Unravelling the phylogeny of armadillos and their kin (Mammalia, Xenarthra, Cingulata) combining morphological, molecular, and stratigraphic data

Cingulata, a major lineage of Xenarthra, comprises extinct and extant armoured placental mammals that diversified throughout the Cenozoic. Despite extensive study, phylogenetic hypotheses based on morphological and molecular data remain incongruent, and no total evidence analysis has been conducted. Here, we integrate the largest morphological dataset for cingulates with molecular and stratigraphic data to infer their phylogeny, divergence times, and diversification dynamics. Morphological data were analysed under maximum parsimony (MP), assessing sensitivity to alternative settings, and under Bayesian inference (BI), exploring state-space partitioning and model adequacy. Combined analyses were conducted under MP, maximum likelihood, and tip-dating BI under a skyline fossilized birth-death model. Results support the monophyly of Cingulata and recover two main clades, Paracingulata and Eucingulata. Eucingulata includes Dasypodoidea and Chlamyphoroidea, the latter comprising Euphracta and Glyptodonta. Divergence estimates indicate Paleogene origins for family-level clades, with most intra-familial diversification predating the Neogene. Diversification analyses reveal increased origination during the Miocene, followed by reduced origination in the Pliocene and elevated extinction in the Quaternary. This study presents the most comprehensive phylogenetic framework for cingulates, clarifying long-standing conflicts between morphological and molecular evidence, and updating their classification, with higher level groups redefined to reflect phylogenetic structure, morphological distinctiveness, and divergence times.