Named By: P. M. Galton & H. -D. Sues - 1983.
Classification: Chordata, Reptilia, Dinosauria, Ornithischia, Pachycephalosauridae,Pachycephalosaurinae.
Species: S. spinifer (type).
Size: Skull reconstructed to be 46 centimetres long. Total body size uncertain but may roughly have been just over three meters long.
Known locations: USA - Ferris Formation, Hell Creek Formation.
Time period: Maastrichtian of the Cretaceous.
Fossil representation: Remains of several individuals.
Stygimoloch is a dubious genus of pachycephalosaurid dinosaur as many palaeontologists are of the opinion that Stygimoloch represents a juvenile/subadult Pachycephalosaurus. In addition to this another genus named Dracorex has also been perceived to be an even younger Stygimoloch, and it is not out of the question that one day both Stygimoloch and Dracorex may be confirmed as juvenile Pachycephalosaurus.
- New data on pachycephalosaurid dinosaurs (Reptilia: Ornithischia) from North America. Canadian Journal of Earth Sciences 20(3):462-472. - P. M. Galton & H. -D. Sues - 1983.
- Cranial anatomy and diagnosis of Stygimoloch spinifer. - Journal of Vertebrate Paleontology 18(2): 363-375. - M. B. E. Goodwin, et al - 1998.
- Extreme cranial ontogeny in the Upper Cretaceous Dinosaur Pachycephalosaurus. - PLoS ONE, 4(10): e7626. - J. R. Horner & M. B. Goodwin - 2009.