Cascabel rattlesnake, Crotalus durissus, and desert horned viper, Cerastes cerastes (Cerastes cornutus). Handcolored engraving by Madame Fournier after an illustration by Oudart from Charles d'Orbigny's Dictionnaire Universel d'Histoire Naturelle (Universal Dictionary of Natural History), Paris, 1849. (Photo by Florilegius/SSPL/Getty Images)