Toxicofera

Beaded Lizard ( Heloderma horridum )

The Toxicofera (Greek τοξίνη, toxins = " poison", Latin ferre = "to carry" ) are a taxon ( a systematic group ) of the Squamata ( Squamata ). It includes the snakes ( Serpentes ), the crawl -like ( Anguimorpha ) and the iguana -like ( Iguania ).

The relationship of these three externally diverse groups based on molecular studies and is supported by only a few morphological features. After based on molecular data pedigree the Squamata are the stealth -like and the iguana -like sister group, the unnamed, formed by two taxa clade is the sister group of snakes.

As toxic Squamata previously were only the poison snakes ( Elapidae ), vipers ( Viperidae ) and the illusion snakes, as well as belonging to the stealth -like beaded lizards ( Heloderma ). Therefore, an independent, at least twice origin of this feature was adopted in the Squamatenevolution. The Toxicofera concept assumes, however, was the ability to produce toxins developed only once in the course of phylogeny ( evolutionary history ). The common ancestor of all Toxicofera to have lived about 230 to 200 million years ago in the Upper Triassic.

Meanwhile, it has also in the upper and lower jaw of a iguana -like, the Eastern Bearded Dragon ( Pogona barbata ), poison -producing glandular tissue found. In addition, symptoms after the bite of the Komodo dragon, Buntwaran and banded Baumwaran ( belonging to the Stealth -like ) occur not only interpreted as the result of a bacterial infection, but as a result of an active Giftsekretion be. It has now been demonstrated venom glands in the lower jaws in a magnetic resonance imaging in the Komodo dragon with the help of 3D scans of a skull. Even with fossil -like crawl from the Upper Cretaceous, there is evidence for the presence of venom glands.

Today consists of about 4600 species of Schuppenkriechtierarten 7900, which is about 58 percent to the Toxicofera.

Cladogram of Toxicofera:

Snakes ( Serpentes )

Sneak behaved ( Anguimorpha )

Iguana -like ( Iguania )