The document discusses the evolution of mammals from synapsids to present-day primates. It describes key characteristics of mammals like hair and mammary glands. It outlines the major groups of mammals including monotremes like platypuses and echidnas, marsupials, and eutherians. Within primates, it discusses prosimians, monkeys, and hominoids including apes and humans. It provides details on several hominid species with a focus on Homo erectus, which lived from 1.8 to 0.5 million years ago.

1. Chapter 34b: Vertebrates (mammals)

2. Mammalia Though mammals predate the dinosaurs, it was only once the dinosaurs were mostly gone that the mammal adaptive radiation began in earnest The defining features of extant mammals are their hair, mammary glands, larger brains, differentiated teeth, modified jaws, etc. The mammal lineage predates the mammals with the synapsids: the mammal-like reptiles

3. Various Synapsids

4. Mammals: Monotremes

5. Monotreme: Echidna

6. Monotreme: Platypus Duck-billed platypuses are aquatic so keep their eggs warm in burrows until hatching

7. Mammals: Marsupials

8. Examples of Marsupials

9. Mammals: Eutherians Eutherians are the placental mammals, i.e., the majority of mammals are eutherians

10. Mammals: Primates The primates inhabit a branch of the mammalian phylogeny also occupied by the rodents

11. Order Primates The anthropoids include the monkeys, the apes, and us Variety of primate hands Prosimians

13. Prosimian: A Lemur

14. Monkeys are Anthropoids

15. Order Primates The hominoids include the apes and us

16. Known or Suspect Hominids Hominids (by your text) are more closely morphologically similar to us than they are to chimpanzees

17. Simplified Tree

18. Australopithicus afarensis

19. Homo habilis

21. Homo erectus Pan H. erectus H. sapiens Homo