Fossils plants and animals that have been converted to stone rare event usually must be covered with something like mud in an anoxic water environment first Then as mineral laden water percolates through it the minerals replace the tissue molecule by molecule Organisms that were once alive that gradually got turned into stone o Snapshot of life in past o Recognition is limited critical in interpreting the fossil record Relative dating science determining the relative order of past events without absolute age Adaptive Radiation diversification of a species into several forms that are each adaptively specialized to a specific environmental niche Fluorine measures levels of fluorine in bones to determine relative age Biostratigraphic Faunal compares different fossil forms based on the first appearance of an organism through its extinction Cultural uses changes in material culture stone tools to est a chronology Absolute Dating result in numerical date Dendrochronology tree ring dating Carbon 14 useful for dating anything that was once alive animals plants textiles K Ar Dating dates volcanic rocks above and below fossils older than 200 000 years Fission Track spontaneous decay of Uranium 238 leaves starches on volcanic glassy rocks and volcanic ash Superimposition relative dating method stacking one top of each other The Molecular Clock changes in DNA happen at steady rate Ichthyosaurus reptile died while giving birth both she and baby were fossilized born tail first Hominid fossils rarely fossilize bc of predators scavengers decomposition need anoxic no oxygen environment which greatly slows decomposition Sedimentary laid down little by little have sea shells Volcanic igneous Isotope different form of a current element Pangaea at 200 mya Earth s 1 continent Taphonomy study of what happens to organisms remains after death Half life K 40 is 1 310 mil years of substance will have changed into Ar 40 Cenozoic is the Age of Mammals Epochs within the Cenozoic from the beginning to present are Paleocene Eocene Oligocene Miocene Pliocene Pleistocene and Holocene Plesiadapiformes evolved in the Paleocene and these were primate like but had rodent like incisors and no postorbital bar Their eyes did not face forward One of the more generalized Plesiadapiformes was Purgatorius During the Eocene several primates of modern aspect evolved they looked much like today s prosimians True Primates these were definitely primates they had a postorbital bar forward facing eyes reduced snout etc Earliest anthropoid primates may have evolved during the Eocene but had a big adaptive radiation during the Oligocene Much evidlence about primate evolution at this time comes from a site in Egypt called the Fayum The fossil Aegyptopithecus is important because it is the potential ancestor for all Old World monkeys and the apes Miocene apes had adaptive radiation many different genera were alive at this time Apes first evolved in Africa and migrated into Europe Asia Towards end of Miocene apes started to decline reproduce very slowly K selected and one theory about their decline is that they began to be outcompeted by the OWM who reproduce more quickly r selected and were having an adaptive radiation modern apes reproduce slowly and live in relict patches of rainforest The human ancestor was some kind of generalized Miocene ape who became bipedal and more r selected Y 5 Molar 5 cusps with grooves running between them characteristic of hominids During the Pliocene and Pleistocene many species of monkeys proliferated climates and environments favored their adaptive radiation The Pleistocene had many episodes of climate change The Ice Ages Honing Teeth sharpening of teeth canine premolar CP3 primitive Nonhoning Teeth non sharpening humans derived The canine is a behavioral tooth large male canines mean strong competition among the males for status and mating opportunities Canine reduction suggests a more peaceful social system Owen Lovejoy theory allowed the freeing of hands for males so they could get food to the females Best evidence for early bipedalism Ardipithecus ramidus fossils show an early form of bipedal locomotion was being practiced while the animal was still very comfortable moving about in the trees Bipedalism evolved in the woodlands not savannah Ardipithecus ramidus Ardy has a pelvis that is somewhat of a hybrid the upper half has several bipedal characteristics short broad ilia that wrap around a k a rotated ilia and the presence of an anterior inferior iliac spine and a wide sacrum while the lower half has a long ape like ischium Australopithecus afarensis fossils Lucy are wonderful examples of mosaic evolution Lucy found in Hadar Ethiopia locomotors system evolved quickly so this species was perfectly bipedal but with a small brain unique teeth The footprints at Laetoli Tanzania 3 6 mya have several features indicating that the creature that made them Au afarensis was a habitual biped These include a big toe hallux that points straight ahead in line with the other toes and the presence of a longitudinal arch Foramen Magnum large opening in the occipital bone where spinal cord connects helps determine when a species began walking on 2 legs Lumbar Lordosis apes do not have one curve in the spine for bipedalism Bicondylar Angle apes do not have one angle of femur from hip to knee allows bipedalism Hallux big toe not opposable for humans Longitudinal Arch allows foot to support weight of body in erect posture with the least weight Anterior Gluteal Muscles best for bipedal walking Australopithecus africanus 3 5 2 0 mya was the first Australopithecus ever discovered Taung Child Raymond Dart an anatomist first named and described it At about 3 my ago there were several types of hominids alive in Africa H habilis used Olduwan tools stone flakes hammers H erectus used Acheulian tools hand axes fire cooking Au garhi found fossils of antelopes with cut marks on it meaning they could have butchered them thought to use stone tools Robusts had large molars premolars a large face with flaring zygomatic arches and massive muscle attachment sites on the skull particularly the sagittal crest Some scientists use the genus name Paranthropus because they are so derived back teeth have pits scratches on them from chewing hard vegetal foods front teeth were reduced to tiny little pegs Analysis of the tooth enamel indicates that even grass was important in their diet All of these characteristics are derived small cranial