Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America

Ankylosaurus is bounded here by Carpenter’s redescription of referred Upper Cretaceous western North American material; the revised diagnosis does not make every isolated ankylosaurid remain part of the genus or define exact global endpoints.

Ankylosaurus is displayed at 72.1–66 Ma only as the stratigraphic coverage of the redescribed type and referred material, not a global genus FAD or LAD. The interval is a source-bounded sample window, not a global FAD, LAD, divergence date, continuous occupancy claim or direct-ancestor assertion.

Carpenter's redescription documents a long, low skull with prominent cranial horns, a large cervical half-ring and a large, low tail club in the type and referred Ankylosaurus material; the claim is limited to those specimens.

This profile is geographically limited to the type and referred Upper Cretaceous Western Interior material from the Hell Creek, Lance and Scollard formations in Montana, Wyoming and Alberta; it does not claim a complete genus range.

Carpenter's anatomical redescription does not directly establish diet, habitat preference, locomotion, body size or ecological guild for Ankylosaurus; those profile fields are explicitly withheld.