Class                         Order                               Suborder                        Family

                                           -Testudinata-

                                          -Crocodilia-

                                          -Squamata-                              -Amphisbeania-                       - Amphisbaenidae

                                                                                                                                                       - Trogonophidae

REPTILIA                                                                                                                                     -Rhineuridae

                                                                                                                                                       - Bipedidae

                                                                                                -Serpentes                                -Viperidae

                                                                                             -Elapidae

                                                                                                              -Boidae

                                                                                           -Aniliidae

- Sauria

                                                                                      -Iguanidae

                                                                                                              -Varanidae

                                                                                                                 -Gekkonidae  

                                                                                                                           -Chamaeleontidae

                                                                                          -Lanthanotida

                                                                                                                         - Helodermatidae

family history:

           Heloderma suspectum, the Gila Monster, is one of the two lizards in the Helodermatidae Family.  The other, its closest relative, is Heladerma horridum which is the Mexican beaded lizard.  The helodermatidae family is also very close with the Monitor lizards (the varanidae family).  A well known member of the Varanidae family is the Komodo Dragon, the biggest lizard in the world.

        This phlogenetic tree is based off the class Reptilia, which includes the turtles, lizards, crocodiles, alligators, and snakes.  The branching off of this tree is separating the morphological features of the skull and jaw between the reptiles.  The Helodermatidae family has skulls with postorbital archs but without the supratemporal arch.  You can trace the Helodermatidae family all the way back the Cretaceous period 65 million years ago.  Fossils history proves that the Helodermatidae family lived during that period.