Compound osteoderms preserved in amber reveal the oldest known skink

Scincidae is one of the most species-rich and cosmopolitan clades of squamate reptiles. Abundant disarticulated fossil material has also been attributed to this group, however, no complete pre-Cenozoic crown-scincid specimens have been found. A specimen in Burmite (99 MYA) is the first fossil that can be unambiguously referred to this clade. Our analyses place it as nested within extant skinks, supported by the presence of compound osteoderms formed by articulated small ostedermites. The specimen has a combination of dorsal and ventral compound osteoderms and overlapping cycloid scales that is limited to skinks. We propose that this type of osteoderm evolved as a response to an increased overlap of scales, and to reduced stiffness of the dermal armour. Compound osteoderms could be a key innovation that facilitated diversification in this megadiverse family.

Fil: Daza, Juan D.. Sam Houston State University; Estados Unidos

Fil: Stanley, Edward L.. University of Florida; Estados Unidos

Fil: Heinicke, Matthew P.. University of Michigan; Estados Unidos

Fil: Leah, Chuck. Houston Museum of Natural Sciences; Estados Unidos

Fil: Doucet, Daniel S.. Sam Houston State University; Estados Unidos

Fil: Fenner, Kelsey L.. University of Florida; Estados Unidos

Fil: Arias Becerra, Joan Salvador. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Posadas; Argentina

Fil: Smith, Ru D. A.. University Malaya; Malasia

Fil: Peretti, Adolf M.. Peretti Museum Foundation; Suiza

Fil: Aung, Nyi Nyi. University of Yangon; Birmania

Fil: Bauer, Aaron M.. Villanova University; Estados Unidos