Central American rattlesnake

Crotalus simus is a venomous pitviper species found in Mexico and Central America. The specific epithet is Latin for "flat-nosed", likely because its head is blunt compared with lanceheads (Bothrops). Three subspecies are recognized, including the nominate subspecies described here.
Adults commonly exceed 130 cm (51 inches) in length, with males growing larger than females. Large males reach 140-160 cm (55-63 inches) in some populations. The maximum length is 180 cm (71inches).
The body has a rough appearance because the dorsal scale keels are accentuated into protuberances or tuberculations. This is most apparent on the scale rows on either side of the body with a decreasing intensity in the lower rows. The vertebral scales are about as prominently keeled as the fourth row down on the flanks (with the vertebral scales as the first row).