The reptile family tree below includes only living reptiles.  The phylogeny of the reptiles is in a state of considerable flux, and some of the relationships indicated below may be regarded as controversial. The traditional taxonomy, with its neat division into turtles, crocodiles, snakes and lizards, has become inadequate to capture the complexities of this fascinating group of animals.  Because the reptiles are a group of such great interest,I have attempted to make a simplified representation of relationships thought to exist among the various reptilian taxa.  This has been a daunting task for somebody practicing herpetology without a license.  The tree you see below has been redrawn from cladograms and other information from several sources; the phylogeny of the squamates has recently been updated from molecular data (Vidal and Hedges, 2005). However, the fault for any errors or misinterpretations in the tree rests with me, not with the original source.  I have omitted some branches in the interest of simplification; I hope your personal favorite is not among them.  Corrections of errors, gross omissions or misinterpretations will gratefully be received.  With the exception of the Tuataras, examples of all of the reptilian taxa below can be seen at the Fort Worth Zoo's outstanding Herpetarium. 

Invertebrate Tree

Fish Tree

Tetrapod Tree

Reptile Tree

Bird Tree

Mammal Tree

Iguanid Rhinoceros Iguana	Agamid Frilled Lizard	Chameleon Parson's Chameleon	Gecko Giant Madagascar Day Gecko	*Amphisbaenid (No picture)
Skink Blue-tongued Skink	Teid Caiman Lizard	Anguid Atitlan Alligator Lizard	Xenosaurid (Oaxacan Rock Lizard)	Monitor Green Tree Monitor
Beaded Lizard Mexican Beaded Lizard	Boid Annulated Boa	Viper Northwestern Neotropical Rattlesnake	Colubrid Honduran Milk Snake	Elapid Tentacled Snake
To the Amphibians				To the Birds
	Crocodilian Dwarf Caiman	Side-necked Turtle Australian Snake-necked Turtle	Hidden-necked Turtle Indian Star Tortoise

*Examples of snakes and lizards not pictured here can be seen at this page from the University of Aberdeen Zoology Museum.

Sources of information:

• Harry Greene.  Snakes:  the Evolution of Mystery in Nature.  University of California Press
• ( Read an excerpt from the book)
• Peter A. Meylan and Eric Ganko.  Higher Relationships of Testudines.
• Cyberlizard's Rough Guide to the Lizard Families.
• Anthony Herrell. Lizards in the Lab
• Kevin de Queiroz and Emilia P. Martins.  Unversity of Arizona's Tree of Life (Squamata)
• Philip J. Heise, et al. Higher-Level Snake Phylogeny Inferred from Mitochondrial DNA Sequences of 12s rRNA and 16s rRNA Genes. Mol. Biol. Evol. 12 (1995): 259-265.
• S. Blair Hedges and Laura L. Poling. A molecular phylogeny of reptiles. Science 283 (12 February 1999): 998-1001.
• Nicholas Vidal and S. Brail Hedges. A phylogeny of squamate reptiles (lizards, snakes and amphisbaenians) inferred from nine nuclear protein-coding genes. C. R. Biologies 328 (2005): 1000-1008.

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