious difference being the adult males have thicker tails and shorter plastrons than the females.
Gigantothermy is a phenomenon with significance in biology and paleontology, whereby large, bulky ectothermic animals are more easily able to maintain a constant, relatively high body temperature than smaller animals by virtue of their smaller surface-area-to-volume ratio. A bigger animal has proportionately less of its body close to the outside environment than a smaller animal of otherwise similar shape, and so it gains heat from, or loses heat to, the environment much more slowly.
Kemp's ridley sea turtle, also called the Atlantic ridley sea turtle, is the rarest species of sea turtle and is the world's most endangered species of sea turtle. It is one of two living species in the genus Lepidochelys.
The narrow-bridged musk turtle is a species of turtle in the family Kinosternidae. The species is endemic to Central America and Mexico.
Temperature-dependent sex determination (TSD) is a type of environmental sex determination in which the temperatures experienced during embryonic/larval development determine the sex of the offspring. It is only observed in reptiles and teleost fish. TSD differs from the chromosomal sex-determination systems common among vertebrates. It is the most studied type of environmental sex determination (ESD). Some other conditions, e.g. density, pH, and environmental background color, are also observed to alter sex ratio, which could be classified either as temperature-dependent sex determination or temperature-dependent sex differentiation, depending on the involved mechanisms. As sex-determining mechanisms, TSD and genetic sex determination (GSD) should be considered in an equivalent manner, which can lead to reconsidering the status of fish species that are claimed to have TSD when submitted to extreme temperatures instead of the temperature experienced during development in the wild, since changes in sex ratio with temperature variation are ecologically and evolutionally relevant.
Marine vertebrates are vertebrates that live in marine environments. These are the marine fish and the marine tetrapods. Vertebrates are a subphylum of chordates that have a vertebral column (backbone). The vertebral column provides the central support structure for an internal skeleton. The internal skeleton gives shape, support, and protection to the body and can provide a means of anchoring fins or limbs to the body. The vertebral column also serves to house and protect the spinal cord that lies within the column.
Bouliachelys is an extinct genus of sea turtle from Cretaceous Australia. Its parent taxon is the clade Dermochelyoidae.
Angolasaurus is an extinct genus of mosasaur. Definite remains from this genus have been recovered from the Turonian of Angola, and possibly the Turonian of the United States and Brazil, and the Maastrichtian of Niger. While at one point considered a species of Platecarpus, recent phylogenetic analyses have placed it between the (then) plioplatecarpines Ectenosaurus and Selmasaurus, maintaining a basal position within the plioplatecarpinae.
The West African mud turtle, also known as the West African side-necked turtle or swamp terrapin, is a species of turtle in the family Pelomedusidae. Pelusios castaneus is a freshwater species and is endemic to West and Central Africa.
Eohupehsuchus is a genus of extinct aquatic diapsid from the Upper Spathian of Hubei Province, located in Central China. The genus is monotypic and belongs to the order Hupehsuchia, whose members are characterized by toothless beak-like snouts, a row of dermal plates along their backs, and aquatic adaptations including paddle-shaped limbs and fusiform bodies with pachyostotic ribs.
David Gruber is an American marine biologist, a Presidential Professor of Biology and Environmental Sciences at Baruch College, City University of New York, and a National Geographic Explorer.
