Mexican beaded lizard generic name "Heloderma" means "studded skin", from the Ancient Greek words "hêlos" (ἧλος)—the head of a nail or stud—and "dérma" (δέρμα), meaning skin. Its specific name, "horrĭdum", is the Latin word meaning rough or rude. The four subspecies of beaded lizard, elevated to full species in 2013, are: Adult beaded lizards range from in length. They are substantially larger than the Gila monster, which only reaches lengths of . The snout-to-vent length of a beaded lizard averages . The average body mass of an adult beaded lizard is , about 45% heavier than the average mass of a gila monster,
Dunn's spinytail lizard it excavates itself, especially under fallen logs. "M. groi" is oviparous. Dunn's spinytail lizard Morunasaurus groi, known commonly as Gro's manticore, Dunn's spinytail iguana, or Dunn's spinytail lizard, is a species of lizard in the family Hoplocercidae. The species is endemic to northwestern South America and Panama. The specific name, "groi", commemorates "Lord Gro", a character in the novel "The Worm Ouroboros" by Eric Rücker Eddison. The tail of "M. groi" is covered with small spines. Males are reddish-brown with dark brown transverse bands across the back, reaching to the middle of the sides and then breaking up into small,