Lizard diversity (Lectures 12-13)

lecture exam 2

Lepidosauria: 

Tuatara and Squamata

Ryncochephalia

“Tuatara”

native to New Zealand

Squamata

contains lizards and snakes

Synapomorphies of squamates:

• Loss of quadratojugal bone

• Hemipenes

Worldwide except Antarctica

most terrestrial

most carnivorous

most oviparous

Archosauria

Contains crocodylians, birds/dinosaurs

Synapomorphies of archosaurs:

• Mandibular fenestra (= hole in lower jaw)

• Antorbital fenestra (= hole in skull anterior to eye [orbit])

Crocodylia

contains alligators, crocodiles, gavials

• Synapomorphies 

  • Secondary palate (also in mammals) 

  • Choanae within pterygoid 

    • Funnel shaped opening 

• 27 species in 3 families 

• Worldwide tropical, only two temperate species are American and Chinese alligator 

• All aquatic, freshwater and coastal marine

• Carnivorous (mostly eat other vertebrates) 

• Egg-laying; all make nests and have parental care 

Aves

• 11,017 species 

• Live everywhere 

• Eat everything (but very few leaf eaters) 

• All egg layers, almost all make nests and have parental care 

Snakes vs Lizards

• Snakes are a specialized group of lizards 

• Lizards is paraphyletic 

Lizard Super Families

• Iguania (iguanas, chameleons, anoles)

• Dibamaia (dibamids)

• Gekkota (geckos)

• Scincomorpha (skinks and allies)

• Lacertoidea (whiptails and lacertids)

• Diploglossa (amphisbaenids, anguids)

• Platynota (varanids, gila monster)

• Shinisauroidea (crocodile lizards)

Iguania

Suborder

iguanas, chameleons, anoles

1,700 species (about ¼ of all lizards)

include many of the common diurnal lizards

no limb reduction

Traditionally considered to consist of three families:

• Agamidae

• Chamaeleonidae

• Iguanidae: now considered to be 12 families

Agamidae

61 gen, 582 sp

Old World (Africa, Asia, Australia)

Diurnal

mostly carnivorous

oviparous

Includes agamas, gliding lizards (draco), fan-throated lizards, Australian frilled-neck lizard

Chamaeleonidae

12 gen, 228 sp

Chameleons

Mostly Africa and Madagascar

• Synapomorphies:

  • Zygodactyl (fingers an toes fused to form mittens) 

  • Laterally compressed body 

  • Eyelids for turrets, eyes can move independently 

  • Head has a bony casque 

  • Projectile tongue 

  • Color change

mostly arboreal

diurnal, carnivorous

oviparous and vivparous

Iguania (Pleurodonta)

sometimes recognized as a single family (Iguanidae); usually split into 12 families

Dominant group of lizards in the New World

All diurnal

mostly oviparous

mostly carnivorous

Crotaphytidae

member of Iguania

2 gen, 12 sp

North America

desert lizards

often run on hind legs

eat other lizards

includes Collared Lizard and Leopard Lizard

Iguanidae

Member of Iguania

• 9 genera, 44 species 

• Large herbivorous lizards from desert southwest US to South America and Fiji Islands 

• Galapagos Marine iguana - only marine lizard 

Phrynosomatidae

• Member of Iguania

• 9 genera, 172 species 

• Common lizards of North America and Mexico; most common in deserts 

• Spiny lizards 

• Horned lizard

Anolidae

Member of Iguania

1 genus, 440 species 

Common arboreal lizards in southeast US and New World tropics 

Amazing example of an adaptive radiation 

Small clutch size

Bright throat flap called a dewlap used for communication 

Liolaemidae 

• Member of Iguania

• 3 genera, 354 species 

• Major radiation of lizards in south america; includes many origins of viviparity and herbivory in cold climates 

• Studied a lot by Stanley Fox and students at OSU

Dibamaia

2 genera, 1 family (dibamidae, 25 species

“blind lizards”

• Snake like, short tailed burrowers 

• Males have tiny external limbs, females legless 

• Vestigial eyes 

• Lack ear openings 

• 1 genus with 1 species in northeast Mexico 

• Other genus has 22 species in Southeast Asia

• Poor fossil record

• Ancient lizard group 

• Long distance (intercontinental) dispersal across the Bering Strait?!?

Gekkota

“Geckos”

97 genera, >1,500 species, ¼ of all lizards, 7 families

almost worldwide

one of the oldest groups of squamates

• Most are nocturnal

• Most lack moveable eyelids 

• Clean eye using tongue 

• Most are not brightly colored

• diurnal geckoes have evolved in several places, especially on islands, many are brightly colored 

• Most nocturnal species communicate vocally 

• Mediterranean house gecko is the most widespread 

Pygopodidae 

• Member og Gekkota

  • 47 species 

  • Legless geckos 

    • Some have vestigial hindlimbs 

  • Burrowing or “swim” through grass 

  • Some have communal nesting 

  • Mainly in Australia 

Scincidae

“Skinks”

• Largest family of lizards 

• round, shiny, overlapping scales underlain by osteoderms (bony plate)

• secretive and terrestrial 

• Often have reduced limbs and snake-like body form

• Typically small

• diurnal

• terrestrial

• carnivorous

• Some are fossorial, aquatic, arboreal, fossorial 

• About 45% are live bearing-viviparous

• Some giant herbivores 

• Australia has incredible diversity of skinks including giant blue-tongued skinks 

Lacertoidea

Clade of families (whiptails and lacertids)

• Lacertidae

• Amphisbaenia

• Teiidae

• Gymnophthalmidae (we’ll skip them)

Lacertidae

Member of Lacertoidea

Old World

most abundant lizard family in Europe

43 genera, 378 species 

Most are diurnal

oviparous

carnivorous, 

One species Lacerta vivipara is viviparous 

• Ranges farther north than any other lizard (into arctic circle) 

The only genus widespread in Asia is the long-tailed grass-swimmer, Takydromus

Teiidae 

• 18 genera, 179 species 

• North, Middle, and South America and West Indies 

• Genus Aspidocelis (whiptail lizards) 

• Common in southern and western US 

• Fastest and most heat-tolerant in US 

• About one-third are all-female parthenogenetic species 

  • Formed through hybridization 

  • Typically diploid or triploid eggs

Diploglossa

Clade of families: (amphisbaenids, anguids)

• Anguidae

• Diploglossidae

• Xenosauridae

• Amphisbaenia

Anguidae & Diploglossidae

• Members of Diploglossa

14 genera, 130 species

• Glass lizards, alligator lizards, and relatives

• Glass lizard (Ophisaurus) – long-tailed grass swimmer, found in North America,

Europe, and Asia

Anguidae

member of diploglossa

alligator lizards

mostly New World

terrestrial

diurnal

carnivores

many viviparous

Abronia, live in bromeliads in cloud forests in Mexico and Guatemala

Diploglossidae

Member of Diplossa

Diploglossus: giant alligator lizards in the West Indies and tropical Latin America

Xenosauridae

member of diploglossa

14 species, 1 genus 

Terrestrial

forest dwelling 

Amphisbaenia 

• Members of diploglossa

• worm lizards

• Short tailed, limb reduced, snake-like, burrowers 

• 24 genera, 217 species 

• Worm-lizard 

• Reduced eyes 

• Specialized low-frequency hearing so they can detect vibrations from prey 

• Limb reduction 

• Despite a pattern that might suggest continental drift, dispersal followed by extinction seems to best explain the distribution

Platynota

paranoids and Gila monster

Platynota

• Helodermatidae

• Lanthanotidae

• Varanidae

Helodermatidae

• Members of Platynota

• 1 genus (Heloderma), 5 species 

• Considered to be the only dangerously venomous lizards 

• Gila Monster 

• Large, slow moving 

• Terrestrial, carnivorous, and oviparous 

• May be diurnal or nocturnal

• Heat-loving

Lanthanotidae 

• Members of Platynota

• Sister taxon of Varanidae 

• One genus and species from island of Borneo 

• Found along rivers and streams in rainforest,

• semi-aquatic,

• burrowing,

• carnivorous,

• nocturnal,

• oviparous 

Varanidae 

• Members of Platynota

• Monitor Lizards

• 1 genus, 88 sp 

• Asia, Africa, Australia 

• Includes the world's largest lizard

• Most terrestrial, some arboreal, 1 semi-aquatic 

• Most carnivorous, a few eat fruit 

• May have some development of venom 

• Diurnal, oviparous 

• Mosasaurs 

  • Giant Extinct marine lizards 

Shinisauroidea

• Crocodile lizards

• 1 species, 1 genus 

• Semi-aquatic 

• Carnivorous 

• Viviparous 

• Southeast Asia