Open Paleo

Silvisaurus

Eaton, 1960 SIL-vi-SAWR-us

From Latin 'silva' (woodland, forest) + Greek 'sauros' (lizard), meaning 'woodland lizard', reflecting the forested environment it likely inhabited.

113.2–93.9 million years ago Albian–Cenomanian, Early Cretaceous–Late Cretaceous
Early Cretaceous and Late Cretaceous stages

Silvisaurus, from the Latin silva "woodland" and Greek sauros "lizard", is a nodosaurid ankylosaur from the Early to Late Cretaceous period. It is the only known dinosaur species named from terrestrial deposits in Kansas and was designated the official state land fossil in 2023.

Diagnosis

  1. Skull pear-shaped, about three-fourths as wide as long, widest at posterior margins of orbits
  2. Dermal armor concealing antorbital and temporal fenestrae without prominent processes
  3. Premaxillary teeth eight or nine, bluntly conical, slightly serrate, lacking cingulum
  4. Maxillary teeth 17-18 with spatulate crowns, margins having 7-9 serrations
  5. Sacrum with 6 fused vertebrae plus presacral rod of 5 additional fused vertebrae
  6. Pterygoids expanded posteriorly but not fusing with quadrates; thin-walled posterior pouches forming resonance chambers

Species

Silvisaurus condrayi Eaton, 1960

Type species

Named for Warren W. Condray, the Kansas rancher who discovered the holotype fossil in the 1950s.

Holotype
KUVP 10296 , University of Kansas Biodiversity Institute
Material
Partial skeleton including skull.
Horizon
Terra Cotta Clay Member, Dakota Formation, Albian–Cenomanian, Early Cretaceous–Late Cretaceous , 113.2–93.9 million years ago
Locality
Condray's farm, ten miles south of Miltonvale, Kansas, United States Eaton (1960) places the site "midway in the Terra Cotta clay member of the Dakota Formation". The member is late Albian below and reaches the early Cenomanian above (Ludvigson and colleagues, 2010), and no source cited here correlates the site with either part.

References

  1. Eaton, T. H., Jr. (1960). A new armored dinosaur from the Cretaceous of Kansas. The University of Kansas Paleontological Contributions: Vertebrata 8: 1-24.

    Places the site "midway in the Terra Cotta clay member of the Dakota Formation".

    eaton1960a
  2. Ludvigson, G. A.; Witzke, B. J.; Joeckel, R. M.; Ravn, R. L.; Phillips, P. L.; González, L. A.; Brenner, R. L. (2010). New insights on the sequence stratigraphic architecture of the Dakota Formation in Kansas–Nebraska–Iowa from a decade of sponsored research activity. Current Research in Earth Sciences, Kansas Geological Survey Bulletin 258(2): 1-35.

    Dates the lower Terra Cotta late Albian and the upper Terra Cotta latest Albian to locally early Cenomanian.

    ludvigson2010a
  3. Paul, G. S. (2024). The Princeton Field Guide to Dinosaurs (3rd ed.). Princeton University Press.

    Source of the mass estimate.

    paul2024a
  4. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026a
  5. Carpenter, K.; Kirkland, J. I.; Burge, D.; Bird, J. (1999). Ankylosaurs (Dinosauria: Ornithischia) of the Cedar Mountain Formation, Utah, and their stratigraphic distribution. Vertebrate Paleontology in Utah (Gillette, D. D., ed.) 99-1: 243-251.

    Compares Animantarx with "Silvisaurus from the Early Cenomanian of Kansas" in dating the Mussentuchit Member, giving no source for the age.

    carpenter1999a
  6. Carpenter, K.; Kirkland, J. I. (1998). Review of Lower and Middle Cretaceous ankylosaurs from North America. Lower and Middle Cretaceous Terrestrial Ecosystems (Lucas, S. G.; Kirkland, J. I.; Estep, J. W., eds.) 14: 249-270.

    Gives the horizon as "Terra Cotta Clay (Albian: Hamilton, 1994)".

    carpenter1998c