group of tetrapods whos extant memebers are rpetiles (including birds) and mammals
amniotes have many adaptions for land life
amniotic egg (terrestrially adapted eggs)
- amniotic egg
- internal fertilization via specializzed intromittent organs
- undergo direct devlopment into landd forms withouth aquatic larvae of metamorphosis
- layings eggs on land than in water (sex without water)
- amnion is fluid filled
- retain eggs interannly or bury them
- eggshells form internally after copulation and interal fertilization
eg. allantois forms the umbilical cord; chorion forms the placenta; amniotic sac continues to enevlop the embryo
an external genitalic organ of males that deliver sperm during copulation
- characterstic of internal fetilization
therefore a mechanism of sperm transfer is present in the common ancetsor of amniotes
- thick, layered, msotly impermeable skin (reduces water loss/ dec. dehydration)
-axial skeletal muscle-powere lung ventilation (muscles ventialle lung) better than buccal pump in amphibians
-from a common ancetsor 250 mya
- amniotes had more tolerance than amphibians to dry land
- earliest known amniotes, small predator with sharp teeth and elongated jaw: hylonomus (look like lizard)
based on number of majro opening, known as temporal fenstra in the post eye area of the skull
-anapsid
-synapsid
-diapsid
lack of temporal fenestrae (turtles)
one pair of temporal fenestrae
two pairs of temporal fenstrae behind the eye socket (reptiles)
- turtles, crocodillians/birds (extant groups of archosaurs), lizards and snakes (lepidosaurs)
-monophyletic
-diapsids (reptiles) and synapsids (mammals and numerous extinct taxa)
-excluded birds (clade aves) from the concept of reptalia
-bird have many unique, derived features doesn't fit w reptiles
- thick, dry waterproof keratinous scales (dessication)& shed in sections like turtles or moutled like snakes
-lay eggs encased in leahtery shells (prevent dessciation)
-most are oviparous (eggs buried in land) few are vivparous, (extra embryonic membranes as simple placenta)
- parental care of eggs or juveniles in minimal (not crocs tho)
-3 chambered hearts (similar to amphibians)
-ectothermic; rely on external heat and behavioural adaptions; low metabolic rate, reduced food and energy requirments
-310 mya in the carbonifeous
-diversity increased in cooler climates coinciding with the collapse of carbonifeous rainforest
-earliest was the hylonomus, formed the diapsid lineage that persits in modern reptils
- lepidosaurs
-archosaurs
tutataras, lizards, snaks, extinct mosasaurs
crocodillians,pterosaurs (first flying) tetrapods), dinos (included bipedal carnviors; theropods which birds came from)
- other than crocodillians and birds rest became extinct
- freshwater, terrestrial and marine reptiles
- 300 extant species, some endaagered (many sea turtles, habitat destruction, harvesting, accidental entanglement)
- some adapted to desert, other in the aqua but all lay eggs on land
- herbivory and carinvory may sea turtles eat jellyfish
- anapsid skulls, without large opening behind eyes, descended from diapsid
-box like bony cartilaginous shell made of dorsal and ventral shields that are fused to the vertebrae, clavicles, and ribs (made of skeletal and dermal bones)
- teeth lost; replaced by toothless beaks
-males have a single intromitten organ
form a monophyletic group
-tutaras (2)
-squamates (lizards and snakes)
- reptiles with teeth fused to the jaw
-body covered in overlapping scales (derived from epidermis, shed collectviley (moulted)
- males have a hemipenis (paired penis)
- remnants of an ancient lineage of lepidosaurs ( widepsread and diverse in 220-100 mya)
- only 2 species left
- lizard like apperance but lack modified jaw structure, and gentalia of sqaumates
- internall fetilization via copulation but lack an intromittent organ, structural precursors for a hemipenis
- extant linegae of lepidosaurs consits of lizards and snakes
- most numerous and diverse group of non avian reptiles (9k+)
- hemipenis
-loosley jointed jaws and skulls
- external ears
- well devloped limbs (but there are legless lizards)
- primarily insectivorous, iguanas are herbivorous tho
- msot bite and swallow no chewing
some are poisonous (gila monster & komodo dragons)
- snakes are monophyletic group of legless lepidosaurs that evolved from burrowing lizards
-no external limbs (vestigal pelvic girldes present in some species)
- carnivorous, have adaptions to capture and consume ( loos articulate jaw bones & elastic skin, most eat vertbrates and some, invertbrates and kill prey by venom or constriction)
- reptiles with socketed teeth (not fused to the jaw, teeth are lost and replaced by a horny beak/bill in some lineages- birds)
- crocs and birds are both ( share a common ancestor)
- late triassic
-freshwater marine; 26 extant species (stay in warm regions)
-semi aqautic
- large, predatory with elongated and flattened skulls
- don't chew, swallow whole or employ spin to rip off in chunks
- single intromittent organ in males
- maternal care: guards nest, carrys youth, communicates in sounds
- ichthyosaurs ( fish-lizard)
-plesiosaurs (near lizards)
dolphin like marin reptiles, 15 m length, short necks , fish like tails adapted for swift swimming
flippered marine reptiles with small heads, long necks, slender tails ranging from 2 to 14 m in length
- pterosaurs
-non avian dinos
with membranous wings 1/3 independent origins of true flapping flight amon vertebrates
- diverse group, withe the largest terrestrial animals to have ever existed
- wide size range
- 2 groups: heribvorous ornithischians and carnivorous saurischians
- unique group of archosaurs ( despite being reptiles, had anatomy fully adpated to support flight)
- evolved from theropods , clade of saurischian bipedal, carinvorous dinos ( had tyrannosaur rex and small theropods with feathers, velociraptor, microrpator part of)
- early featehred theropods prob couldn't fly
- early feathers evovled for insulation (thermoregualtion), camo, or courtship
- evovled from featehred theropods during the jurassic (165-150 mya)
- archaopteryx oldesnt known bird (150 mya-late jurrasic) with dino ( teeth, bony tail, wing claws all absent in modern birds) and bird characterstics (feathers and wings for flight)
- hollow, thin walled bones (other skeletal similarties)
- egg laying and brooding
-feathers are homologus with theropod scales (scales on birds feet, feathers on some theropods)
-numeroud organ simialrites ( brain, heart, muscle arrangement)
- birds and crocodillians are extant sister taxa ( share ancestor)
- comletely divergent in appaernace and ecological niche
-birds form a monophyletic lineage underwent rapid adaptive radiation after the evolution of wings and flight
- phylgoeny is activley debated (deatures of descendant groups arose about the same time, 10k species wide variety)
- wings with keratin feathers
-lightweight hollow bones
- beak that lack teeth
- crop and gizzard (digestive system for flight)
- organ reduction
-endothermy
- birds high metabloic rate (4 chambered heart, complex respiratory)
- feathers finely subdivded keartinous scales (homolgous with reptiles)
- wings are modified tetrapod limbs ( reduced number of digits, wings have 1 main digit and 2 tiny digits)
- no claws on wing digits in extant species
-birds are bi pedal (walk on 2 legs)
- bones have air filled cavities, with a honeycomb structure that enhances bone strength and minimizes weight
beaks are bony extensions of the upper and lower jaws that are sheathed in keratin
- crop for temporay food storage
- gizzard, muscalr part of stomach with swallowed grit that grinds food, compsenating for absence of teeth
- organs reduced in size, small gonads in both sexes, one ovary, no urinary bladder, all for weight reduction in flight
- use metabolic energy to maintain body temp
- high metablic rate to support energy demands of flight
- feather and fat layer help retain body heat
- along with mammals are the only extant endotherms
involves cyclic movment of air between air spces in the bones and the lungs ensuring that fresh air reaches the lings during inhalation and exhalation, optimizing oxygen uptake for flight and energy
- birds are diverse (10 k species), live in land, freshwater, marine ( have to lay eggs on land)
- predators, heribores, scavnegers, omnivores ( beak and foot morpholgy shoes feeding behaviour clues)
- most species have wings adapted for flight
- enhances hunting/ scavenging, escaping predation, migration
body plan is simialr amongst most flying birds
-flightlessness has evolved mutiple times (60 extant species of flightless birds, penguins, ostriches and realtives)
- facilate flight, prvodie inslutation, used for camo, signalling and courtship
- several types of feathers
- maintenance: daily preening (grooming); distribution og waxy secretions along the length of feathers to keep them supple/ removes foreign particles/lice/parasites
- arrangemnt of feather on a bird
- regualry moulted
- internal fertilization bia copulation
- most odnt have intromittent organ (other than ostriches and water fowel
- during copualtion males and females press their cloacas together
- birds are oviparous (eggs on land/ eggs have hard calcarous shells not leathery like reptiles)
shared opening for the digestive, urinary, reproductive tract in birds also found in amphibians and reptiles
- all birds show some degree of parental care
- most incubate eggs with body heat
- chicks are cared by mother or both parents soemtimes
some chicks born with the abiltiy to feed themsleves shortly after hatching
- born helpless, featherless , need intensive parental care for warmth and feeding
- domesticated birds (chickens, ducks, turkey): protein, provide eggs and meath
- animal welfare concerns about intensive commerical poultry farming ( birds also feather farmed)
- waterfowl (ducks and geese) and gamebirds (pheasants and partridge) sport hunted
- recreational bird watching huge for ecotourism
- song birds, parrots sought out for as pets
- 160 species have become extinct cause of humans, threatens over 1400 with extinctions
- over 5300 extant species
-largest living (blue whales) + the most intelligent (elephants, cetaceans and primatea)
- four legged terrestrial animals (some adapted to sea, air, trees, 2 legs only)
- aminotes that have body hair and produce milk
- mammary glands that produce milk for offspring
- hair/fur covering their bodies
- 3 middle ear bones
-endothermic (4 chambered hearrt/high metabloic rate)
-dentary squamosal jaw joint
- differentiated (specialized) teeth (two sets, teeth occlude)
- larger brains compared to other vertebrates
allow mammals to raise their young independ of environmental conditons
- origin of glands are unclear (soft tissues dont fossilize good but they might have come from SWEAT glands
- fine, cylindrical keratin fibres
- provides insulation, protection and sensory perception (whiskers)
- formed by the relocation of leftover jaw bones to middle ear
-arrangment allows the detection of higher frequency sounds than reptiles with 1 bone
-ear drum is located deeep in the head compared to reptiles (so its better protected)
-can regulate their body temp independent of the external environemnt
-independent origin from avian endothermy
-hair and fat help thermoregulation
-endothermy+4 chambered heart supports a high metabolism
- the dentary (lower jaw bone that carries teeth)
-squamosal (small cranial bone)
-both meet together to form jaw joint
- in most gnathosotomes and early snapsids the jaw joint had an articular (small lower back jaw bone) and quaderate (small bone upper back jaw bone); now articular and quaderate reduced in size and incorpated into the ear
- dentition is more complex than reptiles
-greater diversty of tooth morhpolgy between indiviudals and species
- used for cutting, piercing, tearing, grinding, dental diveristy shows wide range of diets
-teeth occlude more closely than reptiles so good can be ground more finely increasing sa which allows rapid digestion
- 2 sets of teeth over their lifespand (milk and adult teeth) most reptiles continually replace their teeth
- devlopment of the neocortex that is involved in higher functions (sensory preception , motor command and language)
- vertical placement of limbs beneath the body ( lateral in reptiles) support the body better and more effcient movement
-limbs modified for running, jumping, burrowing, climbing an d swimming
-diaphragm helps ventiallate lungs (a sheet of muscle at the base of the rib cage)
-mammals copulate using an intromittent organ for internal fertilization (most are viviparous, giving birth to live young)
synapsids: one pair of temporal fenestra in the cranium
- synpasid clade also includes, dimetrodon (sailbacks), numerous therapsids species including mammals and their close realtive
-all non mammalian synapsids are EXTINCT
- progressive enlargment of the dentary bone in the jaw of therapsids which forms the dentary squamosal
- mammal jawbone consists of only the dentary bone whereas the jaw of reptiles is formed by multiple small bones
- Development of a secondary plate, a bone partition between nasal and oral cavities allows for simultaneous chewing and breathing (efficieny in proccesing food)
- early creatcous 3 main lineages of mammals had emerged coexisiting with non avian dinos
-most ealry mammals were small bodies insectivores
-diversified into large and small bodies herbiovers, carnivores and insectivors after the creatceous mass extinction (65 mya)
- after extinction of non avian dinos, mammals had adaptive radation to fill a wide range of now free ecological roles
monotremes (diverged from other mammals 180 mya) single oder
marsupials (divereged frome eutherians 140 mya) single order
eutharians ("placental mammals", contains many orders)
-includes echidnas and the platypus
-small group of egg laying mammals
- 5 extant speices(1 platypus 4 echidnas) in australia and new guinea
-lay eggs (oviparous) but provide milk to young
-no nipples milk comes out of patches of specialized hairs
-have cloacas, single opening for digestive, urinary, reproductive
-feed on invertbrates and lack teeth as adults
-viviparous
-placenta provides intial nourishments
-postbirth nursing from nipples
development of embryos within the parental body, giving birth to already devloped offspring
consists of extraembryonic membranes and the lining of the uterus, exchanges nutrients, metabolic waste, dissolved gases between the mothers and embryos blood
conical outlets from mammary glands
-opossums, kangaroos, koalas
-320 extant species just one species not in the southern hemisphere (dominat in australia because they evolved in the abscence of eutherians)
-embryo development within a palcenta in the mothers uterus is very brief (placenta is simple and less efficient than eutherians)
-born as partially developed embryos
- crawl to mother marsupium (pouch)
-marasupium encloses milk glands and nipples in most species
-embryonic development completed during nursing
-some dont have a marsupium; young hang onto mothers fur
-both males and femals have a CLOACA
- 5000 extant species
- more complex placenta (SDT)
- embryos complete devlopment in motheres uterus connected by placenta , placenta give nourishment, commonly called placental mammals becuase its important for them
- young suckle milk from nipples, nipples not in pouch, # of nipples indicate of number of offspring during pregnancy
- have seperate urinary and anal (no cloaca)
- undeerwent extensive adaptive radiation; many body forms, habitats, feeding behaviours
-molecular phylogentic anyalses gives 4 major lineages all diverged from common ancestor
-molecular and morpholgical data give conflicting dates on diversification of eutherians
-afrotheria
-xenarthra
-euarchontoglires
-laurasiatheria
- typically affrican mammals that underwent diversification in africa when it was seperate from other continents
- mammals that evolved in south america
- eutherians not associated with a particular region but includes rodentia (most diverse; 1800 sp), mammalian order, an primates (incl. humans)
- typically eurasian and north america fforms
-super diverse (terrestrial hooved mammls, even toes and odd toed ungulates) + marine mammals + bats (only mammals that can fly)
-includes lemurs, tarsiers, monkey, apes (540 extant species)
- humans are part of the ape group
-evolved from ancestors the inhabited trees of tropical forests
-many charactersitics are adaptions to this 3d environemnt, most remain atleast partiall arboreal (live in trees), some (great apes) are mostly on land but all species can climb trees
- hands and feet adapted for grasping
-large brain and short jaws
-forward looking eyes, close otgether, provide depth perception for judging distances
-complex social behaviour and parental care (distingiuhes them from other mammals)
- thumb/big toe is widley seprated from other digits (allows grasping)
-fully opposable thumbs (monkeys & apes)
-limbs with opposable digits allow fine manipulation, with flat nails instead of narrow claws
- sterescopic vision: fields of vision from each eye overlap
-vision increased at the expense of smell, the dominant sensory system in most malls due to the shortening of the snouth
- lemurs, lorises, bush babies
-tarsiers
-anthropoids (monkeys, apes, humans)
oldest known anthropid fossil 45 mya, indicate tarsiers are sister taxa
monkeys, evovled in the old world (asia/africa) with new world (south america) monkeys appearing 25 mya
- new and old world monkeys diversified independently after their seperation
-new world: side opening nostrils, prehensile tails
- old word: down opening nostrils , no prehensile tails
-non monkey antropoid are hominoids, primates informally called apes
-diverged from old world anthropids 20-25 mya
- no tails, realtivley large brains
- 7 species of non human great apes (hominids), 5 speices are critically endagered due to habitat loss and illegal hunting
-gibbons (lesser apes)
-hominids the great apes: orangutans, gorillas, chimpanzzes, bonobos and humans
-homo sapies are the only extant species
- realtively young (200k YO)
-anatomical, molecular, fossil evidence show we are descendants of hominids lineage
- large brains and bipedal locomotion
- great apes including humans form a monophyletic (includes descendants and ancestor)
-humans exhibit unique features as well as other great apes, blurring distinctions between groupds
- no apes vs humans contrast, theres no unique features that place them apart from humans
-molecualr systematics say chimpanzees (pan troglodytes) and bonobos (pan paniscus)
- their genomes share 99% of their DNA with humans meaning we share an ancestor and not that we evolved from chimpanzees
- 80 gendes have been lost in humans compared to chimpanzees
-loss of myosin gene (MYH16) is associated with smaller jaw muscles and increased cranial cpacity
-changes in regualtory genes can have large effects
- Miocene (23-5 mya): 100 ape species
-unclear which ape contirbuted to hominin lineage (incomplete fossil evidence)
- fossil and dna evdience show hominin lineage that gave rise to humans diverged from the chimpanzee-human last common ancestor 6-8 mya
chimpanzees, bonobos and humans and their extinct realtives
- upright posture and bipedal locomotion
-larger brains
- reduced jaw bone and jaw muscles
-shorter digestive tract
them traits did not evovle simultaneously early hominins were bipedal w smallbrains
allows for efficent travel on two legs and frees the hands for other uses
- capable of symbolic though, artistic expression, langauge, manufacture and use of complex tool
- larger realtive to body size and other primates
- with increased brain size, humans have modified reduction in jaw bone and jaw muscles
assoicated with changes in diet and the development of cooking method
- used to have many branches and coexsiting species but humans are the only extant ones today
- fossil of 20 species of extinct hominins
2 or more often coexisted
-evolutionary history doesnt follow a linear progression culminating in humans
- in africa about 6-8 mya earliest fossils were found in the great rift valley of east africa and southern africa
-early hominins (ardipithecus) showed icnreasing bipedalism but had small brains still (chimpanzee sized brain, 300-350 cc)
- despite bipedalism they retain skeltal features for arboreal life (grasping feet and long arms)
- bipedalism (early)
-expansion of brain and increased brain compelxity (later)
- mod of pelvis
reduction of teeth, face, jaws
-extended period of infant and child depndency
- increasing hairlessness
-incresed reliance on meet
-emergence of tool use
- early hominins faced significant challneges that favoured for bipedalism (large mammal predators, competition from terrestrial primates, change in habitat decline of arboreal --> expansion of open grasslands)
- enhanced visibilty of predators and prey
-energy efficent locmotion especially for long distances
-better thermoregulation in open habitats (max breeze; min exposure to midday sun )
-free hands for carrying infants/food/tool use
- vulnerabilty to foot injuries
-increased strian on hips, backs, knees, ankles
- skull attachment
-spinal curvature
-pelvis
-legs
-foot
repositioning of the foramen magnum for balanced skull placement atop the VC
developemnt of s shaped spine to align weight over pelvis
reconfiguration of the pelvis to supoort internal organs in upright posture
lengthening of legs for efficent locomotion (long stride) with alrger knee joints for weight support
-legs directly under body
alternations in foot strcture, incl a narrower shape, enlarged hell, and a larger big toe for stability and propulsion
- diverse group of early hominins (4-1.5 mya)
-phylogeny is unresolved but thought to be paraphyletic
- successful, lived for 3 million years
- species australopithecus afarensis (lucy 1974) were fully bipedal (3.5 mya)
- fully bipedal (short, bowl shaped pelvis and alignment of toes for walking upright, long forarms though and somewhat curved toes and fingers)
-short in stature (1.2 to 1.4 meters tall)
- marked sexaul dimorphism (50% size diff between m & f)
- small brains (cranial capacities 375-550 cubic centimeters) comapred to early homo species (550-750 cc) and modern homo sapiens (1300+ cc)
- large protuding jaws
- exhibited evidence of tool use (oldest isntance 2.5 MYA) tool use--> devlopemtn of larger brains
-classified into robust or gracile from their skulls
such as paranthropus species had strudy skulls and powerful jaws
like australopithecus , with more slender and lighter jaws considered possible ancestors of homo species
- adavncements in brain size, tool complexity, soxcial behaviour
- earliest fossil placed in the genus homo are those of homo habilis (2.4-16 mya) in east africa
- simple stone tools found with them
- compared to australopiths they had larger brian capacity (600-750 cc), shorter jaw, short in stature (4.5 ft (1.3m))
- 1.9 to 1.5 mya
- first fully bipedal AND large brained hominin
- compared to habilis it had:
-a larger cranium and brain capaity (900 cc +)
-long slender legs and hip joints adapted for long distance walking
- dietary change supported by smaller teeth, shift towards increased meat consumption
-developmed more sophisticated tools
-significant decrese in sexual dimorphism meaning increased pair bonding and reduced male-male comp
- orginated in africa 2 MYA
- first hominin to migrate out of africa to southern europe, china and indonesia
- oldest fossil found outside africa date back to 1.8 mya
- likely lived in hunter gather societies and demonstrated abiltiy to control fire (significant advancement in cultural and behavioural complexity)
- larger brain (1000-1200cc)
- around 0.7 mya evovled from african popualtions of erectus
-similar to homo sapiens in body proportions, dental adaptions, cognitive abiltiy (cranial capcity- 1200 cc)
- large animal hunter porducing sophisticated tools
-neadenratheral ( european H. 250 kya) and homo sapiens (african H. 200kya) likely evovled from distinct pops of heidelbergensis
- lived in east europe (350-28 kya)
- cold adapted hominins with robust physiques, thick bones, complex behaviours (buried dead, crafted hunting toolds)
-similar brain size to modern humans
coexisted with homo sapies until at least 40kya, sharing europe for 5000 years ( limited interbreeding between two)
- 45 of genome of non african humans is neanderthal ancestry
- genetic contrubtion is absent or uncommon in the genome of most sub saharan african populations
- gentically distinct group of homo that live in eurasia around 50 kya
- shared a common ancestor with neaderthals that diverged 400-700 kya
-interbred with neanderthals and modern humans
- anyalsis of their dna from remain in a denisova cave in sibera show that dna is present in modern human oppualtions in east and southeast asia and oceania
- eventually became extinct along with neanderthals
- taxonomic staus pending more complete fossils
- originated in africa 200 kya
-likely descended from heidelbergensis with all living human tracing their ancestry back to african pops
- large brains (1400 cc)
- advanced tool use and huntin techniques
- increased behavioural complexity
- first group to display evidence of symbolic and sophisiticated thoug, shown in carvings and cave art, providing insights in migration patterns and habitation
- flourished and expanded on african continent
-migration began 200 kya
- by 100 kya humans spread into eurasia, eventually expanding across the globe into australia and the america
-frist arrive in the new world around 15 kya
-replaced other hominins encountered, including neaderthals in europe and asia
- supports origination in africa
-mtDNA inheribited maternall without recombination support out of africa migration hypothesis (phylogenies using y chromosomes came to the same conclusion)
-humans trace back 200kya to a most recent common ancestore in africa this MRCA most likely lived in east africa where modern humans emerged from, this mrca originated later than heirdelbergensis and neanderthals but earlier than the out of africa migration
- little genetic variation compared to other mammal lineages
-reflecting the young evolutionary age (200kya)
- dna of any 2 individuals on avg is 99.9 % identical (only 1/1k base paires varies)
- since we left africa very recently there had been little chance for gentic differences between seperated pops
- within population
- 85% of genetic variation in human found within a single population
-only 7% of human genetic variation segregates between groups that are commonly called races
- racial differences like skin colour, malaria resistance, lactose intolerance evovled through natural selection reflecting adaptions to local environments