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VERTEBRATE ZOOLOGY
(VZ Lecture17 – Spring 2012 Althoff - reference PJH Chapters 13 & 14)
Lizards & Snakes & Tuatara
Part I
Tuatara, Lizards, & Snakes
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• Lizards ~4,800 species
• Snakes ~2,900 species
• Tuatara 2 species (both in New Zealand)
• Predominately terrestrial…but some aquatic,
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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
Fig. 12-3, p307 PJH
Tuatara…
• Sphenodontids = “wedge tooth”
• Thought to have emerged in the Triassic (~250
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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
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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
Squamates
• Two major lineages:
Iguania
Scleroglossa
Iguanidae
Agamidae
Chamaelondiae
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
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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
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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)
Legless
Lizards
California legless lizard
glass 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 body
design facilities movement better than
a short body with legs
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
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