-
Names some basic qualities of turtles
- Similar morphology since the Triassic (250 mya)
- All turtles have shells
- All turtles lay eggs
- All turtles lack parental care
- Most are very long-lived
- In many species, sexis determined by nest temperature
- 13 extant families
- 300 species
- Have a beak, not teeth
-
Describe the shells in the
Pancake tortoise -
Box Turtle -
Pond Turtle -
Soft-Shelled Turtle -
Snapping Turtle -
Tortoise -
- some hinged plastrons to close shell openings
- low, streamlined carapace
- light, reduced ossification
- small plastron, more agile
- night domed shell
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The main lieages that divided turtles is neck morphology when retracted. Name and describe them.
- Cryptodires ("hidden neck") - bend neck into S shape. This occurs in most turtle species - however none in Australia
- Pleurodires ("side neck") - bend neck horizontally. Only found in the Southern hemisphere today.
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Describe the Carapace
- They develop from ribs and vertebrae
- ribs are external to girdles (unique amony vertebrates)
- dermal bone of carapace -
- - 8 plates on dorsal midline fused to neural arches (neural bones)
- - 8 pairs of costal bones on either side fused to ribs
- Leatherback sea turtles have carapace made of cartilage with thousands of small bones within
- In pleurodires, the pelvic girdle is fused to the carapace
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Scutes
- epidermal horny plates that cover the bones of the carapace
- Soft shell turtles lack scutes and ossified peripheral bones
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Discuss the Plastron
- Some of the plastron derived from clavicle and interclavicle
- some tortoises and box turtles have hinged plastrons so that the shell can be closed
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Discuss Turtle Vertebrae
- Only 8 elongated trunk vertebrae
- Centra are fused
-
Turtles cannont breathe through expansion of rib care like other reptiles. Describe how they do breathe.
- Contraction of posterior muscules
- - transverse abdominus
- - reduces visceral cavity, pushes air out
- - (similar to mammalian diaphragm)
- Contraction of abdomial oblique (pelvic) and serratus (pectroral) i
- -increase visceral cavity, expands lungs
- Aquatic turtles exchange oxygen and Co2 in water through pharynx and/or cloaca
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Describe Nesting Behavior of turtles
- Oviparous (lay eggs)
- shells are either soft and flexible or hard
- Development takes 40 - 60 days
- some diapause over winter (arrested development)
-
What are the environmental effects on turtle eggs
- Temperature, humidity, and oxygen can affect development
- in many species, sex is determined by egg temperature with 3 -4 degrees C (same nest can vary)
- higher temp produces larger sex (in turtles, usually female)
- selection - fitness of a sex should be higest at temperature produced
-
Discuss Hatchlings of turtles
- hatchlings are independent in some species (sea turtles), eggs are buried deep in sand hatchlings hatch and dig out together high predation rate as many nest usually hatch at once
- Hatchlings navigate by
- -light - lighest sky at night is over ocean
- -Wave direction - initially swim against the waves
- - magentism - tells turtles not only direction by latitude - how to avoid going to far north or south
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Breeding and Migration of turtles
- For pond turtles, local knowledge is probably enough
- Sea turtles can feed and nest throusands of miles apart
- -tutles mate offshore, then females go ashore to lay eggs
- -Return to natal beach to nest
- -Chemosensory cues (smell increases as get closer
-
Conservation of tutles
- Large tortoises and sea turtles most at risk
- - long life spans plus threatened habitats
- Large tortoises live on small uninhabited (by humans) islands
- - little competition for resources, predation
- Turtles for food - probably about 12 million yearly in China
- (also eaten in USA as turtle soup, much less common now)
- Pet trade - smuggled exotics from madgascar, or within the USA
- - endangered turtles more expensive
- Road Kill
- Loss of Habitat
- target pratice/other unnecessary deaths
-
Stupendemys
- South America
- Pleciocene
- 5 - 6 mya
- carapace more than 2 m long
-
Mata Mata - long necked "snake neck" turtles
- Family Chelidae
- Up to 40 cm long
- South American Freshwater
- Skin folds for camouflage, sensing motion
- Glups food
-
Leatherback Sea Turtle
- Family Dermochelyidae
- Skell reduced to bony platelets in connective tissue
- more than 2 m long, 600 kg
- wide geographic distribution
- dive up to 1200 m deep
-
Turtles
- Class - Reptilia
- Order - Testudines
-
Turtles in Culture
- Symbols of longevity, patience and wisdom
- Important to creation myths (World Turtle)
-
Family Testudinidae
- Tortoises - land-dwelling turtles
- lack of webbing on toes
- short legs
- usually herbivorous
- warm climates
- only 4 rear toes
-
Aldabra Giant Tortoise
- Family Testudinidae
- Dipsochelys dussunieri
- variety of habitats - forest, swamp, and beach
- tortoise turf - coevolved plant species mix eaten by tortoises
- up to 150 cm, 250 kg
- crepuscular
-
crepuscular
active at dawn and dusk
-
Red-eared slider
- Family Emydidae (box and pond turtles)
- Trachemys scripta
- Widespread, new world northern hemisphere
- quiet, mud-bottomed water, good basking spots
- sleep underwater
- up to 30 cm
-
Box turtle
- Family Emydidae (box and pond turtles)
- Terrapene carolina
- North America
- often near ponds, but also woods and meadows
- hinged plastron
- up to 18 cm
- small home range of 250 m diameter
- omnivorous
-
Alligator Snapping Turtle
- Family Chelydridae (3 species, including 2 snapping turtles)
- Macrochelys temminckii
- large heads, limbs cannot be fully retracted
- around large bodies of water in southeastern/middle US fresh water
- 11 -13 years for maturity
- worm-like protrusion on tongue to lure prey
-
Lepidosaurs
- Includes Tuatara, Lizards, Snakes
- a group with Class Reptilia
- Largest group of reptiles
- 4800 lizard species, 2900 snake species, 2 tuatara species
- usually terrestrial and tetrapod
- scaly waterproof skin
- -outer layer shed at intervals
- Sister taxa of archosaurs (crocodilians and birds)
- Two sister groups with Lepidosaurs
- 1. Lizards and snakes = Order Squamata
- - snake loss of limbs = derived trait
- 2. Tuatara = Order Rhynchocephalia
- Major groups had evolved by end of the Jurassic (approx. 150 mya)
- Two major lineages:
- 1. Suborder Iguania includes iguana, collared lizard, chameleons, anoles
- 2.Suborder Scleroglossans skinks and gekkos, amphisbaenians (burrowing lizards), serpentes (snakes)
- Tuatara is Maori for "spines on back"
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Discuss determinate growth in Lizards
- also found in birds and mammals
- in contrast to turtles and crocodilians
- Growth occurs until epiphyses of bones ossify
- A derived trait
- - may be adaptation to diet of small prey
-
Basic facts about Lizards
- most adult lizards weight less than 20 grams
- most adult lizards are insectivores
- - some are extremely specialized
- --ex. horned lizards feed solely on ants
- frequently diurnal, but some (like geckos) are usually nocturnal
- many species are arboreal
-
Easten Fence Lizard
- Family Phrynosomatidae (Iguania)
- Sceloporus undulatus
- most of eastern USA
- eggs double in size after being laid
- active during the day
- males exhibit head bobbing & push up territorial display
- eat mostly arthropods, inc ants
-
Anolis Lizard
- Genus Anolis, various species
- complex territorial and mating displays
-
Iguana
- Family Iguanidae
- herbivorous like most large lizards
- Green Iguana (Iguana iguana) native to central and S America, invasive to Florida, Hawaii
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Marine Iguana
- Family Iguanidae (Iguana)
- Amblyrhynchus cristatus
- Galapagos islands
- probably arrived 10 mya
- unique diving iguana up to 10m
- aggressive at low temps
- black to absorb heat
- at risk from cats and dogs
- nasal gland to excrete salt crystals
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Tuatara
- Order Rhynchocephalia
- sister taxa to squamata (~ 200 mya split)
- diverse during Mesozoic
- only 2 species remain
- first protected reptile species (1895)
- 1 species lives on 30 small islands off new Zealand,
- - to be re-established in New Zealand
- common tuatara, Sphenodon punctatus
- 1 species lives on 1 island,
- -being re-established on several more
- Brothers Island tuatara Sphenodon guntheri
- lack external tympanum of lizards
- -(no eardrum, no hole)
- lack paired, evertable hemipenes (vs. squamates)
- --paired reproductive organ usually inside vent
- nocturnal
- can support low active body temps
- bask during day
- 60 cm long
- diet: mostly invertebrate, some seabirds
- nest in burrows with seabirds
- arthropods attracted by bird refuse
- males and females are territorial
- - vocal & behavioral displays
- - displays: throat puffing, stiffen spines open mouth and snap jaws
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Cranial Features of the Tuatara
- enlarged row of teeth along palatine on maxilla side
- --double row on upper jaw (like some snakes)
- acrodont teeth: fused to top edge of jaw, sharp bone projection, no sockets (like many lizards)
- heterodont teeth: more than one type of tooth
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Discuss the Parietal Eye of the Tuatara
- "third eye" on top of skull
- cornea, lens, retina
- nerves to brain degenerated
- visible in hatchlings, later covered by scales
- covers pineal gland (melatonin)
- chronobiology:
- - circadian rhythms (sleep/wake)
- seasonal rhythms
-
Tuatara Conservation
- in Holocene (10K ya to present) widely spread in New Zealand
- loss of habitat due to Maori 1000 ya, then European arrival rat & dogs as predators
- trampled by cattle
- mature at 12 -15 years,
- - females only reproduce every 3-4 years
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Amphisbaenians
- Order Squamata
- Suborder Scleroglossans
- several families of worm lizards within this suborder
- specialized
- fossorial = diggers
- usually legless, 3 species have forelimbs
- highly modified skull
- bodies with annuli (rings)
- Amphi (double)
- baen (walk)
- skin is loose around body
- can back up in tunnels as easily as move forward
- loss of legs independent of snake limb loss
- remnant of pectoral and pelvic girdles
- median (middle) tooth in upper jaw
- distribution: tropics, southern hemisphere
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Mexican Mole Lizard
- Family: Bipediae
- Bipes biporus
-
Anoles
- Class Reptilia
- Lizards and snakes = Order Squamata
- Suborder Iguania
- Genus Anolis
- inhabitat many islands of the Caribbean,
- - including Hispaniola, Puerto Rico, Jamaica and Cuba
- independently colonized islands over 25 mya
- evolved multiple species on each island
- display head bobbing and dewlap flapping
- females prefer displays of own species
- - used for identifying correct species in mating?
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Ecomorphology
- Ecomorphology = study of relationship between ecology and morphology
- Ecomorph = ecologically equivalent species similar environment may lead to similar forms examples of convergent evolution
- Ecomorphs based on preferred microhabitat
- - distantly related species may physically resemble each other more than closely related species
- Traits that vary by ecomorph include
- body size and shape
- head size
- limb length
- density of toe lamellae (toe pads)
- diet
- selection experiments by moving anoles to new habitats
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Covergent Evolution
- organisms that are not closely related evolve on similar evolutionary lines
- due to response to similar adaptive pressures
-
Anole Ecomorphs
- trunk-ground have longest legs for sprinting and jumping
- twig morph is small and slender
- grass-bush ecomorph have slender bodies but long tarsi and metatarsi for grasping narrow surfaces
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Snakes
- Class Reptilia
- Order Squamata
- Suborder Serpentes
- 2,900 species worldwide (except Anatarctica)
- 10 cm – 10 m
- loss of limbs is derived trait
- None retain pectoral girdle
- Some retain part of pelvic girdle = vestigial limbs
- Probably originally evolved from burrowing lizards with reduced eyes
- forked tongue for chemosensation (Jacobson’s organ)
- Earliest known snakes from Cretaceous 112 mya
- most snakes also have:
- lost pelvic girdle
- single carotid artery
- very moveable skull
- reduced or absent left lung
- right kidney anterior to left kidney
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Titanoboa cerrejonesis
- largest known snake ever
- 60 mya
- 42 feet long (12 m)
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Snake Motion
- 1.Lateral undulation: curves can be very fast
- 2.Rectilinear locomotion: alternate sections lift off the ground waves of contraction slow but in a straight line
- 3. Concertina locomotion: accordion-like used in burrows
- 4. Sidewinding: body loops swung forward primarily in desert snakes where substrate is slippery
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Komodo Dragon
- Scleroglossa
- the largest monitor lizard
- infectious bite
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Parthenogenesis
- Greek for "virgin birth"
- The ability of a female to produce offspring withoutmale genetic contribution (fertilization)
- Most commonly known in squamates
- Evidence in sharks as well
- Probably more common than known
- genetic testing in non-sexually dimorphic species
- Offspring identical genetically to mother
- Every individual in a parthenogenetic species can reproduce = double the reproductive output of a bisexual species useful in areas of severe habitat loss/disruption
- Long-term problem: lack of recombination, lower rate of adaptation
- Occasional sexual reproduction would help
-
Whiptail Lizards
- Genus Cnemidophorus
- includes many parthenogenetic species usually result from hybridization (interspecies breeding)
- clonal population = genetically identical
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Desert Ecotherms
- Low densities of plants -> low densities of insects
- large differences between night and day temperatures
- temperature extremes moderated underground
- burrowing as an adaptation
- Most desert vertebrates are small (low energy in system)
- tortoises are the largest
- - shallow summer burrows for day
- - deep winter burrows for hibernation
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Chuckwalla
- Order Squamata
- Desert Iguanine
- nasal salt gland for excretion
- obtain water from plants
- water can also be produced as a metabolic by-product (metabolic water)
- in winter, hibernate in rock crevaces
- in spring
- - bask much of day
- - eat annual plants (new growth)
- - early spring annual plants have lots of water
- in summer
- - annual plants withered, eating perennial plants (less water, tougher)
- - weight & water loss active only once a day
- - stop eating in July—only bask briefly every 2 or 3 days, hide in crevices otherwise
- by October, weight is 37% less than in early spring
- combat water loss in summer, early fall:
- - stop eating, become inactive -> slower breathing -> less water loss through respiration
- also less loss through excrement
- rock crevices have higher humidity
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Desert Amphibains
- careful use of microhabitats (small locations within the habitat with a slightly more favorable condition)
- most time spend underground
- temporary aquatic environments during rainy season
- (puddles & pools)
- rapid amphibian development
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Spadefoot Toad
- underground burrow September – July
- at end of rainy season (Sept.), burrow is more moist than toad, -> water gradient into toad
- when soil and toad are = in water, toad stops excreting urine and retains urea,
- increasing osmolality of toad -> can absorb water from almost dry soil
- egg-to-metamorphasis in under 3 weeks
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Freezing Ecotherms
- endotherms (mammals & birds) produce metabolic heat & insulate
- ectotherms have two strategies:
- - synthesize antifreeze
- - have freeze-damage resistant tissues
- increased osmolal concentrations lowers freezing point
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Freezing Ecotherms - Fish
- supercooling: body water remains unfrozen below freezing point
- crystallization of water molecules avoided by lack of nucleating agents that hold molecules in structure
- antifreeze compounds: found in vertebrates, invertebrates, plants
- also prevent water molecules from orienting to crystal structure often glycoproteins
-
Freezing Ecotherms - Reptiles
- supercooling, osmolality that resists freezing
- some turtles have a skin barrier that resists ice crystals
- inc. lipid layer under a layer of keratin
-
Freezing Ecotherms - Frogs
- 1)buries deeply in mud or hiberates to avoid freezing temps
- 2) freeze toleration in tissues
- can tolerate freezing of extracellular fluids
- molecules to resist intracellular freezing
- tolerate ice content of 34 -48 % glucose or glycerol in cells to avoid freezing anaerobic metabolism in cells
-
Body size and Shape of Ectotherms
- ectothermic metabolism is low compared to endothermic
- require less energy
- most ectotherms are small
- endothermy is expensive at small sizes, ectothermy is not
- high surface area/mass ratios means more heat exchange
- - dorso-ventral flattening
- less than 10% of endothermic energy goes to growth/biomass rest is to maintain temperatures
- 30 -90% of ectothermic energy goes to growth/biomass
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The Mesozoic Era
- 251- 65.5 mya
- Triassic, Jurassic, and Cretaceous Periods
- 240 mya - Pangaea
- 120 mya - Laurasia and Gondwana
- Diapsids include - dinosaurs, crocodiles and birds
- - also extinct pterosaurs "winged lizards", ichthyosaurs "fish lizards", plesiosaurs "nearly a lizard", placodonts "tablet teeth"(marine reptile (iguana -like))
- Forms evolved multiple times
- - ex. several different lineages of armored quadrupeds like stegasaurs
- difficult to resolve evoltuionary relationships
-
Discuss the Triassic Period (not including vertebrates)
- 251 - 200 mya
- hot and dry, little glaciation even at poles
- adaptive radiation following the Permian Extinctions
- modern corals
- ferns, gymnosperms (conifers, cycads, gingkos)
- shift from ferns to conifers in late Triassic -> changes in tetrapods
- very low atmospheric oxygen = hypoxic
-
Vertebrates of the Traissic Period
- Archosaur reptiles
- - many extinct dinosaurs
- - living examples are birds and crocodilians
- herbivorous vertebrates up to about 1000 kg (2200 lbs)
- mostly small-bodied
- almost no arboreal vertebrates
- pterosaurs "winged lizards" —first flying vertebrates!
- first sphenodontids (related to tuatara)
- first mammmals
- first dinosaurs, turtles, crocodiles
- extinction of some mammal-like reptiles (tidal ventilation)
- radiation of archosaurs (related to crocs and birds, some unidirectional airflow probable)
-
Jurassic Period (200 - 145 mya)
- The Age of Reptiles—rise of dinosaurs
- Fish and marine reptiles are the major vertebrates
- - ichthyosaurs "fish lizard", plesiosaurs "nearly a lizard", crocodiles
- radiation of plankton (marine animals’ diet)
- Archosaurs remain important
- - first salamanders & caecilians
- lizards and modern amphibians
- earliest bird (Archaeopteryx)
- giant herbivorous sauropods (over 50,000 kg)
- how did plants sustain them?
- - high C02 = high plant growth
- By end of period, all modern tetrapod groups have evolved
- - inc. frogs, salamanders, lizards, snakes, turtles, crocodiles, birds, mammals
- even though dinosaurs are the most famous & dominant groups of this period
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Angiosperm Origins - 145 - 208 mya
- In context: 145 mya is the beginning of the Cretaceous Period dinosaurs are the dominant tetrapods (= 4 footed vertebrates)
- small mammals, birds, and pterosaurs. First snakes.
- diversification of insects: ants, bees, termites appear
- CO-EVOLUTION
-
Cretaceous Period (145 - 65 mya)
- warm climate
- angiosperms, birds, and mammals radiate
- ends with the K-T extinction, one of the biggest extinction events
- largest trees still conifers
- grasses evolve by end of period, but not extensive coverage (no grassy prairies or fields)
- evolution of mammals by mid-Cretaceous, have placental, marsupial & monotremes
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Mesozoic Climate
- No polar ice caps at all
- moist poles, drier at equator
- no tropical rainforests
- cooling episode at end of Cretaceous
-
Mesozoic Extinction
- Smaller extinction event at end of Triassic
- - meteor?
- - break up of Pangaea?
- - replaced by new groups like dinosaurs
- Major extinction event at K-T boundary end of Cretaceous
- not as major as the Permian extinction
- dinosaur fauna in decline for some million years previous
- drop in sea levels concurrent with extinction
- climate change from mild (Mesozoic) to cool (Cenozoic)
- mass extinction in a variety of fauna, but not all taxa =differential selection
- iridium layer at KT boundary
-
K-T Extinction
- Hypotheses:
- - Asteroid collision?
- - Volcano activity?
- - Dinosaur plague?
- - Result of Plate Techtonics?
- - Mammals ate everything?
- extinction of 40% of tetrapod families
- inc non-avian dinosaurs,
- all flying reptiles (pterosaurs)
- marine reptiles (ichthyosaurs, plesiosaurs, etc)
- additional extinctions among mammals, birds, plants, marine invertebrates
- debate: how sudden?
- dinosaur fauna in decline for some million years previous
- strong evidence for asterioid hitting Yucatan in Mexico
- - iridium in sediments iridium
- - rare on surface, more common extraterrestrially
- dust clouds have similar impact as volcanic eruptions at Permian extinction
- Deccan Traps: major volcanic eruption, this time in India
- patterns do not equal process
- why do we see patterns?
- most verts larger than 10 Kg became extinct
- better reproductive capabilities?
- modern amphibians are very sensitive to environment --anura, urodela, and gymnophiona all survived
- **Fossil evidence doesn’t always supply what is needed to answer the question**
-
Mesozic Extinction Current Hypotheses
- Asteriod Collision off Yucatan in Mexico
- - Impact Crater of right size and time
- - Iridium layer (rare on Earth, common on asteroid, deep in Earth)
- - Melted Rock at KT boundary
- - Shocked quartz (fractured crystals) at KT boundary
- Deccan Traps: major volcanic eruption, this time in India
- - Deccan Traps (India) cover 200,000square miles
- - Iridium and shocked quartz also possible in this scenario
- note: India was moving toward Asia at
- -about 15 cm/year
- --major techtonic activity
- --touches Asia at about 55-50 mya
- (currently moving at 6 cm/year)
- dust clouds would have similar impact as volcanic eruptions at Permian extinction
- ******Correlation ≠ Causation*******
-
Collision Event is the most accepted (but not only) hypothesis today.
- 180 km (110 mi) diameter crater
- 10 km (6 mi) diameter asteroid impact
- 2,000,000 greater than largest nuclear bomb
-
Parallel Evolution of Wings
- Parallel Evolution of Digits
- Same 5 digits different arrangement
- Membrane off elongated 4th, thumb and first 3 free
- membrane all but thumb
- fused 2 and 3
-
History of Paleontology in the United States
- The Bone Wars
- Edward Cope (National Academy/U Penn) vs. Othniel Marsh (Yale)
- backstabbing, sabotage, and discovery
-
The Bone Wars
- began in late 1960’s
- context: Darwin’s Origin of Species published in 1858
- completion of transcontinental railroad in 1860’s
- competition to excavate and NAME unique species
- in the American West
- support for evolution
- Smithsonian (Washington DC) has top dinosaur collection (Marsh)
- Cope has record for most scientific papers published --1,400!
- Marsh named 80 new dinosaurs to Cope’s 56
- Specimens from both collections described and studied long after deaths
-
Dinosaurs Discoverd by Marsh and Cope
- Marsh -
- - Triceratops
- - Allosaurus
- - Apatosaurus
- - Stegasaurus
- Cope -
- - Lystrosaurus
- - Elasmosaurus
-
Two main groups of derived Diaspids
- 1.Archosauromorpha "ruling lizard form" crocodiles, birds, dinosaurs, pterosaurs
- 2.Lepidosauromorpha "scaled lizard form" tuatara, squamata, *plesiosaurs, *placodonts, *ichthyosaurs
-
Archosaurs
- crocodilians
- secondary palate separates nasal passage from mouth
- --ability to breathe with just nostrils exposed
- most similar extant archosaurs to ancient forms
- 23 extant species
- mainly tropical
- semi-aquatic, salt and fresh water
- depressor mandibulae is short and lacks power (opens jaw)
- levator mandibulae is very powerful—can crush turtles (closes jaw)
- caudofemoral muscle
- origin: base of tail
- insertion: 4th trochanter
-
What do Crocodilians and Birds tell us about dinosaurs
- parental care and vocalizations known in both birds and crocodiles
- hatchling crocodilians call to be dug out of nests -> probably in dinosaurs too
-
What are the two independently evolved clades?
- Ornithischia: "bird hipped"
- -elongated ilium to anterior
- Saurischia "lizard hipped"
- - elongated pubis and ischium , pubis rotated to anterior
- - Selection for increased locomotion
- - legs under body, bipedalism
-
Evolution of bipedalism allowed for what specilazations
- Specialization of forelimbs for
- - grabbing prey
- - flying (evolved twice - birds and pterosaurs)
-
Ornithischian Dinosaurs
- herbivorous
- many had beaks rather than teeth
- armored quadrupeds
- evidence of parental care
- -groups of hatchlings fossilized together
- - fossilized mother protecting eggs
- skulls suggest vocalization
- ex. Stegasaurus
- ex. first recognized dinosaur Iguanodon
- ex. duck-billed dinosaurs
-
Saurischian Dinosaurs
- 1.Sauropodomorpha "reptile foot form"
- - mostly quadrupedal herbivores
- - includes giant quadrupedal herbivores like Diplodocus
- - largest may be over 30 m and 40,000 kg (elephant = 5 m & 5,000 kg)
- - possible herd behavior
- -- evidence from tracks
- 2.Theropoda "beast feet"
- - mostly bipedal carnivores
- - may have attacked with jaws (like T. rex), hind limb or forelimb
-
Bird Origins
- evolved from therapods
- furcula (wishbone) evolved in therapods from clavicles
- Birds evolved during the Late Jurassic -> coexisted with pterosaurs
- Traditional taxonomy
- - Class Reptilia
- - Class Aves
- - but—evolutionarily, Aves are part of Reptilia
-
Common Traits between Birds and Theropods
- hollow bones with air spaces (pneumatic)
- S-shaped neck
- tridactyl foot—three toes forward, one back
- digitigrade posture = walking on toes
-
Trait Evolution in Birds
- birds are very derived (modified) reptiles
- wrists of therapod rotate sideways -> grasp prey
- - in birds, used to direct air over feathers for flight
- orientation of glenoid fossa in therapods -> freer arm movement
- - in birds, used for wing flapping
- feathers
- - evolved in dinosaurs
- - evidence for hollow shafts of beta keratin
- evolved pre-flight-- purpose?
- - insulation and/or display
-
Class Aves
- 9,600 Species
- mechanics of flight shape bird morphology
- flightless birds are secondarily flightless (evolved loss of trait)
- most birds are diurnal = awake during the day
- most birds have excellent vision
-
Archaeopteryx
- theropod dinosaur
- transitional fossil
- 150 mya (Jurassic)
- jaws with teeth
- 3 fingers with claws
- long bony tail
- feathers
-
Bird Evolution from Therapods
- Center of Gravity shifted forward toward wings
- shortened bony part of tail
- pygostyle = fused posterior tail vertebrae
- beak with no teeth
- coracoid bones support pectoral muscles smaller foot claws for perching large sternum = keel
- wrist that bends backward
-
Bird Evolutionary History
- modern birds diversified during Cretaceous ~ 90 mya
- few fossils = few species?
- by late Cretaceous many ecomorphs evolved
- inc. wading, perching, swimming, flightless
-
Bird Structures
- specialization for feeding and locomotion
- body plan evolutionarily conserved for flight
- upper limit to body mass for flight
- long runs for takeoff
-
Discuss Feathers
- develop from follicles in skin
- 90% beta keratin (related to keratin in reptile scales)
- Structures
- Pennaceous Section Vane
- - sheetlike, smooth part
- - tightly formed by hooks on barbules
- - sheds water, protect down
- - directs air
- Rachis
- Barb
- - Barbules: branch off from barbs and hook to neighbors
- Downy Section
- - Downy or plumulaceous section: Fluffy, hookless part at base
- - insulation
- Calamus
-
Preening
behavior in which bird smooths out barbs
-
Contour Feathers
- includes remiges (wing) and rectrices (tail)
- stiff, mainly pennaceous
- used in flight –steering etc
-
Semiplumes
- intermediate between contour and down
- large rachis but entirely plumulaceous
- mostly insulation
-
Down Feathers
- plumulaceous only
- rachis absent or tiny
- insulation
-
Bristles
- Highly Specialized
- Usually around eyes or mouth
- block particulate matter
- may aid tactile sense
-
Filoplumes
- Fine, hairlike, few barbs at tip
- sensory structures underlie contour feathers
- very rarely used in display
-
Bird Skeleton
- Air - filled bones (pneumatic)
- hindlimbs relatively heavier than mammals
- very light skull
- elongated pelvic girdle
- synsacrum: fused vertebrae, firmly attached to ischium and illium
- tail: 5 vertebrate plus fused pygostyle
- pelvic girdle + inflexible thoracic vertebrae + pygostyle = rigid vertebral column
- neck (cervical vertebrae) usually flexible
- keel on sternum for attachment of flight muscles
- fused clavicles -> furcula
- coracoid supports scapula
- joint of ankle within tarsus
- metatarsals fused with distal tarsals -> tarsometatarsus
- tibia fused with proximal tarsals -> tibiotarsus
-
Bird Muscles
- pectoral muscles may be 20% of body mass
- need to maximum gas exchange:
- - large hearts, high blood flow, through-flow lungs, crosscurrent exchange
- need to dissipate heat from muscles
- hind limb muscles can also be strong
- - swimmers like ducks
- - hawks & owls catch prey with feet
- - terrestrial or flightless birds
-
Wings
- function for lift and propulsion
- change of shape, area, and orientation in wings
- ability to maneuver
- Supracoracoideus - raises wing
- pectoralis - lowers wing
-
Avain muscles of the pectoral girdle
- Tendon of Supracoracoideus
- supracoracoideus - raises wing
- pectoralis - lowers wing
- keel of sternum
- coracoid
- humerus
-
Dynamic Soaring
- long, narrow, flat wings
- needs strong persistent winds
- certain seabirds (ex. albatross)
- uses wind gradient
- (slower near water)
-
Elliptical Wings
- birds that fly around objects, like woodland birds fast flapping, slow flight
- good maneuverability
- ex. pheasant
-
High Aspect Ratio
- fast flight
- usually long migrations, aerial foraging, diving
- ex. swifts, barn swallows
-
High - Lift Wing
- static soaring
- maneuverability uses rising air masses
- large birds
- ex. vultures, eagles
-
Bird Migration
- V-shaped formation
- flying in the wake of other birds saves energy
-
Hindlimb Specilizations
- Anisodactyl
- Zygodactyl
- Heterodactyl
-
Perching
- Foot tendons lock so bird doesn’t relax grip & fall off branch
- plantar tendons tighten when legs bend
- sitting bird can safely sleep
- 1. ideally 4 free medium-length toes— 3 toes forward and one backward = anisodactyl foot most passerine (perching birds) ex. robin, blue jay
- 2. 2 toes forward and 2 backward = zygodactylous foot
- ex. parrots and woodpeckers (vertical perching)
-
Running, Hopping and Walking in Birds
- hopping: mainly perching arboreal birds
- - many passerines ( = perching birds) are limited to hopping
- walking: alternate feet touch ground
- running: both feet off ground at same time for part of step
- - usually long legs, small feet
- - often reduction in toe #
- - ostrich has 2 = didactyl
- -rhea has 3 = tridactyl
-
Climbing
- use feet, sometimes also beaks, tails and wings
- ex. woodpecker uses tail for support
-
Surface Swimming
- webbed feet (ex. ducks)
- lobed toes (ex. grebe)
- wide body for stability
- dense plumage for insulation & bouyancy
- large preen gland for waterproofing oil
- water resistant feathers
-
Diving and Underwater Swimming
- through specialization of hindlimb (some loons)
- wings (penguins -> flightless)
-
The blue-footed booby's mating dance
Uses blue feet to attract mates
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