Jurassic Park

Jurassic Park
The Jurassic Period (206-146 MY)
Jarðsaga 1
- Saga Lífs og Lands –
Ólafur Ingólfsson
Jurassic Period
Origin of the Term
Jurassic System. Alexander von Humboldt described
massive limestone formations of the Jura Mountains
in Switzerland as Jura-Kalkstein. Later, Leopold von
Buch in 1839 formally named these rocks the
Jurassic System.
Continental drift during the Jurassic
By Early Jurassic, south-central Asia had assembled. A
wide ocean (Tethys) separated the northern continents
from Gondwana. Pangea was on the werge of breaking up.
The break-up of Pangea
The most spectacular geographic development of the Mesozoic Era was the fragmentation of Pangea. The Tethys Sea
grew progressively larger, first separating Europe from
Africa and later, during the Jurassic, separating North
America from South America/Africa. South America and
Africa did not separate (to form the South Atlantc) until
the Cretaceous times
Late Jurassic continental configuration
Pangea breaking up, opening up of the Tethys Sea, and
the development of the Atlantic Ocean
Early Jurassic climate
The Pangean Mega-monsoon was in full swing during the
Early and Middle Jurassic. The interior of Pangea was very
arid and hot. China, surrounded by moistur bearing winds
was lush and verdant.
Late Jurassic climate
During the Late Jurassic the global climate began to
change due to breakup of Pangea. The interior of Pangea
became less dry, and the polar regions cooled.
Early Jurassic conditions for life:
• The Early Jurassic
was a hothouse, with
very warm global
climates.
• The huge Pangea
landmasses made it
possible for spreading
of plants and animals.
• The warm and shallow seas fringing Pangea, and
in particular the Tethys Sea, was optimal for
development of life in the oceans.
Jurassic sea levels
and temperatures
Global sea level rose, with
some oscillations, during the
Jurassic. Temperature gradients from the Equator to the
poles were gentle.
Two biogeographic provinces of
marine life
A northern province;
the Boreal realm
A southern province,
centered in the
Tethys Sea.
Coral reefs and limestones were centered
in the Tethys Sea,
suggesting it was
primarily tropical.
Jurassic reefs
The seas were populated by...
About 25% of all animal families disappeared at the end
of the Triassic. Ammonites made a huge comeback after
their near extinction. The Jurassic oceans were
populated by squid-like belemnites, fish and ammonites,
hunted by huge marine crocodiles, ichthyosaurs and
plesiosaurs. On the sea floor lived large communities of
urchins, star fish and shell-fish, much like in a modern
tropical sea. This was a time of richness and plenty, but
with big predators patrolling the seas, great violence as
well.
Who ate who in
the Jurassic
Seas?
Just as in modern
marine ecosystems, all
Jurassic life needed
energy to survive and
reproduce. Ultimately,
nearly all forms of life
depend on solar
energy...
At the bottom of the ladder...
Dinoflagellates (skorusvipungar)
are unicellular protists. Many are
photosynthetic, manufacturing
their own food using the energy
from sunlight, and providing a
food source for other organisms.
There are some dinoflagellates
which are parasites on fish or on
other protists.
Coccoliths (kokkólítar;
kalksnúðar): Members of this
group are primarily unicellular,
and are photosynthetic. The
group made a sudden and rapid
appearance of new forms in the
early Jurassic, and reached its
greatest abundance in the Late
Cretaceous.
Animals of the Jurassic Sea floor
Bivalves, brachiopods and echinoderms
were important groups in the Jurassic
seas. The first oysters appered.
The arthropods (liðdýr) florished...
Arthopods were well represented in the Jurassic seas
by crustaceans. These included shrimp, lobsters, and
crabs such as Eryon arctiformis
Jurassic
limestones very
extensive in
Europe
Solnhofen
Sea Lily
Jellyfish
Towards the end of the Jurassic, about 155
MY ago, a warm shallow sea with many
islands covered much of Germany. Sponges
and corals grew on rises in this sea, forming
reefs that divided up parts of this sea into
isolated lagoons. These lagoons were cut off
from the ocean and also from terrestrial
runoff. Within the warm lagoons, the
salinity rose., Aside from cyanobacteria and
small protists, nothing could survive in the
bottom waters of the lagoons for very long.
However, any organism that fell into the
lagoons from the land, or that drifted or
was washed into the lagoons from the ocean,
was buried in soft carbonate muds. Thus,
many delicate creatures were not consumed
by scavengers or torn apart by currents.
Some marine predators from
Solnhofen
Alligatorellus, a small crocodile.
Fish (Ascalabos voithi)
A shrimp
Fish (Tharsis sp)
Ammonites
Fishes evolve rapidly during the
Jurassic
More advanced, skilled predatory
fish (see below) developed. More
primitive fish (picture right) still
had an armour of thick, bony
scales reinforced by a shiny
enamel layer.
The biggest fish in
the sea
During the Jurassic there
swam a fish, the Leedsichthys
problematicus, a monster that
may have approached a length
of 30 metres.
In Leedsichthys, the rod-like gill
bones called gill rakers supported
millions of tiny needle-like teeth.
These formed an effective
filtering device and would have
allowed Leedsichthys to strain
small crustaceans, fish and other
animals out of the water as it
swam along. Leedsichthys was
therefore a Jurassic version of
the blue whale.
A fish the size of Leedsichthys
must have been an important
component of Jurassic marine
ecosystems. It consumed literally
tonnes of plankton. Its dung
fertilized the sea floor, and
during the breeding season
thousands of fish and other
animals would have feasted on the
millions of eggs produced by
Leedsichthys females.
A large predatory fish
A Pachycormid fish. This fish, related to
Leedsichthys, was 1.6 metres long.
The ichtyosaurs
florished
The Jurassic was the time when
ichthyosaurs were a prime
marine predator. They had
developed forms that were
perfectly adapted to the marine
environment
(http://www.sciam.com/article.cfm?articleID=00092A8F-A178-1C72-9EB7809EC588F2D7&pageNumber=1&catID=2)
The Plesiosaurs were the top
predators in the sea
Jurassic Sharks
The Jurassic Period was a
time of shark evolution.
They were an important
but not dominating group
of predators in the
Jurassic seas
Most Jurassic sharks were rather small (1-3 m). It was
not until the great marine reptiles became extinct that
sharks took the top position in the food chain
Protospinax
Protospinax: A shark-like relative of modern rays, the 1.6 m long
Protospinax cruised lagoons in southern Germany about 150 million
years ago. On the sea floor is Pseudorhina, an ancient representative
of angel sharks. Pseudorhina has an oddly flattened body well adapted
for life on the sea floor.
Hybodus
Hybodus: A 2 m long Hybodus pursues a swarm of belemnites. One of
the most common Jurassic sharks, Hybodus lived in the sea, but it
had smaller relatives (some as little as 20 cm long) that lived in
streams and rivers. To the lower left is Palaeospinax which belonged
to the lineage that gave rise to all modern sharks and rays. Typically
less than 1 m long, it was one of the first sharks to have solid
vertebrae instead of a cartilaginous backbone found in more primitive
species of sharks with which it lived.
Paleocarcharias
Paleocarcharias: Another shark from the teeming waters
of Germany 150 MY ago, Paleocarcharias was a primitive
relative of modern bull sharks and hammerheads.
Jurassic crocodiles
The crocodiles of the Jurassic seas, the steneosaurs,
were inhabitants of the offshore sea and of river
deltas. Only fully grown animals ventured out far into
the open sea.
Modern turtles originated during the
Jurassig Period
The oldest fossil turtles have been found in the
Triassic deposits of Germany These fossils have been
assigned to the genus (ættkvísl) Proganochelys. All
other turtles are assigned to the gigaorder (yfirættbálkur) Casichelydia. The Casichelydia became dominant
during the Jurassic and remained so ever since.
Jurassic plants
Ferns, ginkgoes, and cycads flourished in the Jurassic.
Conifers were also present, including close relatives of
living redwoods, cypresses and pines.
The Wollemi Pine, a
plant from Jurassic
times which survived
in a single isolated
Australian grove
If there was ever
a seed plant that
deserved the title
of "living fossil" it
is Ginkgo biloba
(musteristré). Leaf
imprints of an
ancestral species
of this tree are
abundant in
sedimentary rocks
of the Jurassic
The spore plants
Spore-bearing plants, such as ferns, sphenophytes and
lycophytes were abundant in the Jurassic damp forest
understory, as well as in swamps and along lake shores
and rivers. They were importan food source for many
dinosaur herbivores.
Fossil Mesozoic Pines
Pines were very abundant in Jurassic times, and
probably dominated dryer and inland habitats.
Pine log from Petrified Forest,
Arizona
Recent (left) and Jurassic petrified
(right) pine cones (Araucaria sp)
They are widely
distributed in tropical
and subtropical regions
of the world. Prior to
the Theory of
Continental Drift, the
widely scattered
distribution of
present-day cycads in
Australia, South
Africa, and the
Americas was an
enigma. How could
cycads have such a
worldwide distribution
when their seeds are
too large, heavy and
dense to be carried
great distances by
birds, wind, or ocean
currents?
The Cycads
The Mesozoic is often called the
Age of the Cycads, because of their
abundance.
Jurassic Flora in Antarctica
Jurassic plant fossils sampled during the first Swedish
Antarctic expedition (1901-1903) helped pave the way for
the theory of continental drift
Mount Flora, Hope Bay,
Antarctic Peninsula
Insect development during the Jurassic
Period
Insects were able to adapt to change, unlike many
plants and other animals. They escaped relatively
lightly from both the Permian and Triassic ectinction
events.
Among those insects that make their first
appearance during the Jurassic Period are:
• Dermaptera (Earwigs – “Eyrnapöddur”)
• Lepidoptera (Butterflies and Moths “náttfiðrildi”)
• The stinging wasps (Aculeate)
(http://www.discoverlife.org/nh/tx/Insecta/)
Jurassic insects
Dermaptera (Earwigs - eyrnapöddur) are mostly
scavengers or herbivores that hide in dark
recesses during the day and become active at
night. They feed on a wide variety of plant or
animal matter. A few species may be predatory.
The common name "earwig" is derived from an old
superstition that these insects crawl into people's
ears at night and burrow into the brain.
Butterflies and moths can be readily identified
from other insects by the scales on their wings.
Lepidoptera, being derived from Greek, means
"wings of scale." Their life cycle has four stages:
egg, larva (caterpillar), pupa (chrysalis) and adult.
Most butterflies fly during the day; most moths
fly at night. In terms of species numbers,
Lepidoptera is among the largest insect orders
(ættbálkur), with about 300,000 species.
Jurassic insects
Most of the stinging wasps are predators
or scavengers; their ovipositors may be
modified to inject venom used for killing
prey or for defense. But, they are also
highly social animals. The stinging wasps
rely on a nest from which they conduct
many of their activities, especially rearing
young. Wasp nests may be as simple as a
straight burrow in the ground. Some wasp
nests, such as those of mud daubers and
potter wasps, are above ground,
constructed of mud cavities attached to
twigs, rocks, or human structures. They
may house thousands of individual wasps.
Jurassic insect fossils
Butterfly in
amber, China
Grasshopper, Solnhofen
Sinohagla pleioneura, China
Larva of Ephemeyopsis
trisetalis, China
Animals in the air
The Upper Jurassic period had a wider range of pterosaurs
than any other time during the Mesozoic.
Birds originated in Late Jurassic
An artist´s impression of the Solnhofen
shallow sea area in Late Jurassic time
Archaeopterix
Archaeopteryx is from the
Solnhofen Limestone of
Germany, of Upper Jurassic
age, about 150 MY ago. In
the summer 1861 a fossil
casting was discovered with
bird feathers in Solnhofen.
A completely received
skeleton of an animal came
out a little later, which
indicated reptile and bird
features. Until today, only
few complete Archaeopterix skeletons have been
found.
Dinosaur or bird?
The Archaeopterix is a half-way stage in the evolution of
reptiles into birds. Some characters are still reptilian such
as teeth, long bony tail, no keel on the breastbone, claws
on the fore-limbs, no air-spaces in the bones; others are
already bird like (feathers) wings, collarbones fused into
wishbone, big toe opposable to other toes, pubis directed
backwards.
Well, it is a feathered dinosaur
Because Archaeopteryx had well developed feathers, it
is classified as a bird - the oldest known. The size of a
pigeon, it probably lived in trees and glided rather than
flew. It is in reality a feathered dinosaur, rather than a
bird senso stricto.
Other feathered dinosaurs
In recent years, a number of
other feathered dinosaurs have
been discovered: Protarcheopterix, Sinornithosaurus and
Velociraptor mongoliensis
http://www.austmus.gov.au/chinese_dinosaurs/feathered_dinosaurs/photo_gallery.htm
Evolution
of birds
Birds are of dinosaur ancestry, but
the direct descendance is still not
well known.
Simplified phylogeny of the dinosaurs
The Saurischia (eðlungar: reptilehipped”) dinosaurs and the Ornithishia
(“fleglar: bird-hipped”) dinosaurs
The Saurischia were dominant in the Triassic Period (245-210 MY)
and the Jurassic Period (210-145 MY). The Ornithischia dominated
in the Cretaceous Period (about 145 million-65 million years ago).
The evolution of dinosaurs...
The Jurassic Period was a time of dinosaur diversification as they evolved
towards increasing dominance in numbers of genera, species andhabitats
Different groups in different parts of Pangea
Although plants and animals could migrate across the wast
expanses of Pangea, distances and natural barries (deserts,
mountains, Tethys Sea) caused evolution of diffrent
branches of dinosurs. Early Jurassic dinosaurs were small.
Syntarsus – a carniAbrictosaurus - an
plant-eater (with no
canine teeth) from S
Africa, 208-200 MY;
1 m long.
vore from S Africa and
N America. 2-3 m long,
10-40 kg. Ca 200 MY.
Massospondylus - an
Early Jurassic herbivore, ca. 4 m long and
1 m tall. It had large,
five-fingered hands
with a large thumb
claw. Very common
Vulcanodon
Vulcanodon was a
long-necked, about
6.5 m long, herbivorous dinosaur that
lived in S Africa
during the early
Jurassic period,
208-201 MY.
Vulcanodon was a sauropod,
whose intelligence (as measured by its relative brain to
body weight, or EQ) was the
among the lowest of the
dinosaurs.
Cryolophosaurus
Cryolophosaurus ("frozen-crested
lizard“), a carnivorous sauropod
discovered in Antarctica. It was
ca. 6 m long and weighed ca 500
kg. Early Jurassic, ca 196-190 MY
Asian Early Jurassic giants
Zizhongosaurus, an early
Jurassic (ca. 190-177 MY)
herbivore from China. It
was 9 m long.
Barapasaurus, a very large (15 m),
primitive herbivorous sauropod
from India
Megalosaurus
Megalosaurus was a large, meateating dinosaur that lived in
northern Pangea in erly-mid
Jurassic (ca 181-169 MY). It was
the first dinosaur fossil
discovered (England, 1676). It was
also the first dinosaur given a
scientific name - by William
Buckland in 1824. Megalosaurus
walked on two powerful legs, had a
strong, short neck, and a large
head with sharp teeth. Megalosaurus was up to 9 m long, 3 m tall
and weighed about 1 ton.
Late Jurassic dinosaurs
Dinosaur development through the Jurassic Period
shows some main trends: Many groups grow in size, there
is an increase in armour, and predators develop towards
greater agility. The strategy of predators hunting in
groups also becomes wide-spread.
Brachiosaurus – a Late Jurassic giant
Brachiosaurus is one of the largest known land animals, based on a
complete skeleton found in Tanzania. It was >30 m long and it
weighed >50 tons. Each neck vertebra was more than 1 m long. Its
front legs were longer than its rear legs and it stood 7.3 m at the
shoulder. It had small narrow feet for its size and the first digit of
the front foot had a claw as did the first three digits of the hind
foot. The function of the claws is unknown though they may have
been used for raking plants or in self defense.
Large, Late Jurassic predators...
The Allosaurus
Allosaurus ("different lizard") was a powerful N Pangea predator
that walked on two powerful legs. It had a massive tail, a bulky
body, and heavy bones. Its arms were short and had threefingered hands with sharp claws that were up to 15 cm long.
Allosaurus was up to 12 m long and 5 m tall. It weighed about 1.5
tons. It had large, powerful jaws with long, sharp, serrated teeth
5-10 cm long. They may have hunted in packs...
Another Late Jurassic killer
Ceratosaurus was a common meat-eater during the late
Jurassic period. It was 4.5-6 m long, weighing 0.5-1 ton.
This common hunter had powerful jaws with long, sharp,
teeth. It is believed that the Ceratosaurs hunted in packs.
Armed herbivores
Stegosaurus and Kentrosaurus are examples of
Late Jurassic herbivores
that relayed on size and
armour to scare off
predators. 5-9 m long, 35 m high, weighing 2-4
tons...
Small, vicious
dinosaurs
One of the smallest known dinosaurs, Compsognathus, is believed to
be an early relative of Archaeopteryx. Compsognathus was about
the size of a cat. It had long back legs, short arms and a long tail
for balancing while running. Apparently Compsognathus liked to eat
lizards, because a lizard skeleton was found in the abdominal cavity
of a Compsognathus fossil. Compsognathus had hollow bones, like
modern birds.
Mammals on the dinosaur menu
Mammals evolved and diversified slowly during the Jurassic Period.
Morganucodon is a tiny mammal known from Jurassic deposits in
caves in South Wales. They were rat-like and rat-sized animals,
equipped with a pointed snout that probably bristled with sensory
whiskers, and was likely held in a state of constant agitation. The
whiskers have not survived but we know that they were there
because there are many small openings in the bones of the snout
through which nerves and blood vessels passed to them. Since
whiskers are modified hairs it stands to reason that Morganucodon
was also a furry animal.
Jurassic and Cretaceous – a time of
frustrated mammals
Mesozoic mammal remains
are very rare – mostly
teeth from caves and soil
horizons.
Megazostron
From their diminutive size, and from the style of their dentition, we
can be pretty sure that these creatures made their living by eating
insects and other small invertebrates. Their large eye-sockets
suggest that they did their hunting at night, a very sensible strategy
in a world dominated by dinosaurs and flying pterosaurs, which hunted
by day. For many millions of years these tiny ancestors of ours were
able to do little but hang on, changing little in the process. They were
to endure over 150 million years of evolutionary frustration.
Jurassic extintions
There was a minor mass extinction toward the end of
the early Jurassic, which mostly affected marine life.
Another minor mass extinction occurred towards the
end of the Jurassic. During this extinction, most of the
stegosaurid and enormous sauropod dinosaurs died out,
as did many genera of ammonoids, marine reptiles, and
bivalves. No one knows what caused these extinctions.
How to exterminate life on Planet Earth:
- Freeze it
- Boil it
- Drop a meteor on it
- Cover it with ash and Lava
- Drown it or dry it out
- Poison it
References, web-resources
• Stanley, Earth System History, chapter 16
• Fortey, R. : Life – a natural history of the first 4 billion years of life on Earth.
New York, Vintage Books, 346 pp.
• http://www.scotese.com/jurassic.htm
• http://www.ucmp.berkeley.edu/mesozoic/jurassic/jurassintro.html
• http://www.palaeos.com/Mesozoic/Jurassic/Jurassic.htm
• http://palaeo.gly.bris.ac.uk/Palaeofiles/Lagerstatten/solnhofen/index.html
• http://www.yale.edu/ypmip/locations/solnhofen.html
• www.discoverlife.org/nh/tx/Insecta/
• http://www.prehistory.com/timeline/jurassic.htm
• http://www.palaeos.com/Vertebrates/Units/220Lepidosauromorpha/220.400.html
• http://www.bbc.co.uk/dinosaurs/
• http://www.sharkattacks.com/prehistoric.htm
• http://www.enchantedlearning.com/subjects/dinosaurs/
•www.austmus.gov.au/chinese_dinosaurs/feathered_dinosaurs/photo_gallery.htm