Lizards & Snakes & Tuatara Part I

VERTEBRATE ZOOLOGY (VZ Lecture17 – Spring 2012 Althoff - reference PJH Chapters 13 & 14) Lizards & Snakes & Tuatara Part I

Tuatara, Lizards, & Snakes • = • 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)

Classification • Class:Sauropsida • Subclass: Diaspida • Orders:_______________(Tautara) _____________(Snakes & Lizards)

Amniotes Sauropods Diapsids Lepidosaurs Archosaurs Squamates Snakes Lizards Tuatara Fig. 12-3, p307 PJH

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 tuatara B) 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

Squamates • 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

Iguanidae Agamidae Chamaelondiae Squamates • Two major lineages: Iguania Scleroglossa geckos & skinks _________________ burrowing lizards Check Fig. 13-1, p331 PJH to get a “phylogenetic view”

Lizards from 3 cm (some geckos) to …. Fig. 13-2, p332 PJH

Fig. 13-2, p332 PJH ….to 3 m (Komodo monitor lizard)

Lizards • 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 method b) stalk (systematic searching)

LeglessLizards • 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 body design facilities movement better than a short body with legs California legless lizard glass lizards

Ohio Lizards • broad-headed skink • European wall lizard –introduced in 1951, found only in Cincinnati • northern fence lizard • five-lined skink • ground skink

Five-lined skink • Juveniles have “pronounced” blue tail…. …will lose if attacked to _________________

Lizards & Snakes & Tuatara Part I