Open Paleo

Riparovenator

Barker et al., 2021 ri-PAIR-o-ven-AY-tor Disputed

From Latin riparius (of the riverbank) and venator (hunter); meaning "riverbank hunter".

125.8–121.4 million years ago Barremian, Early Cretaceous
Early Cretaceous stages

Riparovenator is a genus of baryonychine spinosaurid dinosaur from the Early Cretaceous (Barremian) period of Britain. The genus contains a single species, Riparovenator milnerae.

Under dispute

Riparovenator milnerae was erected as a distinct baryonychine spinosaurid, sister to the co-occurring Ceratosuchops inferodios (Barker and colleagues, 2021), and both were kept distinct by Rauhut and colleagues (2025). Its distinctness as a genus is contested, however: Sereno and colleagues (2022) tentatively referred the Wessex baryonychine material to a single taxon, Ceratosuchops, attributing the differences to individual variation, and Santos-Cubedo and colleagues (2023) followed that synonymy by omitting Riparovenator from their count of valid baryonychine genera, while Cau (2025) left the question open pending a detailed comparative analysis. Its status as a genus distinct from Ceratosuchops therefore remains unresolved.

Diagnosis

  1. Notched dorsal orbital margin between prefrontal and postorbital process of frontal
  2. Deeply inset facial nerve (CN VII) foramen that is largely obscured from lateral view
  3. Deep subcondylar recess with depth over 1/3 of mediolateral width
  4. Reduced exposure of ventral surface of basipterygoid processes in lateral view
  5. Curved dorsal margin of frontal process of nasal in lateral view
  6. Straight dorsal margin of dorsum sellae
  7. Exoccipital components of occipital condyle closely spaced
  8. Mediolaterally thick crests bordering subcondylar recess
  9. Lateral margins of basipterygoid processes concave in ventral view

Species

Riparovenator milnerae Barker et al., 2021 Disputed

Type species

Named for Angela Milner, a British paleontologist who died in August 2021, shortly before the species was formally described.

Holotype
IWCMS 2014.95.6, IWCMS 2014.96.1, IWCMS 2014.96.2, IWCMS 2014.96.3, IWCMS 2020.448.1, IWCMS 2020.448.2 , Dinosaur Isle Museum
Material
Associated premaxillary bodies, a disarticulated braincase, and a left preorbital fragment preserving partial lacrimal and prefrontal.
Horizon
Wessex Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
Locality
east of Chilton Chine, Isle of Wight, United Kingdom

Notable specimens

  • IWCMS 2020.447.1-39, IWCMS 2014.95.7

    Dinosaur Isle Museum complementary

    Referred material recovered with the holotype, including a posterior nasal fragment and a caudal axial series of twenty-two vertebrae (around fifty bones total), preserving tail anatomy absent from the cranial-only type material.

    Barker et al. (2021)

References

  1. Barker, C. T.; Hone, D. W. E.; Naish, D.; Cau, A.; Lockwood, J. A. F.; Foster, B.; Clarkin, C. E.; Schneider, P.; Gostling, N. J. (2021). New spinosaurids from the Wessex Formation (Early Cretaceous, UK) and the European origins of Spinosauridae. Scientific Reports 11(1). Springer Science and Business Media LLC. doi:10.1038/s41598-021-97870-8

    Erected Riparovenator milnerae as a distinct baryonychine spinosaurid, sister to Ceratosuchops.

    barker2021a
  2. Sereno, P. C.; Myhrvold, N.; Henderson, D. M.; Fish, F. E.; Vidal, D.; Baumgart, S. L.; Keillor, T. M.; Formoso, K. K.; Conroy, L. L. (2022). Spinosaurus is not an aquatic dinosaur. eLife 11: e80092. doi:10.7554/eLife.80092

    Tentatively referred the Wessex baryonychine material to a single taxon, Ceratosuchops, treating Riparovenator's distinguishing features as individual variation.

    sereno2022a
  3. Santos-Cubedo, A.; de Santisteban, C.; Poza, B.; Meseguer, S. (2023). A new spinosaurid dinosaur species from the Early Cretaceous of Cinctorres (Spain). Scientific Reports 13(1). Springer Science and Business Media LLC. doi:10.1038/s41598-023-33418-2

    Followed the synonymy of Sereno and colleagues (2022), omitting Riparovenator from their count of valid baryonychine genera.

    santos-cubedo2023a
  4. Rauhut, O. W. M.; Canudo, J. I.; Castanera, D. (2025). Revision of the theropod dinosaur Camarillasaurus cirugedae from the Early Cretaceous (Barremian) of Teruel province, Spain. Palaeontologia Electronica 28(3): 1-67. doi:10.26879/1543

    Recovered Riparovenator as a baryonychine spinosaurid, keeping it distinct from Ceratosuchops.

    rauhut2025a
  5. Cau, A.; Paterna, A. (2025). Beyond the Stromer's Riddle: the impact of lumping and splitting hypotheses on the systematics of the giant predatory dinosaurs from northern Africa. Italian Journal of Geosciences 144(2): 162-185. doi:10.3301/IJG.2025.10

    Left the Riparovenator–Ceratosuchops synonymy open, deferring to a future detailed comparison.

    cau2025a