Processes of Macroevolution: Mammalian/Primate Evolutionary History Chapter 7 Processes of Macroevolution: Mammalian/Primate Evolutionary History

Chapter Outline The Human Place in the Organic World Principles of Classification Definition of Species Vertebrate Evolutionary History: A Brief Summary

Chapter Outline Mammalian Evolution Major Mammalian Groups Early Primate Evolution Miocene Fossil Hominoids Processes of Macroevolution

The Human Place in the Organic World Classification groups life forms into categories showing evolutionary relationships. Example - human classification Kingdom: Animalia Subkingdom: Metazoan Phyla: Chordata Subphyla: Vertebrata Class: Mammalia

Taxonomic Concepts Homologies - structures shared through descent from a common ancestor. Analogies - structures used for the same function that developed independently and are not the result of common descent. Homoplasy - the process by which similarities can develop in different groups of organisms.

Cladistic Taxonomy Groups species according to shared derived characteristics: Primitive traits reflect the ancestral condition. Shared derived characteristics are shared traits that weren’t present before the group's appearance.

Approaches to the Definition of Species Biological Species Concept Species are defined by reproductive isolation. Only members of the same species can interbreed Recognition Species Concept Key aspect is the ability individuals have to identify members of their own species for mating purposes. Ecological Species Concept A species is a group of organisms exploiting a single niche. Natural selection separates species from one another.

Geological Time Scale ERA PERIOD Began m.y.a. EPOCH CENOZOIC Tertiary 1.8 Holocene Pleistocene 0.01 Quaternary 65 Pliocene Miocene Oligocene Eocene Paleocene 5 23 34 55

Geological Time Scale ERA PERIOD (Began m.y.a.) MESOZOIC Cretaceous 136 Jurassic 190 Triassic 225 PALEOZOIC Permian Carboniferous Devonian Silurian Ordovician Cambrian 280 345 395 430 500 570

Geological Eras Paleozoic Mesozoic Cenozoic The first vertebrates appeared 500 m.m.y.a. Mesozoic Reptiles were dominant land vertebrates. Placental mammals appeared 70 m.Y.A. Cenozoic Divided into two periods: Tertiary and Quaternary and 7 epochs: Paleocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene and Holocene.

Mammalian Evolution The Cenozoic era is known as the Age of Mammals. After dinosaurs became extinct, mammals underwent adaptive radiation, resulting in rapid expansion and diversification. The neocortex, which controls higher brain functions, comprised the majority of brain volume, resulting in greater ability to learn.

Major Mammalian Groups Monotremes Primitive, egg laying mammals Marsupials Infants complete development in an eternal pouch Placental Longer gestation allows the central nervous system to develop more completely

Early Primate Evolution Primate origins began in the placental mammal radiation 65 m.y.a. The earliest undoubted primates appear in the Eocene epoch. Most of our knowledge of primate Oligocene evolution comes from a site in Egypt, the Fayum.

Fayum Forms: Possible Roots of Anthropoid Evolution Apidium Small, primate that may lie near or before the evolutionary divergence of Old and New World anthropoids. Aegyptopithecus Largest of the Fayum primates with a small brain, large snout, and none of the traits of Old World monkeys or the hominoids.

Miocene Fossil Hominoids Marked by a spectacular hominoid radiation and could be called “the golden age of hominoids”. Grouped geographically: African forms (23-14 m.y.a.) European forms (13-11 m.y.a.) Asian forms (16-7 m.y.a.)

Genus and Species Species is the most precise taxonomic level. Genus is a group of species more closely related to each other than to species from another genus. Members of the same genus share derived characteristics not seen in other genera.