Hello Chad,
I study the evolution of the group of skinks you are referring to (family Lygosomatinae). Originally, this somewhat cosmopolitan group of skinks was classified under the generic name "Mabuya" which was later subdivided with the name "Mabuya" retained for South and Central American species, "Trachylepis" assigned to species from Africa, Madagascar & the Middle East, "Eutropis" for Asian species, and "Chioninia" refers to a handful of former mabuyine skinks found on the Cape Verde Islands (see Bauer, 2003).
The Angolan blue tailed skink is a beautiful but secretive skink that lives in rock crevices in arid southern Angola. It has a flattened body and orange head with a pointed snout that fades into an electric blue body overlaid with black latticework (photo:
http://cdn.c.photoshelter.com/img-get/I0000YpClPevebHs/s/750/750/angolan-blue-tailed-skink.jpg). This animals closest relatives are other Trachylepis skinks from mainland Africa (>80 sp.).
The closest relatives to Trachylepis skinks is disputable at the moment. Molecular studies have suggested Mabuya and Chioninia, where as groups like Eutropis and Eumecia are possibly more distantly related, but still in the same subfamily.
Although skinks such as Trachylepis margaritifer, Trachylepis quinquetaeniata, Plestiodon and Eutropis quadricarinata are all within the same family (Scincidae) and share a similar "blue tail, orange head, black stripes" color pattern, it is not due to shared ancestry, and they are not closely related. Instead, something about this color pattern is ecologically advantageous (blue tails attract predators away from the important parts of the body like the head, or orange heads may lure prey closer to the mouth!). They have all independently evolved similar color pattern-strategies for survival across the globe. This "convergent evolution" is seen in many other reptiles, for example, the Eastern Hognose snake (Heterodon) found in the United States has an upturned snout and enlarged rostral scale for digging up eggs to eat and burrowing. The Madagascan hognose snake (Heteroliodon madagascariensis) has the exact same morphology for doing the same exact thing in Madagascar, but is in no way closely related to the Hognose snakes of the eastern US.
hope this helped!
