Triassic-Jurassic Periods

Introduction to the Mesozoic Era
248 to 65 Million Years Ago

• The Mesozoic is divided three time periods:
• the Triassic (245-208 Million Years Ago),
• the Jurassic (208-146 Million Years Ago),
and
• the Cretaceous (146-65 Million Years Ago).
• Mesozoic means "middle animals", and is
the time during which the world fauna
changed drastically from that which had
been seen in the Paleozoic.
• Dinosaurs, which are perhaps the most
popular organisms of the Mesozoic, evolved
in the Triassic, but were not very diverse
until the Jurassic. Except for birds,
dinosaurs became extinct at the end of the
Cretaceous.
• Some of the last dinosaurs to have lived are
found in the late Cretaceous deposits of

• The Mesozoic was also a time of great
change in the terrestrial vegetation.
• The early Mesozoic was dominated by ferns,
cycads, ginkgophytes, bennettitaleans, and
other unusual plants.
• Modern gymnosperms, such as conifers, first
appeared in their current recognizable forms
in the early Triassic.
• By the middle of the Cretaceous, the
earliest angiosperms had appeared and
began to diversify, largely taking over from
the other plant groups.

Or click on a
subdivision of the
Mesozoic to visit its exhibit!
The chart at left shows the
three major subdivisions of
the Mesozoic Era. This chart
is mapped to take you to each
of these subdivisions.
The Mesozoic Era occurs
between the Paleozoic and the
Cenozoic.

Mesozoic Era:Life
The following are examples
of Mesozoic life...
Dinosaurs and
other archosaurs,
such as the
pterosaurs,
dominated the land
biota. . . such as
these dinosaurs
from the
Cretaceous of
Mongolia

Cycads and Bennettitaleans
were among the dominant land

• The first mammals also arrived on the scene
in the Mesozoic,descended from a lineage of
so-called "mammal-like reptiles," or
synapsids. This is Thrinaxodon, an extinct
relative of mammals from the Triassic

Mesozoic Era:
Localities
Mesozoic localities on this server: (see
map above)
Blue Nile Gorge, Ethiopia - Come along on
a fossil-hunting trip to Ethiopia with
UCMP researchers and see the first
dinosaur fossils from Ethiopia.
Clayton Lake, New Mexico - One of the
most extensive and best preserved
dinosaur trackways in the United States is
this Cretaceous site.
Ischigualasto, Argentina - The best-known
and best-preserved early dinosaurs come
from this Triassic locality in South
America.
Karoo Basin, South Africa
Pt. Loma Formation, California - This
Cretaceous locality has yielded important
fossils for understanding western North
American dinosaurs.
Saurian Expedition of 1905 - This
expedition to the West Humboldt Range in
Nevada is known for remarkable finds of
Jurassic ichthyosaurs, and the site has
since become part of Berlin-Ichthyosaur
State Park.
Solnhofen Limestone, Germany -
Exquisitely detailed fossils have come
from these Jurassic deposits in southern
Germany.
Triassic deposits are known
from one locality in Egypt, Arif-
El-Naqa dome, Sinai.
Fossils
As Plicatula, Myphoria, ,
Triassic in Egypt:

• Duration: about 32 million years
• Maximum thickness:30,000 feet
• The Triassic Period (from three-fold division in Germany) spanned the
time from approximately 250 million years ago until 202 mya, and it begins the Mesozoic Era. Life
forms in this time are significantly different to those that lived prior to the mass extinction at the
end of the Permian.
• This system represents the first period in the Mesozoic . The
physical conditions of depositions remined much the same as in
the Permian times but we get different organic remains. Plants
became varied.
• The name " Trias" was given to this group of rocks by Von Alberti
in 1834 from three-fold division in Germany. The three divisions
are also found in the Vosges as follow:-
1-Varigated sandstone or BuntSand stein.
2-Shelly limestone or Muschelkalk.
3-Varicolored marl or Keuper.
The Bunter and Keuper are continental facies , found in Europe in
the(N.R.S.St.) except in the Alpine chains.
• In the Middle Triassic an epicontinental sea of the Mushelkalk
occupied central Germany and Vosges , while in the eastern
Europe, Alps.etc., there was a geosyncline with thick deposits
• In the oceans, the ammonoids were predominant survivors into
the Mesozoic. On land, the condonts arose in the Early Triassic,

Triassic: Facies
TheTriassic shows considerable development of both
continental and marine
The Bunter series (Buntsandstein): consists chiefly of red beds
such as conglomerates, sandstones and shales with some salt and gypsum. They
indicate deposition under desert, arid climatic conditions. These series seem to have
deposited in German and in the interior of United States at the same time.
The Muschelkalk series is mostly a marine limestone formation, thus
showing the presence of marine waters over the German region.
The Keuper (Rhaetic),conditions of depostion on were much as during the
Bunter ( continental facies beds). though late keuper marine water again transgressed
the area .

The Triassic in Germany:-
1- BuntSandstein : It consists of continental or lagoonal sediments , conglomerate,
sandstone,shale...violet and red in colour. Its top shows more or less marine facies, with
Myophoria forming a passage to the next stage.
2- Muschelkalk : It is divided into the following units:
a- Lower corrugated limestone with Terebratulla vulgaris, Myophoria, Lima,..
b-Anhydrite group : marly, dolomitic with gypsum, anhydrite.
c- Muschelkalk proper: marine facies with crinoid (forming the know crinoidal limestone),
Ceratites nodosus, Myphoria vulgaris
3- Keuper(Rhaetic) time:
It consists of upper Keuper or Rhaetian , Middle Keuper and lower Keuper.This
stage shows saliferous formations with green or red marls gypsum, anhydrite
and sandstone with plants remains.
Subdivision of the Triassic:-
Germany
Upper Triassic -----------------------Keuper.
Middle Triassic-----------------------Muschelkalk.
Lower Triassic------------------------BuntSandstein

Significant Events
 Life Restarts
• Ninety-six percent of all species
vanished at the end of the Permian.
The subsequent opening of niches
provided a wonderful opportunity for
new life forms in the Triassic. During
this period we see the rise of the
conodonts and their descendants, the
dinosaurs and birds, and also the rise
of mammals.
 Pangaea
 During the Permian all land masses
were congregated into a single
equatorial supercontinent known as

Triassic Graphics
Triassic View Plateosaurus

The Triassic Period
248 to 206 Million Years
Ago• In many ways, the Triassic was a time of
transition. It was at this time that the
world-continent of Pangaea existed, altering
global climate and ocean circulation.
• The Triassic also follows the largest
extinction event in the history of life, and so
is a time when the survivors of that event
spread and recolonized.
• The organisms of the Triassic can be
considered to belong to one of three groups:
holdovers ‫المتبقين‬ from the Permo-Triassic
extinction, new groups which flourished
briefly, and new groups which went on to
dominate the Mesozoic world. The holdovers
included the lycophytes, glossopterids, and

• Subdivisions of the
Triassic:
• The chart at left shows the
major subdivisions of the
Triassic Period. Click to go
forward to the Jurassic, or back
to the end of the Paleozoic Era,
the Permian Period.
• The Triassic Period is part of
the Mesozoic Era.

Triassic Period: Stratigraphy
• Subdivisions of the
Triassic:
• The chart at left shows the
Triassic Period. The
youngest stage, the
Rhaetian, is found only in
the vicinity of the Alps, in
Europe, and so some
workers feel that it does not
deserve global recognition.
• This chart is mapped. Click
to go forward to the
Jurassic, or back to the end
of the Paleozoic Era, the
Permian Period.
• The Triassic Period is part of
the Mesozoic Era.

Triassic Period:
Localities

• Localities for Triassic fossils are rare
for the Early and Middle portions on the
Period, but more common for the Late
Triassic. Localities fall into one of two
broad regions, corresponding roughly
with the northern and southern
hemispheres, with India belonging to the
latter.
• Triassic localities on this server: (see
map above)
• Chinle Formation, Arizona
• Ischigualasto, Argentina - The best-
known and best-preserved early
dinosaurs come from this locality in
South America.

Triassic in Egypt:
Triassic deposits are known from one locality
in Egypt, Arif- El-Naqa dome, Sinai.
Fossils
As Plicatula, Myphoria, , Ceratites

Triassic Period:Tectonics and
Paleoclimate
• The Triassic period was a transition from
the Paleozoic Era to the Mesozoic. It is
situated between the end of the Permian
period and the beginning of the Jurassic,
lasting from 254 mya to 206 mya. As with
almost any other period of the Earth's
history, the Triassic had a unique climate
and biota indigenous to that time. The
paleoclimate was influenced largely by
tectonic events that never existed before or
since.

• At the beginning of the Triassic period, the land
masses of the world were still bound together into
the vast supercontinent known as Pangaea. Pangaea
began to break apart in the mid-Triassic, forming
Gondwana (South America, Africa, India, Antarctica,
and Australia) in the south and Laurasia (North
America and Eurasia) in the north. The movement of
the two resulting supercontinents was caused by sea
floor spreading at the midocean ridge lying at the
bottom of the Tethys Sea, the body of water between
Gondwana and Laurasia. While Pangaea was breaking
apart, mountains were forming on the west coast of
North America by subduction of the ocean plates
beneath the continental plates. Throughout the
Middle to Late Triassic, mountain forming continued
along the coast extending from Alaska to Chile. As
mountains were forming on the Americas, North
Africa was being split from Europe by the spreading
rift. This division of the continents advanced further
westward, eventually splitting eastern North America
from North Africa

• The climate of the Triassic era was influenced by
Pangaea, its centralized position stradling the
equator, and the geologic activity associated with its
breakup. Generally speaking, the continents were of
high elevation compared to sea level, and the sea
level did not change drastically during the period.
Due to the low sea level, flooding of the continents
to form shallow seas did not occur. Much of the
inland area was isolated from the cooling and moist
effects of the ocean. The result was a globally arid
and dry climate, though regions near the coast most
likely experienced seasonal monsoons. There were
no polar ice caps, and the temperature gradient in
the north-south direction is assumed to have been
more gradual than present day. The sea level rose as
the rift grew between North Africa and southern
Europe, resulting in the flooding of Central and South
Europe; the climates of terrestrial Europe were hot
and dry, as in the Permian. Overall, it appears that
the climate included both arid dune environments
and moist river and lake habitats with gymnosperm
forests.

• Some conclusions can be drawn about more specific
regional climates and species based on experimental
research. The presence of coal-rich sequences in the
high northern and southern latitudes, as well as the
presence of large amphibians there, indicates that
the paleoclimate was wetter in those areas. Living
species of some Mesozoic ferns (including the
families Osmundacae and Dipteridacae) now live in
wet, shady areas under forest canopies, so it is likely
that the paleoclimate their Triassic ancestors
inhabitted were also damp and shaded. The Mesozoic
era might also have had large, open areas with low-
growing vegetation, including savannas or fern
prairie with dry, nutrient poor soil populated by
herbaceous plants, such as ferns of the families
Matoniaceae and Gleicheniaceae. Thus, despite the
union of the continental landmasses, the Triassic
vegetation was quite provincial, though this
decreased as the Triassic wore on. The northern
forests at the beginning of the Triassic were
dominated by conifers, ginkgos, cycads, and
bennettitaleans, while the forests of Gondwana were
dominated by Dicroidium and Thinnfeldia. By the end
of the Triassic, both hemispheres gave way to conifer
and cycad vegetation

• The Triassic-Jurassic boundary is
similar to the Permo-Triassic
boundary in that the global
climate was not radically
altered, though a major
extinction of terrestrial
vertebrates occurred.
• With the end of the Triassic and
the beginning of the Jurassic,
Pangaea continued to break
apart, inevitably ‫حتما‬ affecting the
climate, though not as radically

• Flora:
Age of Cycades (Conifers, Ferns, Sigillaria). Voltzia heterophylla (Age
of Cycades)
Invertebrates:
Sponges and Coelenterates: Corals limestone (hexacorals)developed.
Tetracorals disappeared, Stromatoporids persist till the Cretaceous.
Brachiopods: Rhynchonellas and Terebratualas more developed
Myophoria vulgaris
Ceratites nodosus
Phylloceras
Vertebrates
Reptile :Teleropeton
Swimming Reptiles,Mammals.
 Triassic : Climate:
• Arid to semi-arid , rather hot and dry , climate seems to have been
remarkably widespread during the Trissic.
• The widespread distribution of salt and gypsum adds further
evidence for a widespread aridity.

Life of the Triassic

All fossils in the Triassic
Monotis Ceratites humboldtensis 1998

Owenites koeni
© 2004
Paratropites
antiselli
© 2005

Sagenites
© 2004
Scleractinian
© 1998

Phytosaurus tooth
© 2005
Shastasaurus
pacificus
© 2004

Shonisauru
s popularis
© 2004 Planolites
© 2003

Stegomus arcuatus
© 2005
Phytosauridae
© 2003

Minor Extinctions of Earth History
Although mass extinctions are most studied by the
paleontological community, several smaller-scale
extinctions have also been documented.
• These extinctions, occurring in the Triassic, Jurassic,
Oligocene, and Neogene, did not affect as many species as
the major mass extinctions, but are critical to
understanding the patterns of extinction.
• The Triassic Extinction
• Labyrinthodont amphibians, conodonts, and all
marine reptiles(excluding ichthyosaurs) were
eliminated and mammal-like reptiles, thecodonts,
brachiopods, gastropods, and molluscs were severly
affected by this event.
• The causes of the Triassic extinction are not well
known, but popular explanations for its occurrence
include global climatic cooling, extra-terrestrial
impact, or comet showers. This extinction event is
particularly important because it allowed the

• Duration: about 57 million years
• Maximum thickness: 44, 000 feet
• The Jurassic formations were first known in the
Jura Mountains between France and Switzerland
( from which the name of the system was derived).
• During the Jurassic, North and South America,
Africa, and Australia were joined in a supercontinent
near the equator. Europe and Asia had just broken
off from the Pangean supercontinent.
• There are few outcrops of Jurassic rock in North
America, but the best-known of Jurassic strata, the
Morrison Formation, is found in much of the Western
interior of the U.S. It was during this time that the
huge sauropod dinosaurs such as Apatasaurus and
Brachiosaurus lived.
• Sea level was low but rising during the Early
Jurassic, and high throughout the remainder of the

JURASSC SYSTEM
 Facies
There are two distinct types of facies : marine and non-marine
(continental(:
In the Northern Hemisphere: Marine marls and limestones that
are often oolitic are deposited as a result of submergence of the
great salt lakes and other basins.The marine transgression of the
late Triassic time continued into the Jurassic.
In the Southern Hemisphere : continental facies consisting of
sandstones and shales are well developed.
 In Jura Mountains, the Jurassic is divided into:
1-Black Jura
2-Brown Jura
3- White Jura
This division corresponds to Subdivision of the Jurassic:
Lower Jurassic----------------------------Lias- Black Jura
Middle Jurassic ---------------------------Dogger-BrownJura
Upper Jurassic----------------------------Malm -- White Jura
Oppel divides these formations into 33 biostratigraphic zones of
Ammonites .Later, the number of these zones was greatly

Significant Events
 Continental Breakup
• The Permian-Triassic supercontinent of
Pangaea began to break apart in the
Jurassic, with the splitting off of the
European-Asian component.
 Himalayan Deposition
• The rocks that would ultimately become the
highest point on Earth were deposited in the
Triassic and Jurassic Periods as limestones,
dolomites, and shales.

Rhamphorhynch
us
Stenopterygiu
s
Jurassic Graphics

• Great plant-eating dinosaurs
roaming the earth, feeding on lush
growths of ferns and palm-like
cycads and bennettitaleans. . .
smaller but vicious carnivores
stalking the great herbivores. . .
oceans full of fish, squid, and coiled
ammonites, plus great ichthyosaurs
and long-necked plesiosaurs. . .
vertebrates taking to the air, like
the pterosaurs and the first birds. . .
this was the Jurassic Period,
beginning approximately 210 million
years ago and lasting for 70 million
years of the Mesozoic Era.
• Named for the Jura Mountains on
the border between France and
Switzerland, where rocks of this age
were first studied, the Jurassic has
become a household word with the
success of the movie Jurassic Park.
Outside of Hollywood, the Jurassic
is still important to us today, both
The Jurassic Period
206 to 144 Million Years Ago

Subdivisions of the
Jurassic:
The chart at left shows the
Jurassic Period. This chart
is also mapped to take you
back in time to the
Triassic, or forward to the
Cretaceous.
The Jurassic Period is part
of the Mesozoic Era

Life of the Jurassic Flora: Flora: Age of Cycades (Conifers, Ferns, Cycades).
Cycadeoidea microphylla
 Fauna: Invertebrates:
 Corals: all belong to hexacorals, no stratigraphic
importance. The profusion of Corals
 Braciopods, mostly of Terebratulla and Rhynconella types
Trigonia monilifara, Plicatula spinosa, Cidaris florigemma
Gryphaea arcuata
 Cephalopods, Ammonites are the most striking features of
the period, more abundant than "Belemnites" and hence term :
Age of Ammonites Ammonites: Phylloceras ,
Harpoceras (Lower Jurassic)
Cosmoceras, Aspidocras ( Midle Jurassic(
Perisphinctes, Oppelia (Upper Jurassic(
 Belemnites
Crinoides and sea Urchins of modern aspects were all represented
 Vertebrates:
 Fishes and Amphibian
 Reptiles , Age of Reptiles Ex. (Dino—Terrible, Saures ---Reptile)-
Birds- Mammals.
 Reptiles: Ichthysaurus, Plesiosaurus,Pteroidactylus,
Megalosaurus

• But there was more to life than dinosaurs! In the seas, the
fishlike ichthyosaurs were at their height, sharing the
oceans with the plesiosaurs, with giant marine crocodiles,
and with modern-looking sharks and rays.
• Also prominent in the seas were cephalopods -- relatives
of the squids, nautilus, and octopi of today. Jurassic
cephalopods included the ammonites, with their coiled
external shells (upper left), and the belemnites, close
relatives of modern squid but with heavy, calcified, bullet-
shaped, partially internal shells. Among the plankton in
the oceans, the dinoflagellates became numerous and
diverse, as did the coccolithophorids (microscopic single-
celled algae with an outer covering of calcareous plates).
• Land plants abounded in the Jurassic, but floras were
different from what we see today. Although Jurassic
dinosaurs are sometimes drawn with palm trees, there
were no palms, or any other flowering plants, at least as
we know them today, in the Jurassic. Instead, ferns,
ginkgoes, bennettitaleans or "cycadeoids", and true
cycads -- like the living cycad pictured at the above right
-- flourished in the Jurassic. Conifers were also present,
including close relatives of living redwoods, cypresses,
pines, and yews. Creeping about in this foliage, no bigger

Jurassic Period: Localities
Extensive Jurassic deposits can be
found in the Rocky Mountains of the
United States, England and western
Europe, central Russia, and in many
other parts of the world
Jurassic localities on this server: (see
map above)
Blue Nile Gorge - Come along on a
fossil-hunting trip to Ethiopia with UCMP
researchers and see the first dinosaur
fossils from Ethiopia.
Saurian Expedition of 1905 - This
expedition to the West Humboldt Range
in Nevada is known for remarkable finds
of Jurassic ichthyosaurs, and the site has
since become part of Berlin-Ichthyosaur
State Park.
Solnhofen Limestone -Exquisitely
detailed fossils have come from these
Jurassic deposits in southern Germany.Jurassic in Egypt:
Jurassi deposits are very well developed in :-
•Maghara dome and Risan Aniza (N.Sinai)
•Middle Jurassic is also exposed on the western coast of the
Gulf of Suez
• At Northern Galala Plateau.

• Over much of the world, the Jurassic beds were stable ,
but by late Jurassic time, intense and widespread locallocal
deformationdeformation took place in N. America accompanied by the
intrusion of immense Batholiths of Granite. This Orogeny
has been named, the Nevadian disturbanceNevadian disturbance.
 Jurassic: Climate
• Climate warm, equable and more humid than it had been in
the Triassic.
• Towards the close of the Period, climate was rather warm
and moist over much of the earth. This is indicated by
Dinosaures in Mangolia, where winter temperature now
fall far below zero.
• Dinosaures very probably could not endure freezing
weather.
Jurassic Orogeney:

Life of the JurassicFlora: Age of Cycades (Conifers, Ferns, Cycades). Cycadeoidea microphylla
Fauna:
Invertebrates
Corals: all belong to hexacorals, no stratigraphic importance. The profusion of Corals
Braciopods, mostly of Terebratulla and Rhynconella types
Trigonia monilifara
Plicatula spinosa
Cidaris florigemma
Gryphaea arcuata
Cephalopods, Ammonites are the most striking features of the period, more abundant
than "Belemnites" and hence term : Age of Ammonites.
Ammonites:
Phylloceras , Harpoceras (Lower Jurassic)
Cosmoceras, Aspidocras ( Midle Jurassic)
Perisphinctes, Oppelia (Upper Jurassic)
Belemnites
Vertebrates:
Fishes and Amphibian
Reptiles , Age of Reptiles Ex. (Dino—Terrible, Saures ---Reptile)- Birds- Mammals.
Reptiles: Ichthysaurus, Plesiosaurus,Pteroidactylus, Megalosaurus
Earliest bird : Archaeoptenyx macrura
The Mammalian as in the Triassic

The Jurassic Extinction
Two extinction events are speculated to have
occurred in the Jurassic.
•The first of these events is recognized in Pleinsbachian age
strat from Europe. This extinction eliminated more than
eighty percent of marine bivalve species, along with various
other shallow water species.
•The second crisis occurred near the end of the Jurassic, by
an event that severly affected ammonoids, marine reptiles,
and bivalves.
•Dinosaurs were also severly affected as stegosaurs and
most types of sauropods did not survive into the Cretaceous
period. This event is not well understood so few hypothese
have yet been proposed for its occurrence .

Triassic-Jurassic Periods

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