Table of Contents Nature of a fossil Paleocene Eocene Oligocene Miocene Hominins Table on early hominins Earliest Homo Homo erectus Homo heidelbergensis Neandertals Origin of Homo sapiens Study guide questions Study guide answers P a g e 1 2 3 4 5 5 6 10 11 12 13 14 14 16 P a g e 2 Nature of a fossil Fossil evidence of preexisting species o Can be tooth feather bone imprint o If conditions are favorable minerals replace substances in the bone fill in porous spaces and convert it into rock o Bone consists of organic and inorganic material organic starts to decay after death Forces of destruction o Physical chemical biological forces o For fossilization to occur there must be protection from these forces o Sources of bias in the fossil record that produce non random representation Size of species larger species more likely to fossilize Where fossilization occurs best in a cave or near water Whether the fossil is exposed and discovered o Paleontologists don t just dig randomly they search where underlying sediment is already exposed by natural forces Geological time scale o Important to understand ancestral record o Pre cambrian Paleozoic Mesozoic Cenozoic present Epochs of Cenozoic know names and dates Paleocene 65 56 mya Eocene 56 33 mya Oligocene 33 23 mya Miocene 23 5 mya Pliocene 5 1 8 mya Pliestocene 1 8 mya 10 000 ya Holocene 10 000 ya present Plate tectonics Cenozoic era o Influences migratory routes climate and ecology o North America and Europe were connected by Greenland during Paleocene and Eocene this explains similar species from these periods in both Europe and the Americas o Africa was an island continent before 19 mya Then Africa contacted SW Asia this explains migration of apes throughout the old world Problem how did lemurs colonize Madagascar o It was an island before the emergence of primates o Theory they crossed the Mozambique channel on floating masses of vegetation Problem how did monkeys colonize South America o It was an island continent before the emergence of primates and the isthmus of panama connected north and south America less than 5 mya o Theory ancestor of new world monkeys crossed either the Caribbean sea they island hopped or the Atlantic on floating masses of vegetation Categories of dating techniques o Relative dating Organizing items in terms of rank sequence Stratigraphy P a g e 3 Sequencing of sedimentary rock dating fossils based on their position in the layers of sediment Principle of superposition says that older fossils will be deeper in the ground Problem sedimentation is not constant Biostratigraphy Dating of fossils based on association with fossils of another species If we know that one fossil is 60 million years old then a fossil on top of it must be 60 million years old Index fossils index species fossil species of known age which is used to estimate the age of another species Finding the relative age of a fossil based on fluorine concentration from fluorinated water If two organisms died at the same time in the same environment then they should have the same amount of fluorine Fluorine analysis Charles Dawson and Piltdown specimen Fluorine test was applied to Piltdown Less fluorine than contemporaneous younger fossils Mandible had different fluorine content than cranium Declared a hoax Based on principle of radioactive decay radioactive isotope releases Radioactive potassium decays into stable argon Half life is 1 25 billion years Uses volcanic rock date rock underneath and on top of a fossil to determine fossil s age Argon argon dating Same procedure less material Carbon 14 dating We and animals eat plants which have C14 and C12 Half life of C14 is 5 730 years Determine ratio of C14 C12 Only for relatively recent specimens o Chronometric dating energy as a half life Potassium argon dating Paleocene o Fossil primates found primarily in North America and Europe o Not all anthropologists believe that these are primates o Differences between plesiadapiforms primitive primates and modern primates Longer snout Eyes not at front of skull No post orbital bar Smaller brain Specialized dentition Claws not nails Non prehensile hands and feet o Anatomies that suggest that Paleocene species may be primates Anatomy of molars grinding more suggestive of primate than P a g e 4 insectivore Middle ear Eocene o Primates look more modern o Anatomies Eyes face forward Post orbital bar Short snout Prehensile hands and feet Nails Larger cranial capacity o Where fossils of Eocene primates are found Principally in north America and Europe remember connection of North America and Europe by Greenland may explain similarity of these Later in Asia and North Africa end of Eocene o Environmental context of Eocene primates Tropical and subtropical forests o Taxonomy and phylogeny Two lineages adapids and omomyids Adapids may be ancestral to lemurs and lorises Omomyids may be ancestral to tarsiers and antrhopoids o Inferences about Eocene primates Some were diurnal others were nocturnal o Locomotion Quadrupedality and leaping o Diet Insectivory frugivory folivory o Absence of tooth comb Oligocene o Where fossils are found in Oligocene Fayum Egypt 33 35 mya Environment tropical forest o 2 lineages o Propliopithecines Propliopithecines and parapithecines Dental formula 2 1 2 3 2 1 2 3 Same dental formula as modern catarrhines Has 5 molar cusps but not Y 5 pattern May be ancestor divergence has not yet occurred o Parapithecines Dental formula 2 1 3 3 2 1 3 3 Same dental formula as modern platyrrhines May be ancestor Inferences about Oligocene antrhopoids o Locomotion Aegyptopithecus slow quadrupedal climber Apidium quadrupedal runner and leaper more slender P a g e 5 o Body size and diet 2 4 pounds for Apidium 13 18 pounds for Aegyptopithecus Diet frugivory rounded cusps for crushing o Oligocene antrhopoids were diurnal o Social organization Aegyptopithecus shows sexual dimorphism in canines which implies In early Miocene Africa was an island separated from Europe and Asia by the Tethys sea About 19 mya the Arabian plate formed a migratory corridor from Africa to Europe and Asia Miocene polygyny o First hominoids hominins o Geographical distribution o African taxa 23 14 mya Proconsul o European taxa 16 11 mya Dryopithecus o Asian taxa 15 5 mya Sivapithecus o Miocene hominoids were dental apes Had Y 5 cusps o Diversity in locomotion Their anatomies were similar to OW monkeys suggests they were aboreally adapted in early Miocene quadrupedal in middle of Miocene