Paramacellodidae

Paramacellodidae is an extinct family of scincomorph lizards that first appeared in the Middle Jurassic around 170 million years ago (Ma) and became extinct in the Early Cretaceous about 100 Ma.[1] It was one of the earliest groups of lizards to have undergone an evolutionary radiation, with members found across the supercontinent Laurasia. The phylogenetic relationships and constituent species of Paramacellodidae are uncertain.[2][3] Many studies regard it to be closely related to Scincoidea, a large group that includes skinks and their closest extinct relatives, and possibly also to Cordyoidea, a group that includes spinytail lizards and relatives. Like modern skinks, paramacelloidids had rectangular bony plates called osteoderms covering most of their bodies, including their backs, undersides, and tails. They also had short and robust limbs.[1]

The family was named in 1983 to include two well-known genera, Paramacellodus and Becklesius, from the Late Jurassic and Early Cretaceous of Europe. A third genus, Sharovisaurus, was named in 1984 from the Late Jurassic of Kazakhstan, and a fourth, Mimobecklesisaurus, in 1985 from the Late Jurassic of China. Remains of Paramacellodus were later described from the Morrison Formation in Utah. Possible paramacellodid remains have also been found in Late Cretaceous deposits in Mongolia, as well as the Late Jurassic Tendaguru Formation in Tanzania, which would indicate that the family was also present in Gondwana. Three other early scincomorphs—Pseudosaurillus, Saurillodon, and Saurillus—have also commonly been referred to Paramacellodidae, although some recent phylogenetic studies find them to be non-paramacellodid scincomorphs. Collectively, paramacellodids and taxa formerly referred to Paramacellodidae may represent a paraphyletic grade of basal scincomorphs closely related to Scincoidea. In 2002, the newly named genus Atokasaurus from the Early Cretaceous Antlers Formation in Oklahoma was described as a "paramacellodid-grade" scincomorph to reflect this phylogenetic ambiguity.[2]

Paramacellodidae
Temporal range: Middle JurassicEarly Cretaceous, 170–100 Ma
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Infraorder: Scincomorpha
Family: Paramacellodidae
Estes, 1983
Genera

?Atokasaurus
Becklesius
Mimobecklesisaurus
Naimanosaurus
Paramacellodus
?Parasaurillus
?Pseudosaurillus
Sharovisaurus

References

  1. ^ a b Evans, S.E.; Chure, D.J. (1998). "Paramacellodid lizard skulls from the Jurassic Morrison Formation at Dinosaur National Monument, Utah" (PDF). Journal of Vertebrate Paleontology. 18 (1): 99–114. doi:10.1080/02724634.1998.10011037.
  2. ^ a b Nydam, R.; Cifelli, R. (2002). "Lizards from the Lower Cretaceous (Aptian-Albian) Antlers and Cloverly Formations" (PDF). Journal of Vertebrate Paleontology. 22 (2): 286–298. doi:10.1671/0272-4634(2002)022[0286:lftlca]2.0.co;2.
  3. ^ Nydam, R. (2002). "Lizards of the Mussentuchit Local Fauna (Albian–Cenomanian boundary) and comments on the evolution of the Cretaceous lizard fauna of North America" (PDF). Journal of Vertebrate Paleontology. 22 (3): 645–660. doi:10.1671/0272-4634(2002)022[0645:lotmlf]2.0.co;2.
Armandisaurus

Armandisaurus explorator is an extinct species of iguanid that lived in what is now Santa Fe County, New Mexico, in the Early Middle Miocene period. The fossil specimen is a well-preserved cranium with mandibles and parts of seven cervical vertebrae collected by J. C. Blick in 1940. Fossil evidence suggests that A. explorator was a blunt, medium-sized iguana that grew to about 61 cm (24 in) including its tail.

Atokasaurus

Atokasaurus is an extinct genus of scincomorph lizard from the Early Cretaceous of Oklahoma. The type and only species is Atokasaurus metarsiodon, named in 2002 on the basis of a single isolated lower jaw bone found within the Antlers Formation in Atoka County. It is similar in appearance to extinct lizards in the family Paramacellodidae and may itself be a paramacellodid, although the phylogenetic relationships of the group are uncertain. Atokasaurus differs from other paramacellodids in having teeth in the lower jaw with enlarged bases and an S-shaped profile when viewed edge-on.

Calanguban

Calanguban is an extinct genus of scincomorph lizard from the Early Cretaceous of South America. The type species Calanguban alamoi was named in 2014 from the Crato Formation of Brazil and is the oldest known non-iguanian lizard from the continent. It likely had an arboreal lifestyle.

Desertiguana

Desertiguana is an extinct genus of lizard in the family Phrynosomatidae. It is a monotypic genus represented by the type species Desertiguana gobiensis from the Late Cretaceous of Mongolia. Desertiguana gobiensis is known from a single left lower jaw.

Distortodon

Distortodon is an extinct genus of Polyglyphanodontid lizard from the Late Cretaceous of Europe, containing the species D. rhomboideus found in the Csehbánya Formation from the Santonian of Hungary. It is distinguished from other Polyglyphanodontids by having a more distal lingual cusp, creating distinctive rhomboidal shape in occlusal view.

Gilmoreteius

Gilmoreteius is an extinct genus of lizard from the Late Cretaceous period in Mongolia.

Indiagama

Indiagama is an extinct genus of agamid lizard known from the type species Indiagama gujarata from the early Eocene of India. Indiagama was named in 2013 on the basis of a single lower jaw from the Cambay Formation in Gujarat. The rectangular shape of its teeth distinguish it from all other agamids, living and extinct.

Isodontosaurus

Isodontosaurus is an extinct genus of iguanian lizard from the Late Cretaceous of Mongolia. The type species is Isodontosaurus gracilis. Isodontosaurus is part of an extinct group of Late Cretaceous iguanians called Gobiguania, which is currently thought to be endemic to Mongolia.

Jucaraseps

Jucaraseps is an extinct genus of small squamate lizard known from the Early Cretaceous of Las Hoyas, Spain. It contains a single species, Jucaraseps grandipes. It belonged to the clade Scincogekkonomorpha (containing scleroglossan squamates and those taxa which were more closely related to them than to Iguania) and was related to the clade Scleroglossa as well to Jurassic and Cretaceous taxa Eichstaettisaurus, Ardeosaurus, Bavarisaurus, Parviraptor, Yabeinosaurus and Sakurasaurus

Kuwajimalla

Kuwajimalla kagaensis is an extinct species of plant-eating lizard from the Early Cretaceous Kuwajima Formation in Japan. K. kagaensis is the type species.

Palaeosaniwa

Palaeosaniwa canadensis is an extinct species of carnivorous lizard from the late Cretaceous of North America. The name, given by Charles Whitney Gilmore in 1928, means "ancient Saniwa from Canada".

Paramacellodus

Paramacellodus is an extinct genus of scincomorph lizards from the Early Cretaceous of England the Late Jurassic of Portugal and the western United States. The type species, Paramacellodus oweni, was named in 1967 from the Purbeck Formation in Dorset, England. Additional material referable to a species of Paramacellodus, possibly P. oweni, has been described from the Morrison Formation, specifically in Como Bluff, Wyoming, and Dinosaur National Monument, Utah. Paramacellodus belongs to an extinct family of scincomorphs called Paramacellodidae, which spanned most of Laurasia during the Late Jurassic and Early Cretaceous and represented one of the earliest evolutionary radiations of lizards.

Paraplacosauriops

Paraplacosauriops (near Placosauriops) is an extinct genus of anguid lizards from the middle Eocene of France.

Polychrotidae

The Polychrotidae family (sometimes classified as the Polychrotinae subfamily instead) of iguanian lizards contains the living genus Polychrus (commonly called bush anoles) and the extinct genus Afairiguana. The family Polychrotidae was once thought to encompass all anoles, including those in the genus Anolis (which are now included in the family Dactyloidae). Studies of the evolutionary relationships of anoles based on molecular information has shown that Polychrus is not closely related to Anolis, but instead closer to Hoplocercidae. It is therefore not part of Dactyloidae and instead is treated as the family, Polychrotidae.

Polyglyphanodon

Polyglyphanodon is an extinct genus of Polyglyphanodontid lizard containing the species P. sternbergi from the Maastrichtian aged North Horn Formation of Utah. The species is known from several mostly complete and partial skeletons. It is distinguished by its transversely orientated interlocking teeth, which suggest a herbivorous diet

Ptilotodon

Ptilotodon is an extinct genus of teiid lizard from the Early Cretaceous of Oklahoma. The type and only known species is Ptilotodon wilsoni, named in 2002 on the basis of a single lower jaw with four teeth found in the Antlers Formation. The small size of the specimen may be an indication that it belonged to a juvenile.

Scincomorpha

Scincomorpha is an infraorder of lizards. They first appear in the fossil record about 170 million years ago, during the Jurassic period.

Sharovisaurus

Sharovisaurus is an extinct genus of scincomorph lizard from the Late Jurassic of Kazakhstan. It belongs to an extinct family of Mesozoic lizards called Paramacellodidae, which existed across most of Laurasia during the Late Jurassic and Early Cretaceous. The type and only species is Sharovisaurus karatauensis, named in 1984 on the basis of a nearly complete articulated skeleton from the Kimmeridgian-age Karatau Formation. The back and tail of the skeleton are covered in rectangular-shaped bony plates called osteoderms, which have a similar arrangement to those of modern skinks. At 138 millimetres (5.4 in) in length from the tip of its snout to the base of its tail, Sharovisaurus was one of the largest paramacellodids. Like other paramacellodids it had relatively short and robust limbs in comparison to the rest of its body.

Suratagama

Suratagama is an extinct genus of agamid lizard known from the type species Suratagama neeraae from the early Eocene of India. It was named in 2013 on the basis of three isolated jaw bones from the Cambay Formation in Gujarat.

Extinct squamate genera

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