The group Lepidosauria is located within Eureptilia and is sister to the Archosauromorphs. The Lepidosaurs are represented by members of Sphenodontida (extant Tuataras), Sauria (lizards), and Serpentes (snakes). Some synapomorphies that tie these groups together include :
· A transverse cloacal opening
· A notched tongue
· Full-body ecdysis
· Imperperforate columella
· Teeth attached to jaws
· The pelvic bones in adults are fused
· Fracture planes (septa) in caudal vertebrae
The division of Lepidosauria containing both Serpentes (snakes) and Sauria (lizards) is called Squamata. Squamates can thrive in a wide variety of climates, elevations, environments, and habitats and are found on every continent except Antarctica. The members of Squamata are linked by over 50 synapomorphies, however, some of the most outstanding and most easily recognizable include a fused premaxillae, fused parietals, reduced nasals, and well developed hemipenes. They also have the presence of a Jacobson’s organ which is separated from the nasal capsule, they possess femoral and pre-anal glands and exhibit and egg tooth at hatching.
In order to better understand the synapomorphies of Squamata, a Varanus skull was examined. By doing this the examples of a fused premaxilla and parietals could be easily distinguished. As well as the lack of vomerine teeth, which is another synapomorphy that links the Squamates.
The following are examples of some of the families present in Sauria, this is by no means an exhaustive list and there is an ongoing debate to the exact number of families present in Sauria. This is due solely to the debate over some subfamilies being promoted to families. We were given examples of the following in lab:
Distribution: Africa, Asia, Australia
1. Polychrotinae: This subfamily contains 8 genera. In this subfamily the males are typically larger and possess a gular flap but no femoral pores.
2. Phrynosomatinae: This subfamily contains 10 genera including an Ohio species (Sceloporus undulates-Northern Fence Lizard). This subfamily is sexually dimorphic with the males showing femoral pores.
3. Corytophaninae: This subfamily contains 3 genera and extend from Southern Mexico to northern South America.
4. Iguaninae: This subfamily contains 8 genera and have a huge distribution. In this family the adults are mainly herbivorous and the juveniles are very opportunistic feeders. They have large keeled scales, have pleurodont
Distribution: Huge distribution (Nearly worldwide)
Characteristics: They exhibit smooth cycloid overlapping scales, and typically possess osteoderms. Show long to moderately long tails and some may exhibit reduced limbs. This family is highly speciated and there are both oviparous and viviparous examples in this family. This family is where many Ohio apecies are classified. These include:
· Scincella lateralis (Ground Skink)
· Eumeces fasciatus (Five-lined Skink)
· Eumeces anthracinus (Northern Coal Skink)
Distribution: Northern United States to Argentina and Chile
Characteristics: Possess small granular scales on the dorsal surface, but large rectangular scales ventrally. They have typically long tails and show caudal autonomy. The example seen in lab was from the subfamily Teiinae. The dentition of members of this family is also pleurodont.
Distribution: Africa (warm temperate and tropical), Asia, and Australia
Characteristics: They are venomous lizards and lack caudal autonomy. Typically large with highly defined limbs. The ventral scales are generally visibly larger than those located on the dorsal surface. This is the family that the largest living lizard, the Komodo Dragon, belongs.