| Helochelydra Temporal range: Early Cretaceous | |
|---|---|
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Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Pantestudines |
| Clade: | Testudinata |
| Family: | † Helochelydridae |
| Genus: | † Helochelydra Nopcsa, 1928 |
| Type species | |
| †Helochelydra nopcsai Lapparent de Broin and Murelaga, 1999 | |
Helochelydra is an extinct genus of extinct stem turtle known from the Early Cretaceous (Barremian) of the Isle of Wight, southern England. [1] [2] [3] [4]
Helochelydra is a member of the stem turtle family Helochelydridae, which is known from Late Jurassic to Late Cretaceous deposits in North America and Europe. Cladistic analysis recovers Helochelydridae outside the clade leading to crown turtles (Testudines). [5]
Helochelydra was named in 1928 by Franz Baron Nopcsa for a partial shell (NHMUK R171) from the Early Cretaceous Wessex Formation of the Isle of Wight that Lydekker (1889) had referred to Tretosternon punctatum, a turtle taxon from the Purbeck Group of Dorset, but no species name was provided. [6] [7] Lapparent de Broin and Murelaga (1999) recognized Helochelydra as closely related to the Late Cretaceous stem turtle Solemys , and erected the type species epithet nopcsai for NHMUK R171, even as they considered Tretosternon a possible synonym of Pleurosternon . [8] The turtles "Trionyx" bakewelli and "Platychelys" anglica were referred to Helochelydra by Milner (2004) based on morphological similarities with the shell of the type species, but were placed in Compsemyidae by Joyce et al. (2012). [5]
Echinodon is a genus of heterodontosaurid dinosaur that lived during the earliest Cretaceous of southern England and possibly western France in the Berriasian epoch. The first specimens were jaw bones named Echinodon becklesii by Sir Richard Owen in 1861, and since their original description only additional teeth have been discovered. The specific name honours collector Samuel Beckles who discovered the material of Echinodon and many other taxa from across England, while the genus name translates as "prickly tooth" in reference to the dental anatomy of the taxon.
Calamospondylus is a genus of theropod dinosaur. It lived during the Early Cretaceous and its fossils were found on the Isle of Wight in southern England. The type species is C. oweni.
Bothriospondylus is a dubious genus of neosauropod sauropod dinosaur. It lived during the Late Jurassic in England, and the type and only species is B. suffossus.
Calamosaurus was a genus of small theropod dinosaur from the Barremian-age Lower Cretaceous Wessex Formation of the Isle of Wight, England. It is based on two cervical vertebrae, collected by Reverend William Fox.
Nuthetes is the name given to a genus of theropod dinosaur, likely a dromaeosaurid, known only from fossil teeth and jaw fragments found in rocks of the middle Berriasian age in the Cherty Freshwater Member of the Lulworth Formation in England and also the Angeac-Charente bonebed in France. As a dromaeosaurid, Nuthetes would have been a small predator.
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.
Syllomus is an extinct genus of sea turtle from the Miocene-age deposits in the US Eastern Seaboard and Egypt.
The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vectis Formation and overlies the Durlston Formation. The dominant lithology of this unit is mudstone with some interbedded sandstones. It is part of the strata of the Wessex Basin, exposed in both the Isle of Purbeck and the Isle of Wight. While the Purbeck sections are largely barren of vertebrate remains, the Isle of Wight sections are well known for producing the richest and most diverse fauna in Early Cretaceous Europe.
Cyclanorbinae, also known commonly as the flapshell turtles, is a subfamily of softshell turtles in the family Trionychidae. The subfamily is native to Africa and Asia.
Pleurosternon is an extinct genus of freshwater pleurosternid turtle from the latest Jurassic to earliest Cretaceous of Europe. Its type species, P. bullockii was described by the paleontologist Richard Owen in 1853. Since then, and throughout the late 19th century, many fossil turtles were incorrectly assigned to this genus, though only two are currently considered valid.
Protoxinjiangchelys is an extinct genus of xinjiangchelyid turtle known from the Early to Late Jurassic of China. It is known from the single species P. salis, which was named and described in 2012. It contains only the holotype, ZDM 3009, which consists of a complete shell with an articulated carapace and a complete plastron and possibly another, older specimen.
Kallokibotion is an extinct genus of stem-turtle from the Upper Cretaceous, known from fossils found in Romania. One species is known, Kallokibotion bajazidi, which was named by Franz Nopcsa after his lover Bajazid Doda. It literally means 'beautiful box of Bajazid'; Nopcsa chose the name because, in the words of British palaeontologist Gareth Dyke, "the shape of the shell reminded him of Bajazid's arse". A second undescribed species is known from the Santonian of Hungary.
Pleurosternidae is an extinct family of freshwater turtles belonging to Paracryptodira. They are definitively known from the Late Jurassic to Early Cretaceous (Albian) of Western Europe and North America.
The Helochelydridae are an extinct family of stem-turtles known from fossils found in North America and Europe spanning the Early to Late Cretaceous.
Helochelys is an extinct genus of stem turtle known from the Late Cretaceous (Cenomanian) of southern Germany.
Naomichelys is an extinct genus of helochelydrid stem turtle known from the Cretaceous (Aptian-Campanian) of North America. It is the only member of the family known to be native to North America.
Solemys is an extinct genus of stem turtle known from the Late Cretaceous of southern France and eastern Spain.
Hylaeochelys is an extinct genus of plesiochelyid turtle that lived during the Late Jurassic-Early Cretaceous in Portugal, Spain, France, and southern England. The type species was originally named by Richard Owen as Pleurosternon latiscutatum in 1853, before being moved to the new genus Hylaeochelys by Richard Lydekker in 1889. Other species included in the genus are H. belli, H. kappa and H. lata, originally named under different genera by Gideon Mantell and Owen, respectively. All species are represented by carapaces, primarily from the Lulworth Formation of the Purbeck Limestone Group that was deposited during the Berriasian.
Dortokidae is an extinct family of freshwater pan-pleurodiran turtles, known from the Cretaceous and Paleocene of Europe. Only four species have been named, but indeterminate fossils show that they were abundant across western and eastern-central Europe during the Cretaceous. The family is only known from postcranial remains.
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