page_title: Ziapelta
section_title: Osteoderms
hierarchical_section_title: Ziapelta / Description / Osteoderms
caption_attribution_description: English: Cervical half rings of Ziapelta sanjuanensis. A) Incomplete first and second cervical half rings of NMMNH P-64484 (holotype), with isolated post-cervical osteoderm, as preserved in situ. First cervical half ring is in posterior view. B) Dorsal view of left medial osteoderm showing smaller interstitial osteoderms, anterior is up. C) Isolated first cervical half ring NMMNH P-66930 (referred specimen) in anterior view. Abbreviations: b, band; g, groove; i, interstitial osteoderm; ld, left distal osteoderm; ll, left lateral osteoderm; lm, left medial osteoderm; mid, midline of the cervical half ring; os, osteoderm; pc os, post-cervical osteoderm; rl, right lateral osteoderm; rm, right medial osteoderm.
context_page_description: Ziapelta sanjuanensis is an extinct species of ankylosaurid from Upper Cretaceous formations in New Mexico.
context_section_description: The body of Ziapelta was protected by osteoderms, skin ossifications. Apart from the osteoderms that are part of the skull, two cervical halfrings were present to protect the upper side of the neck and rows of oval scutes probably ran along the back and sides of the torso; the latter are only known as detached specimens. All osteoderms found have a surface that is densely pitted but lacks veins.
  The cervical halfrings with ankylosaurids typically each consisted of six fused segments that were paired: per side one at the top, a second segment at the upper side and a third one at the lower side. These segments were fused to an underlying continuous bone ring. In Ziapelta the segments consisted of osteoderms that were in-between an oval and a rectangular shape. These osteoderms were keeled, featuring a high cutting edge. The osteoderms were between 146 and 169 millimetres long, between 58 and 104 millimetres wide and their keels varied between 2.4 centimetres (0.94 in) and 10.9 centimetres (4.3 in) tall. Where the middle segments touched each other on the midline, an irregular  punctuated row of small trapezium-shaped "interstitial" osteoderms was present within the suture. At the front of the suture of the first cervical halfring, a small cone-shaped interstitial osteoderm protruded. Such interstitial elements were absent with the side segments.
  Specimen NMMNH P-66930, a first cervical halfring, shared several traits with its counterpart of the holotype: high narrow keels, interstitial osteoderms in the middle and a lower side osteoderm that does not wrap around the lower edge. It was therefore referred to Ziapelta sanjuanensis.
  Several unconnected osteoderms have been discovered. One of these might originally have been part of a halfring. A second one was seen as originating from the pectoral, upper breast, region. A third, measuring 118 by 68 millimetres, had a narrow keel and the shark fin shape typical of the ankylosaurian side spikes and was thus identified as a lateral rump osteoderm. Some small ossicles were discovered also, round scutes of between two and four centimetres in cross-section, with a conical or flat shape and featuring a pitted surface. Their original position cannot be determined.
caption: Three cervical half-rings
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