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Macroevolution and Early Primate Evolution: Origins, Characteristics, and Relationships

Explore the process of macroevolution and the early evolution of primates, including the appearance and characteristics of the first primates, monkeys, and apes. Learn about the isolating mechanisms that contribute to the formation of new species and the concept of anagenesis and convergence. Discover how continental drift and ecological changes influenced primate evolution, and trace the evolutionary timeline of early primates and their distribution across the globe.

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Macroevolution and Early Primate Evolution: Origins, Characteristics, and Relationships

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  1. Chapter 5 Macroevolution and the Early Primates

  2. Chapter Outline • What Is Macroevevolution? • When and Where Did the First Primates Appear, and What Were They Like? • When Did the First Monkeys and Apes Appear, and What Were They Like?

  3. Macroevolution • Over time, macroevolutionary forces produce new species from old ones. • Macroevolution focuses upon the formation of new species and on the evolutionary relationships between groups of species. • Isolating mechanisms can separate breeding populations and lead to the appearance of new species.

  4. Isolating Mechanisms • Geographical • Anatomical structure • Social and cultural concepts

  5. Cladogenesis

  6. Isolating Mechanisms • In branching evolution, isolating mechanisms separate breeding populations, creating divergent subspecies and then divergent species. • Geographical, biological, or social isolating mechanisms block gene flow between groups, contributing to the accumulation of genetic mutations in each population. • Biological isolating mechanisms include phenomena such as the sterility of hybrid offspring.

  7. Anagenesis and Convergence • Anagenesis • When natural selection, over time, favors some variants over others. • Creates a change in a population’s average characteristics. • Convergence • Occurs when two unrelated species come to resemble each other owing to functional similarities.

  8. Anagenesis

  9. Continental Drift

  10. Primate Evolution • Primates arose from a branching of mammalian forms that began more than 100 million years after the appearance of the first mammals. • Most ecological niches that mammals have since occupied were • preempted by reptiles • nonexistent until flowering plants became widespread about 65 million years ago.

  11. Ancestral Features • Features in the Eocene genus Adapis are found in prosimians today. Like modern lemurs, it has a postorbital bar, a bony ring around the eye orbit. Note that the orbit is open behind the ring.

  12. Primate Evolution • Geological changes in the orientation and position of the earth’s continents affected the global climate. • This played a key role in the evolution and distribution of the primates. • The first primates were arboreal insect eaters and the characteristics of all primates developed as adaptations to this early way of life.

  13. Early Primates • The earliest primates developed 60 million years ago in the Paleocene epoch. • They were small arboreal creatures. • Diverse prosimianlike forms were common in the Eocene across what is now North America and Eurasia. • By the late Eocene, 45 million years ago, small primates combining prosimian and anthropoid had emerged.

  14. Location of Hominid Fossils

  15. Primate Evolution • By the late Eocene small primates combining lemurlike and tarsierlike features with those in monkeys and apes developed. • In the Miocene epoch, apes proliferated and spread over many parts of the Old World. • Ancestors of large apes and humans appeared by 16 m.y.a. and were widespread as recently as 8 m.y.a.

  16. Primate Evolution • Details of dentition suggest that hominines arose from these earlier apes. • Some populations lived in parts of Africa where pressures existed to transform a creature just like it into a primitive hominine. • Other populations remained in the forests, developing into today’s bonobo, chimpanzee, and gorilla.

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