Lecture Notes for first Midterm
Lecture Notes for first Midterm ANTHROP 3300
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Date Created: 09/27/15
Lecture Notes leading up to Midterm 1 Today fossHs fossilization taphonomy dating methods paleoecology Taung child first Australopithecus discovered had indicts of the brain from southern africa people didn t like this because of ethnocentric racism challenged idea that brains evolved first before other aspects like teeth and foramen magnum Fossils dug from the earthquot definition remains or traces of ancient organisms Laetoli footprints context of the fossil is most important without it the fossil means nothing 0 for dating sequences 0 reconstructing past environments where were they found original site 0 reconstructing ways of life butchered animal remains stone tools with fossHs Fossta on limestone is shelly material compacted down with calcium carbonate good way to preserve fossils mineral in groundwater infiltrates tiny spaces in bone minerals from soil replace bone bone turns to mineralstone soft parts tend not to fossilize decay before mineralization bonesteeth are most common Factors of fossilization 0 Lucky acidic soils bacteria scavenging prevent it o BURIAL under sediments lakes rivers and their margins alkaline soils volcanic ash in limestone caves Olduvai Gorge o faultingerosion reveal 2miion year geological sequence from ancient lake fossils in sedimentary layers 0 rift valley formation makes it a rich area for fossils Taphonomy taphos burial nomos law definition study of the processes that occur after death including fossilization but not only community to death assemblage to deposition to fossilization then repeat try to understand how fossils got to be where they are crowned eagle and Tong child study The Killer Ape Hypothesis Dart thought killer instinct made humans different from apes smarter and more brutal because of bone deposits in caves that he thought were used as weapons 0 had enormous influence on paleoanthropology for a long time o the bones were actually brought in by other animals humans were being hunted not the ones hunting 0 discovered by Bob Brain using skulls from cave and a mandible of a leopard found in the cave 0 trees growing around cave entrances because of limestone bones drop down into the caves 0 called Leopard Refuse Hyaena den Porcupine collection some bones are chewed on my porcupines try to understand preservation bias 0 some parts of skeleton preserve better than others Dating Methods relative establishes one object as older than another Chronometric provides an actual time frame in years for age of the object relative dating 0 superposition based on undisturbed stratigraphy o biostratigraphy faunal correlation o fluorine dating based on fluorine content in bone more is older 0 Paleomagnetism based upon the idea that different times during Earth s history the poles have switched apparent in sea floor spreading led to idea of tectonic plate movement Discussion on Tuesday pay attention to the material may be a short answer on the midterm Group meeting today in class John Hawkes paleoanthropology web blog is good source to find whats been written out there ESR back 2 3million years correct in notes Evolutionary Processes forces of evolution micro v macro speciation modes and patterns of marco evolution Four Forces of Evolution produce changes in population gene pools from one generation to the next mutation ultimate source of genetic variation gene flow both enhance variation natural selection and genetic drift decrease variation natural selection is the only force that produces adaptation all forces result in population change and can result in speciation genetic drift random changes in frequency of alleles keep getting same allele over and over again can result in directional change Micro v Macro micro changes in gene pools that do not result in new species macro changes in gene pools that result in new species genera families Speciation process by which new species form Biological Species Concept groups of actually or potentially interbreeding organisms which are reproductively isolated from other such groups focusing on process by which species come about and how they stay different Reporductive Isolation postzygotic isolating mechanisms prevent breeding AFTER mating the embryo is not viable Hybrid sterility embryo is viable but can t pass along its genes mule Prezygotic isolating mechanisms prevent breeding BEFORE mating temporal isolation frogs only mate in certain months different from other species Reinforcement selection against hybrid may reinforce reproductive isolation via prezygotic isolating mechanisms Speciation Allopatric original population gtinitial step of speciation happens with barrier gtevolution of reproductive isolation gt new distinct species after equilibrium of new ranges Speciation Peripatric peripheral isolates original gt new niches entered little group gt adapts to new environment in new niche and speciate small subpopulation in a new niche happens fast because its a small population Speciation Parapatric new niche is entered but population isn t out off still possibility for gene flow differentiation speciation adjacent populations metaltolerant and intolerant grasses developing different flowering times populations right next to each other with different breeding habits Speciation Sympatric within the same place differentiation of species within same population fish in great rift lakes initial differentiation based on diet females would only mate with a certain color sexual selection Modes of Macroevolution Anagenesis one species transformed into another Cladogenesis gene pool splits gives rise to one or more new species Undergraduate Anthropology Club Meeting 99 5pm in Smith Lab 4094 September 15th Bring in research notes Done from the library The Salamander s Tale Why is there a problem to consider them separate species 0 all along the coast around the loop there are hybrid Salamanders all of them are mating along the loop but the two ends of the loop don t hybridize yet are connected How did this happen 0 possibly ancestral species started from the top and as they moved along the two sides they diverged 0 possibly started at the bottom and moved around in a circle and speciate Another ring species C Herring gul and black backed gull don t mate but in a loop the gulls hybridize around arctic circle 0 kept separate because its too cold so they migrate around the pole Ring species show us in the spacial dimension what must have happened in the time dimension 0 shows the evolution of the species as they moved around in the ring 0 hybrid intermediates still alive show the evolution 0 time and space dimensions mirror each other Why is it impossible for one species to form into another 0 reproductive isolation can t make new speciesquot 0 lawyer guy getting stuck on this definition didn t see the middle ground 0 thinking of species as being very distinct non graded thing discontinuous mind 0 focus on putting things into distinct categories 0 often times these categories don t exist What is plato s philosophy of essentialism o everything on earth is just a reflection of a perfect being 0 variations don t matter they have an essence that connects them 0 if theres an essence then evolution is not possible Humans evolved from chimps What would Dawkins say 0 we didn t evolve from chimps we evolved from a common ancestor Arguments over names of fossils in the human fossil record 0 can t put everything into categories 0 there will be things with features of two kinds of homo because of gradualism Narrowmouth s Tale if they hybridize why are they separate species 0 reproductively isolated prezygotic different mating calls How do calls compare in zones where they don t overlap o more similar they are farther apart but where they do overlap they are very different Reinforcement 0 natural selection is favoring the divergence of the species and don t form hybrids because hybrids are less fit this reinforces reproductive isolation Another reason for differentiation when overlap Darwin 0 where they overlap more competition 0 selection will favor those who don t compete as much 0 Character Displacement Macroevolution punctuated equilibrium explaining why we see the patterns in the fossil record 0 stimulated by observation of fossil records layers of fossil record wouldn t show transition species intermediate forms not preserved for whatever reason Phyletic Gradualism most speciation by anagenesis miss transitions because fossil record is imperfect speciation is happening very fast so they do pop up in fossil record Punctuated Equilibrium peripatric speciation speciation is abrupt by cladogenesis only stasis within lineages transitional forms not found mainly because speciation is FAST explains abrupt changes in species in fossil record 0 O O O 0 Classification and Cladistics Taxonomy How to classify 3 schools The Cladistics school wins Taxonomy taxis arrangement nomos law science of classifying and naming life forms Linnaeus Systema Naturae 1758 binomial nomentclature two names Genus species Nested hierarchy of taxa Class Order Genus species levels within levels within levels like a Russian nesting doll nested because all species within the Class shared a common ancestor and same within Order and within Genus How to Classify Linnaeus similarity After Darwin based on evolutionary relationships those most closely related grouped together School 1 Evolutionary Systematics O O taxonomy should reflect evolutionary relationships in part but also key differences Phylogeny evolutionary relationships based on characters inherited from a common parentquot Key Differences adaptively significant features Homology similar structure in different taxa due to common descent Homoplasy similar characteristics acquired independently not from common descent convergence parallelism acquired separately in related groups reversals Hominidae vs Pongidae so much morphological change due to adaptive differences makes them different families School 2 Phenetics 0 back to Linnaeus based on all similarities too hard to figure out which similarities are due to common descent School 3 Cladistics 0 000 0 based ONLY on phylogenetic relationships based on branching sequence Hominidae gorilla pan and homoaustra within that sub family level gorillinae and homininae divide again panini and homini just how they branch off and that s it How to figure out branching sequence 0 GOO 000 O Distinction between primitive features and derived features Primitive plesiomorphies near Derived apomorphies away from Example Mammals What do they have in common Backbone primitive feature not just mammal that has backbone Mammary gland derived feature exclusive to mammals derived characteristic makes up branches shared derived characteristics synapomorphies key to cladistics more synamorphies closer relationship shared primitive characteristics symplesiomorphies not relevant traits unique to a taxon autapomorphies also not relevant How to do a cladistic analysis 0 take several taxa 0 list their traits DETERMINE TRAIT POLARITY which traits are primitive and which are denved USE PARSIMONY PRINCIPLE use simplest explanation homoplasy is infrequent Example Worksheet Hard example of cladistics Homoplasy example Today Geological Time Scale Highlight in Vertebrate and Mammalian Evolution Primate Taxonomy Geologic Time Scale Eons gt Eras gt Periods gt Epochs Eon Phanerozoic time of living things solid rock forms 38 billion years ago first third of Earth s history no oxygen on the planet cyanobacteria build the oxygen in Earth s atmosphere during Archean stromatolites are the evidence for this period made by cyanobacteria Proterozoic Era towards end is the very first multicellular life forms very strange diskfrond type creatures all of this is Precambrian 87 of Earth s history before phanerozoic Paleozoic Era 540225MYA O 0000 Cambrian period explosion of life lots of fossils mouthparts and hard pans Burgess Shale incredibly well preserved Cambrian set of fossils diversity of forms early Chordate has stiffened rod down the back allows muscles to pull against it and swim back and forth first vertebrates jawless fish then jaws some with cartilage skeletons some with bone Coelacanth lobed fleshy fins still around today Lungfish primitive lung if water sources dry up gave rise to tetrapods 4 limb animals fishlike tetrapod Tiktaalik 375MYA front fin with wrist and elbows head flattened top to bottom lungs and gills first amphibians appear just after Problems of life on land desiccation drying out skin food sources 0 during Paleozoic all continents connected as Pangea Mesozoic Era Age of Reptiles O O 2 continents Laurasia N and Gondwanaland S Reptiles completely terrestrial vertebrates waterproof skin amniote egg prevents desiccation dinosaurs dominate mammallike reptiles therapsids lay eggs heterodont multicusped teeth all mammals hair produce milk endotherms heterodont 3 bones of the middle ear one group of therapsids gave rise to 3 modern mammalian sublcasses Monotreme lay eggs but still produce milk lack teeth Marsupial pouches Placental nurse embryo through placenta diversity of mammals end of Cretaceous period 75 of all species extinct mammal diversity low due to impact of huge crater in the Yucatan Cenozoic Era 65MYA O adaptive radiation from early mammalian insectivores Modern Primates an order of Mammals Kingdom Animalia Phylum Chordata Class Mammalia Order Primates over 300 species tropicalsubtropical Primate characteristics and trends 0 generalized skeleton plesiomorphies clavicle 5 digits adaptable tendency towards erect posture prehensile hands and feets opposable toethumb nails not clawstactile pads deemphasis on olfaction emphasis on vision forward facing eyes stereoscopic color in diurnal primates post orbital bar auditory bulla formed from petrosal bone surround middle ear increasing brain size relative to body size longer periods of infant dependency tendency to live in social groups 0000 on Tuesday discussing the ERerserve 5 and 6 and there is a handout to do Today Primate characteristics nails prehensile hands eyes facing forward stereoscopic vision depth perception opposable thumbsbig toes generalized skeleton petrosal auditory bulla larger brain size relative to body size long period of infant dependency tendency to live in social group deemphasis on sense of smell tactile pads color vision tendency towards erect posture post orbital bar Primate taxonomy Origins of trends Arboreal Hypothesis 0 most primates live in trees tree living is responsible for traits associated with primates o grasping hands and feet for climbing o depth perception needed in complex environment Visual Predation Hypothesis 0 orbital convergence in animals that are visual predators needs to be able locate its prey owls big cats for example squirrels live in trees without all these characteristics came from small animal that needs grasping for small support branches with orbital convergence to locate prey GraspLeaping 0 like vertical leapers today but grasp onto support with all four limbs and leaped 0 need prehensile opposable depth perception Angiosperm Exploitation Hypothesis 0 angiosperm flowering plants o began to adapt to flowering plants that began to diversify around time primates came about made room for new niches 0 need to be able to grasp onto small supports and depth perception to locate fruits and flowers at end of branched Primate Order Prosimii o lemurs lorises tarsiers 0 characteristics smaller brains relative to body size as compared to Anthropoidea not T wet nose not D enhanced sense of smell eyes are not fully forward Not D orbits not enclosed part D many nocturnal tooth comb not D unfused mandible frontal bone Anthr0poidea o monkeys apes and humans 0 characteristics larger brains relative to body size dry noses eyes forward post orbital closure most diurnal no tooth comb fused mandible and frontal bone Platyrrhini New World Monkeys flat nosequot dental formular 2 133 prehensile tails broad flat noses round nostrils almost all arboreal M Old World monkeys apes and humans narrow noses nostrils point down 2 123 dental formula none with prehensile tails Cercopitehcoidea Old World Monkeys tails large brains usually terrestrial quadrupedal stable elbow joint short digits bilophodont molars two crests that connectcusps Hominoidea DNA hybridization apeshumans no tails larger brains suspensory adaptations mobile shoulder joint scapula on back elongated clavicle ball and socket joint in shoulder long arms curved finger bones reduced thorax and short lumbar region bunodont Y 5 pattern incestral trait Hylobatidaegibbonssiamangs lesser apes brachiators Pongidae orangutans Asian Great ape Honinidae african apes humans Gorillinae gorillas knuckle walkers Honininae chimps bonobos and humans Panini chimps and bonobos Homini humans and bipedal ancestors 0 use DNA from two organisms let their DNA come together 0000 because hard to break apart complete hybridization organisms identical partial hybridization organisms related no hybridization organisms unrelated use heat to break apart the new DNA strand more heat more related Cladistic Analysis another way of grouping primates O Strepsirhini quotsplit nosequot lemurs and Iorises o Haplorhini quotsingle nosequot tarsiers share many common traits with anthropoids tarsiers monkeys apes and humans Review for Midterm next Thursday Study guide on Carmen there will be questions from readings power points are on Carmen Review from last lecture DNA hybridization 0 hybrid molecules 0 DNA from one and seeing how well it sticks together with another organism apply heat to see if you can pull them apart takes a lot of heat to pull apart completely hybridized species can calibrate difference in melting temp by when divergences happened Today Primate Comparative Anatomy Primate Evolution Paleocene Sexual Dimorphism any difference between the sexes that is not related to the genitalia bodycanine size dimorphism and mating system 0 Gorillas vs Gibbons Mating System Gorillas harems one male for several females greater competition for mates Gibbons monogamous mating system everyone is paired up not great competition 0 Chimps multi male multi female not as much competition not as much sexual dimorphism huge testes more spermmore chance of fertilizing but physically lntermembral lndex ratio length of forelimb to length of hindlimb x 100 HRFTx100 o humerus radius fibula tibia related to type of locomotion 0 Vertical Clinging Leaper 70 O Quadrupedal 80100 0 Brachiating gt100 Body Size and Diet lnsectivores Kay s Threshold 500 grams 0 lose a lot of heat quickly high metabolic rate o more energy per gram body weight but less total energy Frugivores and Folivores need more than 500 grams 0 don t need more energy per gram body weight just need more total energy 0 more time for food to digest Teeth and Diet Fruit broad incisors low round molar cusps Leaves welldeveloped molar shearing crests small incisors Gum stout incisors Insects sharp cusps Posterior teeth Shearing and Grinding hard foods ow bulbous cusps thick enamel 0 thick enamel so teeth don t crack or wear down leaves high cusps with shearing crests thin enamel 0 thin enamel wears off until an enamel razor sharp ridge with exposed dentine becoming razor sharp teeth to tear through leaves Cranium and diet 2 major chewing muscles 0 Temporalis origin side of craniumsagittal crest insertion coronoid process of mandible can tell something about its size from where it attaches o Masseter origin zygomatic arch insertion gonial angle of mandible Jaw and diet 0 lever system tall ascending ramus gives more length to lever arm greater mechanical advantage helps us understand what it is more adapted for diet wise Primate Evolution Part 1 Review Precambrian hadean archaean proterozoic Phanerozoic paleozoic mesozoic cenozoic we will be talking about cenozoic primates originate in cenozoic 0 order of mammals o by end of paleozoic have 70 families after major extinction 0 tree shrews and flying lemurs are the closest relatives to Order Primates Epochs of Cenozoic Paleocene 65 MYA Eocene 55 MYA dawn of a lot of modern forms of mammals Oligocene 34 MYA means few correlates to mass extinction Miocene 23 MYA Pliocene 5 MYA Pleistocene 18 MYA Holocene 10000 present Paleocene Geography 0 paleo old 0 Eurasia and N America connected Climate o warm humid climate Wyoming would have been tropical Mammals 0 small insectivores o 5 digits 0 3143 dental formula Recognizing primates in the fossil record 0 Primate synapomorphies postorbital bar orbital convergence nails divergent big toe petrosal auditory bulla Plesiadapiformes o 6 families 75 species diverse 0 North America Eurasia 0 Characteristics some with petrosal buas no postorbital bar claws snouty most have a reduced number of premolars some with low rounded molar cusps o Carpolestes Reading and Discussion lacks orbital convergence and postorbital bar has grasping foot with opposable big toe with a nail not a claw dentition shows that it is not an early primate primate like traits are starting to evolve back then so its interesting for the consideration of ecology and evolutionary processes Exam score correlation looking at diagrams on Carmen produce higher exam grades Review is on Carmen not totally comprehensive review readings in class discussions and lecture notes as well as book Review Angiosperm grasping hands first to grab the angiosperms and flowers and fruit eyes followed Carpolestes Paleocene Primates plesiadapiformes gradually extinct in Eocene Primate Evolution Eocene Oligocene temperature plays a role Eocene temperature levels really go up methane ice at the oceans melted and a lot of methane was released causing a green house effect Antartica moves over south pole and develops glaciation and kills off many of the warm temperature species on it really fucking cold decrease in life during the ice age Eocene climate 0 hot broadleaved rainforests far north mammals 0 E0 quotdawnquot 0 first appearance of many direct ancestors of modern mammals no question about it o primates appear here too o proto horses rhinos bats whales etc Primates o Euprimates north america and eurasia petrosal bulla postorbital bar orbits diverge less larger brain case EQs lt 1 shorter snout retain four premolars nails opposable big toes Adapoids arboreal diurnal most gt 500g some molars with shearing crests others low bulbous OOOOOOOOO index 70 Ida well preserved skeleton Messa Cave 0 Omomyoids arboreal nocturnal most lt 500g pointy molar cusps long hindlimbs Adapids lemurlike but no dental comb o Omomyids tarsier like but no postorbital closure Basal anthropoids I Esomias China 44MYA found with an Omomyid Adapoid and Tarsier dentition looks anthropoid like major anthropoid synapomorphies fused frontal bone eyes forward post orbital closure fused mandible reduced snout The Fayum one of richest fossil sites sandy dessert today but was a swampy area millions of years ago earliest definite anthropoid Catopithecus 37MYA fused frontal forward facing eye orbits post orbital closure mandible not fused dietary adaptation Summary of Eocene o Euprimates Adapoids Omomyoids Eosimias Catopithecus Oligocene Geography 0 North America breaks from Eurasia 0 Africa separated from Eurasia by the Thethys Sea South America closer to Africa than North America 0 important to keep in mind when looking at distribution Climate 0 End of Eocene Antarctic glaciation global cooling 0 woodlands replace tropical forests in N America and Eurasia Mammals O Oligo a few 0 60 of mammals in Europe and N America went extinct 0 Grand Coupure big cut Primates o primate nearly absent in Oligocene northern hemisphere o well represented only in the Fayum mentioned above 0 Aegyptopithecus Catarrhine Plesiomorphies snouty small cranium EQ 153 Anthropoid traits postorbital closure fused frontal and mandible small eye orbits Catarrhine trait of 2123 dental formula Y 5 molar primitive for catarrhines Mosaic 0 Parapithecus Platyrrhine traits 2133 dental formula arboreal quadruped o Platyrrhines first see in Bolivia BraniseIa 27 MYA African origin argument molecular evidence CatPlat split 4OMYA anthropoids only in Africa at this time Africa was closer to So America porcupinelike rodents in Africa and S America Next Thursday no class just appointments Early Miocene235MYA antarctic thaws warmer temperatures origins of ape clade during Miocene planet of the apes about 100 species of apes 4O genera of apes 2317mya o hominoidCercopithecoid divergence o hominoid diverse and abundant unlike Cercopithecoids Climate o warmer wetter with many rainforests 0 many African hominoids Cercopithecoid 0 early miocene 2317mya o lictoriapithecus bilophodont molars like Old World Monkeys o Proconsul The First Ape debated 2217MYA Tanzania tropical forest with open floor nearby river system Catarrhine plesiomorphies Y 5 molars narrow central incisors no brow ridge low EQ for ape shoulder monkeylike inflexible wrist flexible lumbar region intermembral index 8090 Hominoid apomorphies no tail elbow flexibility pace of dental development Apes vs Monkeys o apes scapula on back shoulder joint faces outwards elongated clavicle thorax wide compressed front to back short relatively stiff lunar region 0 Morotopithecus o 2021mya o chimp sized 0 short stiff lumbar region 0 enlarged glenoid cavity in scapula
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