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71 Cards in this Set

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When did reptiles originate?

Late Carboniferous period (300mya)

Why did reptiles originate?

Expansion of insect orders due to increasing quantity and diversity of vegetation created a potential food source for a carnivorous vertebrate

What is the Age of Reptiles?

Extensive radiation of reptiles when they dominated life on land


Jurassic-Cretaceous, lasted 165my

Changes associated with life on land

Lungs and internal nostrils for breathing air


Increased efficiency in vascular system


Loss of gill and opercular bones


Impermeable skin to avoid dessication


Strengthened skeleton


Improved locomotory muscles


Limbs replace fins


Mobile neck

Reproduction

No aquatic larval stages


Miniature adults born


Eggs used to a greater or lesser extent

Cleoidoic/amniotic egg

Key step in making reptiles independent from water


Contains food and protective membranes for supporting embryonic development on land

What 3 main needs of the embryo must a terrestrial egg meet?

Prevention of desiccation


Exchange of respiratory gasses


Disposal of excretory products

Oviparity

Occurs in most reptiles and all birds


Eggs deposited in soil or nest


Exchange water and gases with environment


Sometime there is maternal care (birds-always)


Young are independent at birth (birds-need care)

Reptile eggshell

Low calcium -> soft, flexible, permeable to water


Eggs usually deposited in damp soil and grow during incubation at rates dependent on temperature


Temperature of incubation may determine the sex of the hatchling

Bird eggshells

Shell has higher calcium -> hard, impermeable to water


Eggs usually incubated at constant warm temperatures by parents

Ovoviviparity

Some lizards and snakes


Eggs are retained in oviduct but are nutritionally self-contained


Yolk sustains the embryo rather than food from the mother, exchange water and gases with mother


Born live

Viviparity

Some lizards and snakes


Shell never forms


Eggs retained in oviduct


Yolk size is variable


Young receive some nutrition from the mother


If large amount of nutrition are required a placenta forms to enable exchange of materials between mother and embryo

Fertilisation

Need to be internal


All extant reptiles except tuatara have an intromittent organ, either a single penis of a paired hemipenes

Jaws

Jaw muscles enlarged and arranged for better mechanical advantage

Kinetic skull

Hinges at front and back of skull


Allow skull to change shape, better potentialto manipulate prey once caught, allows skull to bend producing a large gape

Skin

Tough, dry, scaly -> prevention against desiccation and injury


Few glands


Keratinised scales

Keratinized scales

Derived from epidermis


Not homologous to dermal fish scales

Crocodile scales

Remain throughout life


Gradually grow

Lizards and snakes

Scales are periodically shed

Turtles

New layers of keratin are added under platelike scutes

Circulation

3-chambered heart


Right atrium is partitioned from the left


Complete ventricular separation in crocodiles


In others flow patterns prevent mixture

Respiration

Gill slits present only in embryos, never functional


Suck air into lungs by enlarging thoracic cavity, snakes and lizards use rib cage, turtles and crocodiles move internal organs


Cutaneous respiration is not used


No muscular diaphragm

Water conservation

Have a metanephric kidney


Many have slat glands near nose and eyes to excrete salts


Nitrogenous waste excreted as uric acid - easily precipitates out of solution, conserves water

Strengthened skeleton

Skeleton well ossified


Rib with sternum forming a complete thoracic basket


Limbs paired, usually 5 digits


Adapted for climbing, running or paddling

Reptilian limb design

Most modern reptiles walk with splayed legs and belly close to the grounds


A few modern lizards and most dinosaurs walked on upright legs

Nervous syste

Relatively large cerebrum


Connections to the central nervous system are more advanced permitting more complex behavior


Lateral line organs lost


Sense organs well developed

Ectothermal thermoregulation

Gain or lose heat by convection, conduction, evaporation or metabolism

Behavioural thermoregulation

Movement between shade or sunlight


Orientation - parallel to perpendicular to sun


Colour change

Reptile skull

Generally higher and narrow than in amphibians


Number of bones is reduced

Fenestrae

Openings which allow jaw muscles to enlarge and bulge out


Edges of fenestrae are attachment sites for those muscles

Anapsid skull

No fenestrae


Earliest reptiles - order Cotylosauria


Turtles and tortoises - order Testudines

Synapsid skull

1 fenestrae high on cheek


Subclass Synapsida


All synapsids are extinct except for the mammals

Euryapsid skull

1 fenestrae high on cheek


Subclass Icthyopterygia


Subclass Euryapsida

Diapsid skull

2 fenestrae, 1 low 1 high


Subclass Lepidosauria


Subclass Archosauria

Order Cotylosauria

Originte from labyrinthodont amphibians


Carboniferous to Triassic

Order Testudines

Triassic to present


Emarginated skull


Horny beak, no teeth


Heavy body armor for protection - have long mobile neck which can be withdrawn into shell by bending in S-shapes, breathe by thoracic pumping, limb movement, or cloacal respiration

Order Pelycosauria

Synapsid


Generalised reptiles


Trends toward mammalian features


Quadrupedal


Heterodont teeth

Order Therapsida

Hervorous forms - reduced or no teeth, horny beak


Carnviorous forms transitional to mammals

Subclass Icthyopterygia

Fish-reptiles


Marine


Extension of the finger bones to support fins


Homodont teeth on long beak-like skull


Viviparous

Subclass Euryapsida

Order Protosauria: lizard-like terrestrial reptiles


Gave rise to Sauropterygies: amphibious or fully marine

Subclass Lepidosauria

Order Eosuchia


Order Sphenodontia


Order Squamata

Order Eosuchia

Extinct order


Lizard-like, quadrupedal, terrestrial, aquatic


Thecodont (socketed) teeth


Fully diapsid skull

Order Sphenodontia

Fully diapsid skull


Acrodont teeth (fused to jaw)


No intromittent organ in male

Order Squamata

Bodies covered with horny epidermal scales


Teeth acrodont or pleurodont


Reduced diapsid skull


Kinetic skull

Suborders of Order Squamata

Mosasaurs


Lacertilia


Ophidia


Amphisbaenia

Suborder Lactertilia

Lizards


Infratemporal arcade lost


Terrestrial, arboreal, semi-aquatic


Geckos, iguanids, skins, chameleons


Moveable eyelids


Ears not usually important


Can live in arid conditions

Geckos

Small, agile, mostly nocturnal


Toe pads to allow climbing

Iguanids

Often brightly coloured with ornamental crests

Skinks

Elongated bodies

Chameleons

Arboreal


Accurate sticky tongue

Suborder Ophidia

Both arcades lost, also sternum, pectoral girdle and sacrum


Highly skinetic skulls with symphysis of jaws - each operates independently when swallowing prey


Elastic skin


No secondary palate but trachae can extrude from mouth to breathe while swallowing


One lung


Sperm storage



How do snakes hunt?

Hunt prey chemically - olfactory, Jacobsen's organs


Flick tongue transfers scent particles to Jacobsen's organs in the mouth

Suborder Amphisbaenia

Highly specialised burrowers


Lack external limbs


Solid skull used for digging


Feed on invertebrates

Subclass Archosauria

The ruling reptiles


Many large and bipedal


Thecodont teeth in some, horny beaks in others


Oviparous


Five orders, order Order Crocodilia surviving

Order Crocodilia

Largely unchanged since early Mesozoic


21 surviving species


Three families - alligatores and caimons (Americas), crocodiles (widespread), gavials (Burma)


Elongate robust skull


4 chambered heart


Complete diaphragm


Aquatic

Order Thecodontia

Lizard-like or crocodile-like


Tendency to bipedalism

Order Pterosauria

Flying reptiles


Keeled sternum


Wings supported by elongated limb bones


Elongated skull


Homodont or absent teeth


Long tail for stability


Slender legs


Excellent gliders,weak fliers

Two main dinosaur lineages

Order Saurischia


Order Ornithischia

Order Saurichschia

Triradiate pelvis


Suborder Sauropoda: quadrupedal, amphibious, herbivores


Suborder Theropoda: bipedal, terrestrial, carnivores, ancestors of birds

Order Ornithischia

More complex tetraradiate pelvis


All large and herbivorous


Both bipedal and quadrupedal forms


Suborder Ornithopoda - duck billed dinosaurs


Suborder Stegosauria - armoured dinosaurs


Suborder Ankylosauria - armorued dinosuars


Suborder Ceratopia - horned dinosaurs

Characteristics of NZ reptiles

Isolated and small


Relatively fe groups


16 extinct orders



What are the living reptile orders in NZ?

Tuatara


Squamates


Marine turtles


Marine crocodiles

Order Crocodilia in NZ

21 species worldwide


Australia salt-water crocodile may sometimes wander nto NZ water

Order Testudines in NZ

Three species are found in NZ waters: Leathery turtle, Pacific loggerhead turtle, green turtle


Hawksbill turtle and Olive Ridley turtle occasionally visit

Order Sphenodontia in NZ

Only species in Sphenodon punctatus


Restricted to 32 islands


Most of STephen's island

Suborder Ophidia in NZ

Until recently illegal in NZ

3 species of sea snakes in 2 families



Suborder Lactertilia in NZ

About 100 extant species - geckos and skinks


High diversity


Equal in diversity to endemic land birds


Many species per genus


High local diversity


Great antiquity


Many species now restricted to islands


High habitat diversity


High longevity


Highly philopatric


Omnivorous

Family Gekkonidae in NZ

Viviparous in NZ unlike in the rest of the world


Non-vocal unlike in other areas

Family Gekkonidae characteristics

Geckos


Large eyes


Transparent scales


Distinct diamond-shaped head


Skin soft, loose, matt


Vocal

Family Scincidae characteristics

Skinks


Skin firm and tight


Scales flat, shiny, overlapping


Head not differentiated from body

Conservation of NZ lizards

Reduction in number and extinctions due to introduced mammals

Many species restricted to islands


Habitat modification and destruction


Deforestation


Largest species are extinct


Nocturnal species more vulnerable