The reptiles are an ancient order which formed the ancestors of both birds and reptiles.  They are characterized by being the only entirely scaly air breathing vertebrates, being cold blooded and most species lay eggs.  Although in prehistory they were the dominant terrestrial group for millions of years, the modern class is represented by just four groups - crocodilia (containing crocodiles, alligators, caiman and gharial), sphenodontia (containing just the tuatara), testudines (containing turtles, tortoises and terrapins) and squamata (containing lizards, snakes and amphisbaenians). Squamata is by far the most diverse of these containing around 96% of the total of a bit over 10,000 species classically considered reptile.  Some modern taxonomists consider birds to be a fifth group within reptilia, but here they are not included and the species below are limited to the other groups.

Containing around 9,600 species split into three main categories - the four legged lizards which comprise 6000 species, the legless snakes representing 3,600 species and the remaining 160 represent the little known amphisbaenians or worm lizards.  This is both the most common and widespread family of reptiles - lizards and snakes are among the most northerly reptile families and present on almost every major body of land.

Probably the group of reptiles most familiar to the largest number of people, lizards are a typical reptiles found in most countries on earth to some degree, though variety is severely lower in cold and temperate climates than in the tropics.  The UK is on the lower end of the spectrum with only 3 native species.  Some species have evolved into having no legs, but are still lizards rather than snakes.

Asian Water Monitor (Varanus salvator)
Common House Gecko (Hemidactylus frenatus)
Common Gliding Lizard (Draco sumatranus)
Common Lizard (Zootoca vivpara)
Flat-tailed House Gecko (Hemidactylus platyurus)
Iberian Wall Lizard (Podarcis hispanica)
Italian Wall Lizard (Podarcis sicula)
Japanese Gecko (Gekko japonicus)
Moorish Gecko (Tarentola mauritanica)
Ocellated Lizard (Timon lepidus)
Sand Lizard (Lacerta agilis)
Slow Worm (Anguis fragilis)

Generally less common than lizards, snakes are famously legless animals which move through undulation of their bodies.  Snakes as a group contain a number of species dangerous to humans, either as poisonous species or constrictors, however, the species in Europe are probably the least dangerous of any continent with only a small number of fairly scarce poisonous species across the region.

European Adder (Vipera berus)
Grass Snake (Natrix natrix)
Western Whip Snake (Hierophis viridflavus)

Chenolians are a distinctive group characterised by a thick bony carapace that covers their torso both above and below.  Aquatic species are generally known at Turtles, terrestrial as tortoises and terrapins to certain smaller species that are generally found in smaller bodies of fresh water like ponds.  

Green Sea Turtle (Chelonia mydas)

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