In 1990, Mike Novacek followed in the footsteps of Roy Chapman Andrews, who had ventured into the Gobi Desert looking for fossils in the 1920s. Novacek and his team found hundreds of mammal fossils. In this interview, he describes the experience of discovering such a rich source and shares what we can learn from the bones of mammals that co-existed with dinosaurs.
Discuss two cases for which this interview explains the important combination of luck and ability to spot the unexpected in searching for fossils.
The reproductive habits in mammals are among the most important characteristics of the group. Explain how this interview reveals new evidence for hypotheses about reproductive evolution -- even though the soft tissues most intimately involved in this process do not fossilize.
This interview explicitly states a specific perspective on the relationship between mass extinctions and adaptive radiations. Describe and discuss this relationship as it applies to dinosaurs and mammals.
Discuss how Dr. Novacek's view of the relationship between the K-T extinction and the evolution of mammals refutes the old notion that evolution represents progressive improvement.
10H ( Grades: K-2 ): Explaining the Diversity of Life
10H ( Grades: 3-5 ): Explaining the Diversity of Life
10H ( Grades: 6-8 ): Explaining the Diversity of Life
10H/H2a ( Grades: 9-12 ): Prior to the 1800s, the most widespread belief was that all known species were created and remained unchanged throughout history.
10H/H3 ( Grades: 9-12 ): Darwin argued that certain biologically inherited characteristics give an organism an advantage in surviving and reproducing compared to other organisms of the same species. The offspring would also inherit and pass on those advantages, and over generations the accumulation of these inherited advantages would lead to a new species.
10H/H5 ( Grades: 9-12 ): A mechanism that explained the origin of variation within species was suggested by several lines of evidence: findings from Gregor Mendel's experiments on the inheritance of traits in plants, the identification of genes and how they are sorted in reproduction, and the discovery of the mutability and near universality of the genetic code found in DNA.
10H/H6ab ( Grades: 9-12 ): By the 1900s, nearly all scientists had accepted Darwin's basic idea of evolution through natural selection. Today, scientists continue to work out the details of the evolutionary history of specific organisms.
4B/M6 ( Grades: 6-8 ): Climates have sometimes changed abruptly in the past as a result of volcanic eruptions or impacts of huge rocks from space.
5A/H1a ( Grades: 9-12 ): The variation of organisms within a species increases the likelihood that at least some members of the species will survive under changed environmental conditions.
5A/H1b ( Grades: 9-12 ): A great diversity of species increases the chance that at least some living things will survive in the face of large changes in the environment.
5A/H2 ( Grades: 9-12 ): The degree of relatedness between organisms or species can be estimated from the similarity of their DNA sequences, which often closely match their classification based on anatomical similarities.
5A/H3 ( Grades: 9-12 ): Similar patterns of development and internal anatomy suggest relatedness among organisms.
5A/H5 ( Grades: 9-12 ): A classification system is a framework created by scientists for describing the vast diversity of organisms, indicating the degree of relatedness between organisms, and framing research questions.
5A/M3a ( Grades: 6-8 ): Similarities among organisms are found in internal anatomical features, which can be used to infer the degree of relatedness among organisms.
5B/H1 ( Grades: 9-12 ): Some new gene combinations make little difference, some can produce organisms with new and perhaps enhanced capabilities, and some can be deleterious.
5B/H2 ( Grades: 9-12 ): The sorting and recombination of genes in sexual reproduction results in a great variety of possible gene combinations in the offspring of any two parents.
5B/H4 ( Grades: 9-12 ): Genes are segments of DNA molecules. Inserting, deleting, or substituting segments of DNA molecules can alter genes. An altered gene may be passed on to every cell that develops from it. The resulting features may help, harm, or have little or no effect on the offspring's success in its environment.
5B/H5 ( Grades: 9-12 ): Gene mutations can be caused by such things as radiation and chemicals. When they occur in sex cells, they can be passed on to offspring; if they occur in other cells, they can be passed on to descendant cells only. The experiences an organism has during its lifetime can affect its offspring only if the genes in its own sex cells are changed by the experience.
5B/P1 ( Grades: K-2 ): There is variation among individuals of one kind within a population.
5D/E1 ( Grades: 3-5 ): For any particular environment, some kinds of plants and animals thrive, some do not live as well, and some do not survive at all.
5D/H1 ( Grades: 9-12 ): Ecosystems can be reasonably stable over hundreds or thousands of years. As any population grows, its size is limited by one or more environmental factors: availability of food, availability of nesting sites, or number of predators.
5D/H2 ( Grades: 9-12 ): If a disturbance such as flood, fire, or the addition or loss of species occurs, the affected ecosystem may return to a system similar to the original one, or it may take a new direction, leading to a very different type of ecosystem. Changes in climate can produce very large changes in ecosystems.
5D/M1b ( Grades: 6-8 ): The world contains a wide diversity of physical conditions, which creates a wide variety of environments: freshwater, marine, forest, desert, grassland, mountain, and others. In any particular environment, the growth and survival of organisms depend on the physical conditions.
5D/M2 ( Grades: 6-8 ): Interactions between organisms may be for nourishment, reproduction, or protection and may benefit one of the organisms or both of them. Some species have become so dependent on each other that neither could survive without the other.
5F/E1 ( Grades: 3-5 ): Individuals of the same kind differ in their characteristics, and sometimes the differences give individuals an advantage in surviving and reproducing.
5F/E2 ( Grades: 3-5 ): Fossils can be compared to one another and to living organisms according to their similarities and differences. Some organisms that lived long ago are similar to existing organisms, but some are quite different.
5F/H10 ( Grades: 9-12 ): The continuing operation of natural selection on new characteristics and in diverse and changing environments, over and over again for millions of years, has produced a succession of diverse new species.
5F/H2 ( Grades: 9-12 ): Molecular evidence substantiates the anatomical evidence for evolution and provides additional detail about the sequence in which various lines of descent branched off from one another.
5F/H3 ( Grades: 9-12 ): Natural selection provides the following mechanism for evolution: Some variation in heritable characteristics exists within every species; some of these characteristics give individuals an advantage over others in surviving and reproducing; and the advantaged offspring, in turn, are more likely than others to survive and reproduce. As a result, the proportion of individuals that have advantageous characteristics will increase.
5F/H4b ( Grades: 9-12 ): Heritable characteristics influence how likely an organism is to survive and reproduce.
5F/H5 ( Grades: 9-12 ): New heritable characteristics can result from new combinations of existing genes or from mutations of genes in reproductive cells. Changes in other cells of an organism cannot be passed on to the next generation.
5F/H6a ( Grades: 9-12 ): Natural selection leads to organisms that are well-suited for survival in particular environments.
5F/H6b ( Grades: 9-12 ): Chance alone can result in the persistence of some heritable characteristics having no survival or reproductive advantage or disadvantage for the organism.
5F/H6c ( Grades: 9-12 ): When an environment, including other organisms that inhabit it changes, the survival value of inherited characteristics may change.
5F/H7 ( Grades: 9-12 ): Modern ideas about evolution and heredity provide a scientific explanation for the history of life on Earth as depicted in the fossil record and in the similarities evident within the diversity of existing organisms.
5F/H8 ( Grades: 9-12 ): Life on earth is thought to have begun as simple, one-celled organisms about four billion years ago. Once cells with nuclei developed about a billion years ago, increasingly complex multi-cellular organisms evolved.
5F/H9 ( Grades: 9-12 ): Evolution builds on what already exists, so the more variety there is, the more there can be in the future. But evolution does not necessitate long-term progress in some set direction. Evolutionary change appears to be like the growth of a bush: Some branches survive from the beginning with little or no change; many die out altogether; and others branch repeatedly, sometimes giving rise to more complex organisms.
5F/M2a ( Grades: 6-8 ): Individual organisms with certain traits are more likely than others to survive and have offspring.
5F/M2b ( Grades: 6-8 ): Changes in environmental conditions can affect the survival of individual organisms and entire species.
5F/M3b ( Grades: 6-8 ): More recently deposited rock layers are more likely to contain fossils resembling existing species.
5F/M4 ( Grades: 6-8 ): Most species that have lived on the earth are now extinct. Extinction of species occurs when the environment changes and the individual organisms of that species do not have the traits necessary to survive and reproduce in the changed environment.
5F/M5 ( Grades: 6-8 ): Reproduction is necessary for the survival of any species.
5F/P1 ( Grades: K-2 ): Different plants and animals have external features that help them thrive in different kinds of places.
5F/P2 ( Grades: K-2 ): Some kinds of organisms that once lived on Earth have completely disappeared, although they were something like others that are alive today.
6A/E3 ( Grades: 3-5 ): Artifacts and preserved remains provide some evidence of the physical characteristics and possible behavior of human beings who lived a very long time ago.
6A/H1 ( Grades: 9-12 ): The similarity of humans in their cell chemistry and DNA sequences reinforces the idea that all humans are part of a single species.
6A/H3 ( Grades: 9-12 ): Fossil and molecular evidence supports the idea that human beings evolved from earlier species.
9B/H1a ( Grades: 9-12 ): In some cases the more of something there is, the more rapidly it may change (as the number of births is proportional to the size of the population).
NSTA National Science Education Standards
4.1 ( Grades: K-12 ): Evolution is a series of changes, some gradual and some sporadic, that accounts for the present form and function of objects, organisms, and natural and designed systems. The general idea of evolution is that the present arises from materials and forms of the past. Although evolution is most commonly associated with the biological theory explaining the process of descent with modification of organisms from common ancestors, evolution also describes changes in the universe.
C.3.1 ( Grades: 9-12 ): Species evolve over time. Evolution is the consequence of the interactions of (1) the potential for a species to increase its numbers, (2) the genetic variability of offspring due to mutation and recombination of genes, (3) a finite supply of the resources required for life, and (4) the ensuing selection by the environment of those offspring better able to survive and leave offspring.
C.3.2 ( Grades: 9-12 ): The great diversity of organisms is the result of more than 3.5 billion years of evolution that has filled every available niche with life forms.
C.3.3 ( Grades: 9-12 ): Natural selection and its evolutionary consequences provide a scientific explanation for the fossil record of ancient life forms, as well as for the striking molecular similarities observed among the diverse species of living organisms.
C.5.1 ( Grades: 5-8 ): Millions of species of animals, plants, and microorganisms are alive today. Although different species might look dissimilar, the unity among organisms becomes apparent from an analysis of internal structures, the similarity of their chemical processes, and the evidence of common ancestry.
C.5.2 ( Grades: 5-8 ): Biological evolution accounts for the diversity of species developed through gradual processes over many generations. Species acquire many of their unique characteristics through biological adaptation, which involves the selection of naturally occurring variations in populations. Biological adaptations include changes in structures, behaviors, or physiology that enhance survival and reproductive success in a particular environment.
D.1.3 ( Grades: K-4 ): Fossils provide evidence about the plants and animals that lived long ago and the nature of the environment at that time.
D.1.4 ( Grades: 9-12 ): Global climate is determined by energy transfer from the sun at and near the earth's surface. This energy transfer is influenced by dynamic processes such as cloud cover and the earth's rotation, and static conditions such as the position of mountain ranges and oceans.
F.2.1 ( Grades: 9-12 ): Populations grow or decline through the combined effects of births and deaths, and through emigration and immigration. Populations can increase through linear or exponential growth, with effects on resource use and environmental pollution.