Lizards & Snakes & Tuatara Part I

VERTEBRATE ZOOLOGY (VZ Lecture17 – Spring 2012 Althoff - reference PJH Chapters 13 & 14)

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• Lizards ~4,800 species

• Snakes ~2,900 species

• Tuatara 2 species (both in New Zealand)

• Predominately terrestrial…but some aquatic, semiaquatic (particularly among snakes)

• Outer layer of ___________ is shed at intervals

• Tuatara = 4 limbs, Lizards reduction or complete loss of limbs evident among some species, Snakes all are limbless

• Cloacal slit is _________________ (all others have longitudinal cloacal slit)

Tuatara, Lizards, & Snakes

• Class: Sauropsida

• Subclass: Diaspida

• Orders:

_______________ (Tautara)

_____________ (Snakes & Lizards)

Classification

Fig. 12-3, p307 PJH

AmniotesSauropods

Diapsids

Lepidosaurs ArchosaursSquamates

Tuat

ara

Liza

rds

Sna

kes

Tuatara…• Sphenodontids = “wedge tooth”

• Thought to have emerged in the Triassic (~250 MYA)…similar to turtle lineage

• Early on, thought to be very diverse group:terrestrial, arboreal, and marine forms…and insectivores and herbivores

• Two dental “arrangements” early on:A) teeth fused to top edges of jawbones

(acrodont)….status for extant tuataraB) teeth attached to inner sides of jawbones

(pleurodont)….similar to some lizards

• Two rows of upper teeth, one row of bottom teeth create unusual bite/mastication combination

Tuatara…

• Tuatara is Maori for “spines on the back”

• Before human “intervention”, tuatara found on both north and south main islands of New Zealand… now restricted to 30 small islands off the coast

• One species, Sphenodon punctatus, is doing “ok” and has been under protection since 1895

• 2nd species, S. guentheri, was not “recognized” until more recently…only ~300 adults known living on 1.7 hectares (~4 acres)

• ~ 60 cm long, are nocturnal, mostly feed on seabirds

• Squamata = “scaled”

• Exhibit determinate growth (like birds, like mammals)….growth occurs in the cartilaginous epiphyseal plate region of long bones until epiphyses fuse to shafts of bone

Squamates

• Two major lineages: Iguania Scleroglossa

Squamates

IguanidaeAgamidaeChamaelondiae

geckos & skinks_________________burrowing lizards

Check Fig. 13-1, p331 PJHto get a “phylogenetic view”

Fig. 13-2, p332 PJH

Lizards from 3 cm (some geckos) to ….

Fig. 13-2, p332 PJH

….to 3 m (Komodo monitor lizard)

• Most are small lizards are insectivores…some highly specialized (for example feeding only on ants)

• Many species are arboreal (ex. Chameleons)aided by a) zygodactylous feet (grasp)

b) prehensile tail

• Like many salamander species, chameleon’s tongue & hyoid apparatus are specialized to permit projection of tongue more than length of body to capture insects….combined with good eyesight (eyes can move independently)

Lizards

• Most are large lizards are herbivores…notable exception would be the monitor lizards

• Monitor lizards the exception, also, in that they can sustain locomotion and extended activity with a gular pump that assist the axial muscles…

they can use hunting methods much like some mammalian predators:

a) ambush methodb) stalk (systematic searching)

Lizards

• Believed that significant ________________ has evolved >60 times among lizards a) every continent has species that are

either legless or nearly legless b) usually associated with dense grass or shrubbery where slim, elongate bodydesign facilities movement better than a short body with legs

LeglessLizards

California legless lizard glass lizards

• broad-headed skink

• European wall lizard –introduced in 1951, foundonly in Cincinnati

• northern fence lizard

• five-lined skink

• ground skink

Ohio Lizards

Five-lined skink

• Juveniles have “pronounced” blue tail….

…will lose if attacked to _________________