An ankylosaurid ( Ankylosauridae ) are family of armored dinosaurs that evolved 125 million years ago ( along with another family of ankylosaurs , the Nodosauridae ) and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event . An ankylosaurid is a member of the Ankylosauridae family of armored dinosaurs that evolved 125 million years ago ( along with another family of ankylosaurs , the Nodosauridae ) and became extinct 65 million years ago during the Cretaceous-Tertiary extinction event .