USNM Dunkleosteus anterior snout

Videos of a mounted specimen of <i>Dunkleosteus terrelli</i> (USNM V 21314), showing the anterior snout of this specimen, particularly the position of the well developed ethmoid ossification and the structure (internasal? combined internasal and ethmoid) immediately medial to it that denotes a large, well-developed fossa at the anterior end of the suborbital groove. The specimen was behind glass thus the quality of the video and ability to examine it is limited. Note the supragnathals, ethmoid ossification, and internasal of this specimen are out of position; the ethmoid ossification is detached from its contact surface on the postnasal plate, and the posterior supragnathal is dislocated from its life position on the internal face of the linguiform process of the suborbital plate.This specimen is a composite and it is not clear what material is original or even pertains to the same individual (H. Little, pers. comm., 2025), but it seems likely that the ethmoid/internasal articulation has some merit as David Dunkle has previously mentioned there were <i>Dunkleosteus </i><i>terrelli </i>specimens that preserved an ethmoid internasal contact (D. Dunkle to B. Carr).Specimen GUID: http://n2t.net/ark:/65665/3ec33152b-62d5-4288-86fc-7f445189e3ab

本视频展示了美国国家博物馆编号为USNM V 21314的邓氏鱼·特雷尔种（Dunkleosteus terrelli）馆藏标本的吻部前部细节，重点呈现该标本发育完好的骨化筛骨（ethmoid ossification）的位置，以及紧邻其内侧的结构（鼻间骨？或鼻间骨与骨化筛骨的复合结构）——该结构对应眶下沟（suborbital groove）前端一处大型且发育完善的凹陷。因该标本被置于玻璃展柜中，视频画质及细节检视能力均受到限制。需注意，本标本的上腭骨（supragnathals）、骨化筛骨及鼻间骨已脱离原生位置：骨化筛骨与鼻后板（postnasal plate）的接触面发生分离，后侧上腭骨也从眶下板（suborbital plate）舌状突（linguiform process）的内表面原生位置发生脱位。本标本为复合拼接标本，目前无法明确哪些材质为原始遗存，甚至无法确认是否属于同一个体（H. Little，个人通信，2025）。不过戴维·邓克尔此前曾提及，部分邓氏鱼·特雷尔种标本保留了鼻间骨与骨化筛骨的连接结构（D. Dunkle致B. Carr的信函），因此该标本的骨化筛骨/鼻间骨连接结构仍具备一定研究价值。本标本的全球唯一标识符（GUID）为：http://n2t.net/ark:/65665/3ec33152b-62d5-4288-86fc-7f445189e3ab