Encyclopedia of Evolution.pdf - Online Reading Center

Java man See Homo erectus.
Johanson, Donald (1943– ) American Anthropologist
Donald Johanson is an anthropologist who has made some
of the most important discoveries of the fossils of possible
human ancestors. He is most famous for the 1974 discovery
of a 3.2-million-year-old fossil of one of the australopithecines,
an Australopithecus afarensis individual known to the
world as “Lucy.” This nearly complete skeleton left little to
the imagination and demonstrated that before the hominin
lineage began to use tools, and before their brains began to
expand, they were walking upright (see bipedalism).
Johanson was born June 28, 1943. As a teenager, Johanson
read Man’s Place in Nature (see Huxley, Thomas
Henry), which inspired him to devote his life to the research
of human evolution. After receiving his doctorate at the University
of Chicago, Johanson undertook field research in Ethiopia
(where he found Lucy) and Tanzania. He has continued
to discover important hominin fossils, including numerous A.
afarensis fossils from a single site (called the “First Family”)
and some specimens that may represent Homo Habilis.
Johanson has not only made discoveries and written scientific
papers but has had a major impact on educating the
public about human evolution. He founded the Institute of
Human Origins, which is currently affiliated with Northern
Arizona University in Flagstaff, in 1981. Besides writing several
popular books, Johanson hosted and narrated a widely
watched public television series about human evolution. For
Johanson, human evolution is not merely interesting. He
believes it is vital for the survival of humans and of all other
species that people understand their evolutionary origins.
Humans have deep biological roots in a world that they share
with millions of other species, and therefore they must not
treat the Earth like conquerors.
J
Further Reading
Johanson, Donald, and Maitland A. Edey. Lucy: the Beginnings of
Humankind. New York: Simon and Schuster, 1981.
———, and James Shreeve. Lucy’s Child: The Discovery of a Human
Ancestor. New York: Early Man Publishing, Inc., 1989.
Jurassic period The Jurassic period (210 million to 140
million years ago) was the middle period of the Mesozoic
era (see geological time scale). It followed the Triassic
period. The Mesozoic era is also known as the Age of
Dinosaurs, because dinosaurs were the largest land animals
during that time. Dinosaurs became extinct during the Cretaceous
extinction, which is one of the two most important
mass extinctions in the history of the Earth.
Climate. In the mild climate of the Jurassic period,
swamps and shallow seas covered widespread areas.
Continents. The continents formed by the breakup of
Pangaea continued to separate (see continental drift).
Marine life. All modern groups of marine organisms
existed during the Cretaceous, except aquatic mammals.
Large aquatic reptiles lived in the oceans.
Life on land. Gymnosperms dominated the terrestrial
forests (see gymnosperms, evolution of). Dinosaurs,
some very large, flourished. The earliest known birds lived
during the Jurassic period (see arcHaeopteryx; birds,
evolution of). Mammals were small and represented by
few species compared to the dinosaurs (see mammals, evolution
of).
Further Reading
Museum of Paleontology, University of California, Berkeley. “Jurassic
period: Life.” Available online. URL: http://www.ucmp.
berkeley.edu/mesozoic/jurassic/jurassiclife.html. Accessed April
18, 2005.