Snakes of the genus Bothrops were responsible for 265 snakebite cases (75.5%), the genus Crotalus
for 21 (6.0%), Micrurus for 8 (2.3%), and Lachesis for 2 (0.6%).
Carl Ernst (George Mason U.) and Evelyn Ernst, who taught high school chemistry and biology, offer the second volume in their set on venomous reptiles of North America, focusing on 21 rattlesnake species of the genus Crotalus
of the family Viperidae found in the US, Canada, and northern Mexico, for readers interested in venom, snakes, and herpetology.
This enabled them to map the expansion and contraction at 4,000-year intervals of the ranges of 11 North American species of the rattlesnake genus Crotalus
He taught science and biology--and retains the humorous manner of a hip high school teacher--then decided he could be of more use helping the world understand the genus Crotalus
The overall shape (squareness), robustness, and low neural arch of the vertebra are characteristic of the genus Crotalus
. Because of the poor preservation and fragmentation of the specimens, allocation to species cannot be ascertained.
Although these patterns suggest competition may be an important factor driving distribution, there was no observed overlap in the genus Phrynosoma and habitat requirements vary widely among members of the genus Crotalus
. Therefore, distributions of these populations were not driven by interspecific competition (Hofer et al., 1999).