Meeting Abstract
The order Squamata contains over 10,000 species, many of which are small-bodied and occupy a low trophic position. As a result, the group displays a bewildering diversity of anti-predation defenses, which include camouflage, audible, visual and chemical warning displays, a broad range of fight/flight behaviors and, universally, armor. All squamates are protected by toughened, keratinized scales but in some lineages these scales are buttressed by osteoderms: bony subdermal plates which strengthen the integument, provide additional ornamentation in the form of spines or keels, and may play a role in calcium sequestration and thermoregulation. Osteoderms are found in several orders of fish, mammals, amphibians, archosaurs, turtles and in 13 extant families of squamates. This study employs comparative phylogenetic analyses of microcomputed Tomography (µCT) data to quantify and investigate the diversity of dermal armor across Squamata, with deep sampling in the families that are known to possess osteoderms. Our analysis reveals multiple independent origins of osteoderms within the order, with three clades—Cordylidae, Anguidae and egerniine skinks—displaying increased rate-shifts in the distribution and extent of their armor. There are repeated losses and gains of ossified armor within these three lineages, and variations in the extent and distribution of osteoderms are shown to be correlated with microhabitat but not climate.
