Terminocavus sealeyi is a genus of ceratopsian dinosaur that lived in New Mexico during the Late Cretaceous period.
Taxonomy[]
The genus contains the type species Terminocavus sealeyi, known from a parietal and some other associated fragments. It was similar in anatomy to Pentaceratops and Anchiceratops, which is was closely related to, but had a distinctive heart-shaped upper frill with very narrow notch.
Anatomy[]
Known from limited material, Terminocavus is different from its relatives such as Pentaceratops and Anchiceratops by the anatomy of its parietal, which forms a heart shape. The prominent median embayment of earlier taxa is largely reduced, being largely narrow as opposed to wide and U-shaped. Terminocavus's parietal bars is thin and extremely broad compared to earlier relatives; it is more plate-shaped than bar-shaped. Its median bar has also expanded, bearing more pronounced flanges than its ancestor Navajoceratops. The parietal fenestrae have a more rounded shape than the ancestral angular state, and are smaller due to the expanded parietal and median bars. Overall, the anatomy is intermediate between that of more primitive genera like Pentaceratops and that of more derived ones like Anchiceratops and Triceratops.
Like most other chasmosaurs, its paired fused parietals combined bear six epiparietals, symmetrically arranged with three on each side. The first pair, small and triangular, project from the top edge of the median embayment, and in life would have touched each other. The second pair are a larger set of triangles, whereas the third epiparietals have a rounded, D-shape; both project upwards, angled in line with the rest of the parietal. The preserved right squamosal is long, indicating adult Terminocavus had a very large frill similar to that of its relatives. A singular, fused episquamosal is also known from the holotype; it is rugose and indistinct from that of other ceratopsids. The left epijugal horn is known as well, fused to the jugal and quadratojugal bones; it robust and large, but unlike that of Pentaceratops is not especially long.
Terminocavus known remains are smaller than Utahceratops and Pentaceratops, indicating that it was almost an adult size.
Discovery and naming[]
The holotype specimen was discovered in the Kirtland Formation of New Mexico,United States in 1997, and was later named in the 2020 study.