Varanoidea

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Varans VARANUS exanthematicus

Order: Reorder
Duration: 1:11
Published: 22 Feb 2009
Uploaded: 16 May 2011
Author: Neovejita

VARANUS exanthematicus Classe: Reptilia - Reptiles. Sous-classe: Lepidosauromorpha - Lepidosauriens. Ordre: Squamata - Squamates (Sauro-ophidiens). Sous-ordre: Sauria - Lézards (lacertilia). Ordre intermédiaire: Anguinomorpha - Anguinomorphes. Super famille: Varanoidea - Varanoidés. Famille: Varanidae - Varanidés. Genre: Varanus. Espèce: exanthematicus. Nom vernaculaire: Varan des savanes. Nom scientifique: Varanus exanthematicus.

Gila Monster (Heloderma Suspectum)

Order: Reorder
Duration: 0:31
Published: 29 Apr 2010
Uploaded: 24 Mar 2011
Author: khaledazamnoor

Gila Monster (Heloderma Suspectum) * Family: Helodermatidae, * Superfamily: Varanoidea, * Genus: Heloderma, * Species: H. suspectum, *Phylum: Chordata, * Class: Reptilia, * Order: Squamata, * Type: Reptile, * Diet: Carnivore, * Average life span in the wild: 20 to 30 years, * Size: 20 in (50 cm), * Weight: 4 lbs (1.8 kg), * Group name: Lounge, * Protection status: Threatened. ** Did you know? A synthetic version of a protein found in Gila saliva is used as a treatment for diabetes in humans. More info: animals.nationalgeographic.com or en.wikipedia.org

Beaded lizard (Heloderma horridum)

Order: Reorder
Duration: 0:24
Published: 09 Feb 2011
Uploaded: 16 Feb 2011
Author: khaledazamnoor

Beaded lizard (Heloderma horridum) * Family: Helodermatidae, * Genus: Heloderma, * Species: H. horridum, * Phylum: Chordata, * Class: Reptilia, * Order: Squamata, * Superfamily: Varanoidea, * Type: Reptile, * Diet: Carnivore, * Average life span in the wild: no data, * Size: 24 inches (61 cm) to 36 inches (91 cm) in length, * Weight: 2.3-2.7 kg (5-6 lb.) ** The Beaded lizard (Heloderma horridum) is a species of venomous lizard found principally in Mexico and southern Guatemala. Along with its congener, the Gila monster (Heloderma suspectum), it is the only lizard to have evolved an overt venom delivery system, and has long been considered the only venomous lizard. The beaded lizard is larger than the Gila monster but has duller coloration, black with yellowish bands of differing width depending on the subspecies. A specialized predator that feeds primarily upon eggs, the primary use of its venom is still a source of debate among scientists. However, this venom has been found to contain several enzymes useful for manufacturing drugs in the treatment of diabetes, and research on the pharmacological use of its venom is ongoing. More info: en.wikipedia.org

Varanoidea

Varanoidea is a superfamily of lizards, including the well-known family Varanidae (the monitors or goanna). Also included in the Varanoidea are such extinct marine and semi-aquatic forms as mosasaurs and dolichosaurs, the venomous helodermatids (Gila monsters and beaded lizards), the Lanthanotidae (earless monitor lizards), and the extinct Necrosauridae.

Throughout their long evolutionary history, varanoids have exhibited great diversity both in habitat and form. This superfamily includes both the largest aquatic lizards known, the mosasaurs Tylosaurus and Mosasaurus (15+ meters in length), but also the largest-known terrestrial lizard, Megalania (5-6 meters), and the largest extant lizard, the Komodo dragon (Varanus komodoensis, 3+ meters).

Evolution

Also known by the more archaic term "platynotans," the varanoids first appear in the fossil record in the latter part of Early Cretaceous, but possible varanoid ancestors have been traced back as far as Early Jurassic times. Among the earliest known varanoids are the monitor-like necrosaurids Palaeosaniwa canadensis from the Campanian (roughly 71-82 mya) of North America and Estesia mongoliensis and Telmasaurus grangeri, both from the Campanian of Mongolia. Varanoids survived the Cretaceous–Tertiary extinction event and flourished worldwide during the Cenozoic Era. Current evidence strongly suggests that snakes evolved from an aquatic or burrowing varanoid ancestor, though much debate continues over precisely which lineage of varanoids.

Carroll characterizes the varanoids as "the most advanced of all lizards in achieving large size and an active, predaceous way of life." Some taxa, such as the Gila monster (Heloderma) and the extinct necrosaurs are armoured with osteoderms (bony deposits on the skin), and many forms have hinged jaws, allowing them to dislocate and distended their jaws during feeding.

References

Category:lizards

This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.