LEPIDOSAURIA

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LEPIDOSAURIA

• Sister taxon to Archosauria (Birds
  Crocodilians)
• Includes Rhynchocephalia, Squamata (Lizards
  Amphisbaenia Snakes)
• Characterized by transverse cloacal slit, regular
  skin shedding in one time, etc

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Squamata

• Made of 2 (or 3) suborders
• Sauria
• Serpentes
• Amphisbaenia
• Serpentes are nested within Sauria
• Thus, lizards are paraphyletic
• But Squamata is monophyletic, and members of this
  order share many derived characters (e.g.,
  hemipenes)

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Sauria

• 11 families in the U.S.
• Iguanidae
• Crotaphytidae
• Polychrotidae
• Phrynosomatidae
• Gekkonidae
• Eublepharidae
• Teiidae
• Xantusiidae
• Scincidae
• Anguidae
• Helodermatidae

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Family Iguanidae

• 8 genera, ca. 34 species
• Nearctic and neotropical distribution
• 1 exception
• Brachylophus (Fiji Islands)

Brachylophus spp.
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Family Iguanidae

• Characteristics of family (in U.S.)
• 2 pairs of limbs
• Toe pads not expanded
• Eyelids present

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Family Iguanidae

• Genera found in the US
• Ctenosaura
• Disposaurus
• Sauromalus
• Terrestrial and rock-dwelling
• Herbivores

Ctenosaura spp.
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Family Iguanidae

• Characteristics of the family (in U.S.)
• Femoral pores present
• Rostral scale divided
• Middorsal scale row present (except Sauromalus)

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Iguanids of Nevada

• Desert Iguana (Dipsosaurus dorsalis)
• Chuckwalla (Sauromalus obesus)

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Family Phrynosomatidae

• Ca. 10 genera, 125 species
• Endemic to Western Hemisphere (from Canada to
  Panama)
• Genera found in the U.S.
• Sceloporus
• Phrynosoma
• Uma
• Callisaurus
• Cophosaurus
• Holbrookia
• Petrosaurus
• Uta
• Urosaurus

Phrynosoma spp.
Uma scoparia
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Family Phrynosomatidae

• Characteristics of the family (in U.S.)
• Femoral pores present
• Rostral scale not divided
• Interparietal scale large (or if not large, bony
  spines or projecting ridge on the head, or scales
  projecting over the ear, or fringed toes)

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Phrynosomatids of Nevada

• Zebra-tailed Lizard (Callisaurus draconoides)
• Desert Spiny Lizard (Sceloporus magister)
• Western Fence Lizard (S. occidentalis)
• Eastern Fence Lizard (S. undulatus)
• Sagebrush Lizard (S. graciosus)
• Ornate Tree Lizard (Urosaurus ornatus)
• Long-tailed Brush Lizard (U. graciosus)
• Side-blotched Lizard (Uta stansburiana)
• Greater Short-horned Lizard (Phrynosoma
  hernandesi)
• Pigmy Short-Horned Lizard (P. douglasii)
• Desert Horned Lizard (P. platyrhinos)

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Family Polychrotidae

• Ca. 11 genera, 440 species
• Western hemisphere distribution
• Genus found in the U.S.
• Anolis (Southeastern US)
• Characteristics of the family (in U.S.)
• Toe pads expanded
• Dewlaps

Anolis carolinensis
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Family Crotaphytidae

• 2 genera, ca. 12 species
• Distributed in U.S. and northern Mexico
• Genera found in the U.S.
• Crotaphytus
• Gambelia
• Found in arid areas
• Mostly rock dwelling (Crotaphytus)
• Gambelia found in flatlands
• Insectivores, as well as small vertebrates

Crotaphytus collaris
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Family Crotaphytidae

• Characteristics of the family
• Femoral pores present
• Rostral scale not divided
• Interparietal scale smaller than ear opening

Gambelia wislizeni
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Crotaphytids of Nevada

• Long-nosed Leopard Lizard (Gambelia wislizenii)
• Great Basin Collared Lizard (Crotaphytus
  bicinctores)

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Family Anguidae

• 15 genera, 102 species
• Western hemisphere, Eurasia
• Mostly terrestrial (some species like Anniella
  are fossorial)
• Mostly diurnal
• Tail autotomize readily
• Loss of legs has evolved several times

Ophisaurus spp.
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Family Anguidae

• Genera found in the U.S.
• Ophisaurus
• Anniella
• Gerrhonotus
• Elgaria
• Characteristics of the family (in U.S.)
• Limbs absent in some taxa (Ophisaurus, Anniella)
• Limbs present but lateral skin fold with very
  small scales (All genera)

Elgaria kingii
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Anguids of Nevada

• Southern Alligator Lizard (Elgaria
  multicarinatus)
• Panamint Alligator Lizard (Elgaria panamintina)
• Northern Alligator Lizard (Elgaria coeruela)

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Family Teiidae

• 9 genera, 105 species
• Endemic to Western Hemisphere
• Mainly active, diurnal species
• All species oviparous
• Parthenogenesis prevalent in Aspidoscelis (used
  to be Cnemidophorus)

Aspidoscelis marmoratus
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Family Teiidae

• Genus found in the U.S.
• Aspidoscelis (23 species)
• Characteristics of the Subfamily
• Limbs present
• Eyelid present
• Ventral scales quadrangular (and less than 12
  longitudinal rows)

Aspidoscelis sexlineatus
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Teeids of Nevada

• Great Basin Whiptail (Aspidoscelis tigris)

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Family Xantusiidae

• 3 genera, 17 species
• Relatively small lizards
• Often nocturnal and secretive
• Some are habitat specialist, e.g. Xantusia
  vigilis, associated with Joshua Tree formation

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Family Xantusiidae

• Genus found in the U.S.
• Xantusia (3 species)
• Characteristics of the Family
• Lack eyelid
• Ventral scales rectangular

Xantusia henshawi
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Xantusiid of Nevada

• Desert Night Lizard (Xantusia vigilis)

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Family Scincidae

• 100 genera, 1100 species
• Cosmopolitan distribution
• Ecologically diverse (with prevalence of
  terrestrial and fossorial forms)
• Mostly diurnal
• Limb reduction and loss has occurred multiple
  times
• Mainly insectivores

Eumeces laticeps
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Family Scincidae

• Genera found in the U.S.
• Neoseps
• Scincella
• Eumeces
• Characteristics of the Family (in U.S.)
• Limbs present
• Scales around body large ca. all equal in size
• Scales smooth and shiny

Neoseps reynoldsi
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Scincids of Nevada

• Gilberts Skink (Eumeces gilberti)
• Western Skink (E. skiltonianus)

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Family Gekkonidae

• 70 genera, 790 species
• Almost cosmopolitan
• Primarily nocturnal
• Most have subdigital setae that give them
  exceptional climbing abilities
• Gekkonids lack eyelids

Phyllodactylus xanti
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Gekkonid of Nevada
Mediterranean House Gecko (Hemidactylus
turcicus), introduced
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Family Eublepharidae

• 7 genera, 25 species
• Disjunct distribution throughout the world
• Eublepharids have eyelids and lack setae (mostly
  terrestrial)

Coleonyx variegatus
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Eublepharid of Nevada
Western Banded Gecko (Coleonyx variegatus)
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Family Helodermatidae

• 2 species
• Heloderma suspectum (Gila monster)
• Heloderma horridum (Beaded lizard)
• Central America and SW North America

Heloderma horridum
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Family Helodermatidae

• The only 2 species of venomous lizard in the
  world
• Unlike snakes, the venom gland is not
  muscularized
• Venom flows passively into the mouth through many
  ducts

Heloderma suspectum
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Family Helodermatidae

• Large, stout lizard
• Carnivorous, mostly vertebrates
• Somewhat prehensile tail
• Climb readily
• Characteristics of the family
• Dorsal scale beadlike
• Ventral scales squarish and arranged in
  transverse rows

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Helodermatids of Nevada

• Gila Monster (Heloderma suspectum)