Gnathostome Evolution - Waterford Mott...
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Transcript of Gnathostome Evolution - Waterford Mott...
Origins of BonesMineralization originated with mouthparts
The entire skeleton was mineralized much laterGnathostomes are vertebrates that have jaws
Jaws evolved from skeletal supports of the pharyngeal slitsAlso have enhanced sensory systems, mineralized endoskeleton, and paired appendages
Gill slits Cranium
Skeletal rods Mouth
Fig. 34.13
0.5 m
Fig. 34.14
Gnathostome EvolutionPlacoderms - extinct lineage of armored vertebratesAcanthodians - radiated during the Devonian period (closely related to osteichthyans)
(a) Coccosteus, a placoderm
(b) Climatius, an acanthodian
Class ChondrichthyansSkeleton composed primarily of cartilageCartilaginous skeleton evolved secondarily from an ancestral mineralized skeletonReproductive tract excretory system and digestive tract empty into a common cloacaIncludes: sharks, rays, and ratfish
Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia
(a) Blacktip reef shark (Carcharhinus melanopterus)
(b) Southern stingray (Dasyatis americana)
(c) Spotted ratfish (Hydrolagus colliei)
Dorsal fins
Pectoral fins Pelvic fins
Fig. 34.15
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OstiechthyesNearly all have a bony skeletonWe informally call them fishControl their buoyancy with an air sac known as a swim bladderBreath by drawing water over gills
Located in chambers covered by a protective bony flap called the operculum
Fig. 34.16
Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia
Nostril
Brain Spinal cord
Swim bladder
Dorsal fin
Adipose fin Caudal fin
Cut edge of operculum
Gills Kidney
Heart
Liver
Stomach
Intestine
Gonad
Pelvic fin
Anus
Anal fin
Lateral line
Urinary bladder
OstiechthyesClass Actinopterygii
Ray-finned fish - fins supported by long flexible rays modified for maneuvering, defense, and other functions
Class Sarcopterygii - have muscular, pectoral fins (ex. Coelacanths, lungfish, tetrapods)
Figs. 34.17 & 34.19
Yellowfin tuna (Thunnus albacares)
Red lionfish (Pterois volitans)
Common sea horse (Hippocampus ramulosus)
Fine-spotted moray eel (Gymnothorax dovii)
Lower jaw
Scaly covering Dorsal
spine
5 cm
TetrapodsGnathostomes that have limbs and feetOne of the most significant events in vertebrate history was when the fin of lobe-fins evolved into the limbs and feet of tetrapods
Fins became more limb-like
Have four limbs and feet with digitsHave ears for detecting airborne sounds
Figs. 34.20
& 34.21
Flat skull
Eyes on top of skull Head
Neck
Shoulder bones Ribs
Scales
Fin Fin skeleton
Elbow Radius
Humerus Ulna “Wrist”
Scales Fins Gills and lungs
Neck Ribs Fin skeleton Flat skull Eyes on top of skull
Tetrapod Characters
Fish Characters
Lungfishes
Limbs with digits
Amphibians
Amniotes
Silurian PALEOZOIC Devonian Carboniferous Permian
415 400 385 370 355 340 325 310 295 280 265 0 Time (millions of years ago)
Key to limb bones
Ulna Radius Humerus
Eusthenopteron
Panderichthys
Tiktaalik
Acanthostega
Tulerpeton
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Class Amphibia4,800 speciesMost have moist skin that complements the lungs in gas exchangeName means “two lives” - undergo metamorphosis from aquatic larva to terrestrial adultOrder Urodela (salamanders) - have tailsOrder Anura (frogs, toads) - lack tailsOrder Apoda (caecilians) - legless and resemble worms
Figs. 34.20-34.21
Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia
(a) Order Urodela (salamanders)
(b) Order Anura (frogs)
Order Apoda (caecilians)
(c)
(a) Tadpole
(b) During metamorphosis
(c) Mating adults
ANCESTRAL AMNIOTE
Parareptiles
Turtles
Crocodilians
Pterosaurs
Ornithischian dinosaurs Saurischian dinosaurs other than birds Birds
Plesiosaurs
Ichthyosaurs
Tuataras
Squamates
Mammals
Reptiles
Synapsids
Diapsids
Archosaurs
Lepidosaurs
Dinosaurs
Saurischians
Fig. 34.25
AmniotesTetrapods that have a terrestrially adapted eggLiving members are reptiles, birds, and some mammalsNamed for the major derived character (amniotic egg)
Amniotic egg contains specialized membranes that protect the embryo
Also have relatively impermeable skin and the ability to use the rib cage to ventilate the lungsAppeared in the Carboniferous period
Fig. 34.26
Extraembryonic membranes
Shell
Amniotic cavity with amniotic fluid
Embryo
Amnion Allantois Chorion
Yolk sac
Yolk (nutrients)
Albumen
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ReptilesIncludes tuatara, lizards, snakes, turtles, crocodilians, birds, and dinosaursHave scales that create a waterproof barrierLay shelled eggs on landMost are ectothermic - absorb external heat as main source of body heat (Birds are endothermic - keep body warm through metabolism)Date back to about 300 million years ago
First major group were parareptiles (large, stocky herbivores)As parareptiles dwindled, diapsids were diversifying (lepidosaurs and archosaurs) One surviving lineage of lepidosaurs is the two species lizard-like reptiles called tuataraThe other lineage are lizards and snakes
Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia
Fig. 34.28
ReptilesSnakes - legless lepidosaursTurtles - have boxlike shells with upper and lower shields that fuse the the vertebrae, clavicles, and ribsCrocodilians - belong to the archosaur lineage that dates back to the TriassicBirds - archosaurs (almost every reptilian feature has undergone modification in adaptation to flight
(a) Tuatara (Sphenodon punctatus)
Australian thorny devil lizard (Moloch horridus)
(b)
(d) Eastern box turtle (Terrapene carolina carolina)
(c) Wagler’s pit viper (Tropidolaemus wagleri)
(e) American alligator (Alligator mississippiensis)
Fig. 34.27
BirdsMost obvious adaptations are wings and feathersProbably descended from theropods (group of small, carnivorous dinosaurs)
150 millions years ago - Arhaeopteryx (oldest known bird)
Order Struthioniforms (flightless birds)Demands of flight have caused a general body form to evolveFoot structure also shows variation Figs. 34.30-34.34
(a) Wing
Vane
Shaft
Forearm Wrist
Shaft Barb Barbule Hook (c) Feather structure
(b) Bone structure
Finger 1
Finger 2
Finger 3
Palm
Airfoil wing with contour feathers
Long tail with many vertebrae
Toothed beak Wing claw
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MammalsAmniotes that have hair and produce milkGenerally have larger brains than other vertebrates of equivalent sizeEvolved from synapsids in the late Triassic
Jaw was remodeled (two bones that were part of the jaw joint were incorporated into the middle earLiving lineages originated in the Jurassic but did not undergo significant adaptive radiation until after the Cretaceous
Fig. 34.32
Cephalochordata Urochordata Myxini Petromyzontida Chondrichthyes Actinopterygii Actinistia Dipnoi Amphibia Reptilia Mammalia
Key
Articular Quadrate Dentary Squamosal
Biarmosuchus, a synapsid
Temporal fenestra
Jaw joint
(a) Articular and quadrate bones in the jaw
Eardrum Middle ear
Stapes Inner ear
Sound
Present-day reptile
(b) Articular and quadrate bones in the middle ear
Sound
Present-day mammal
Eardrum Middle ear
Inner ear
Stapes
Incus (quadrate)
Malleus (articular)
MammalsMonotremes - small group of egg-laying mammals (echidnas and platypus)Marsupials - opossums, kangaroos, and koalas
Born very early in its development In some the marsupium opens in the rear
(a) A young brushtail possum
(b) Long-nosed bandicoot
Plantigale
Marsupial mammals
Eutherian mammals
Marsupial mole
Sugar glider
Wombat
Tasmanian devil
Kangaroo
Deer mouse
Mole
Flying squirrel
Woodchuck
Wolverine
Patagonian cavy Figs. 34.38-34.40
MammalsEutherians - placental mammals
Have a longer period of pregnancy (compared to marsupials)Young eutherians complete their embryonic development within a uterus joined to the mother by a placenta
Fig. 34.41Monotremata
Orders and Examples Main Characteristics Orders and Examples Main Characteristics
Platypuses, echidnas
Echidna
Proboscidea Elephants
African elephant
Sirenia Manatees, dugongs
Manatee
Lay eggs; no nipples; young suck milk from fur of mother
Long, muscular trunk; thick, loose skin; upper incisors elongated as tusks
Aquatic; finlike fore- limbs and no hind limbs; herbivorous
Xenarthra Sloths, anteaters, armadillos
Tamandua
Lagomorpha Rabbits, hares, picas
Jackrabbit
Reduced teeth or no teeth; herbivorous (sloths) or carnivorous (anteaters, armadillos)
Chisel-like incisors; hind legs longer than forelegs and adapted for running and jumping; herbivorous
Sharp, pointed canine teeth and molars for shearing; carnivorous
Hooves with an even number of toes on each foot; herbivorous
Aquatic; streamlined body; paddle-like fore-limbs and no hind limbs; thick layer of insulating blubber; carnivorous
Carnivora Dogs, wolves, bears, cats, weasels, otters, seals, walruses Coyote
Cetartiodactyla Artiodactyls Sheep, pigs, cattle, deer, giraffes
Cetaceans Whales, dolphins, porpoises
Marsupialia Kangaroos, opossums, koalas
Koala
Completes embryonic development in pouch on mother’s body
Tubulidentata Aardvarks
Aardvark
Teeth consisting of many thin tubes cemented together; eats ants and termites
Hyracoidea Hyraxes
Rock hyrax
Short legs; stumpy tail; herbivorous; complex, multi- chambered stomach
Rodentia Squirrels, beavers, rats, porcupines, mice Red squirrel
Chisel-like, continuously growing incisors worn down by gnawing; herbivorous
Primates Lemurs, monkeys, chimpanzees, gorillas, humans Golden lion
tamarin
Opposable thumbs; forward-facing eyes; well-developed cerebral cortex; omnivorous
Perissodactyla Horses, zebras, tapirs, rhinoceroses
Indian rhinoceros
Hooves with an odd number of toes on each foot; herbivorous
Chiroptera Bats
Frog-eating bat
Eulipotyphla “Core insectivores”: some moles, some shrews
Star-nosed mole
Eat mainly insects and other small invertebrates
Adapted for flight; broad skinfold that extends from elongated fingers to body and legs; carnivorous or herbivorous Bighorn sheep
Pacific white- sided porpoise
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MammalsPrimates - include lemurs, tarsiers, monkeys, and apes
Hands and feet adapted for graspingLarge brain and short jawForward-looking eyes close together on the face providing depth perceptionWell-developed parental care and complex social behaviorOpposable thumbsOldest known anthropoid fossils are from about 45 million years ago
Fig. 34.43-34.44
ANCESTRAL PRIMATE
Time (millions of years ago) 60 50 40 30 20 10 0
Lemurs, lorises, and bush babies
Tarsiers
New World monkeys
Old World monkeys
Gibbons
Orangutans
Gorillas
Chimpanzees and bonobos
Humans
Anthropoids
(b) Old World monkey: macaque (a) New World monkey: spider monkey
Evolution of PrimatesNew and Old World monkeys underwent separate adaptive radiations during millions of years of separationThe other group of anthropoids are hominoids (consist of primates called apes)Hominoids diverged from Old World monkeys about 20-25 million years ago
Figs. 34.39-34.40
(a) Gibbon (b) Orangutan
(c) Gorilla
(d) Chimpanzees
(e) Bonobos
Derived Characters of HomininsBipedal hominoids with a large brainLanguage capabilitiesSymbolic thoughtManufacture and use of complex toolsShortened jawHumans and chimpanzee genomes are more than 99% identical
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
Mill
ions
of y
ears
ago
Australo- pithecus anamensis
Kenyanthropus platyops
Australopithecus africanus
Paranthropus boisei
Paranthropus robustus
Homo ergaster
Homo neanderthalensis
Homo sapiens
Homo erectus
Homo rudolfensis Homo
habilis
Australopithecus garhi
?
Australopithecus afarensis
Ardipithecus ramidus
Orrorin tugensis
Sahelanthropus tchadensis
Fig. 34.46
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HominidsStudy of human origins is paleoanthropology20 species of distinct hominins have been discoveredOriginated in Africa 6-7 million years ago
Australopiths lived between 4 and 2 million years ago
Early hominids had a small brainTwo common misconceptions:
Often thought of as chimpanzeesThinking of human evolution as a ladder leading to Homo sapiens
Began to walk on two legs for long distances about 1.9 million years agoBegan to use tools (cut marks on animal bones) about 2.5 million years ago
Figs. 34.47 & 34.48
(a) The Laetoli footprints (b) Artist’s reconstruction of A. afarensis
HominidsHomo habilis - 2.4 to 1.6 million years ago
Stone tools have been found with themHomo ergaster - 1.9 to 1.6 million years ago
First fully bipedal, large brained hominidHomo erectus - about 1.8 million years ago
First hominid to leave AfricaHomo neanderthalensis - 200,000 to 30,000 years ago
Lived in Europe and the Near EastLarge, thick browedBecame extinct a few thousand years after Homo sapiens arrived in Europe
Homo sapiens - 160,000 years agoOldest fossils outside of Africa about 50,000 years ago
Figs. 34.49 & 34.50
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