Terminocavus
From Latin 'terminus' meaning 'end' and 'cavus' meaning 'cavity', meaning 'coming to the end of the cavity', referring to the nearly closed parietal embayment before its complete loss in more derived taxa
Terminocavus is a genus of ceratopsid dinosaur from the late Cretaceous Period of what is now North America. The genus contains a single species, the type species Terminocavus sealeyi, known from a parietal and some other associated fragments. The holotype specimen was discovered in the Kirtland Formation of New Mexico in 1997, and was later described and named in a 2020 study. It was similar in anatomy to Pentaceratops and Anchiceratops, which it was closely related to, but had a distinctive heart-shaped upper frill with very narrow notch. It has been hypothesized to form an anagenetic series with several other chasmosaur species.
Diagnosis
- Posterior bar flattened and plate-like, not bar-like
- Lateral rami of posterior bar strongly expanded anteroposteriorly both medially and laterally
- Maximum anteroposterior thickness of posterior bar ~35% of parietal maximum width
- Median embayment of posterior bar narrower and more notch-like
- Parietal fenestrae subrounded rather than subangular
- Lateral rami meet at steep angle of ~73 degrees
- Epiparietals remain large and triangular through to adulthood
Species
Terminocavus sealeyi Fowler & Freedman Fowler, 2020
Type species
Named for Paul Sealey, the discoverer of the holotype specimen in the Kirtland Formation of New Mexico in 1997.
- Holotype
- NMMNH P-27468 , New Mexico Museum of Natural History and Science
- Material
- Parietal, partial squamosal, jugal, epijugal, partial quadratojugal, partial sacrum, vertebral fragments
- Horizon
- middle Hunter Wash Member, Kirtland Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
- Locality
- NMMNH L-3503, New Mexico, United States
References
- Fowler, D. W.; Freedman Fowler, E. A. (2020). Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs: evidence from the Campanian of New Mexico. PeerJ 8: e9251. PeerJ. doi:10.7717/peerj.9251 fowler2020a
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Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Source of the body length estimate, and the appearance features.
jones2026a