Lecture 19 and 20 Notes
Lecture 19 and 20 Notes 81463 - BIOL 3030 - 001
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This 16 page Class Notes was uploaded by Abigail Towe on Thursday November 5, 2015. The Class Notes belongs to 81463 - BIOL 3030 - 001 at Clemson University taught by Richard W. Blob in Fall 2015. Since its upload, it has received 16 views. For similar materials see Vertebrate Biology in Biological Sciences at Clemson University.
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Date Created: 11/05/15
Review: Dinosaurs = two major groups = Ornithischians + Saurischians ● orinthisicna hip pointed backwards ○ “bird-hipped dinos” ● saurischian - pubic bone points forward ○ “lizard-hipped dinos” Asteroid hit and killed most dinosaurs. The Aves (birds) survived. Birds are part of the theropod lineage of dinosaurs. Theropods are the meat eating lineage ( T. Rex). Recognize that birds are part of the lizard-hipped dinosaur lineage. Birds are part of Saurischians! The name ornithischian was named after what is seen in birds- because they do look like birds. But birds are traced back to saurischian lizard- hipped dinosaurs. so birds but not bird-hipped dinosaurs. Birds---- Clade Aves Theropod Dinosaurs include birds (saurischians) ● The features that unite birds with theropod dinosaurs are FEATHERS ○ they have downy feathers ○ microraptor had complex feathers on forelegs and hind legs. implying that it used all appendages for gliding- but probably not flapping all 4 limbs at same time. but from evolutionary standpoint, the features were actually present in a wide range of animal species in the theropod lineage well before birds. ○ so feathers are not unique to only birds ● But the features that distinguish birds from theropod dinosaurs: 1. birds have a shorter tail a. it has less than 25 vertebrae 2. their feet has a fully reversed hallux a. hallux = big toe b. so they have toes forward and then their hallux is pointed backwards ● These two qualities are different from theropods that have a long tail and forward big toe ○ Archaeopteryx was the specimen analyzed for bird, while Deinonychus was observed for theropod non-bird specimens. ■ Deinonychus - used the forward big toe to dig and injure prey further. Additional specializations of modern birds to allow flight: A closer look at feather construction: ● feathers are a special type of integumentary body covering ● feathers are made from mostly Beta keratin ● made up of: ○ shaft- central structure that includes= rachis + quill ■ it’s long and tapering ○ quill - “calamus” ■ it’s the basal (bottom) portion anchored to skin ■ this portion is hollow and cylindrical ○ rachis - solid, squarish ending portion ---- supports parallel branches ○ barbs - the parallel branches that comes off of the rachis ○ barbules - they come off each bar and interlock of the barbules - helps produce continuous surface on either side of rachis ○ vane - the collection of bars that interlock and form a continuous surface on each side of rachis ■ function: ● provide flight surface to make for a aerodynamic structure that allows flight ● sheds water ● protects against sun Feather types: ● ● Contour- form outline of body ■ large firm vane ■ downy base ○ primary flight feathers - grow off the hand ○ secondary feathers- grow off the arm (making up the base of the wing close to the body) ○ primary + secondary = flight feathers and covers body and tail ● down = small, fluffy layer found beneath and between contour feathers. The bars do not interlock so they can trap air-- this provides insulation. ○ rachis is shorter than bars ● semiplumes- loosely webbed contour feathers. ○ has loose vane, rachis is longer than bars ○ helps to insulate body and aid in buoyancy of water birds ● bristles- vaneless feather, consist only of shaft ○ filter dirt near eyes and nose ○ also has tactile sensory function ○ filoplumes- hairlike feathers ■ lack vane ■ mainly shaft ■ widely distributed ■ found between contour feathers ■ function: decorative and sensory ● in addition to have nerve supply, they can serve as tactile receptor structures (sort of like whiskers) because they stick out from body ● feathers are plates?? ○ they are replaced through molting - replaces old with new Bird foreflight specialization: ● bones are hollow/air-filled (neumatic) ○ reinforced with internal struts ○ the hollowness is pneumaticity ■ this is ancestral from theropods ■ however, birds add to this condition - they had the internal struts to add stiffness of bones. so light weight but allows bone to withstand forces from flapping in flight ■ this condition is lost in diving birds because they want to be heavy so they can dive well. so they lose the pneumaticity and have thicker, denser limb bones Skeletal features of derived birds: 1. has keel on sternum a. it’s like a keel of boat (large keel) b. serves for origin of pectoralis muscles i. muscles of chest that when they contract they pull limbs toward midline to flap in air (downstroke) 2. synsacrum - fusion of previously separate pelvis bones of sacrum a. function: absorbs impact forces of landing from flight 3. pygostyle- the defining shortening of tail that occurs in modern birds a. the short fused tail → helps with reducing drag b. functions to reduce tail feathers, thus reducing drag 4. the collar bones (clavicles) - in birds they are fused into a single U-shaped structure = furcula a. this structure makes a spring in the bird's chest b. so when they flap their wings, they create energy c. helps to save energy in upstroke d. energy is stored in the U-shaped furcula e. keep in mind that bone doesn’t like to be bent against it’s shape so it will naturally want to go back to normal position 5. uncinate processes on ribs - a. function: allows consecutive bones of ribs to overlap i. keeps the bones stiff and stable so that they don’t roll while they move ii. stiffens tunk for stability iii. compresses length of trunk, overlaps ribs to make it more solid and prevent side to side movement. 6. several bones in arms and legs that fuse together (from previously separate centers) a. serves to add stability b. in the forelimb- the bones of wrist and hands fusese down to one bone (carpometacarpus) c. in hindlimb- bones of ankles (tarsals) will fuse onto bones of foot (metatarsals) to be a single bone (tarsometatarsus bone) i. also: tibiotarsus = fusion of tibia and tarsus (ankle) 7. reduction of total number of digits in hand (we have 5, birds have 3 digits) ● indirectly to flight, the impact of this structure is more related to terrestrial locomotion. so tail is short to reduce drag, birds walk with their trunk pointed down (looking at down) and their thigh bone is horizontal (forwards). ○ if thigh were not pointing forwards, if it was straight up and down.. it would place all the weight in front of hips. not advantageous for survival because it would ?? ○ so now the weight is shifted to counteract gravity ● birds pick up their feet, they are picking up their knee (whereas we move our hips??) ● the thigh is located really high so when a bird walks they just pick up their knee and move their ankle 8. large acromion - it’s a process that comes off of shoulder ● it’s enlarged in birds ● forms shoulder joint ● forms channel that runs through the junction of 3 bones - these form the triosseal canal ○ bones: scapula, clavicle, and ?? How flight works: ● the pectoralis muscle powers the downstroke ○ it’s exactly in the part of the body where you think it’s located based on its function ○ origin: keel ○ insertion: humerus ○ so when in contracts- it pulls humerus toward midline to produce midline ● supracoracoideus powers upstroke ○ another ventral muscle ○ this muscle is deep to pectoralis muscle ○ so it’s located below the wing- but trying to pull the wing up…. how do you pull the wing up when the muscle for that is located below it? ○ the supracoracoideus is connected to tendon ?? ○ the acromion acts like a pulley and takes the force ?? ● all of the muscles for wing are located below wing ○ so it saves their energy to allow them to fly in a straight, level line. ○ it's a stabilizing and energy-saving feature ○ archaeopteryx had these structures too, so it’s believed they had flight also ● the muscles that make up flight are the light and dark meat you eat. ○ the color difference is related to the myoglobin ■ lots of myoglobin = use aerobic respiration - used for behaviors that require endurance . dark meat muscles ■ little myoglobin - anaerobic - used for quick bursts of activity- tire quickly and experience high fatigue. white meat. ○ birds that tend to fly long distances (like for migrations) have mostly dark meat muscles. ○ birds that only run/fly to escape (chickens) have mostly white meat muscles to allow burst of flight) If a bird uses flight then they need to have respiration specializations ● flight demands efficient oxygen extractions ● air sacs are holding chambers without gas change ○ they are just location where air is held ○ they functionally allow birds to achieve unidirectional flow of air through respiratory system ■ different from humans ■ this is functionally advantageous for birds- you prevent mixing of stale and new air. ● this mixing occurs in any animal, including humans, with bidirectional flow ○ air sacs allow unidirectional flow by doing 2 cycles of inspiration and expiration cycles. ○ air sac - lung expansion/ compression coupled with wingbeats ○ ○ air -- trachea - posterior air sacs - then exhaled and goes to lungs where oxygen is pulled out of air ○ ○ ???? 51 mins ● cross-current exchange - allows blood to extract more oxygen from air ○ every blood vessel is low in oxygen, so each can extract it from air even as oxygen gets depleted ○ rather than paring one oxygen containing vessel with one blood vessel--- the oxygen vessel runs through where many blood vessels run perpendicular to allow all of them to extract oxygen as it passes through the vessel. ● also: they have a 4 chambered heart to prevent blood from mixing Excretory system specializations: ● NO urinary bladder! that’s just more weight that isn’t needed that hinders flight. ● so waste is excreted as uric acid (white paste) Reproductive: ● females only have 1 ovary ● males have gonads regress inside of them so that they don’t have excess drag when they aren’t needed How flight works: the mechanics ● flight = thrust and lift ○ forwards directed thrust and stay aloft in the air ○ so they need to produce forces in two directions - forward and upward ● they generate these two forces by using their surrounding environment (air) to use reaction forces ● how to produce upward lift: ○ partly do to downstroke of wings ○ primary reason of light is due to airflow over wing ■ bird wings have particular shape: cambering ● wing is convex on top ● longer distance for fluid to travel ● upper surface is convex, under surface is concave ■ the difference of air flow because of the convex/concave sides of wings decreases pressure to generate a lift ■ a couple of ways to add to advantage of that shape: they tip their wings to increase angle of attack ● this improves lift until it rotates past 15 degrees - this creates a stall because this angle causes turbulence ● so there are structures found in birds that reduce possibility of turbulence of birds- ○ one of these is slotting (alula) on wing leading edge smooths flow, prevents stall ○ second way: there is slotting between tips of feathers ● how to produce thrust: ○ wing orientation determines reaction force orientation ® ○ flexible wings twist toward tip ■ at base of wing, there is little twisting of wings. the natural reaction force is mostly going to point upwards to generate lift (almost a little bit of backwards) ■ but as you go out towards tip of the wing and rotate the wing and slope it downwards - it helps you to generate forward thrust ● lift is generated from base of wing ● forward thrust is generated from end of wings Wing shape and flight function ● different wing shapes suited for different types of flights ● wing shape is compared using aspect ratio (AR) = length / breadth ● types: ○ dynamic soaring- high AR ■ glide in high-speed sea winds ○ elliptical wings- low AR ■ short of maneuvering in woods ○ “high aspect ratio wings” ■ high speed foragers, swept back ○ high lift: for static soaring (rising thermal air currents) - vulture, hawks, eagles has slots that reduce turbulence and stall at slow speeds ● video clips: ○ flamingos- very high AR ○ hawk- example of soaring behavior. has slotting on tips. no motion of wings- mostly soaring. ○ penguin - uses underwater flight to swim. flaps wings. uses forewings to propel itself ■ do not have webbed feet so that’s why they use flight Flight in birds- migration ● birds fly for many reasons but one of the most impressive - migration ○ the birds that fly so far ● migrations allow use of season resources and avoid temperature stress ● to prepare for stress of journey birds acquire 10x fat deposits ● save energy through formation flying & traveling with wind (so the actual flight path that they use) ○ so maybe take longer journeys just to go with the wind, instead of flying against the wind ● birds find their way around by navigation using multiple cues (sun position, odors, magnetic fields) ○ this gives them multiple avenues to find their way, especially if one cue isn’t available ○ so if it’s cloudy or night time, they can use cues other than the sun Review: ● last time we observed the flight of modern birds. Now we are going to look at origin of birds from theropod dinosaurs, and look at evolution of past behaviors. Understand where birds came from and diversity of modern birds. And look at over specialized features besides having wings for flight. Birds are highly specialized theropod dinosaurs. ● How do we know they emerged from theropod lineage? ○ united by evidence of feather structures in some theropod lineages. ■ lineages range from: Ceratosaur (oldest) to Allosaurus (close to T. Rex) to Deinonychosaur (velociraptor) and archaeopteryx to modern bird (pigeon) ○ beyond that one feature, there is also evidence such as: ■ between deinonychosaur and archaeopteryx: emergence of feathers ■ chances in the pubis: rotated backwards (instead of forward): this starts in Deinonychosaurs and is complete in modern birds ■ in animals after deinonychosaurs, the carpal bones start to solidify into one big bone (similar to half moon shape) called semilunate carpal. ● this chances nature of movements that are possible ■ also as early as allosaurus we see a reduction of fingers (3 finger hand that is typical of modern birds) ■ starting with allosaurus the clavicle is fused, referred to as furcula. ● important for flight. however, the early lineages used it but not for flight. their body size/weight didn’t support flight (too big/tall) Archaeopteryx and the Evolution of Flight ● Archaeopteryx found in - Limestones -found lagoon, shallow water, marine setting- because such fine rock it allows exquisite detail of preservation. animal buried in sediment with low oxygen so it preserves soft tissue features and other details. FEATURES: • Well-formed flight feathers • S“ill has “ee“h ( ● however, teeth are lost in modern birds • Hand s“ill has dis“inc“ fingers, claws ● now, fingers are not distinctive. • Fea“hered “ail long ● tail is still long. reduced number of vertebrate than velociraptor. but still more vertebrate/ longer tail than modern bird. • Long legs legs were longer than modern birds. but shorter than velociraptors. SOME QUESTIONS • Did †Archaeopteryx use powered flight? → PROBABLY could! Probably not the fastest/best. (at least short distances) • Reasons s”ppor“ing “ha“ “hey probably had powered fligh“: Asymmetric feathers (good for flight) Wing as large as modern (weak) fliers Some enlargement of sternum some development of keel on midline that allows attachment of large pectoralis muscles to pull down wing = allowing powered flight Wing shape differs from living/modern gliders rather than using gliding behavior, wing shape implies powered flight instead Advanced morphology for upstroke morphology: large acromion and triosseal canal • Did fligh“ evolve from▯gro”nd-”p▯ (from r”nning “hen “ake a s“ep ”p “o fligh“) or ▯“rees down▯ which is gliding? → SOME EVIDENCE FOR GROUND UP • Evidence no“ ”niversally accep“ed… I“’s based on “wo fea“”res: ● Ances“ors ran & lived on gro”nd so i“ doesn’“ make sense for “hem “o climb trees ● Some modern birds flap & run to take off ○ many large birds use this method of running to gain enough momentum to have flight ■ exame: allpostrosts Evolution of Flight: ● Ken Dial - experiments in Montana (2003) ○ noticed that parchis of various sizes (even babies) run and then take a right turn and run up hay bale surface, while flapping wings during this, and then start flight ○ he filmed high speed video of birds running up side of treatment to measure acceleration to determine force and the direction of the force from the wings at various steps. ○ ABCE force of wing is applied to ground ■ so the reaction force is coming up off of ground to help gain lift (upwards movement) for flight ○ even baby birds use same behavior to generate lift vectors/forces. ■ this proves that even not fully developed wings could have worked to fly Early Fossil Bird Lineage: Enantiornithines includes specimens: Sinornis and Protopteryx diverse lineage that were distinctive for number of reasons: ● FEATURES ○ Many species, long duration lineage (whole Cretaceous) ○ Diverse habits: waders, & terrestrial ( first perching birds) ○ World-wide: China, Spain, Alabama, Argentina, Australia ○ Growth lines in bones - could be from a possible low metabolism ■ if you look at cross-section of limb bones- you can see lines from where the bone grows, stops, leaves a line, and then starts growing later again. ■ seasonally grow s“ar“s. and when i“’s advan“ageo”s for having growth again, it starts again ■ flying requires a lot of energy- high metabolic behavior- so do these birds have low metabolic rate that causes them to have growth lines? ● two species of Enantiornithines that both had teeth: Hesperornis and Ichthyornis ● Hesperornis ○ no keel → less flying ○ bigger feet → more swimming ● Ichthyornis ○ very strong keel on sternum ○ deposits found in near shore ■ early gull based on habits Modern Birds: Neornithes (new birds) ● start on clade after Hesperornis and Ichthyornis ● includes paleognaths and neognathae ○ gnathic - ▯jaws▯ ○ neo- new ○ paleo - old ○ so the species differ with their new and old jaw , specially the palate of the mouth ● neognathae- united by having paleognathous palate that unites them with most modern birds ● paleognaths- including flying tinamous and secondarily flightless ratites (ostrich, emu) Paleogna“hs: ▯Ra“i“es▯ + “inamo”s ● Ratites - flightless ○ ostrich in African ○ Rhea in South american ○ Emu - Australia ○ Kiwi - New Zealand ○ Cassowary - Australia and New Guinea ■ dis“inc“ive species beca”se i“’s an aggressive species “ha“ ”ses claws to kick/claw ○ their diverse locations reflect that they could have been together in gondwana, then split up with the landmass split up ○ reduce wings and keel of sternum ○ strengthens legs for running ● tinamous: flies ○ has 47 species ○ smaller body size (living birds) Neognathae: ● the other 9550 living birds ● Key points to know: 1. chickens and ducks (Galliformes and Anseriformes) are the basal lineage among the neognathae 2. who is related to passerines? who is not a passerine? a. passerine = songbirds/ perching birds i. these are the most diverse clade of birds b. who is most closely related to passerines? i. sister taxa: parrots (Psittaciformes) c. a few highlights of diverse habits: i. different swimming modes: penguins ii. novel behaviors and cartoons: cockatoos iii. funky fossils: doves ● diversity: Pelicans, Penguins, and Grebes ○ all highly aquatic, but use different structures to swim ○ Clade Pelicaniformes ■ includes: pelicans, boobies ■ uses webbed feet ■ boobies: don’“ have “hroa“ po”ch, b”“ “hey have drama“ic color pattern (red or blue of feet) ● toes are completely webbed so they use their feet as paddles ○ Clade Podicipediformes ■ includes: Grebes ■ has lobed feet (so not completely webbed) ● each toe has individual enlargements ● also used for paddling ○ Clade Sphenisciformes ■ includes: Southern Hemisphere ■ penguins only in south pole, polars bears only in north pole ■ penguinis do not swim with the feet (no webbing) - they have enlarged wings that are used to maneuver in water ● Diversity: Woodpeckers and Cuckoos ○ Clade Piciformes: Woodpeckers ■ has zygodactylous feet (some point forward, some point backwards) ● woodpecker has 2 toes backwards, 2 point forwards ■ they have a shock absorbing skull - helpful to bang head on tree to get grub/food out ■ has tongue protrusion - allows tongue to insert inside hole they make to get bugs out ○ Clade Cuculiformes: Roadrunners and Cuckoos ■ Road Runners: fast runners ■ Cuckoos: ● exhibits nest parasitism ○ female lays egg in nest of another species for a different mother to hatch . ○ so the cuckoo egg hatches first, is larger- and ends up moving the other eggs out/ or underdeveloped hatched young out ○ Host species inadvertently rears baby cuckoo; own young often starve ○ Diversity: Pigeons and Cranes ■ Clade columbiformes: doves and pigeons ● dodo (Raphus) was a pigeon ○ dodo found off coast of madagascar. flightless. round bird. walked on ground. no native predator. in 1500s, they became easy source of food and for fun, sailors started capturing them - they were 150 po”nds and co”ldn’“ really r”n away. ■ Clade Gruiformes: Cranes ● has long-legs - allowed for fast running ● but fossil cranes = giant killers of death ○ 3 meters tall, better than person ○ jaw forces that could crush bones and extract the marrow ○ distributed from south america to florida ○ two clades: Phorusrhacidae (older fossils) and Diatryma (younger fossils) ■ Large (phorusrhacids up to 3 m), carnivorous, flightless ■ long limbs - active running predators; heavily reinforced skulls - prevents bone crushing ■ May have occupied niches of modern large mammalian carnivores Bird Specializations: Feeding! ● no teeth → but diversity of beak and bill ○ the various shapes allow for variety of different foods for diet ● beak/bill= extended jaws covered in keratin ● feet gasp and kill items and the beak is used to tear off/eat prey ● Ibis bill - has probe bill to get in between rocks ● hummingbird pill has probe bill to get into feeder or flower ● heron - has beak used for stabbing ● puffin-fish and parrow has tall beak to allow for cracking nuts ● swan and flamingo- flatten bill - filter small invertebrates out of water ○ unique: flamingo puts head upside down to filter that way ● cranial kinesis: extra mobility of skull & jaw bones - allows greater range of prey ○ example: snipe ”ses jaw as pinches wi“ho”“ opening i“’s mo”“h. moves tip of mouth. gives birds better range of motion for jaw to kill prey. Bird Specialization: Digestion: ● Crop - holding sac ending esophagus for quickly gathered food, moistens & (sometimes) ferments it ○ birds don’t have teeth so not a lot of oral processing. so after food is gathered rapidly and swallowed after only being moistened. it ends up in crop. ● Gizzard - no teeth, but modified stomach holds swallowed rocks to grind food (also in other archosaurs) ○ muscular chamber in stomach that holds small pebbles to muscular churn food that is rapidly gained. mechanically grind the food down. Bird Specialization: Sensory System - Vision is important because flight demands vision. Birds have excellent vision because: 1. they have big eyes a. example: owl has huge eye (bigger than humans) 2. large optic lobe (control system of visual signals) a. if you compare bird brains to crocodile, the optic lobe is larger in bird. so i“’s rela“ively larger compared “o body size. ● interesting fact: many birds sleep with 1 eye open at a time. so only half of brain is resting at a time. rotates resting halves of brain. - Hearing- ● with smaller heads- it makes it harder to localize where the sound is coming from because before they would time how long it takes the sound to travel from one side of head to another. ● skull asymmetry- amplifies differences in sound perception from left and right side. allows them to localized the exact location of sound. ● important for nocturnal animals like owls that rely on sound, rather than vision. Bird Specialization: Social Systems and Reproductive system ● Courtship (and other) displays can involve sound (song), dances, and bright colors ○ existence of color as a signal is very often (a bright orange/red color) that is derived from molecules called carotenoids that are obtained through diet. ○ so if you have more carotenoids, you have a more/greater diet. so that means be““er heal“h. so “ha“’s what you are showing off to potential mate. this is an honest signal. ● SOCIAL MONOGAMY ○ Most common system, both sexes care for clutch ○ even “ho”gh i“’s monogamy, mos“ ma“e o”“side of pair : EXTRA-PAIR COPULATIONS ■ one benefit is: helping to spread reproduction investment over many nest. ● incase theres a disaster, you have young everywhere. ● RESOURCE DEFENSE POLYGAMY ○ one sex has regularized matings with other sex ○ Polygyny (>1 female) : one male mates with all females in territory with food, or prefered nesting locations. mates with females in territory to use resources. ○ Polyandry (>1 male) : females mate with several males, each controlling a nest site ■ females visit the multiple nest sites to distribute their risk across the locations. ● in birds, sex is determined by genetic ○ unlike crocs, which gets sex by temperature (Temperature sex determination) ○ females have the two different chromosomes (ZW) ■ females are heterogametic ZW ○ males are ZZ (homogametic) ● incubation in nests: ○ some species have single nests ○ but some have colonies for protection ■ example: seabirds ● once the eggs hatch, chicks are between two extremes of life: ○ primitive - precocial young - rarely can fly, can move around, feed themselves ○ derived condition: altricial - defenseless, need protection, no feathers, need care from parents ■ derived- so wha“’s “he advan“ageo”s? ● maybe not advantage. altricial species are smaller in body size- so maybe mothers cannot give enough yolk to be larger body size to be more developed. so they then have to keep nesting their babies. ● evolved as a consequence of evolution of smaller body size. so to balance the smaller cost of eggs (smaller eggs) than they have a greater cost of taking care of young after they hatch.
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