Counts of dinosaur families found in three stratigraphic levels of the Cretaceous period in the Hell Creek formation in North Dakota.
The eight families are the Ceratopsidae (Ce), Hadrosauridae (Ha), Hypsilophodontidae (Hy), Pachycephalosauridae (Pa), Tyrannosauridae (Ty), Ornithomimidae
(Or), Sauronithoididae (Sa) and Dromiaeosauridae (Dr).
Usage
data(HCD)
Arguments
Format
A data frame with 3 observations on the following 9 variables.
Level
a factor with levels Lower, Middle, Upper, specifiyng the stratigraphic levels
Cr
a numeric vector, counts of the Ceratopsidae
Ha
a numeric vector, counts of the Hadrosauridae
Hy
a numeric vector, counts of the Hypsilophodontidae
Pa
a numeric vector, counts of the Pachycephalosauridae
Ty
a numeric vector, counts of the Tyrannosauridae
Or
a numeric vector, counts of the Ornithomimidae
Sa
a numeric vector, counts of the Sauronithoididae
Dr
a numeric vector, counts of the Dromiaeosauridae
References
Sheehan, P.M., et al. (1991): Sudden extinction of the Dinosaurs: Latest Cretaceous, Upper Great Plains, U.S.A. Science 254, 835-839.