| Henodontidae Temporal range: Late Triassic, | |
|---|---|
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| Henodus fossil at University of Tübingen | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | † Sauropterygia |
| Order: | † Placodontia |
| Superfamily: | † Cyamodontoidea |
| Family: | † Henodontidae von Huene, 1936 |
| Genera | |
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Henodontidae is an extinct family of superficially turtle-like placodonts belonging to the superfamily Cyamodontoidea. Fossils have been found in Germany and Spain. [1] [2]
Placodonts are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were generally between 1 and 2 m in length, with some of the largest measuring 3 m (9.8 ft) long.
Honghesaurus is an extinct genus of pachypleurosaur from the Anisian-age Guanling Formation of China. The type specimen measures about 47.1 cm (18.5 in) in total body length.
Placochelys is an extinct genus of placodont reptiles erected by Otto Jaekel in 1902.
Cyamodus is a genus of placodonts known from several species described from Middle-Late Triassic of Europe and China. The genus was described by Christian Erich Hermann von Meyer in 1863, based on specimens found in Germany. Like some other placodonts, Cyamodus has an armoured carapace composed of irregular hexagonal plates, with the mouth containing a small number of large, rounded teeth that were likely involved in crushing hard shelled organisms (durophagy).
Paraplacodus broilli is an extinct placodont sauropterygian from the middle Triassic period, from the Anisian until Ladinian stages. The fossils were uncovered in Northern Italy and the species was named in 1931 by Bernhard Peyer. Paraplacodus means "Almost Placodus", in reference to its similarity to Placodus.
Omphalosaurus is an extinct genus of marine reptile from the Early Triassic to Middle Triassic, thought to be in the order of Ichthyosauria. Most of what is known about Omphalosaurus is based on multiple jaw fragments, ribs, and vertebrae. Specimens of Omphalosaurus have been described from the western United States, Poland, Austria and the island of Spitsbergen off the northern coast of Norway.
Helveticosaurus is an extinct genus of diapsid marine reptile known from the Middle Triassic of southern Switzerland. It contains a single species, Helveticosaurus zollingeri, known from the nearly complete holotype T 4352 collected at Cava Tre Fontane of Monte San Giorgio, an area well known for its rich record of marine life during the Middle Triassic.
Henodus is an extinct placodont of the Late Triassic period during the early Carnian age. Fossils of Henodus chelyops were found in the Estherienschichten Member of the Grabfeld Formation, near Tübingen, Germany. It was around 1 metre (3.3 ft) in length. The single species within the genus is H. chelyops.
Sinocyamodus is an extinct genus of placodont reptile from the Late Triassic (Tuvalian) Xiaowa Formation of China. Only one species, Sinocyamodus xinpuensis, is currently assigned to this genus. This genus was the first placodont to be discovered in the eastern Tethys, overthrowing traditional views that the group was restricted to the western Tethys.
Psephochelys is an extinct genus of placodont reptile from the Late Triassic of China. It is represented by a single species, Psephochelys polyosteoderma, named in 2002 on the basis of a single partial skeleton found in an outcrop of the Carnian-age Falong Formation in Guizhou Province. Psephochelys is classified as a member of the family Placochelyidae, which is within the larger placodont superfamily Cyamodontoidea. Like other cyamodontoids, Psephochelys has a wide shell covering its body, similar to that of a turtle. However, unlike those of other cyamodontoids, the shell of Psephochelys only covers its back. The plastron, which covers the underside of other cyamodontoids, is absent, and in its place are rib-like gastralia surrounded by loosely connecting osteoderms or bony plates.
Cyamodontoidea is an extinct superfamily of placodont marine reptiles from the Triassic period. It is one of the two main groups of placodonts, the other being Placodontoidea. Cyamodontoids are distinguished from placodontoids by their large shells, formed from fused bony plates called osteoderms and superficially resembling the shells of turtles. Cyamodontoids also have distinctive skulls with narrow, often toothless jaws and wide, flaring temporal regions behind the eyes. Two large temporal openings are positioned at the top of the back of the skull, an arrangement that is known as the euryapsid condition and seen throughout Sauropterygia, the marine reptile group to which placodonts belong. Cyamodontoids are also distinguished by their large crushing teeth, which grow from the palatine bones on the roof of the mouth.
Psephosauriscus is an extinct genus of placodont reptile from the Middle Triassic of Israel and Egypt. It is known from bony armor plates that have been found from Makhtesh Ramon in Israel's Negev desert and Araif en Naqua on Egypt's Sinai Peninsula. The genus was erected in 2002 as a replacement name for several species of the genus Psephosaurus, which was named in 1957. It includes the species P. mosis, P. ramonensis, P. sinaiticus, and a possible fourth species, P. rhombifer. All species, with the exception of P. ramonensis, were once assigned to the genus Psephosaurus. Remains of P. mosis and P. ramonensis were found in Makhtesh Ramon, while P. sinaiticus and P. rhombifer were found in Araif en Naqua.
Macroplacus is an extinct genus of placodont reptiles. The type species is M. raeticus and the fossil record of this species dates back to the upper Triassic, Rhaetian age. These fossils have been found in Germany, at Hinterstein near Hindelang im Allgäu.
Palatodonta is an extinct genus of basal placodontiform marine reptile known from the early Middle Triassic of the Netherlands. It is closely related to a group of marine reptiles called placodonts, characterized by their crushing teeth and shell-like body armor. Palatodonta is transitional between placodonts and earlier reptiles; like placodonts, it has teeth on its palate, but while these teeth are thick and blunt in placodonts, Palatodonta has palatal teeth that are thin and pointed.
Placodontiformes is an extinct clade of sauropterygian marine reptiles that includes placodonts and the non-placodont Palatodonta. It was erected in 2013 with the description of Palatodonta. Placodontiformes is the most basal clade of Sauropterygia and the sister group of Eosauropterygia, which includes all other sauropterygians.
Pararcus is an extinct genus of placodont marine reptile from the Middle Triassic of the Netherlands. The genus is monotypic and the type species is Pararcus diepenbroeki. Pararcus is known from a holotype skeleton about 1.35 metres (4.4 ft) long from the Lower Muschelkalk of Winterswijk.
Placochelyidae is an extinct family of placodonts belonging to the superfamily Cyamodontoidea.
Saurosphargidae is an extinct family of marine reptiles known from the Early Triassic and early Middle Triassic of Europe and China.
Parahenodus is an extinct genus of henodontid placodont only known from a skull, discovered between 2008 and 2015 and described in 2018. It lived during the Late Triassic (Carnian–Norian). The skull, named and described as Parahenodus atancensis, was discovered in Keuper Facies of the Castilian Branche of the Iberian Range in the reservoir of El Atance. It was the sister taxon to Henodus.
Protenodontosaurus is an extinct genus of placodont from Italy.
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