Kinds of lizards
(cold-blooded) vertebrates that breathe air. Most reptiles are oviparous (egg-laying) animals with the exception of some ovoviviparous (live-bearing) constrictor snakes and vipers, as well as a few lizard species. They are also tetropods, vertebrate animals that have four limbs or are descended from animals with four limbs.
Deciphering the lizard classification system can at first seem like a daunting task. To the non-scientific mind lizard taxonomy is like a maze constructed of a bunch of unfamiliar, latin based terms that lead this way and that. But its the lizard itself, whose physical, anatomical features solve the mystery of the maze. Answering a simple question about the lizard at each juncture, from the kingdom down, leads through all the twists and turns to the lizard's family. And finally within the lizard families, you can find the individual species, which is your lizard.
To follow the lizard classification hierarchy, the predominant taxonomic ranks are highlighted. It starts with the largest number of animals in the top rank, the kingdom, and then moves sequentially down to smaller and smaller subsets. These include the subkingdom, phylum, superclass, class, subclass, order, suborder, and family. Notes are included about new classification expansions and inclusions of additional ranks where appropriate. The additional ranks are inset.
Kingdom: Animalia or Metazoa
The kingdom contains two subkingdoms (the other being Subkingdom Parazoa Porifera). The kingdom is then divided into Superphylums, the Superphylum containing the lizards is:
The phylum Chordata contains three subphyla, with Subphylum Vertebrata containing the lizards and the other two being;: Subphylum Tunicata (Urochordata) and Subphylum Cephalochordata (Acraniata) .
Subphylum: Vertebrata (Craniata)
These are vertebrates, animals with backbones, with approximately 58, 000 species.
Note: In traditional classification, the path would then move directly from here to the Class Reptilia (reptiles). But as the study of animals has evolved, there are additional developments in refining classifications at this point, particularly for reptiles and amphibians. Under the Subphylum Vertebrata, reptiles can then be placed in the following Infraphylum:
This infraphylum is defined as vertebrates with jaws.
Tetrapoda means four-limbed vertebrates, this rank currently contains about 28, 000+ species.
Class: Reptilia (reptiles)
Class Reptilia contains over 8, 225 species.
Note: As tetrapods, in newer classifications, they are associated with the clade Amniota. These are animals that have a terrestrially adapted egg and includes mammals, reptiles, and birds. Birds and mammals are distinguished with the subclades, Mammalia and Aves respectively, but reptiles are not so distinguished. Reptiles are sort of just out there. Lacking feathers and fur, it could just be said they are 'non-avian, non-mammalian amniotes'.
Note: As reptilia, in newer classifications they are associated with the clade Eureptilia ("true reptiles"). This is one of the two major clades of the Sauropsida ("lizard faces"), with the other being Theropsida ("beast faces"), This is a group of amniotes that includes all existing reptiles and birds and their fossil ancestors, including the dinosaurs.
These are reptiles that have developed two holes (temporal fenestra) in each side of their skull. This group contains most of the reptiles, including lizards, snakes, crocodilians, dinosaurs and pterosaurs
The Squamata order contains the scaled reptiles, animals distinguished by their skin being covered with horny scales or shields. There are currently about 7, 900 species. Here we are using the current ITIS taxonomical hierarchy where the Squamata order has five suborders. It is structured with four suborders that contain lizards, and a fifth that contains snakes (Suborder Serpentes) so won't be covered here. We also expanded this to include the Suborder Sauria containing the unique Burrowing Lizards and Burrowing Slow Worms.
Note: In traditional classification, the Squamata order had three suborders: Lacertilia containing the lizards, Serpentes containing the snakes, and Amphisbaenia containing the worm lizards. Then later the Lacertilia suborder itself contained the four generally recognized suborders; Iguania, Gekkota, Amphisbaenia, and Autarchoglossa. Note: In newer classifications the name Sauria is a clade that is used for reptiles and birds in general, and the Squamata are divided differently. But more recently it has been discovered that a couple other groups are now known to have venomous lizards. Note: Part of this re-classification is due to the discovery that more lizards are venomous than were previously thought. It had long been thought that only the Gila Monsters and the Beaded lizards, in the Family Helodermatidae, were venomous lizards. One group contains the monitor lizards of the Family Varanidae, like the Komodo dragon Varanus komodoensis. The other contains lizards in the Suborder Iguania from the Family Agamidae, like the Bearded Dragon, and from the Family Iguanidae, like the Green Iguana.