History/Origins/Future of Energy,
Matter, Space, Time, and Life (4 of 7) 

From ~145 Million Years Ago
to ~23 Million Years Ago

(updated August 16, 2009)

Years Ago



~145 million to ~65 million ....

Cretaceous Period
145 Million to 65 Million Years Ago
"... At the start of the period, dinosaurs ruled the
loosening remnants of the supercontinent Pangaea
... At the end of the period, about 80 million years
later, oceans filled yawning gaps between isolated
continents shaped much as they are today. 
Flowering plants were spreading across the land-
scape. And mammals sat poised to fill the void that
soon would be left by the vanished dinosaurs.

A giant crater smoldered on what would become
known as the Yucatán Peninsula.

Whether or not the asteroid or comet that carved
the Chicxulub crater caused the extinction of more
than half the planet's species at the end of the Creta-
ceous remains a matter of scientific debate. ...

... the Cretaceous picked up where the Jurassic left
off: Gigantic sauropods led parades of dinosaurs
through the forests, over the plains, and along the
coasts; long-necked and toothy marine reptiles ter-
rorized fish, ammonites, and mollusks in the seas;
pterosaurs and hairy-feathered birds filled the skies. 

This rendering of Cretaceous life shows the diverse range of dinosaurs that lived between 145 and 65 million years ago, including maiasaurs (front left); tarbosaurs (top right), and pterosaurs (top center). In the foreground are depicted the first flowering plants and one of the earliest mammal relatives, both of which developed during this period and went on to survive the dinosaur extinction at the end of the Cretaceous.

But as the continents spread, the ocean currents
churned with ever more vigor. After a temperature
spike in the mid-Cretaceous, the climate began to
cool ... 

The chalk cliffs on Germany's Rügen Island rise 330 feet or more over the Baltic Sea. These ancient structures are made nearly entirely of the skeletons of calcite-covered plankton called coccolithophores, deposited by the trillions during the Cretaceous period. Sediments like these actually give the Cretaceous its name: Creta means "chalk" in Latin.

Microscope image reveals the intricate patterning of ancient coccolithophores, microscopic plankton abundant in shallow seas during the Cretaceous period. As these organisms died, their skeletons, called cocospheres, fell by the trillions to the seafloor, forming layer upon layer of calcium carbonate. Millions of years of pressure and heat turned these layers into chalk & helped to preserve countless fossils from the Cretaceous.

Though dinosaurs ruled throughout the Cretaceous,
the dominant groups shifted and many new types
evolved. Sauropods dominated the southern con-
tinents but became rare in the north. Herd-dwelling 
ornithischians like Iguanodon spread everywhere
but Antarctica. 

Toward the close of the Cretaceous, vast herds of
horned beasts such as Triceratops munched cycads
and other low-lying plants on the northern continents. 
The carnivore Tyrannosaurus rex dominated the late 
Cretaceous in the north while monstrous meat-eaters
like Spinosaurus, which had a huge sail-like fin on its
back, thrived in the south. Smaller carnivores likely
battled for the scraps.

Tyrannosaurus rex arose during the Cretaceous period about 85 million years ago and thrived as a top land predator until the dinosaurs went extinct 20 million years later. This skeleton, on display in Chicago's Field Museum, is a cast of perhaps the world's most famous fossil: "Sue," a 67-million-year-old T. rex discovered in 1990 in South Dakota by field paleontologist Sue Hendrickson. It is the most complete, best preserved, and, at 42 feet, the largest T. rex specimen ever found.

Other creatures, such as frogs, salamanders, turtles,
crocodiles, and snakes, proliferated on the expanded
coasts. Shrewlike mammals scurried about the forests. 

The largest pterosaur known soared overhead though
the group as a whole faced ever stiffening competition
from fast diversifying birds: Ancestors to modern
grebes, cormorants, pelicans, and sandpipers all show
up in the Cretaceous. 

In the warm, shallow seas that spilled onto the continents,
the long-necked plesiosaurs gave way to the giant, snake-
like mosasaurs. Rays and modern sharks became com-
mon. Sea urchins and sea stars (starfish) thrived; coral
reefs continued to grow. Diatoms, a type of shelled plank-
ton, made their first radiation into the ocean.

But it was the rapid dispersal of flowering plants that stole
the show—a spread enhanced with the help of insects from
bees and wasps to ants and beetles. Magnolia, ficus, and
sassafras quickly outnumbered ferns, conifers, gingkoes,
and cycads.

Much of this rich life—including all dinosaurs, pterosaurs,
pliosaurs, and ammonites—perished in the extinction event
at the end of the period 65 million years ago. ...

~130 million to ~125 million ....

"... X-FACTOR: Double row of spines on neck and back
WHEN:       130-125 million years ago
WHERE:     Argentina

Like the tail fins on a 1959 Cadillac, a bizarre double
row of spines extending from the vertebrae of Amar-
gasaurus may have served little purpose other than to
turn heads. Since the discovery of the sauropod was
announced in 1991, paleontologists have pondered
the function of the delicate bony rods, which would
have offered limited defense at best against predators."

~127 million ....

Giants of the Skies - the Early Cretaceous Earth

Walking With Dinosaurs -- Giants of the Sky
"... 127 million years ago — Early Cretaceous — Young Atlantic Ocean

Filming locations: New Zealand, Tasmania

Conditions: Sea and coastlands.

[featured in this episode]
  • Ornithocheirus.
  • Iguanodon
  • Utahraptor
  • Polacanthus
  • Tapejara
  • Unidentified small pterosaur
  • Iberomesornis (identified as bird, revealed on website, in book and encyclopedia)
  • Pliosaur (identified as Plesiopleurodon on BBC website)
  • Saurophthirus (identified as parasite, revealed on website and book)
  • Fish (live acted)
  • Wasp (live acted) ..."
~110  million ....
Plants with flowers evolve; dinosaurs evolving
in this period (Cretaceous) include Iguanodon,
Tyrannosaurus rex, Diplodocus, Triceratops,
Protoceratops, Hypsilophodon, Polocanthus,
Baryonyx, Styracosaurus, Brachyceratops,
Centrosaurus, Chasmosaurus, Gallimimus,
Saltasaurus, Alamosaurus, Corythosaurus,

~110 million year old dinosaur, the largest
ever discovered; weighed 60 tonnes and
stood 18 metres (60 feet) tall - Sauroposeidon:

~106 million ....

Spirits of the Ice Forest - Dinosaurs at the Poles

Walking With Dinosaurs -- Spirits of the Ice Forest
"... 106 million years ago — Mid Cretaceous, in the
rift valley where Australia is beginning to separate from

Conditions: Forest dominated by podocarps, very near
South Pole (the sun did not rise for 5 months in the winter).
The lopsided arrangement of the continents keeps ocean
currents and strong monsoon winds blowing across the
polar area, keeping it free of icecap and warm enough
for forests to grow.

Filming location: New Zealand

[featured in this episode]
  • Leaellynasaura
  • Muttaburrasaurus
  • Unidentified allosaur (identified as a polar allosaur)
  • Koolasuchus
  • Unidentified pterosaurs
  • Steropodon (identified as mammal, revealed in website and book, live-acted by a coati)
  • Tuatara (live acted)
  • Weta (live acted)
  • Mosquito (live acted) ..."

~100 million ....

Marsupials (including kangaroos, koalas, and
opossums) evolve; insectivores (the first placental
mammals) evolve; almost all are small and nocturnal
or crepuscular (active at dusk or dawn).

~100 million year old dinosaur, the largest meat
ever discovered (45 feet long), on the eastern
slopes of the Argentinian Andes:

Click-drag virtual reality display of continental drift
in the Caribbean Sea, with Cuba moving from south
of Mexico to its current position from ~100 million
years ago to the present day:

~94 million ....

View of the earth in the late Cretaceous:

~90 million ....

Click-drag virtual reality display of continental drift
resulting in the merger of India with Asia from ~90
million years ago to the present day:

~82 million to ~67 million ....

"... X-FACTOR: Bull horns, tiny arms
WHEN:       82-67 million years ago
WHERE:     Argentina

Consider the evolutionary hand dealt to Carnotaurus,
or 'meat-eating bull': a big, bad, but seemingly under-
equipped predator, as if nature had set out to design
a perfect killing machine but ran out of funding.

Powerful jaws and long, agile legs suggest a highly
mobile hunter prowling the lakeshores of what is
now Patagonia. "

~80 million ....

Scientists have unearthed a remarkable dinosaur nesting
ground strewn with thousands of ~80 million year old
fossilised eggs, in Argentina:

~70 million to ~65 million ....

"... X-FACTOR: Inscrutable teeth
WHEN:       70-65 million years ago
WHERE:     Madagascar

The mouth of Masiakasaurus speaks to how this German
shepherd-size meat-eater survived in the river basins of
northwestern Madagascar, near the end of the dinosaurs’
reign. But what is it saying?"

~66 million ....

~66 million year old dinosaur heart discovered:

View of the earth at the K/T boundary:

~65 million to ~23 million ....

Paleogene Period
65 Million to 23 Million Years Ago
"... At the dawn of the Paleogene—the beginning
of the Cenozoic era—dinosaurs, pterosaurs, and
giant marine reptiles were conspicuously absent
from the face of the Earth. Rodent-size (and perhaps
larger) mammals emerged from the shadow of the
night, suddenly free to fill the void. Over the next
42 million years, they grew in size, number, and
diversity. As the period came to a close, life-forms
still common today filled the seas, dominated the
land, and had taken to the air.

During the Paleogene the continents drifted farther
apart, heading toward their modern positions. Oceans
widened the gaps, Europe severed its last ties with
North America, and Australia and Antarctica finally
parted ways. As the climate significantly cooled and
dried, sea levels continued to drop from late Creta-
ceous levels, draining most interior seaways.

... the biggest development in the seas was the appear-
ance of whales in the mid- to late Paleogene. The huge
animals evolved from land mammals that took to the

Meanwhile, smaller reptiles that survived the Creta-
ceous, such as turtles, snakes, crocodiles, and lizards,
basked in the tropical warmth along the coasts. Birds,
the holdouts of the dinosaur age, diversified and flour-
ished in the skies. But the rapidly evolving mammals
stole the show. Starting from a fairly humble position
65 million years ago, primates, horses, bats, pigs, cats,
and dogs had all evolved by the close of the period,
23 million years ago.

What Killed the Dinosaurs?

Asteroid impacts discussed, with details on the
likelihood the Chicxulub impact was the cause of
the Cretaceous mass extinction event as well
as the theory that since the antipodal point for
the impact (i.e., the opposite side of the earth
at the time of the impact) was India, the impact
was the cause of the Deccan Traps flood basalt
lava flows:

K/T impact Chicxulub Crater, Yucatan Peninsula,
124-186 miles wide:

Dinosaurs were not going extinct before they
were wiped out:

Were dinosaurs done in by gas?
"...  When a giant asteroid slammed into the Yucatan
Peninsula 65 million years ago, the results were devas-
tating: rock and ocean water vaporized, searing debris
flung into outer space, and a smoldering hole in the
Earth almost 75 miles wide.

Scientists debate whether the cataclysm was enough
to wipe out the dinosaurs. But a new set of experi-
ments shows the impact produced a huge amount of
carbon monoxide, a compound commonly found in
car exhaust. The sudden pulse of gas may have been
enough to cause a large spike in global temperatures,
and trigger a mass extinction. ..."

More than 170 Humongous Holes
Scientists still counting impacts found
across all continents and sea floor
"... At last count, there were more than 170 known
mpact craters on our planet, according to the Earth
Impact Database maintained by the University of New
Brunswick in Canada. These puncture wounds are
littered over every continent, as well as the seafloor.

There would be countless more if it weren't for Earth's
constant remodeling. Plates shift, mountains form, vol-
canoes erupt and erosion washes over the planet's sur-
face, continually hiding the evidence of most craters.

... One of Earth's most recently-formed holes is Ari-
zona's Barringer Meteor Crater, created around
50,000 years ago. Though this crater, one of the
most famous, awes tourists with its roughly three-
quarters of a mile diameter, it is considered quite
dinky on the geological scale.

... A major heavyweight is South Africa's Vredefort
crater, which at 186 miles wide, is said to be Earth's
largest verified impact crater. At more than 2 billion
years old, it is also one of the most ancient.

Other contenders are the 155 mile-wide Sudbury
Basin in Ontario, Canada, and the roughly 110 mile-
wide Chicxulub crater, half submerged off the coast
of the Yucatán Peninsula in Mexico.

... If it weren't for erosion and other geological pro-
cesses that erase evidence of craters, there would
likely be hundreds of thousands of impact craters
on the Earth ..."

Volcanoes could have caused dinosaur deaths

Death of a Dynasty - The End of the Cretaceaous

Walking With Dinosaurs -- Death of a Dynasty
"... 65 million years ago — Late Cretaceous — Montana

Conditions: Areas of low herbaceous plant cover, and forest,
affected by volcanism. The episode shows some effects of
volcanic activity

Filming location: Chile (Conguillío National Park)

[featured in this episode]
  • Tyrannosaurus
  • Anatotitan
  • Torosaurus
  • Ankylosaurus
  • Dromaeosaurus
  • ornithopods
  • Didelphodon
  • Quetzalcoatlus
  • Deinosuchus crocodile)
  • Dinilysia snake, live acted by a red-tailed boa
  • butterfly (live acted)
  • Triceratops carcass
  • theropod mammal carcass
~60 million ...
Earliest-known rodents evolve, resembling small
squirrels - rodents are the largest order of
mammals in the present day, by far, with about
2,000 species in 35 families; first armadillos
evolve; creodonts, the dominant flesh-eating
mammals for 30 million years, appear on the

~55 million ....

Mammals begin to thrive; earliest lagomorph
(ancestor to pikas, rabbits, hares) evolves.

~50 million ....

Fossil record shows a diversification of ancestral
primates resulting in around 6,000 species of the
subsequent millennia, of which there are about 200
species alive today.

Bear-dogs, a varied and successful group of
hunting animals, originate and spread through
Europe and North America.

View of the earth in the middle Eocene:

~49 million ....

Walking With Beasts -- New Dawn
"... Film location: Java
49,000,000 years ago — Early Eocene — Germany

[featured in this episode]
  • Ambulocetus, "walking whale", lying in ambush for its prey,
    both on land and underneath the water
  • Birds, including the giant carnivorous Gastornis, rule this world
  • lemur-like Godinotia
  • a Leptictidium (a small leaping shrew-like mammal) family
    foraging for food
  • Propalaeotherium
  • Formicium (identified as a giant ant)
  • unidentified Creodont
  • Paleotis (in book)
  • Eurotamandua (live-acted by anteater)
  • Tyrannosaurus (seen at intro)
  • Ankylosaurus (seen at intro)
  • Didelphodon (seen at intro)
  • Tree frog (live-acted)
  • dragonfly (live-acted)
  • gecko (live-acted)
  • squirrel (live-acted)
  • crocodile (live-acted)
  • snake (live-acted)
  • bark beetle (live-acted)
  • bat (in book) ..."

~47 million ....

Ida, 'Missing Link' in Human Family Tree?

~45 million ....

First anteaters evolve.

Shallow seas retreat in North America; continents
appear fairly modern in form; quite a large sea area
still separates Africa from Europe and Asia; India
is now north of the equator on its journey towards
its eventual landfall in Asia.

~40 million ....

Life thrives and expands in cold but nutrient-
rich Antarctic bottom waters; toothed whales'
land-roving mammalian ancestors return to the
sea; canids (including the modern foxes, jackals,
coyotes, wolves, and dogs) originate at this
time; camels make their debut.

~36 million ....

Walking With Beasts -- Whale Killer
"... Filming Location: Florida
36,000,000 years ago — Late Eocene — Pakistan - Egypt

[featured in this episode]

  • explains how an early whale, Basilosaurus, mates and how
    the world is changing into an ocean famine; a starving mother
    Basilosaurus is forced to hunt in the mangrove swamps; unable
    to catch the early monkey Apidium, she is then hunting a Moer-
    itherium which crawls on to land, but in the mangroves, land does
    not last long -- the Moeritherium escapes and the Basilosaurus
    returns to the sea
  • an Andrewsarchus driven to the beach to feed on turtles;
    Andrewsarchus, the largest land mammal predator ever to
    walk the earth, has hooves and is related to sheep, so it is,
    in a sense, a "sheep in wolf's clothing"
  • a herd of Embolotherium (identified as a Brontothere) struggle
    to survive: one of their calves dies and two Andrewsarchus
    feast on it but the mother Embolotherium drives them away
    because she has a strong bond with her offspring, even if it
    is dead
  • the mother Basilosaurus preys on a group of Dorudon and is
    successful; the episode ends with the mother Basilosaurus
    swimming with her newborn calf.
  • shark (live acted)
  • crab (live acted)
  • sea turtle (live acted)
  • herring (live acted) ..."

~35 million ....

Beavers evolve - the early beaver was small
and lived on and near freshwater lakes;
creodonts evolve to a large size in Mongolia
with one of the largest, Sarkastodon, bigger
than the biggest bear; modern raccoons and
pandas first appear; earliest cats evolve;
rhinoceroses evolve; deerlike animals evolve.

~33 million ....

New world monkeys evolve in South
America (Bolivia).

~30 million ....

Grassland and trees with fruits spread; mammals
help pollinate and fertilize as they graze and
swallow fruits; earth grows cooler and extinction
overtakes animals requiring steamy climates;
seals first appear; pigs make their debut.
~25 million ....

Onset of Antarctic ice shelf.

Walking With Beasts -- Land of Giants
"... Filming Location: Mexico and Arizona (Grand Canyon)
25,000,000 years ago — Late Oligocene — Mongolia

[featured in this episode]

  • a mother Indricotherium, a massive hornless rhinoceros that
    was the largest land mammal to have ever lived; first shows
    the mother Indricotherium giving birth, and then tending to the
    male calf as it matures -- a few minutes after giving birth, the
    mother defends the helpless calf from several Hyaenodon,
    large creodont predators
  • the young paraceratherium travels until it reaches adulthood,
    including encounters with Cynodictis (identified as a bear-dog),
    and large aggressive Entelodon, which are distant relatives to
    the modern-day pig 
  • Chalicotherium
  • Hyracodon (in book)
  • unidentified primitive rabbit (in book)
  • unidentified Nimravid (in book)
  • Eogrus (in book) ..."
~24 million ....

Ancestors of modern apes appear.

--- end 4 of 7 ---