Lepidosaurs: Tuatara and Lizards

Chameleonidae (9)

-160 species, over half of which are found in Madagascar -Largely arboreal and insectivorous -Prehensile tails •This functions as another limb that they can use to hang onto branches. It is well suited to their arboreal lifestyle -Zygodactylous •3 digits in one pocket and 2 digits in another pocket -Long sticky tongues •Chameleons are not fast so they use their long, muscular tongue to snatch prey •Sit and wait type of predator -Unusual eyes. They can move their eyes independently of each other •Can rotate one eye forward and one backward to see forwards and backwards at the same time •Or can rotate both eyes forward to achieve binocular vision -Most are oviparous but some are oviviparous •Clutch size is highly variable from 10-100 •No parental care -There is great variability in size -Capable of color change

Dactyloidae (8)

-Anoles -Almost 400 species in the genus Anoles -Primarily arboreal -One of the most common lizards in urban areas -Diurnal -Sometimes called the American chameleon due to its ability to change its color between brown and green -Color change occurs due to stress or aggression. •It is not related to camouflage -Scientists use it as a model for studying courtship and mating behaviors for lizards

Geckos can stick to almost any surface...Explain (5)

-Exception: Teflon, which is what non-stick pans are coated in -Gecko feet are covered in spatula tipped setae. The setae are the hairs and the spatulae are the frayed ends that bond to the surface. -Molecular interactions between the spatula and surface make contact so close that the gecko almost becomes a part of the surface it is attached to -The molecular interactions are complicated and may involve static electricity rather than van der Waals forces -This is important because there are many practical applications to understanding how geckos feet stick

Anguidae (5)

-Fork tongue lizards •Notched/forked tongues are used to orient themselves using chemical detection and subsequent interpretation of positioning of that chemical •Ex: chemical on left side of tongue means that the lizard is positioned to the right of the chemical -Snakes also have forked tongues. Anguidae are different from snakes -Over 100 species -Many are fossorial and limbless -Oviparous and oviviparous

Iguanidae (5)

-Found in the tropical Americas -They are variable in the type of habitat that they live in. They can be terrestrial, rock dwelling, or arboreal -Most are adapted to arid landscapes -Oviparous -Some synapomorphies have been suggested by iguanidae may actually be paraphyletic

Skink tail automization (4)

-Function is to escape predation -When the predator tries to bite the skink's tail it will drop it to 1) shock the predator and stall it to gain time 2)distract the predator because the tail will squirm and resemble the skink and 3) it might also confer an escape advantage because dropping the tail would lead to decreased burden to the skink and with a lighten body weight it would be able to run away faster -It is not good for the skink to lose its tail because it might not grow back -Losing the tail is not painful. The loss of tail is not random, it is lost at a distinct fracture line.

Chameleon color change (4:4,1,1,1)

-Function: thermoregulation and expression •Thermoregulation: will change their color to black when cold to attract heat •Expression: color change is a way to express a certain kind of state Ex: red and orange are associated with aggression Ex: blue and green are indicative of a calm state •So can be used to communicate "emotional" state to other chameleons -Triggers for color change: temperature, light, physiological state •So they do not change color based on their surroundings -There are four basic chromatophores located in the dermis •Erythrophores (red), Xanothophores (yellow), Iridiophores (blue), Melanophores (brown/black) -The chameleons actively tune the spacing between nanoscale crystals to create structural colors of all light spectrum •The color change in chameleons is a lot more complicated, but also a lot more elegant, than researchers previously thought

Lepidosaur basic phylogeny

-Lepidosaurs are the sister group to archosaurs -Lepidosauria: squamata (snakes and lizards) and rhynchocephalia (tuatara) -Archosauria: crocodiles and birds

Varanidae (6)

-Monitor lizards •Ex: komodo dragon -They look similar to lizards in Teiidae due to convergent evolution •Monitor lizards-old world vs. teiidae-new world -Large in size •Komodo dragon is the largest •It can bring down its prey with a single bite •It was previously thought that the komodo dragon killed its prey by sepsis (blood poisoning) due to bacteria in their mouths capable of causing infection •As of 2009, it is known that they kill with a potent venom •Only 2% of lizards produce venom -Most monitor lizards are carnivorous, but not all •There is a fruit eating arboreal monitor lizard -Most lizards can't sustain running •Their running motion compresses the right and left lung alternatively. •So costal ventilation is ineffective while running. Lizards hold their breath when they run. -Monitor lizards use positive gular pumping •The purpose of the gular pump and buccal pump is the same. But in buccal pumping only the mouth expands to create a negative pressure to intake air whereas in gular pumping both the mouth and the throat expand.

How can you tell the difference between skinks and salamanders? (6)

-Skink is lizard vs. slimy salamander is amphibian. Skinks have: -Large head scales -Body scales with underlying bony plates -Roof of mouth made with two flat bony plates -Visible ear -Eyelids

Scincidae (10)

-Skinks -Very diverse group •Over 1,000 species •We study this group because it is so common -Broad range of habitats: forest, desert, grassland -Tend to be terrestrial or fossorial -Most are diurnal -Tend to have short necks and limbs -Skinks resemble the slimy salamanders but these two animals are not the same. -Some skinks use color as a way to distract or frighten predators •Ex: blue tongue skink -Skinks are capable of tail automization. They will voluntarily lose their tail. -Can be oviparous, oviviparous, viviparous

Phyrnosomatidae (6)

-Spiny lizards -Defined by numerous skeletal synapomorphies -Found largely in North America -Preferred habitats are deserts, rocky outcrops, etc. -Characterized by heavy thick scales -Ex: Regal horned lizard can squirt blood from its eye to ward off coyote predators

Squamata (3)

-The squamata and rhynchocephalia last shared a common ancestor 250 million years ago •They have been separated for a very long time -Order includes lizards and snakes -Determinate growth is one of the most important derived characters of squamates

Iguania (9)

-There is a lot of taxonomic uncertainty General Features: -Largely herbivorous and insectivorous -Single row of spines from nape to tip of tail -Five thin clawed toes -Diurnal -Oviparous -Ectothermic -Largely a new world distribution, so North and South America -Dewlap-flap of skin beneath jaw or neck •Can be mobile and brightly colored in some •It is a way of communicating, including mating and to ward off predators

Tuatara unique traits (10)

-They are active at low body temperatures •Reptiles are ectotherms. They do not need to expend their energy maintaining body temperature. -They have a slow metabolic rate •This enables them to operate at a low body temperature -They are nocturnal feeders as adults but feed during the day as juveniles •A nocturnal lifestyle is a means of protecting the juveniles. The adults will eat juveniles of their own kind -They live in burrows that they often share with seabirds •It is easy for them to share with the seabird because the seabird will occupy the location during the day while the tuatara occupies it at night -No external earholes or eardrums •Vs. lizards have a small earhole leading to the eardrum -They exhibit indeterminate growth, meaning that they never stop growing. They will continue to grow as long as they live -They have a parietal eye with a lens, cornea and retina •This eye may function in determining the relative presence/absence of light overhead and thus can be used to infer information about the presence of a predator overhead •The third eye can also be seen when the tuatara is a baby -Feed primarily off insects but are carnivorous and opportunistic -Tuataras have the longest reproductive cycle of any reptile •They produce 5-18 eggs every four years •They typically reach reproductive maturity at 15 years •They can reproduce past 100 years of age -They have two sets of teeth on their upper jaw and a single set of teeth on the bottom •These teeth are fused to the bone •The teeth on the bottom jaw fit neatly into a groove on the top teeth •When it bites, it locks down really hard •The teeth wear away and are not replaceable •No other vertebrate has teeth like this

Amphisbaenidae dental structure (4)

-This is a distinctive trait of amphisbaenidae -Have an enlarged median tooth in the upper jaw -This upper tooth fits into the groove between the two lower teeth -This makes them efficient rippers so they can take chunks of flesh from their prey

Amphisbaenidae skull morphology (6)

-This is a distinctive trait of amphisbaenidae -The individual bones of the skull are all fused, which makes it very sturdy and strong -Functional Categories: blunt, shovel, wedge •Different skulls use different burrowing mechanisms -Lizards with blunt skulls with ram their heads into the end of the tunnel •Tend to live in upper sandy soil that is loosely compacted -Lizards with wedge heads will ram their heads and use their snouth/side of the neck to compress materials into the tunnel wall •Push the soil side to side -Lizards with shovel heads will ram their head then lift their head in order to shovel up dirt out of the way •Shovel up the soil and shove their heads under

Amphisbaenidae skin (3)

-This is a distinctive trait of amphisbaenidae -The skin consists of annuli that are comprised of longitudinal muscles that contract and expand -There are few connections between the body and the skin. When it moves, the skin will move first and the body will then slide within the tube of skin.

Green iguana traits (9)

-This is a type of iguanidae -Arboreal but often found near water -Herbivorous -Diurnal -Excellent eyesight with very sharp color vision -Parietal eye that can't form images but can detect light and movement -Oviparous -20-30 eggs laid per clutch, survival is 35% Survivorship is low because they do not provide parental care -Juveniles will stay in familial groups for about a year

Green iguana anatomical traits (8)

-This is a type of iguanidae -Tympaneum/ear drum -Subtympanic shield -Parietal eye for detecting changes in movement of predators that are located above -Nostril -Dewlap -Dorsal/caudal spines -Tuberculate scales

Gekkonidae (6)

-True geckos -Found all around the world in tropical climates •Over 2,000 species -Unique because of vocalizations -No eyelids •Have a transparent scale that covers the eye. The geckos clean this scale by licking it. •Vs. most lizards have an eyelid and will blink their eye -Some are parthenogenic •Ex: Mourning gecko. All are females and the females will mimic sexual activity to stimulate egg development. It is not truly sex because there is no exchange of genetic material. But the process of pretending to have sex is enough to stimulate egg development and the offspring that are born are clones of the mother. -Can stick to almost any surface

Rhynchocephalia (4)

-Tuatara -Has a single family called sphenodontidae -May be represented by two extant species of tuatara, which are found in New Zealand •Difference between the two species is the color of their spots •Their distribution is highly restrictive because they are only found in NZ -They superficially look like lizards but they are not lizards

Amphisbaenidae (9)

-Worm lizards -Most people have not heard of this type of lizard because they live in the dirt or really close to the ground floor •Have not heard of it despite the fact that it is distributed worldwide •Poorly known group -Highly fossorial, as evidenced by remnants of the pectoral and pelvic girdles -Vestigial eyes -No external ear openings -Carnivorous -Tail can be automized but it does not regenerate -Limbless, except for one species •But not closely related to legless lizard •Losing legs happened 60 different times within squamates •Loss of legs is associated with dense vegetation -Right lung is reduced •Vs. in snakes and caecilians it is the left lung that is reduced •Significance: amphisbaenia is not closely related to snakes and caecilians because the side of the lung that was lost is arbitrary

Lizard lineages of squamates (2)

1) Iguania -Dactyloidae -Phyrnosomatidae -Iguanidae -Chameleonidae 2) Scleroglossa -Gekkonidae -Scincidae -Anguidae -Varanidae -Amphisbaenidae

Anguidae vs. Snakes (6)

Anguidae: -They have fleshy tongues -They have eyelids, which indicates that they have eyes that blink -Many have visible ears •Visible ear is an ear hole/external ear opening -They shed skin in patches -Pattern of ventral scales is different -Can automize their tails as a defense mechanism

Members of the scleroglossa lineage (5)

Gekkonidae-True geckos Scincidae-Skinks Anguidae-Forked tongue lizards Varanidae-Monitor lizards Amphisbaenidae-Worm lizards

Amhisbaenidae distinctive traits

Skin Dental structure Skull morphology