Lecture Exam PT 2 ( Animals 3-5)

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what are the benefits of a chitinized cuticle?

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what are the benefits of a chitinized cuticle?

  • protects organs -prevents water loss -supports organs effects, locomotion

  • specialized appendages ( spears, wings, hairs)

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what are the drawback of having a chitinized cuticle?

-cannot grow so must shed periodically

  • motling energetically expensive -newly molted animals are unprotected until new exoskeleton hardens -evolutionary constraints on size

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what animals are apart of the basal ecdyszoans?

  • priapulids( penis worms)

  • kinorhynchs ( mud dragons)

  • loriciferans

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Priapulids: (penis worms)

three-part bodies (proboscis, trunk, and tail); live in mud and feed on slow-moving invertebrates; major predators in Cambrian

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Kinorhynchs: (mud dragons)

live in marine sands and muds and are virtually microscopic (1 millimeter or less). Bodies are divided into 13 segments, each with a separate cuticular plate.

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are also less than 1 millimeter long. Body is divided into a head, neck, thorax, and abdomen and is covered by six plates; miniaturized versions of animals found in Cambrian

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worm like- thread like

  • phylogenetic position disrupted -unsegmented -pseudocoelomate -dioecious and parthenogenetic -many plant, animal, and human pathogens

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Ascaris - round worm

-intestinal parasitic disease caused by Ascaris Lumbricoides -eggs in human feces or untreated water can be picked up through contaminated food

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infectious, generally caused by eating undercooked pork

  • various species of Trichinella, mainly T. spiralis

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Enterobius Vermicularis

-pin worm -causal agent of most common human parasitic disease developed in countries

  • fecal- oral transmissiond

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dracunculiasis ( guinea worm disease)

caused by nematode Dracunculus medinensis

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Onychophora and tardigrades

  • related to arthropods ( unjointed legs) -like arthropods, but lost coelom body cavity, instead have hemocoel ( blood chamber) -internal body cavity in which fluids bathe internal organs

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Onychophora " velvet worms"

  • segmented by lack jointed appendages -cuticles with chitin -Tropical/temperate -squirt slime to subdue prey -live in social groups -elaborate behaviors

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Tardigrada "water beards"

Microscopic • Found worldwide • 4-layered cuticle • Extremely hardy • Cryptobiosis resting state (like suspended animation) – Near freezing to extreme heat (- 190°C to 70°C) – High salinity – Lack of Oxygen – Have survived space vacuum and radiation

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what are arthropods characteristics

  1. Jointed legs

  2. Versatile and protective exoskeleton

  3. Segmentation yields efficient locomotion and neofunctionalization

  4. Efficient tracheal gas exchange system (Hexapoda, Myriapoda) or book lungs (Chelicerates); oldest land animals (437 mya), about the same time as the earliest vascular plants The jumping spider family: +5000 species Arthropods

  5. Highly developed sensory organs

  6. Complex behaviors

  7. Monophyletic and ancient (Cambrian)

  8. Largest group of animals (nematodes may eventually be found to be as numerous); 80% of all described animals

  9. Thick exoskeleton reinforced with chitin or calcium carbonate

  10. Successful in terrestrial habitats, along with amniote vertebrates

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what are the different arthropod groups

-Trilobitomorpha -Chelicerata -Myriapods -Crustaceans -Hexapods

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what does the General phylogeny of arthropods show?

-monophyly of arthropods undisputed -"crown group" includes all recognized groups most genes show :

  • chelicerates as first diverging branch

  • then myriapods -then various groups of crustaceans (paraphyletic)w hexapods

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what is the body plan of an arthropod?

  • skeletal muscle moves exoskeleton

  • continuous, thick waxy, cuticle

  • lost condition of coelom

  • hemocoel -fluid (hemolymph)

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what is tagmosis

fusion of segments into functionalwh units (tagmata)

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for hexapods and myriapods what is the tracheal system composed of?

composed of chitin-ringed tubes ( trachea) that connects directly to the air through openings in the body wall ( spiracles)

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when were spiracles of myriapod fossils found?

428 mya

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what are ommatidia?

eyes composed of units called

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Trilobites = “Three-lobed” • Three-lobed body plan (Head/Thorax/Tail) • Calcified exoskeleton • Cambrian explosion (535-525 mya) • Fully extinct after Permian mass extinction (~ 250 mya) • Very successful for over 250 my

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subphylum Cephalothorax

-abdomen • No antennae • Six pairs of appendages: – Chelicerae • Clawlike feeding appendages – Pedipalps – 4 pairs walking legs

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what are chelicerates characterized by?

y a head bearing two pairs of appendages modified to form mouthparts, chelicerae and pedipalps (piercing instead of chewing; no mandibles).

  • no antennae -Many chelicerates have four pairs of walking legs

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what groups are also apart of chelicerates?

-pycnogonids (sea spiders)

  • horseshoe crab -arachnids

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what is the oldest land animal from the fossil record?

scorpion silurianw 437 mya

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what is the chelicerata- arachnid anatomy?

-all spiders produce silk proteins in silk glands and spinnerets to produce silk thread -earliest spiders use silk threads to protects eggs, line nests and wrap prey -later elaborated to form web

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Subphylum Myriapoda

" many legs" -9 or more pairs -antennae

  • terrrestrial tracheal system for gas exchange 2 classes wht

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what are two classes of myriapoda?

diplopodaD and chilopoda

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Diplopoda " double footed"

2 pairs of walking legs per segment (fusion of 2) • 25-100 body segments • Feed on decaying plant matter • Slow-moving • Small jaws and legsV

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Terrestrial carnivores • Fast-moving • 1 pair of walking legs per segment • Venomous claws

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Highly specialized appendages • Only arthropods with 2 pairs of antennae • Calcium carbonate with chitin in exoskeleton • 2 to 3 body segments • 3 or more pairs of legs • Abdominal appendages (unlike insects that have only thoracic appendages) • Mostly marine

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what is the largest group of arthropods?

hexapods w

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what was the first aniaml group to fly?

arthropods 300 mya ago

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-Largest group of arthropods -Insecta and Entognatha -More than a million species described, mostly insects -Most are terrestrial -Six legs; usually three tagmata (head, thorax, abdomen) -Insects the only invertebrate group (and the first animal group) to have evolved powered flight

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what is the most basal lineage of hexapoda?

Entognatha E

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  • internal mouthparts

  • no wings

  • springtails, bristletails, and maybe proturans

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• Small soil-dwelling hexapods • No eyes, wings or antennae • “Coneheads” • Basal hexapods; probably a separate group sister to the rest of the hexapods (Entognatha + Insects)

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Springtails • Very diverse soil-dwelling animals • Except for one family, lack tracheal system • Possess a specialized abdominal, tail-like appendage folded under the body; when alarmed this can flick the animal meters away

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One of several groups called “bristletails” (some “bristletails” are actually insects) • Paired cerci on posterior (“bristle tail”) • No eyes, long antennae, bead-like segments • Biting mouthparts, predaceous

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what are the general characteristics of insects?

  • single pair of antennae

  • wing extensions of the cuticle

  • 3 pairs of legs attached to the thorax -tracheal system for gas exchange -well developed senses

  • internal fertilization 3 tagmata : head, thorax, and abdomen

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Have insects always had wings?

no, some of the earliest insects were wingless, most have two pairs of wings; some have lost wings secondarily

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what are the two insect life cycles

-Hemimetabolous (incomplete)

  • Holometabolous (complete)

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Insect flight

  • only invertebrates to develop powdered flight -oldest fossils of flying insects ( carboniferous 300 mya)

  • major contributor to insect success

  • enabled dispersal across land

  • wings only evolved once

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what are the theories of how insects wings initially evolved?

gills, gliding, heat fans, and swimming

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what is the direct flight mechanism?

wing muscles directly at wing base

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what is the indirect flight mechanism?

wing muscles attach to the thorax and deform it, causing the wings to moveH

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Hemiptera ( sucking mouthparts)

-half wings -hemimetabolous -aphids, leafhoppers, cicadas

  • some are blood sucking

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Orthoptera ( enlarged hind legs)

  • straight wings -hemimetabolous

  • some produce sound by rubbing wings against each other or legs ex: grasshoppers/crickets

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Coleoptera (hardened forewings)

shield wings” • Beetles • 400,000 spp. • Most species of any animal group • Elytra (shield-like forewings) open new niches (burrowing, etc.) • Holometabolous

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Hymenoptera (thing transparent wings)

membrane wings” • 125,000 spp. • holometabolous • Eusocial behavior • Ants, wasps, bees • Haplodiploid • Some venomous

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Lepidoptera ( scaled wings)

scale wings” – 250,000 spp. – Butterflies and moths – holometabolous

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Diptera ( hind leg modified into halteres)

– “two wings” – 120,000 spp. – Halteres control balance, guidance and stability during flight (gyroscopes) – Flies, mosquitos – holometabolous

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blastopore forms anus, cleavage radial and intermediate and coelom formation enterocoelous ( all coelomates)

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what are the characters of deuterostomes?

  • triploblastic coelomate -radia cleavage

  • formation of mouth at opposite end of the embryo

  • development of coelom from mesodermal pouches that bud from archenteron walls

  • internal skeletal system and segmentation

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what is the ancestral conditions for bilateria?

Blastopore becomes the anus • Radial cleavage • Suggests protostomes are derived

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what are the ancestral conditions for the deuterostomes?

Bilateral symmetry • Segmentation • Pharyngeal slits • Chordates retain these characters • Suggests that echinoderms are derived

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what ae the two clades that have duterostomes?

Ambulacrarians (Echinoderms and Hemichordates) • Chordates

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• Used to be considered a chordate subphylum • Retain bilateral symmetry of larvae as adults • Acorn worms and pterobranchs • Acorn worms are solitary marine worm-like animals that live in burrows; deposit feeders or suspension feeders • Most similar to the common ancestor of chordates and the rest of the deuterostomes

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what are the different clades that fall under echinoderm?

  • asteroidea - sea stars -ophiuroidea - brittle stars

  • echinoidea - sea urchins -crinoidea - sea lilies

  • holothuroidea - sea cucumbers

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what are the characteristics of echinoderms?

  • all marine, no osmoregulation

  • sessile or slow moving, lost pharyngeal slits

  • adults radially symmetrical

  • larvae bilaterally symmetrical

  • most species gonochoric and some hermaphroditic

  • some capable of regeneration lost parts

  • thin skin covering the endoskeleton

  • water vascular system and tube feet in all groups

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what are the clades of chordata?

urochordata and cephalochordata

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  • chordate from the cambrian period

  • described as a polychaete worm -segmented with a notochord ( chordates are segmented)

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what are the chordate characters?

  1. notochord

  2. muscular, postanal tail

  3. pharyngeal slits

  4. dorsal nerve cord

  5. endostyle

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what are the characters of vertebrates?

Anterior skull containing a relatively large brain

  • Rigid endoskeleton (bony or cartilaginous) supported on vertebral column (except hagfishes, which some exclude from the vertebrates)

  • Well-developed closed circulatory system driven by contractions of a ventral heart

  • Coelom with suspended organs

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what is the oldest vertebrate?

haikouichthys ( 530 mya)

  • distinct head, tail and gills

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  • tooth like structures common in cambrian strata up to the jurassic

  • distinctive index fossils

  • now part of jawless vertebrates

  • made up of hydroxyapatite

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cyclostomes- hagfishes

  • cartilaginous endoskeleton -not supported by complete vertebral column;

  • persistent notochord ( not technically vertebrates)

  • sister to lampreys - structural differences -Skull not complete; brain with no cerebrum or cerebellum -No jointed vertebral column; cartilaginous -Tooth-like structures of keratin -All are marine -Scavengers, predators and suspension feeders -Direct development (no larval stage) -Notable ability to produce defensive slime

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Cyclostomes- lampreys

Adult is sometimes a fish ectoparasite and larvae are filter feeders (some adults do not feed) -Complete metamorphosis to adult -Complete braincase; rudimentary vertebral column -Cartilaginous endoskeleton; horny keratinous teeth -Molecular data indicate hagfish and lampreys are sisters and that the two together are sister to other vertebrates

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jawed fishes

  • first observed in late ordovician fishes

  • presumed to have developed from the first gill arch

  • probably adaptive to originally in buccal pumping of water across the gills

  • jawed cartilaginous and bony lineages represented

  • radiated in the devonian and replaced most of the jawless fishes

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Placoderms - Jawed fishes

  • teeth seen as the outgrowths of the jaw

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Chondrichthyans ( sharks, rays, and chimaeras)

• Mostly marine • No lungs or swim bladders • Cartilaginous skeleton • Internal fertilization • Many produce live young, but do not exhibit parental care • Skin covered by placoid scales,

  • homologous to vertebrate teeth with a central pulp surrounded by dentiner

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Close relatives of sharks • Contain the largest number of species • Dorsiventrally flattened bodies, enlarged pectoral fins fused to the head and ventral gill slits • Mostly marine and feed on invertebrates close to the sea floor in coastal areas; large Manta rays are pelagic and filter feed on plankton

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what are the characters of bony fish?

Marine and freshwater

  • Calcium phosphate in cartilage matrix to form bony skeleton

  • Fins with rods of cartilage for support in ray-finned fishes; fleshy lobed fins in lobe-finned fishes

  • Heart with two chambers (atrium and ventricle)

  • Most have swim bladders derived from lungs (lungs represent a primitive character found in the earliest bony fishes and retained in the basal lineages of ray-finned fishes, such as bichirs and reedfishes, and also in lobe-finned fishes)

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what two fishes are apart of the lobe-finned fishes (sarcopterygians)

coelacanths and lungfishes

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Lungfish ( air breathers- devonian origin)

Six living species representing the remnants of a larger Mesozoic distribution • Retain many characteristics of ancient bony fishes and Sarcopterygian fishes • Lungs homologous to those of tetrapods

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what were the problems associated when moving to land?

  1. mass and structural support

  2. locomotion

  3. air breathing

  4. feeding ( no more filter feeding)

  5. sensory

  6. water loss

  7. reproduction ( earliest animals fully aquatic and reproduced in water)

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Fossil discovered in 2004 in northern Canada • Dates from late Devonian (375 mya) • Considered a sarcopterygian fish species • Important as a transitional animal; limbs intermediate between fully aquatic fishes and terrestrial tetrapods

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what are the general characters of the amphibian clade?

  1. skeleton mostly bony

  2. four limbs ( quadrupedal)

  3. three chambered heart

  4. gas exchange through smooth moist glandular skin

  5. carnivorous as adults

  6. both lungs and gills during lifecycle

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• Frogs and toads • Carnivorous and tailless as adults; herbivorous tailed larvae • Glandular skin defensive • Warty frogs called toads • Larvae “tadpoles” with internal gills • Complex vocalizations and breeding behaviors

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Salamanders • About 550 species; earliest date from Jurassic • Moist skins, skin glands • Tailed as larvae and adults • Capable of regenerating lost limbsa

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• Caecilians • Completely legless, nearly blind amphibians • Mostly tropical, live in soils and are seldom seen • Look like earthworms • Earliest fossil caecilians date from Jurassic and had fully developed legs and eyes • Internal fertilization and development of young inside female • Remarkable maternal care

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what are amniotes?

  • have covered eggs and internal fertilization

  • (340 mya to present)

  • shell and shell membranes protect and retards evaporation of water

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what are the different parts of the extraembryonic membrane?

chorion- outermost outer membrane, used in gas exchange allantois- encloses wastes and used in gas exchange amnion- protects embryo yolk sac- provides nutrients

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what are the different amniote lineages?

  • diapsids

  • synapsids

  • anapsides

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what are diapsids?

have 2 fenestrae behind the orbital linings of the skull ( reptiles)

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what are synapsids?

have a single opening (“mammals”)

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what are anapsids?

have no opening, but this is a derivation in a single lineage (turtles) of diapsids

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what are the extant diapsid reptlies?

  • testudines

  • lepidosauria

  • archosauria

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Testudines - Turtles

-Fossils date from Late Triassic (215-220 mya -ca. 300 extant species; mostly aquatic -Dorsal carapace and ventral plastron are fused vertebrae, ribs and dermal bone. -Lack teeth -Have an anapsid skull; however, they are derived diapsids based on molecular data -sister to the Archosaurs -All are oviparous (egg-layers)

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Lepidosauria - tuatara - squamata ( lizards)

Scaled skin (squamata); scales of keratin produced by the epidermis

  • Extremely diverse incudes terrestrial, burrowing, aquatic, arboreal and aerial members

  • Most have four limbs but in many the limbs are reduced and are absent in the glass lizards

  • Most have moveable eyelids

  • Oviparous (egg-layers) and Viviparous (livebearers)

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Lepidosauria - squamata ( snakes)

Derived lizards (Cretaceous)

  • Limbless, always lacking pectoral girdle (Hox genes), and usually also the pelvic girdle (vestigial in some snakes, e.g., pythons and boids)

  • Numerous vertebrae (body basically an extended thorax)

  • Highly kinetic skull

  • No movable eyelids

  • Modified salivary glands produce venom in 20% of species

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archosaurs General characteristics

Crocodilians, pterosaurs, dinosaurs and birds • Date from the late Permian/early Triassic • Synapomorphies: • Teeth set in sockets • Openings in front of the eyes and in front of the jaw • A ridge on the femur that permitted muscle attachment allowing

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Archosauria - Crocodilians

Mostly unchanged for 200 My

  • ca. 23 extant species, widespread (tropical aquatic) top predator.

  • Elongate, well reinforced skull with massive jaw muscles

  • Teeth are set in sockets - same as dinosaurs (a synapomorphy for all archosaurs). Mammals evolved these independently

  • Oviparous

  • Closest living relative to birds

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Archosauria - birds

Ca. 10,000 species • Forelimbs modified for flight but some do not fly (Paleognaths and many island endemics) • Feathers, no teeth (developmentally repressed) • Four-chambered heart • Uniquely efficient respiratory system • Semi-solid uric acid waste • Endothermic • Light weight skeleton - hollowed bonesco

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Early unequivocal bird discovered in China • Cretaceous (125-140 mya) • Claws on wings • First toothless bird with beak • Feathers definitely enabled powered flight (although other non-flying dinosaurs also produced feathers)

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how many times did powered flight evolve in animals?

3 times in vertebrates 1 time in invertebrates

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Archosauria - Pterosaurs

• Pterosaurs were the first vertebrates to evolve powered flight; very diverse •Triassic to Cretaceous (228-66 mya) • Hollow bones, keeled breastbone, air sacs/lungs similar to birds • Extinct at the K/T boundary

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