Ch 18

Question 1

most of the animal phyla

living today appeared for the first time _____ yrs ago during the _____.

Answer 1

543 yrs ago, Cambrian Period

Question 2

Cambrian to Present =

Answer 2

Phanerozoic

Question 3

Any trace left by an organism that lived in the past.

Answer 3

Fossil

Question 4

4 Types of Fossils

Answer 4

Unaltered remains (amber and freezing), premineralized remaines, casts and molds, and trace fossils

Question 5

Unaltered remains examples

Answer 5

2,ooo yr old cadavers in peat bog, wooly mammoths in permafrost

Question 6

Permineralized fossils are made how?

and examples

Answer 6

When structures are buried in sediments and dissolved minerals precipitate in the cells. Can preserve details of internal structure.

Fossilized dinosaurs and petrified wood

Question 7

How are casts and molds made?

Answer 7

When remains decay after being buried in sediment. Casts form when
new materials infiltrate the resulting open space and harden into rock.
Molds consist of unfilled spaces.

Question 8

Trace fossils are useful because?

Answer 8

Trace fossils
How Organic Remains Fossilize
Record behavior instead of form.
Dinosaur trackways can tell us about an animal’s
stride length and thus yield an estimate of
maximum speed.
Coprolites, or fossilized feces, represent another
type of trace fossil.

Question 9

The fossil record consists primarily of hard structures left

in depositional environments such as

Answer 9

river deltas, beaches, floodplains,

marshes, lakeshores, and seafloors.

Question 10

What 3 factors slow decomposition making preservation more likely?

Answer 10

Durability
Burial (usually in a water-saturated sediment)
Lack of oxygen

Question 11

study of fossilization process

Answer 11

taphonomy

Question 12

Taxon

Answer 12

any named group of organisms

Question 13

The divergence of a clade into populations adapted to many ecological niches

Answer 13

adaptive radiation

Question 14

Tiny glass particles created when minerals are melted by heat generated by a meteor or asteroid impact

Answer 14

microtektites

Question 15

Compared to animals present earlier in the fossil record, the hallmarks of
the Cambrian fauna are

Answer 15

a dramatic increase in body size, the origin of
hard exoskeletons and complex body parts like limbs, and a
diversification in basic body shapes and organization.

Question 16

The Burgess Shale and Chengjiang faunas are dominated by

Answer 16

large, bilaterally

symmetric animals with well-developed segmentation, heads, and appendages

Question 17

The Fish–Tetrapod Transition

Answer 17

Late Devonian
vertebrates that span the
fish-to- tetrapod
transition—characterized
by a single proximal
bone in the fin/limb
recognized as the
humerus (forelimb) or
femur (hindlimb)

Question 18

Dino- bird transition

Answer 18

Evolution of theropod feathers. A collection of transitional fossils documents
evolution of feathers in theropod dinosaurs.

Question 19

Derived traits of synapsids

Answer 19

Dimetrodon was the top carnivore of the Early Permian.
It had most features we associate with reptiles today.
• Sprawling posture
• Simple teeth
• Ectothermic physiology
• Multiple bones forming its
lower jaw.

Question 20

Where did the two extra bones in ear come from?

Answer 20

An extraordinary series of
fossils show that the two
bones that form the jaw hinge
in non mammalian cynodonts
were reduced in size and
eventually incorporated into
the middle ear (Luo 2011).

Question 21

background extinctions

Answer 21

(occurred at

normal rates).

Question 22

Mass extinctions occur as a

Answer 22

consequence of short-term,

catastrophic episodes of environmental change.

Question 23

Today climet is changing and ______________________________ is preventing ____________

Answer 23

Dramatic loss of habitat not allowing gentic diversity and stability

Question 24

Cretaceous–Paleogene Extinction

Answer 24

The K–Pg extinction, which included the demise of the non-avian dinosaurs, is
the most recent and best understood of the Big Five.

Question 25

The K-Pg extinction was caused by…

Answer 25

an asteroid ~10 km wide.

More recent estimates suggest ~15 km wide.

Question 26

Evedence for the Cretaceous-paleogene extinction

Answer 26

Anomalous concentrations of iridium (rare in the earths crust, but common
in meteorites) worldwide at this time, laid down at the K-Pg boundary
• Shocked quartz particles
• Microtektites
• Crater 180km in diameter near Chicxulub, Mexico (Yucatan)

Question 27

Possible mass extinction killing mechanisms

Answer 27

• Intense acid rain
• Global cooling
• Widespread wildfires
• Massive earthquakes
• Volcanoes
• Massive tsunami
Long-term disruption of ecological processes, biogeochemical cycles of
nutrients, and interactions among species.

Question 28

Biologists have employed three types of approaches to predict how
continued habitat destruction will affect extinction rates

Answer 28

1. Multiply the number of species found per hectare in different
   environments by rates of habitat loss measured from satellite photos.
2. Quantify the rate that well-known species are moving from
   threatened to endangered to extinct status in the lists maintained by
   conservation groups.
3. Estimate the probability that all species currently listed as threatened
   or endangered will actually go extinct over the next 100 or 200 years.

Question 29

extinctions are now occurring at ______________ the normal, or background, rate of extinction

Answer 29

100 to

1,000 times

Question 30

Lack of appreciable morphological change or

speciation over long periods of time.

Answer 30

Evolutionary stasis -

Question 31

punctuated equilibrium

Answer 31

punctuated equilibrium,
all morphological variation
occurs at the time of a
speciation (branching) event;
otherwise, there is stasis.

Question 32

phyletic gradualism,

Answer 32

morphological change occurs
gradually and is unrelated to
speciation events.

Question 33

Although it might appear static, morphology in a lineage may actually
fluctuate over time around a long-term average.
This phenomenon has been called

Answer 33

habitat tracking or dynamic stasis.

Question 34

What are some other species or clade-level characteristics upon which
selection could act?

Answer 34

• Abundance
• Reproductive mode
• Generation time
• Geographic range
• Aspects of life history (such as feeding ecology)

Question 35

Occur when a single or small group of ancestral
species diversifies into a large number of descendant species that
occupy a wide variety of ecological niches

Answer 35

adaptive radeation

Question 36

What factors trigger adaptive radiations?

Answer 36

Ecological Opportunity
A lineage can diversify into many different species with divergent ways
of life in response to the availability of new habitats and resources!
(by dispersal to a new habitat, creation of a new habitat, extinction of
competitors)
Morphological Innovation
! or in response to a newly evolved morphological trait that allows
individuals to exploit resources in a new way, e.g., arthropods and
modification and elaboration of their jointed limbs.