Jawed vertebrates fall into one of two lineages: chondrichthyans (sharks, skates, and relatives), and osteichthyans (bony fishes and tetrapods). One of the features that make chondrichthyans unique among jawed vertebrates is that their endoskeletal elements are lined with discrete tiles of mineralized tissue called tesserae. Tesserae exhibit a polygonal mineralization pattern which is morphologically different from the compact and trabecular mineralization patterns seen in osteichthyans. Recently, tesserae were shown to also exhibit a trabecular mineralization pattern that is morphologically identical to trabecular mineralization pattern of osteichthyans. The morphological relationship between polygonal and trabecular tesseral mineralization patterns remains only descriptive at this point from adult studies. How tesserae develop during embryogenesis to exhibit either a trabecular or polygonal pattern is unclear. With the trabecular tesseral pattern appearing to be more abundant in the endoskeleton of the adult little skate Leucoraja erinacea, we hypothesize that trabecular tesseral pattern is the primary mineralization pattern during tesseral development. To test this hypothesis, synchrotron radiation micro-CT imaging and histological analyses were used to characterize the development of tesserae in several endoskeletal regions of the little skate. Data from these analyses suggest that the trabecular pattern is the primary mineralization pattern of tesserae, which is retained in some endoskeletal regions or developed further to a polygonal pattern in other endoskeletal regions. These preliminary ontogenetic data from tesserae offer some insights into the phylogenetic appearance of trabecular mineralization in jawed vertebrates.