Black or Spiny Tail Iguana - Ctenosaura similis

They are the largest of the ctenosaura lizards, growning to about 1.5 metres in length. Large males can weigh as much as 5.5 lbs. The coloration of adults can be silver-gray, gray, bluish, or peach, with infusions of red or dark orange. Most adults, especially males have black chevrons. Juveniles are green with thin bands of black or gray. Males from certain areas can have very large crests.

They are great diggers and baskers. They are found around ruins, stonewalls, rocky open slopes and branches of large trees along the open borders of the forests. They generally live in dry, arid, open terrain. They are found in groups usually dominated by a major male. They can easily be seen at Chichen Itza and Uxmal.

Their range extends from Southern Mexico to Panama.

>> Good overview article from Corwin's Carnival of Creatures.  ...link 

>> Brief overview with several good photos from West Coast Iguana Research.  ...link