Data from: Ankylosaurian body armor function and evolution with insights from osteohistology and morphometrics of new specimens from the Late Cretaceous of Antarctica

The body armor of ankylosaurians is a unique morphological feature among
dinosaurs. Despite being studied for decades, paleohistological analyses
have only started to uncover the details of its function. Yet, there has
been an overall bias toward sampling ankylosaurian remains from the
Northern Hemisphere and limited quantitative studies on the morphological
and functional evolution. Here, we describe new ankylosaurian materials
recovered from the Late Cretaceous of Antarctica that, in combination with
data compiled from the literature, reveal new insights into the evolution
of the ankylosaurian body armor. Based on histological microstructure and
phylogenetic results, the new Antarctic material can be assigned to
Nodosauridae. This group shares the absence/poor development of the basal
cortex and highly ordered sets of orthogonal structural fibers in the
superficial cortex. Our morphospace analyses indicate that large
morphological diversity is observed among both nodosaurids and
ankylosaurids, but they became more functionally specialized in
late-diverging nodosaurids. Besides acting as effective protection against
predation, osteoderms also exhibit highly ordered structural fibers in
nodosaurids, enabling a decrease in cortical bone thickness (as in
titanosaurs), which could have been co-opted for secondary functions, such
as calcium remobilization for physiological balance. The latter may have
played a key role in nodosaurid colonization of high-latitude
environments, such as Antarctica and the Arctic Circle.