Paleozoic Era

PARAÑAQUE SCIENCE HIGH SCHOOL FRESHMEN BATCH 22
Prepared and Presented by: Group 2 I-B

1. PALEOZOIC ERA
Group 2

2. Prepared by: Louis
Bautista and Van Salvador

CAMBRIAN PERIOD

3. The Cambrian Period marks an important point
in the history of life on Earth; it is the time when
most of the major groups of animals first
appear in the fossil record. This event is
sometimes called the "Cambrian Explosion,"
because of the relatively short time over which
this diversity of forms appears. It was once
thought that Cambrian rocks contained the
first and oldest fossil animals, but these are
now found in the earlier Ediacaran (Vendian)
strata.
CAMBRIAN PERIOD

4. Cambrian is the name given to a period
of time in Earth's history (i.e., Cambrian
Period), which spanned 570 - 510 million
years ago. The proper name Cambrian
is also given to all the rocks that formed
during that time (i.e., Cambrian System).
In other words, the Cambrian System is
the rock record of events that occurred
and organisms that lived during an
interval of geological time called
Cambrian Period. Cambrian is the initial
period of the Paleozoic Era.

5. During Cambrian, the breakup of the
supercontinent of Gondwana began with
the separation of some landmasses
including part of Asia and the ancient
continents called Baltica and Laurentia (i.e.,
proto-North America). During its separation
from the main Gondwana land mass,
Laurentia had a collision with the southern
end of what is now South
America (specifically western Argentina),
which resulted in some crustal deformation
and mountain building. At this time, there
was essentially a single world ocean, which
is referred to as Panthalassa.

6. MOVEMENT OF PLATE TECTONICS
•The continental plate
movement and collisions during
this period generated pressure
and heat between continents.
this resulted in the folding,
faulting, and crumpling of rock
which formed large mountain
ranges.

7. CAMBRIAN PERIOD

8. GONDWANA, PANTHALASSA

9. ORGANISMS
Almost every metazoan phylum with
hard parts, and many
that lack hard parts, made its first
appearance in the Cambrian.
The only modern phylum with an
adequate fossil record to appear after
the Cambrian was the phylum Bryozoa,
which is not known before the
early Ordovician. A few mineralized
animal fossils, including sponge spicules
and probable worm tubes, are known
from the Ediacaran Period immediately
preceding the Cambrian.

10. Some of the odd fossils of
the biota from the Ediacaran may
also have been animals
representative of living phyla,
although this remains a somewhat
controversial topic. However, the
Cambrian was nonetheless a time of
great evolutionary innovation, with
many major groups of organisms
appearing within a span of only forty
million years.

11. Trace fossils made by animals also
show increased diversity in Cambrian
rocks, showing that the animals of the
Cambrian were developing new
ecological niches and strategies —
such as active hunting, burrowing
deeply into sediment, and making
complex branching burrows. Finally,
the Cambrian saw the appearance
and/or diversification of mineralized
algae of various types, such as the
coralline red algae and the dasyclad
green algae.

12. BRACHIOPODA

13. CAMBRIAN ECHINODERMS

14. EDRIOASTEROID

15. EOCRINOIDS

16. HELICOPLACOIDS

17. CRINOIDS

18. JAWLESS VERTIBRATES

19. TRILOBITES

20. BURGESS SHALE

21. ARCHAEOCYATHIDS

22. Cambrian was a time of rising global
temperatures and Cambrian
global climate ultimately became
warmer than today. During Cambrian,
there were essentially no polar or high-
altitude Glaciers. Further, there were no
continents located at polar positions.
The Cambrian Earth likely had more
equitable climates than present
because of the large amount of surficial
seawater (approximately 85% or more,
compared to approximately 70% at
present) and lack of significant
topographic relief.
CLIMATE

23. Winds were likely confined to
rather well-defined belts, and
there is good evidence of
persistent trade winds
preserved in vast cross-bedded
Cambrian sandstones.
The end of Cambrian came
gradually with falling sea levels
and the onset of slightly cooler
global temperatures.

24. WATER FEATURES
During most of Cambrian, global sea
levels were at relatively high
elevations as compared with most of
the balance of Earth's history. The
world's continents were mainly low-
lying deserts and alluvial plains, and
the rising Cambrian seaâin what is
known as the Sauk
transgressionâencroached upon
these areas, thus forming vast
epicontinental seas.

25. GEOLOGIC FACTORS
Cambrian life on land was probably
quite limited. There is evidence that
stromatolitic growth of blue-green algae
and bacteria covered rocks and
formed sediment layers at or near
oceanic shorelines and lake margins.
However, complex life forms are not
found in Cambrian terrestrial sediments.
It is possible that some arthropods may
have lived partially or entirely upon land
at this time, but this is speculative in the
absence of fossil evidence. 10% of that
found in the modern atmosphere.

26. There were no land plants at this
time, and thus Cambrian
landscapes were at the mercy
of wind and water
erosion without any protection
from vegetation. The minimal
level of photosynthetic activity
before and during Cambrian
raised oxygen levels in Earth's
atmosphere.

27.  The most famous of fossil localities
with such Cambrian fossils is at Mount
Wapta, British Columbia, Canada
(i.e., Burgess Shale outcrops). In these
strata, the earliest known chordate
(spinal cord-bearing animal), Pikaia,
was first found.

28. ORDOVICIAN PERIOD
Prepared by: Ricky Perez and Kyle
Galiluyo

29. ORDOVICIAN PERIOD
The Ordovician is a geologic period
and system, the second of six of
the Paleozoic Era, and covers the
time between 41.7 to 443.7±1.5 MYA .
It follows the Cambrian Period and is
followed by the Silurian Period. The
Ordovician, named after
the Celtic tribe of the Ordovices, was
defined by Charles Lapworth in 1879

30. ORDOVICIAN PERIOD

31. EVENTS THAT HAPPENED
Life continued to flourish during the
Ordovician as it did in the Cambrian,
although the end of the period was marked
by a significant mass extinction.
Invertebrates, namely mollusks and
arthropods, dominated the oceans. Fish,
the world's first true vertebrates, continued
to evolve, and those with jaws may have
first appeared late in the period. Life had
yet to diversify on land.

32. The Ordovician Period started at a
major extinction event called the
Cambrian–Ordovician extinction
events some time about 488.3 ± 1.7
Mya (million years ago), and lasted
for about 44.6 million years. It ended
with the Ordovician–Silurian extinction
event, about 443.7 ± 1.5 Mya (ICS,
2004) that wiped out 60% of marine
genera.

33. ORGANISMS
Invertebrate life became
increasingly diverse and
complex through the
Ordovician. Both calcareous
and siliceous sponges are
known; among other types,
the stromatoporoids first
appeared in the Ordovician.

34. CALCAREOUS AND SILICEOUS
SPONGES

35. STROMATOPOROIDS

36. Tabulata and Rugosa first appeared in
the Ordovician, the solitary or horn
corals being especially distinctive.
Bryozoans and brachiopods were a
dominant component of many
assemblages. mollusks were also
common and included the
gastropods, monoplacophorans,
bivalves, cephalopods, chits,
scaphopods, and rostroconchs.

37. TUBULATA

38. RUGOSA

39. HORN CORALS

40. BRYOZOA

41. BRACHIOPODS

42. MOLLUSKS

43. The fossil record of Ordovician annelids
consists chiefly of small, calcareous
tubes, tiny jaws made up of phosphate
material, and trace fossils.Trilobites are
common and diverse in Ordovician
strata but do not dominate assemblages
as they did in the Cambrian Period.
Ordovician arthropods are also
represented by the ostacods as well as
by much rarer forms such as
branchiopods, barnacles, phyllocarid
shrimp, aglaspids, and eurypterids.

44. ORDOVICIAN ANNELIDS

45. ECHINODERMS
Echinoderms reached their peak
diversity of 20 classes during the
Ordovician, with crinoids , cystoids,
asteroids, edrioasteroids and
homalozoans being the most
common. Graptolites and conodonts
are among the most important fossils
in the Ordovician for correlating, or
demonstrating age equivalence
between, different layers of rock.

46. ECHINODERMS

47. EARLY FISHES

48. MICROFOSSILS AND PLANKTONS
Ordovician seas were characterized by a
rich and diverse assemblage of species.
Calcified microbial mats, known as
stromatolites, are found in Ordovician
rocks, although they are not as common
there as in strata from the Proterozoic Eon
and Cambrian Period. Chitinozoans or
acritarchs, microfossils with a hollow cavity
and organic walls, represent the
phytoplankton.

49. Ordovician foraminiferans
include both agglutinated
and calcareous forms,
including the first fusulinids
(single-celled, amoeba-like
organisms with complex
shells). The siliceous that lived
as zooplankton are also found
in Ordovician rocks.

50. ORDOVICIAN PLANKTONS

51. The food chain became more
complicated as new varieties of life
occurred.
New life forms includes true corals,
nautiloids, starfish, brachiopods, etc.
Conodonts (small, eel-like creatures)
became common and their fossils
serve as markers in the rock layers
greatly aiding paleontologists in their
efforts to determine the different ages
of the rocks

52. CONODONTS

53. CLIMATE
At the beginning of the period, around
480 million years ago, the climate was
very hot due to high levels of CO2,
which gave a strong greenhouse effect.
The marine waters are assumed to have
been around 45°C, which restricted the
diversification of complex multi-cellular
organisms. But over time, the climate
become cooler, and around 460 million
years ago, the ocean temperatures
became comparable to those of
present day equatorial waters.

54. As with North America and Europe,
Gondwana was largely covered with
shallow seas during the Ordovician.
Shallow clear waters over continental
shelves encouraged the growth of
organisms that deposit calcium
carbonates in their shells and hard
parts. The Panthalassic Ocean
covered much of the northern
hemisphere, and other minor oceans
included Proto-Tethys, Paleo-Tethys,
Khanty Ocean, which was closed off
by the Late Ordovician, Iapetus
Ocean, and the new Rheic Ocean.

55. As the Ordovician progressed,
we see evidence of glaciers
on the land we now know as
Africa and South America. At
the time these land masses
were sitting at the South Pole,
and covered by ice caps.

56. GEOLOGIC FACTORS
Much of it was submerged
underwater
During the Ordovician the first
plants appeared.
The seas receded from their high
points
The seas reached the highest
point ever recorded

57. The supercontinent Gondwana drifted
slowly southward towards the South
Pole: having begun its journey in
tropic latitudes, it gradually
accumulated glaciers as it arrived in
cooler regions.
This heralded a 20-million-year ice
age during which shallow, life-rich
seas shrank away with
sea levels rising as much as 1,970 feet
(600 meters) above those of today.

58. WATER FEATURES
The Ordovician saw the highest sea levels
of the Paleozoic, and the low relief of the
continents led to many shelf deposits being
formed under hundreds of metres of water.
Sea level rose more or less continuously
throughout the Early Ordovician, levelling
off somewhat during the middle of the
period. Locally, some regressions occurred,
but sea level rise continued in the
beginning of the Late Ordovician.

59. A change was soon on the cards,
however, and sea levels fell steadily
in accord with the cooling
temperatures for the ~30 million years
leading up to the Hirnantian
glaciation. Within this icy stage, sea
level seems to have risen and
dropped somewhat, but despite
much study the details remain
unresolved.

60. Silurian Period
Prepared by: Russen Galano, Christine Agua
and Jewel Potenciano

61. SILURIAN PERIOD
The Silurian Period begins 435
million years ago and spans 23
million years ago.
The Silurian Period is named after
the ”Silures”, an ancient British
tribe which inhabited the Welsh
Borderland during the Roman
times.

62. MAJOR EVENTS
As with other geologic periods,
the rock beds that define the
period's start and end are well
identified, but the exact dates
are uncertain by several million
years. The base of the Silurian is
set at a major extinction event
when 60% of marine species were
wiped out.

63. MOVEMENT OF PLATE TECTONICS
During the Silurian, Gondwana
continued a slow southward
drift to high southern latitudes,
but there is evidence that the
Silurian icecaps were less
extensive than those of the
late Ordovician glaciation. The
southern continents remained
united during this period.

64. The melting of icecaps and
glaciers contributed to a rise in sea
level, recognizable from the fact
that Silurian sediments overlie
eroded Ordovician sediments,
forming an unconformity.
The continents of Avalonia,
Baltica, and Laurentia drifted
together near the equator,
starting the formation of a second
supercontinent known as
Euramerica.

65. SILURIAN PERIOD

66. ORGANISMS
 All animal life still lived in the seas. A
significant evolutionary milestone during
the Silurian was the appearance of
jawed and bony fish. Life also began to
appear on land in the form of small,
moss-like, vascular plants which grew
beside lakes, streams, and coastlines.
However, terrestrial life would not greatly
diversify and impact the landscape until
the Devonian.

67. silurian sea

68. NAUTILOIDS
The Nautiloids decreased greatly in number,
and those surviving had coiled and frilled
shells.

69. CRINOIDS
Crinoids, many beautifully colored, still
waved about on their stalks in
response to the sea currents.

70. KING CRABS
KING CRABS APPEARED, AND THEY HAVE
CHANGED BUT LITTLE IN ALL HUNDREDS OF
MILLIONS OF YEARS FROM SILURIAN PERIOD TO
PRESENT.

71. TRILOBITES
Some Trilobites crawled on the sea bottom.
Trilobites are animals that got their name
because their bodies were formed in three
lobes; that is they were trilobed.

72. PLACEODERMS
Paleceoderms are armored by their
extensive dermal skeleton. These
dermal bones (or plates) form head
and thoracic shields that are either
articulated by distinctive joints or fused
into a single unit. Pectoral fins are
typically well developed. Bony
shearing or crushing structures on the
jaws substitute for true teeth, which are
absent. The jaw joint is simple.

73. PLACEODERMS

74. BRACHIOPODS
Brachiopods are a phylum of marine
animals that have hard "valves" (shells) on
the upper and lower surfaces, unlike the
left and right arrangement in bivalve
molluscs.

75. BRYOZOA
The Bryozoa, also known as Ectoprocta or
commonly as moss animals, are a phylum
of aquatic invertebrate animals.

76. MOLLUSCA
The Mollusca, common name
molluscs or mollusks, is a large phylum
of invertebrate animals.

77. HEDERELLIDS
Hederellids are extinct colonial
animals with calcitic tubular
branching exoskeletons.

78. LEECHES
Leeches also made their appearance
during the Silurian Period. Leeches are
segmented worms that belong to the
phylum Annelida and comprise the
subclass Hirudinea.

79. EURYPTERID
But the form of life that dominated
this period was the eurypterid also
known as sea scorpion. These sea-
living animals looked very much
like the scorpions that live on land
today. There were many kinds of
sea scorpions, varying in length
from two-inch pygmies to nine-
foot giants.

80. EURYPTERID

81. COOKSONIA
Cooksonia, the earliest vascular
plant, was formed in the middle
Silurian.

82. CLIMATE
•The Silurian period enjoyed
relatively stable and warm
temperatures, in contrast
with the extreme glaciations
of the Ordovician before it,
and the extreme heat of the
ensuing Devonian. 

83. •Sea levels rose from their Hirnantian
low throughout the first half of the
Silurian; they subsequently fell
throughout the rest of the period,
although smaller scale patterns are
superimposed on this general trend;
fifteen high-stands can be
identified, and the highest Silurian
sea level was probably around
140 m higher than the lowest level
reached.

84. •During this period, the Earth entered a
long warm greenhouse phase, and
warm shallow seas covered much of
the equatorial land masses. Early in the
Silurian, glaciers retreated back into
the South Pole until they almost
disappeared in the middle of Silurian.
The period witnessed a relative
stabilization of the Earth's general
climate, ending the previous pattern of
erratic climatic fluctuations.

85. •Layers of broken shells
(called coquina) provide strong
evidence of a climate dominated
by violent storms generated then
as now by warm sea surfaces.
Later in the Silurian, the climate
cooled slightly, but in the Silurian-
Devonian boundary, the climate
became warmer

86. •The period witnessed a relative
stabilization of the Earth's general climate,
ending the previous pattern of erratic
climatic fluctuations. Layers of broken
shells (called coquina) provide strong
evidence of a climate dominated by
violent storms generated then as now by
warm sea surfaces. Later in the Silurian, the
climate cooled slightly, but in the Silurian-
Devonian boundary, the climate became
warmer.

87. •Glaciers formed 430 million
years ago. They may have
only lasted one or a few
million years. During this time,
ice covered the northern part
of Africa, which was located
over the South Pole.

88. •Climate models have been
used to help
understand weather and
regional climates of the
supercontinent Pangaea. The
models suggest that monsoons
affected the subtropical east
coast and that interior of
Pangaea was dry.

89. Did You Know?
•The length of a year has not always
been 365 days.  During the early
Silurian Period, it has been calculated
that a year lasted 421 days.  By the
Middle Devonian Period 100 million
years later, it had decreased to 410
days per year.  This downward trend
would continue until we reached our
present number of days (365.25)

90. GEOLOGY AND CLIMATE
•During the Silurian, Earth underwent considerable
changes that had important repercussions for the
environment and life within it. Plate tectonic
activity continued to shift the continents during
the Silurian. The great southern continent
of Gondwana drifted farther across the South
Pole, while Siberia, Laurentia and Baltica
clustered around the
equator.Laurentia and Baltica collided at the end
of the Silurian, forming a new supercontinent,
Euramerica, and raising new mountain ranges.
Rising sea level formed a nearly continuous sea
from New York to Nevada, and other shallow seas
still covered parts of other continents.

91. •The Early Silurian was also a time of
global icehouse climate that included
great ice sheets at high latitudes. By
the middle of the Silurian, however,
global climate had become much
warmer, comparable to that of most
of
the Ordovician and Devonian Periods.
A new greenhouse phase began,
leading to the melting of many large
glacial ice sheets, which contributed
to a substantial rise in global sea level.

92. •The result was a world with
distinct north-south climatic
zones, much as today. Glaciers
remained at high latitudes, but
lower latitudes were relatively
warm and arid conditions led
to the formation of extensive
evaporite (salt) deposits near
the equator.

93. GEOLOGIC FACTORS
• The geographically two continents were
found totally interlocked, the northern
Laurasia and the southern part called the
Gondwana, alternatively both parts were
submerged underwater. The North Pole
was somewhere near the northern Pacific
Ocean and the South Pole somewhere
near southwestern Africa. The equator
passed over the southeastern Europe
over the northern Australia and
Greenland to the center of America

94. WATER FEATURES
•The Silurian period enjoyed relatively stable and
warm temperatures, in contrast with the
extreme glaciations of the Ordovician before it,
and the extreme heat of the ensuing Devonian.
Sea levels rose from their Hirnantian low
throughout the first half of the Silurian; they
subsequently fell throughout the rest of the
period, although smaller scale patterns are
superimposed on this general trend; fifteen
high-stands can be identified, and the highest
Silurian sea level was probably around 140 m
higher than the lowest level reached.