| Panchelonioidea Temporal range: Early Cretaceous to Holocene | |
|---|---|
 | |
| Fossil of Toxochelys | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Testudines |
| Suborder: | Cryptodira |
| Clade: | Americhelydia |
| Clade: | Panchelonioidea Joyce et al., 2004 |
Panchelonioidea is a clade of marine turtles that includes the sea turtles and related taxa.
Evers et al. (2019): [1]
| Panchelonioidea |
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Turtles are reptiles of the order Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira and Cryptodira, which differ in the way the head retracts. There are 360 living and recently extinct species of turtles, including land-dwelling tortoises and freshwater terrapins. They are found on most continents, some islands and, in the case of sea turtles, much of the ocean. Like other amniotes they breathe air and do not lay eggs underwater, although many species live in or around water.
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 flatback, green, hawksbill, leatherback, loggerhead, Kemp's ridley, and olive ridley. Six of the seven sea turtle species, all but the flatback, are present in U.S. waters, and are listed as endangered and/or threatened under the Endangered Species Act. All but the flatback turtle are listed as threatened with extinction globally on the IUCN Red List of Threatened Species. The flatback turtle is found only in the waters of Australia, Papua New Guinea, and Indonesia.
The leatherback sea turtle, sometimes called the lute turtle, leathery turtle or simply the luth, is the largest of all living turtles and the heaviest non-crocodilian reptile, reaching lengths of up to 1.8 metres and weights of 500 kilograms (1,100 lb). It is the only living species in the genus Dermochelys and family Dermochelyidae. It can easily be differentiated from other modern sea turtles by its lack of a bony shell; instead, its carapace is covered by oily flesh and flexible, leather-like skin, for which it is named.
A flipper is a broad, flattened limb adapted for aquatic locomotion. It refers to the fully webbed, swimming appendages of aquatic vertebrates that are not fish.
Dermochelyidae is a family of turtles which has seven extinct genera and one extant genus, including the largest living sea turtles.
Trionychia is a superfamily of turtles which encompasses the species that are commonly referred to as softshelled turtles as well as some others. The group contains two families, Carettochelyidae, which has only one living species, the pig-nosed turtle native to New Guinea and Northern Australia, and Trionychidae, the softshelled turtles, containing numerous species native to Asia, North America and Africa. These families likely diverged during the late Jurassic. The oldest known stem-trionychian is Sinaspideretes from the Late Jurassic of China.
Allopleuron is a genus of extinct sea turtle, which measured 2-to-2.5-metre long in life. The type species is Allopleuron hofmanni. It is a basal member of the clade Pancheloniidae, closely related to Protosphargis. Similar to Protosphargis, it was characterized by shell reduction.
Paracryptodira is an extinct group of reptiles in the clade Testudinata, known from the Jurassic to Paleogene of North America and Europe. Initially treated as a suborder sister to Cryptodira, they were then thought to be a very primitive lineage inside the Cryptodira according to the most common use of the latter taxon. They are now often regarded as late-diverging stem-turtles, lying outside the clade formed by Cryptodira and Pleurodira. The paracryptodires are said to have phylogenic relationships, noted as primary subclades, within the Baenidae and Pleurosternidae. Within each subclade, lies many biodiverse turtles that are continuously being investigated and added to the fossil record. Paracryptodires are divided into three main groups, Compsemydidae, known from the Late Jurassic to Paleocene of North America and Europe, Pleurosternidae, known from the Late Jurassic to Early Cretaceous of North America and Europe, and Baenidae, known from the Early Cretaceous to Eocene of North America. The latter two groups are more closely related to each other than to Compsemys, forming the clade Baenoidea.
Sinaspideretes is an extinct genus of turtle from the Late Jurassic of China, probably from the Shaximiao Formation. It is considered the earliest and most basal representative of the Trionychia, and is possibly the oldest known member of Cryptodira. In 2013, it was proposed that this animal and the genus Yehguia are in fact one and the same.
Bouliachelys is an extinct genus of sea turtle from Cretaceous Australia. It was originally described as a member of Protostegidae. In 2013 study it was considered to be a member of Dermochelyoidae, although later studies consider it as a protostegid again.
The hawksbill sea turtle is a critically endangered sea turtle belonging to the family Cheloniidae. It is the only extant species in the genus Eretmochelys. The species has a global distribution that is largely limited to tropical and subtropical marine and estuary ecosystems.
Ocepechelon is an extinct genus of giant protostegid sea turtle known from Late Cretaceous phosphatic deposits of the Oulad Abdoun Basin, Khouribga Province of Morocco. It is known from the holotype OCP DEK/GE 516, a complete but isolated 70-cm-long skull, making it one of the largest marine turtles ever described. It was first named by Nathalie Bardet, Nour-Eddine Jalil, France de Lapparent de Broin, Damien Germain, Olivier Lambert and Mbarek Amaghzaz in 2013, and the type species is Ocepechelon bouyai. The feeding apparatus of Ocepechelon, a bony pipette-like snout, is unique among tetrapods and shares unique convergences with both syngnathid fishes and beaked whales.
Plesiochelys is a genus of late Jurassic European and Asian turtle. The type species is Plesiochelys etalloni.
Archelosauria is a clade grouping turtles and archosaurs and their fossil relatives, to the exclusion of lepidosaurs. The majority of phylogenetic analyses based on molecular data have supported a sister-group relationship between turtles and archosaurs. On the other hand, Archelosauria had not been historically supported by most morphological analyses, which have instead found turtles to either be descendants of parareptiles, early-diverging diapsids outside of Sauria, or close relatives of lepidosaurs within the clade Ankylopoda. Some recent morphological analyses have also found support for Archelosauria.
The Plesiochelyidae are an extinct family of turtles in the clade Thalassochelydia originally classified within the Cryptodira suborder, mostly belonging from the Jurassic period. An alternate study placed the clade Thalassochelydia in the Angolachelonia and outside the Testudines.
Rhinochelys is an extinct genus of sea turtles belonging to the family Protostegidae.
Leyvachelys is an extinct genus of turtles in the family Sandownidae from the Early Cretaceous of the present-day Altiplano Cundiboyacense, Eastern Ranges, Colombian Andes. The genus is known only from its type species, Leyvachelys cipadi, described in 2015 by Colombian paleontologist Edwin Cadena. Fossils of Leyvachelys have been found in the fossiliferous Paja Formation, close to Villa de Leyva, Boyacá, after which the genus is named. The holotype specimen is the oldest and most complete sandownid turtle found to date.
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.
Perichelydia is a clade within Pantestudines known from the Middle Jurassic to Holocene. Alongside crown group Testudines, it also contains Helochelydridae, which is known from the Cretaceous of Europe and North America, Sichuanchelyidae from the Middle Jurassic to Paleocene of Asia and Europe, Meiolaniformes, which is known from the Cretaceous to Holocene of South America, Australia and Oceania, and Spoochelys, known from the Mid-Cretaceous Griman Creek Formation of Australia. Kallokibotion from the Late Cretaceous of Europe is also considered part of this group. Several other groups, including the proposed clade Angolachelonia, Paracryptodira, Macrobaenidae, Sinemydidae and Xinjiangchelyidae, which are sometimes considered members of Cryptodira, have also been found outside crown Testudines in several analyses. These groups are usually considered to be closer to the crown group than the other members of Perichelydia.
Thalassochelydia is a clade of extinct marine turtles from the Late Jurassic and earliest Cretaceous of Europe and South America. The group is defined as including Eurysternum, Plesiochelys and Thalassemys to the exclusion of Pelomedusa, Testudo and Protostega. While a clade uniting the families Eurysternidae, Plesiochelyidae and Thalassemydidae had been supported by phylogenetic evidence, a name was not given for the clade until 2017, when Jérémy Anquetin and colleagues coined Thalassochelydia.
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