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Study Guide Test Two

by: Bri M

Study Guide Test Two BIOL 3030

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Lectures 10-14
Vertebrate Biology
Richard Blob
Study Guide
vertebrate, Biology
50 ?




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This 18 page Study Guide was uploaded by Bri M on Sunday October 9, 2016. The Study Guide belongs to BIOL 3030 at Clemson University taught by Richard Blob in Fall 2016. Since its upload, it has received 136 views. For similar materials see Vertebrate Biology in Biology at Clemson University.


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Date Created: 10/09/16
Lecture 10 - Invading Land ❖ Land and air are different than WATER → physical characteristics ➢ Air is 800x less dense than water ➢ Environment doesn’t support body on land ➢ SKELETON has to take over body support ❖ Air has more 02 than water does which makes it easier for animals to move ➢ Respiration is less energetically expensive ❖ The air temp is much less stable on land than it is on water ➢ Land vertebrates need to THERMOREGULATE ❖ Sensory mechanisms ➢ Sensation of electrical fields is not viable on land like in water ➢ Air movement won’t stimulate lateral line system and it is lost in land vertebrates SO…. not being surrounded by water can account for water loss, and problems in locomotion INVADING LAND: DESIGN ISSUES ❖ Support ➢ Density of body tissue → 1050 kg/m^3 ➢ Density of water → 998 - 1024 kg/m^3 ➢ Density of air → 1.205 kg/m^3 ■ This is about 800x less than WATER ❖ Since tissue density is closest to that of is able to minimize effects of gravity ❖ In water the skeleton serves as ➢ An area for muscle attachment ➢ Menas for transmitting forces throughout the body ➢ This is not necessarily required to maintain body shape ❖ When an animal is on land it requires more support than it would in water because it’s body is less dense than the surrounding environment MODIFICATIONS TO INTERNAL SKELETON IN LAND VERTEBRATES 1. Robust ribs a. Helps to support abdominal organs ( such as digestive tract, heart, and lungs) 2. Changes in girdle attachments (support off the ground) a. Pectoral girdle is detached from the skull (this increases head mobility) b. Firmly attached limb girdles to vertebrae column allows for legs to swing 3. Zygapophyses → the facets between vertebrae a. This helps support the body when it is off the ground (ie walking/running rather than slithering like a snake) AS ANIMALS GET BIGGER, FORCES ON THEIR BONES GET BIGGER AT A FASTER RATE THAN ABILITY TO RESIST FORCES INVADING LAND: Consequences of Size ❖ Accommodating size increases ➢ Relatively more robust skeleton → positive allometry ➢ This is less risky/vigorous activity INVADING LAND: LOCOMOTION AND SUPPORT ❖ Newton’s third law of motion → applies to ALL LOCOMOTION ➢ For every active force there is an equal and opposite reaction force ➢ To move… animals must exert force on their surrounding environment, which exerts a propulsive reaction force back on animals ➢ Ex: ■ Fish use any part of their body to exert forces on it (ex: caudal swimming) ■ Land vert’s make POINT CONTACTS with environment to exert force on it ❖ Land vertebrates use the same structures (limbs) for support AND locomotion ➢ Must be stiff, strong, and flexible ■ Land vertebrates limbs use JOINTED SEGMENTS​ (bones are still; joints allow for mobility) ■ These limbs evolved from SARCOPTERYGIAN FINS with a robust skeleton in which rays were lost ➢ A typical fish fin wouldn't work on land because it’s boy rays are too flexible ➢ A body must be stiff, strong, AND flexible ❖ A fish's body axis movements dominate locomotion ❖ A land vertebrate body axis movements are reduced and limbs become more important for locomotion INVADING LAND: CHANGES IN FEEDING SUCTION ❖ Suction → draw viscous water into mouth, take food in ➢ Most often seen in fish and other aquatic animals ➢ Class example: humans can’t use suction on land ❖ Air is less viscous than water so suction DOESN’T WORK ❖ Land vertebrates must use different strategies ❖ RAM FEEDING​: move head over prey and engulf whole ❖ BITING​: taking chunks out of bigger prey with teeth ❖ Other changes required since water is not brought in with food ❖ Use ​MOBILE, MUSCULAR TONGUE​ to move food around and help swallow ❖ SALIVARY GLANDS​: secrete lubricating fluid, help chemically digest carbs INVADING LAND: CHANGES IN RESPIRATORY FUNCTION ❖ Gills don’t work on land ➢ They are too floppy and delicate - they collapse in air so surface area is covered and can’t extract oxygen ❖ LUNGS WORK ON LAND ➢ Air is less dense than water ➢ This is not so energy costly to breathe into sac and turn around to exhale ❖ Muscle contraction EXPANDS CHEST CAVITY → decreases lung pressure ❖ Muscles relax COMPRESS CHEST CAVITY → increase lung pressure, force air out INVADING LAND: CHANGES IN CIRCULATORY FUNCTION ❖ Higher blood pressure is required on land​ because blood must be pumped vs. gravity ❖ 2 circulatory circuits: ➢ PULMONARY CIRCUIT: ​ heart to lungs, back to heart ➢ SYSTEMIC CIRCUIT​: oxygenated blood from heart to body, return to heart ❖ In fish with gills ➢ They have a TUBULAR HEART that pumps blood to gills blood picks up 02, then goes to rest of body ❖ In land vertebrates with lungs ➢ There are side-by-side pumps ➢ Right side pumps to lungs and returns to heart with oxygen (PULMONARY) ➢ Left side pumps out to body and returns to heart, minus 02 (SYSTEMIC) ❖ Loss of reorganization of blood vessels running to gills (AORTIC ARCHES) ➢ Fish with gills and lungs → ​ ncestrally 6 arches ■ First lost with evolution of jaws ➢ Land vertebrates with lungs only ■ Arch 2 and part of arch 6 are lost with loss of gills INVADING LAND: PREVENTING WATER LOSS 1. SKIN a. Terrestrial verts have epidermis with two layers i. Stratum germinativum (deep, living) ii. Stratum corneum (outermost, dead) 1. Protein and lipid protect against water loss b. Aquatic animals i. Have epidermis and dermis 2. URINARY BLADDER a. Stores urine so doesn’t drain constantly b. Ancestrally probably capable of recovering water to body, as in many modern amphibians and reptiles INVADING LAND: REGULATING BODY TEMPERATURE ❖ Land temps are much less stable than water ❖ Verts must THERMOREGULATE to achieve best level of performance ➢ Avenues for gaining/losing heat: ■ CONVECTION: through air ■ CONDUCTION: through ground ■ EVAPORATION: through water loss only ■ METABOLISM: internally generated (gain only) ❖ HOW TO CONTROL HEAT GAIN OR LOSS ➢ Behavioral - move in or out of hot/cold locations (ie basking in sun) ➢ Physiological - dilation(expansion) or constriction of blood vessels ■ Expanding blood vessels close to body surface allows more blood to flow faster through them and heat up ■ Heated blood travels to body core which warms it up TETRAPOD ORIGINS - LECTURE 11 SARCOPTERYGIANS are osteichthyans that have a robust, skinny skeleton in appendages (fins/limbs) Tetrapodomorpha are united together by sharing a CHOANAE (internal nostril) FOSSIL RELATIVES OF EARLY TETRAPODS (DEVONIAN) ❖ Eusthenopteron ➢ They have a choana but generally retain fish like traits/features ❖ Panderichthys ➢ Lose dorsal and anal fins ➢ Flat body ➢ Fore fin is closer to tetrapod limb than hindlimb ➢ Still looks like a fish ❖ Acanthostega (early tetrapod) ➢ Has dactylus limbs → limbs with digits ➢ Still contains a tail ❖ As evolution and time went on the animals began to look more like what we know as tetrapods ➢ Their limbs used to be all fused together with large bones ➢ As evolution continued the shapes of toes and fingers became more distinct and less connected TETRAPODS SYNAPOMORPHY → have four feet EARLY TETRAPODS ❖ Acanthostega (discovered in Greenland) ❖ They had limbs but… ➢ Retain tail fin rays ➢ Hand and foot polydactylous (7 hind and 8 fore digits) ➢ Gills (blood vessel grooves on arches) ■ Are able to be seen in fossil records that have been found ❖ The first tetrapods were aquatic - tetrapod features are not necessarily for living on land (possible for walking in shallow water or living sometimes on land/sometimes in water) EARLY TETRAPODS AND EVOLUTION OF DEVELOPMENT ❖ Polydactyly in fossil taxa - they conta​ digits NOT ancestral for tetrapods ❖ As the foot develops it starts from the ankle, down to one side of the toes to the other ➢ So as evolution went on...the three extra toes in development stopped EARLY TETRAPODS: CHANGES IN FEEDING AND HEARING ❖ Skull mobility is reduced ➢ Suction is not longer used for feeding (because suction doesn’t work on land) ➢ HYOMANDIBULA changes function, from skull flaring to head ■ It now connects skill to tympanic membrane = eardrum, passing sound waves to the brain ❖ ACANTHOSTEGA (early tetrapod skull) ➢ Flat head, nose, and eyes on top of skull ➢ Looks almost snake like ➢ Hunting in shallows, not surrounded by water so use biting/ram feeding in place of suction (need solid skull to do this) ➢ 1st STAPES big and chunky, vibrate slowly so bad for high pitch (frequency) sounds EARLY TETRAPODS AND THE INVASION OF LAND ❖ Old idea → escape drying conditions of the sea ➢ But tock record from Devonian shows no sign of droughts ❖ New idea → exploration of novel food sources ➢ Other animals (invertebrates) and plants had already invaded land so many vertebrates were just following them ❖ Newer idea → go on land to heat up their bodies more quickly and they are then able to carry heat with them back into the water ➢ Maybe the water temp was very cool EARLY TETRAPOD RELATIONSHIPS ❖ Basal tetrapod diversity ❖ Batrachomorphs vs. reptilamorphs (similar to amphib vs. amniote) ❖ Pre-batrachomorph diversity (lepospondyls) ❖ Representative temnospondyls and origin of modern amphibians (lissamphibians) Basal Taxa Pre-Batrachomorph (Lepospondyls) ❖ BATRACHOMORPHS include most taxa thought of as AMPHIBIANS, distinguished by: ➢ Have flat skill, no kinesis and four or fewer fingers on hand ➢ LEPOSPONDYLS include diverse small taxa ❖ Derived Batrachomorphs = TEMNOSPONDYLS ➢ Many of them were bigger in size ➢ The later survivors were mainly aquatic ➢ They are a GRADE of taxa from which modern amphibian groups evolved ➢ Survived permian, but, except for modern groups, died out in Cretaceous ❖ Basil reptilomorph diversity ➢ Deeper skills, more terrestrial ➢ More specialized for land than earlier animals In Paleozoic World - Contents converging to supercontinent PANGEA - No flowering plants, trees from ferns, horsetail etc, - There was a higher 02 level so bugs/insects grew larger Amphibian Diversity (Part 1) Lissamphibia → modern amphibians Living Batrachomorphs: The Lissamphibia (modern amphibians) ❖ Caecilians - clade Gymnophiona → about two hundred species ➢ They are all limbless (worm looking) ❖ Salamanders - clade Urodela → about six hundred species ❖ Frogs - clade Anura → about six thousand species ➢ They are specialized jumpers Lissamphibia Synapomorphies ❖ Smooth, glandular skin (highly permeable, no armor) ❖ They contain a mucus gland and a poison gland ➢ The mucus gland is closer to the skin and empty round looking ➢ Poison gland is deeper and filled with little dots ❖ All predators have bicuspid, pedicellate teeth Lissamphibians: Bimodal life history (and exceptions) ❖ Amphi means double ❖ Frogs start off as eggs in the water as tadpoles ❖ Then they continue to grow and their tail shortens and legs amerge ❖ They then walk onto land and continue their life as a land vertebrate ➢ This is known as metamorphosis ❖ Direct development ( eggs are laid and out emerges a full formed frog on land) ❖ Paedomorphosis (grown ups retain juvenile traits) CLADE GYMNOPHIONA (CAECILIANS) ❖ Worm looking creatures ❖ Fossil record to jurassic, today they live in tropics worldwide ❖ They are limbless ➢ Smaller than 1 foot and they are specialized for burrowing ■ Highly ossified (solid bony) skulls, their jaws produce high biting forces ■ Reduced eyes, special chemosensory organ (because they live underground) → organ is called a TENTACLE ■ Burrow using their head and they throw their backbone into curves which requires them to have loose skin ■ They have a terminal anus (so when they move along they don’t drag their body in their own waste) ➢ External evidence of segments (annuli), some retain dermal scaled (small) ➢ Many viviparous (live-bearing) young eat the uterine lining of mother to survive ■ Other caecilians lay eggs that the mother protects CLADE BATRACHIA (SALAMANDERS AND FROGS) ❖ SYNAPOMORPHY ➢ Opercular apparatus (not the same as an operculum in fishes) ■ Connects ear to shoulder girdle via opercularis muscle and operculum and columella bones ➢ Let’s animals “hear” ground borne vibrations ❖ Salamanders ➢ Synapomorphies ■ Development traits ■ Recognized by their longer tail (which is a primitive feature) ❖ Frogs ➢ Synapomorphies ■ Saltatory locomotion (this means jumping) SALAMANDER DIVERSITY ❖ Sirens (loose hindlimb, smaller forelimb) ❖ Plethodontidae​ are lungless ❖ Mudpuppies are paedomorphic ❖ Giant salamanders (andrias) → can get about five feet long FROG DIVERSITY ❖ Pipid’s are totally aquatic swimmers ❖ Bufonids are true toads ❖ Hylids are also known as tree frogs ❖ Dendrobatidae are poison dart frogs ❖ Ranids are what you typically think frogs are (they are small and jump far) AMPHIBIAN MUSCULOSKELETAL FUNCTION: Locomotion ❖ Regional specialization of vertebral column: ➢ ATLAS (cervical-neck) ➢ TRUNK (with ribs) ➢ SACRUM (fused to hip girdle) ➢ CAUDALS (tail) ❖ Side to side (lateral) bending is how amphibians walk ➢ They are able to increase their stride length ➢ This kind of walking allows only one lung to work at a time because their leg squishes one of the lungs ❖ Sprawling limb posture AMPHIBIAN MUSCULOSKELETAL FUNCTION ❖ Specializations for jumping in frogs ➢ Short, stiff trunk (no tail) ➢ Short forelimbs but have long hind limbs ■ This means that the tibia and fibula are fused together so that their hind legs can brace the impact ➢ Heavily muscled hind legs for high power production ❖ Arboreal species ➢ TOE PADS ■ Glandular disks at toe tips ; air in grasping, climbing on trees/branches ■ Secrete mucus in order to adhere to different surfaces by using surface tension ➢ INTERCALARY BONE ■ Assists with adhesive force, causes toe pads to be offset from digits (this allows for more surface contact) ➢ Recurved spatulate terminal phalanges (toe bones) ■ These are found in some species (green salamander) without toe pads ❖ TONGUE PROTRUSION ➢ Tongue flips over from the back side of AMPHIBIANS ➢ Tongue is best developed in plethodontidae (lungless) salamanders Amphibian Diversity (Part Two) Amphibian Respiration ❖ Organs include gills, lungs and skin ➢ Cutaneous respiration → gas exchange through moist, highly vascular skin ❖ Most animals shift from gills (when they are larvae) to lungs (when they are adults) ❖ Some adults keep their kills ➢ Known as ​paedomorphs​ (retaining their juvenile traits in their adult form) ➢ Example: blind cave olm, mud puppies ❖ Some adults have no lungs (known as p ​ lethodontids)​ ➢ They rely exclusively on cutaneous respiration ❖ All amphibians can use cutaneous respiration at any stage of their life ❖ Lungs used more at high temperatures and activity (as oxygen demand increases) ➢ Cutaneous respiration isn’t enough to meet needs of salamander ➢ Use VENTILATION ❖ Air moved into lungs (by ventilation) via a FORCE-PUMP MECHANISM ➢ 1. Drop floor of their mouth, buccal cavity because glottis (connecting slit to lungs) is held closed ■ This increases volume of buccal cavity ■ Able to suck air in through coana (internal nostril) ➢ 2. ​Nostrils close,​ floor of buccal cavity rises forcing fresh air into lungs through open glottis ■ 2-a - glottis closes → oscillations of buccal cavity floor clear residual spent air ● Basically just glottis closes ➢ 3. Glottis opens rapidly, chest compressed by body wall muscles and spent air released from elastic recoil of lungs (decrease volume, increase pressure) ■ This moves deoxygenated air out of body ❖ These events are known as VENTILATION CYCLE Amphibian Circulation ❖ TADPOLE STAGE (using gills) ➢ Three sets of VEINS deliver blood to heart​ (right atrium/auricle) ■ ANTERIOR CARDINAL (jugular) from ​head ■ VINTELLINE from ​gut organs ■ POSTERIOR CARDINAL from ​rest of body ➢ Heart pumps blood out through: ■ EXTERNAL CAROTID ARTERIES to head (leaving heart) ■ AORTIC ARCHES 3-6 to gills and rest of body (only four arches in tetrapods) ❖ Adult stage (using lungs) ➢ FOUR sets of VEINS deliver blood to heart​ (3 to right atrium) ■ ANTERIOR CARDINAL (JUGULAR) from head ■ HEPATIC from gut organs (via liver) ■ POSTERIOR VENA CAVA from rest of body ➢ PULMONARY VEIN from lungs (going to heart from lungs and skin) ■ This is specific to adults ➢ Arch 4 (like aorta) is called dorsal aorta ➢ Arch 5 is lost ➢ Arch 3 is internal carotids ➢ Arch 6 supplies blood to lungs and skin = PULMOCUTANEOUS ARTERIES Amphibian circulation - 3 chambered heart ❖ Has two atria and one ventricle ❖ WITH LUNGS ➢ Left and right atrium ➢ Deoxygenated blood enters heart in right atrium (blue) means no 02 ➢ Blood flows into ventricle ➢ Blood pumped out through aorta ■ Going to lungs via pulmocutaneous arch ➢ SPIRAL VALVE → in aorta it keeps blood flow to lungs and to body separate ➢ Oxygenated blood returns to heart via LEFT ATRIUM ■ Now ventricle pumps oxygenated blood to rest of body ➢ When lung is being used, the heart and ventricle contains both oxygenated and deoxygenated blood ➢ The blood flow, for the most part, are separated by their different direction of flow ❖ WITH CUTANEOUS RESPIRATION ➢ All blood in heart is ALL OXYGENATED ➢ No flow into left atrium ➢ Spiral valve doesnt channel anything to lungs, it just goes out to body to supple body with oxygen ➢ BLOOD CIRCUIT ■ Skin → right atrium → ventricle → aorta → body ■ RIGHT ATRIUM IS CUT OUT Amphibian water uptake and regulation of water loss ❖ WATER UPTAKE ➢ Amphibians do ​not​ drink water ➢ Rapid uptake through highly vascular patch of pelvis ski​ ELVIC PATCH) ​ ■ Allows use of very shallow water resources or limited ■ Little pools of dew → animal sits in it and soaks it up ➢ Urinary bladder ■ Collects urine from opisthonephros, stores a​ llow water reabsorption ❖ PREVENTING WATER LOSS ➢ Some tree frogs (like Phyllomedusa ) secrete lipids(fats) from skin and spread over body with legs ■ Helps make skin less permeable ➢ Posture change (behavioral mechanism) ■ Body facing up if it’s wet ■ Body hunkered down if it’s dry (this saves more than 20% of water) ➢ Desert frogs may live underground except in the rainy season Amphibian Skin color - CRYPSIS AND APOSEMATICS ❖ Skin helps animals to hide or to stand out ❖ Crypsis skin color ➢ Skin patterns (color or bumps) tha​ onceal animals​ to hide from predators or prey ❖ Aposematic patterns ➢ Bright coloring to advertise toxicity Amphibian reproduction and development ❖ FERTILIZATION - different modes in main groups ❖ CAECILIANS - use internal fertilization ➢ Male inserts organ into female and deliver sperm ❖ SALAMANDERS - a few external, most INTERNAL and SPERMATOPHORE (sperm packet), not intromittent organ ➢ Spermatophores deposited by males, collected by females utilizing cloacal lips kept in cloacal sacs ➢ Other species males hold female and insert spermatophore with feet ➢ Sometimes female picks up sperm and holds onto sperm for weeks or months and only allows fertilization to occur when external environment is optimal ❖ FROGS - mostly external, accomplished via AMPLEXUS ➢ Amplexus is the name of the position (male on top of female) and can go on for hours ➢ Male grabs female with forelimbs and fertilizes eggs as they are laid ➢ Amplexus maintained for house, male forelimb muscles grow huge from hormonal release ❖ COURTSHIP - males convincing females to allow mating ➢ SALAMANDERS males may apply pheromones, abrade with teeth, or v ​ isual display ➢ FROGS - ​calls​! With LARYNX and throat inflation, males call to attract females ■ Downside - energy cost, attract predators too ■ Upside - males with long calls have tadpoles that develop faster ● This advertises “good genes” to females ❖ EGGS AND YOUNG ➢ Eggs often deposited in the nest, sometimes guarded by female ➢ Eggs deposited on back of female in some species ■ Hatch as free tadpoles or froglets (pipids) ■ Mother carries babies (hylids, dendrobatids) ❖ Gastric brooding frogs ➢ Mother swallows fertilized eggs and 6-7 weeks later, gives birth THROUGH MOUTH to young ➢ Mother doesn’t eat or produce gastric juices during this period ➢ Both species who did this are now extinct ❖ STANDARD TADPOLE DEVELOPMENT ➢ 3 Stages of metamorphosis ■ Growth ■ Emergence of hindlegs ■ Emergence of front legs and regression of tail ➢ Process mediated by ENDOCRINE SYSTEM ■ Pituitary gland secretes thyroid stimulating hormone (TSH) ■ Thyroid gland secretes THYROXINE, stimulation metamorphosis ➢ Final metamorphosis stage must be rapid since legs and tail together impede jumping and swimming, increasing vulnerability to predators ❖ TADPOLE DIVERSITY ➢ Different feeding habits of tadpoles show corresponding specialization of the mouthparts ➢ Some species have multiple tadpoles morphs ■ E.g. spadefoot toad and herbivore and carnivore morphs in temporary pools ➢ Carnivore may eat herbivores sibs, ensuring that some frogs metamorphose and escape ponds ❖ GLOBAL AMPHIBIAN EXTINCTIONS AND DECLINES ➢ Extinctions and declines have increased dramatically through the past 20 years Origin of Amniotes What are amniotes? - Non-amphibian tetrapods - Continued independence from aquatic habitats - Ex: tortoise (sauropsids), cat/humans (synapsids) Amniote Synapomorphies ❖ Amniotic Egg​ (and amnion membrane) during reproduction ➢ Each embryo surrounded by f ​ our extraembryonic membranes ■ Egg develops in mother (in groups that don’t lay eggs) ➢ Surrounded by shell, or retained internally, resistant to drying out ➢ Unlike amphibian, reproduction NOT TIED TO AQUATIC HABITATS ■ Most amphibians have to go back to water to lay their eggs ■ Now they have reproductive freedom ❖ Parts of the membrane ➢ AMNION ■ Forms fluid filled sac that cushions the embryo ➢ YOLK SAC ■ Connects to the gut tube, provides nutrients to embryo ■ It’s functional role in vertebrates ➢ ALLANTOIS ■ Connects to end of gut tube, sequesters wastes ➢ CHORION ■ Outer membrane (against shell), aids gas exchange ➢ SO… now we have an embryo that has nutrients, a way to get nutrients, a place to store waste, and protection around the outside of embryo Distinctive Aspects of Amniote Function ❖ ASTRAGALUS ➢ New borne in ankle that provides articulation between hindleg and foot ➢ Astragalus is a single bone in the ankle (most bones fused together) ➢ Instead of 6 or 7 not strongly connected bones...not there is one strongly connected ➢ What does it do? ■ New connection between foot and hindleg ■ ONE STRUCTURE ❖ 2 or more SACRAL VERTEBRAE ➢ Pelvis is attached by two vertebrae (OR MORE) ➢ In amphibians it was connected only by one ➢ This makes for an increased stability for locomotion on land ❖ COSTAL (rib mediated) BREATHING ➢ Contraction of muscles between ribs (intercostals) pulls them out and forwards, aids breathing in INSPIRATION ■ This increases volume in chest cavity ■ Decrease pressure = suck air in (costal breathing) ➢ Different from amphibians because… ■ Amphibians → force-pump used body muscles for exhalation, not inhalation ■ Amphibians squeezed air out ❖ TRACHEA (windpipe) ➢ Tubular connection to lungs through long nec​ inforced with cartilage rings to prevent collapse ➢ This is needed because air coming in from nose/mouth has a longer path to travel (through the neck) to arrive at the lungs ■ Trachea is needed to keep air “safe” and non infiltrated Amniote Phylogeny ❖ MAJOR BRANCHES ➢ Sauropsids​ (reptiles) and​ ynapsids​ (mammal and fossil ancestors) ➢ Birds are a special kind of reptile (in sauropsids) ■ When talking about reptiles as a clade YOU MUST INCLUDE BIRDS ■ If you are talking about a grade you don’t have to include birds AMNIOTE PHYLOGENY ❖ Major groups of amniotes distinguished by holes in skull (TEMPORAL FENESTRAE) ❖ SYNAPSIDS ➢ 1 fenestra surrounded by 3 distinct bones: postorbital(po), jugal(j), squamosal(j) ❖ SAUROPSIDS ➢ Anapsids have 0 fenestrae ■ Primitive (not a synapomorphy) ➢ Diapsids have 2 fenestrae ■ This IS a synapomorphy ■ Upper fenestra surrounded by : Parietal, postorbital, squamosal ■ Lower fenestra surrounded by : postorbital, squamosal, jugal, quadratojugal ● THESE ARE NOT THE SAME AS BONES THAT SURROUND THE FENESTRA IN SYNAPSIDS ● Temporal fenestra evolved INDEPENDENTLY IN SYNAPSIDS AND DIAPSIDS Why temporal fenestrae? ❖ Hole in skull of roof allo​ igger jaw closing muscles​ to spread onto skull roof, increasing bite power ❖ In SYNAPSIDS ➢ Jaw muscles don’t just stop at inside of the wall, they move over and attach ON THE TOP of the skull ❖ In humans, muscles attach on sides of skull (FEEL YOUR HEAD WHEN YOU CHEW) Many differences between sauropsids and synapsids 1. Method of increasing locomotor stamina 2. Lung structure 3. Skin structure 4. Excretory system 5. Sensory perception and brain structure ❖ Method of increasing locomotor stamina ➢ Ancestral pattern of lateral bending interferes with breathing ■ Only one lung inflates at a time → this decreases stamina ➢ SAUROPSIDS (bipedality) → walking on two feet (back feet) ■ No more conflict when bending the body and breathing ● You can inflate both lungs at the same time ■ In dino’s (and birds), removes conflict by removing trunk motion from locomotion ■ Cros, monitor lizards, use different methods ■ Many sauropsids still experience low stamina ➢ Synapsids (upright posture and flex back up and down) ■ Inflate both lungs at the same time, compress both lungs at the same time ■ Diaphragm (muscle sheet diving lung cavity from abdomen) ● Diaphragm contracts when you inhale (can increase volume in lungs) ● Diaphragm isn’t in conflict with using your legs ● Contraction aids inhalation, no locomotor conflict ❖ Lung structure ➢ Typically greater internal surface area than amphibians, but achieve this differently ➢ Sauropsids ■ FAVEOLAR LUNGS ● Single branches to common space with chambers off that space ● Looks more structured ➢ Synapsids ■ ALVEOLAR LUNGS ● Repeated branching to tiny chambers (alveoli) ● Alveoli are random placement ➢ Both achieve increase in internal SA ■ They independently evolved → but both work just as well ❖ Skin structure ➢ Both have ALPHA keratin protein, but differing skin structures ultimately affect social and reproductive behaviors ➢ Sauropsids ■ Unique ​BETA variety of keratin​ forms hard surface of scales, ultimately contributes to feathers ■ FEATHERS ARE JUST SPECIALIZED SCALES ➢ Synapsids ■ No beta keratin (so no feathers/scales) ■ Hair forms from​ ALPHA KERATIN ■ Glandular skin secretions include sweat and MILK ■ Direct maternal care (with milk) may explain why care by males is rarer in synapsids than sauropsids ➢ Excretory System ■ Different nitrogenous waste products and locations of water conservation ■ Sauropsids ● Waste → ​URIC ACID​ (solid but mostly liquid) ● Travels through short tubules to BLADDER where the acid precipitates as solid and water is then reabsorbed ● Many sauropsids (sea birds, turtles, sea snakes) have additional salt excreting glands in face/tongue ● Penis NOT urinary, only intromittent organ ■ Synapsids ● Waste → ​UREA​ (stays dissolved in liquid urine) ● Water content of urine regulated in nephron, through long LOOP OF HENLE, where water extraction depends on hydration of body ● No water absorption in bladder ➢ Sensory perception and brain structure ■ Retina cell types ● ROD: broad sensitivity ● CONE: sensitive to particular light wavelengths (color perception) ■ Sauropsids ● Strong vision, weaker smell ● Good color vision (rods AND cones) ● Optic tectum large in brain ■ Synapsids ● Most have strong sense of smell, weaker vision ● Poor color vision (some 2 cone types, primates 4) - possibly passed through nocturnal phase in evolution ● Small optic lobes, visual processing performed mostly in cerebrum


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