Prenatal and perinatal cranial ontogeny in Dasypus hybridus (Xenarthra, Cingulata): A precocial armadillo?

Abstract

During cranial development, ossification centers appear sequentially, either through chondral or membranous processes. Birth represents a critical transition to life into a new environment, involving a progressive reduction in maternal dependence and exhibiting varying degrees of neonatal maturity, from altricial to precocial. Twenty-five prenatal and fourteen postnatal specimens of Dasypus hybridus (Xenarthra, Mammalia) were processed using an enzymatic clearing and double-staining technique, with Alcian Blue to identify cartilage and Alizarin Red to reveal ossifications. Using Total Cranial Length (TCL) as a proxy, eight prenatal cranial ontogenetic stages and three postnatal stages, spanning from two to thirty days of age, were identified. The first ossification centers to appear are those of the facial region, followed by the vault and the base of the skull, with the ethmoid complex being the last to ossify. The cranial, postcranial, and integumentary skeletal maturity data presented here suggest that D. hybridus is relatively precocial compared to other armadillos, such as Chaetophractus villosus and Chaetophractus vellerosus, which are positioned further along the altricial spectrum”