Dinosaurs & Early
Araeoscelis was a 2 foot long lizard, a reptile that lived
in North America during the Permian period almost 300 million years ago.
Araeoscelis was a diapsid, a reptile with two openings in
the side of the skull. Its significance is that it differed from
its early diapsid relatives in that these openings were closed, making its
skull more solid. The resulting powerful head and firmer bite gave it the
ability to eat tougher insects like beetles with hard shells, leading to
species survivability. From the Diapsida, came the dinosaurs and pterosaurs
and most of today's surviving reptiles and crocodiles.
280 million years ago during Permian period, before
dinosaurs appeared, Dimetrodon lived in swamps and flood plains of North
America and Europe and went extinct during the Permian extinction, 245
million years ago. It was a carnivore with a huge head, jaws and mouth. It
grew to 12 feet long and weighed 600 lbs. It had sharp canines and shearing teeth.
Dimetrodon was the dominant predator of the Permian Period.
It is sometimes called a "sail-back" dimetrodon. The "sail" on it's back
absorbed the sun's heat and blood flow then warmed its body to become mobile
earlier than other cold-blooded animals, which it could then catch and eat.
Dimetrodon left no descendants.
Casea was one of the first terrestrial herbivores that lived
in North America and Europe during the Late Permian from about 260 to 251
million years ago. It had a big gut for digesting ferns and other plants of
the day. It lived about the same time as Dimetrodon, which likely ate
on cold mornings before they warmed enough to move.
Mastodonsaurus giganteus was an amphibian from the Middle
Triassic that lived in Europe from about 245 to 228 million years ago. It
was one of three species in the genus Mastodonsaurus.
M. giganteus could grow up to 20 feet long and its huge head was 4 feet
long. Two upward pointing tusks protruded through holes in the top of M. giganteus's snout. It was mostly aquatic and may have been unable to leave
water as large numbers of fossil remains have been discovered together in
what may have been pools which dried during droughts.
It lived in swamps and ate fish, which have been found in its fossil
remains. Other amphibians' fossil remains have been discovered with tooth
marks which may have come from Mastodonsaurus attacks.
Anchisaurus lived in Connecticut around 180 million years ago during the Early Jurassic Period. It grew to about 6 or 7 feet long and weighed about 60 lbs.
One Anchisaurus discovery was mistaken for human bones.
Anchisaurus was a herbivore and had stones in its stomach to grind hard to digest plants.
Megalosaurus was a large carnivore that lived in
Europe about 181 to 169 million years ago during the Jurassic Period. It
grew to about 30 feet long and weighed over 2,000 lbs. It had a large head
and jaws with massive teeth. Megalausaurus would have had to eat
other dinosaurs to consume sufficient food, most likely stegosaurs and
Ceratosaurus ("horned lizard") was a large predatory
dinosaur that lived in North America and Europe around 156 to 145 million
years ago during the Late Jurassic Period. It could grow to more than 20
feet long and weigh more than 3,000 lbs. Ceratosaurus had large jaws
with blade-like teeth, a large horn on the snout, two small horns over the
eyes and very short but strong forelimbs. It most likely ate other
Allosaurus was a large carnivorous dinosaur that
lived in North America, Europe and Africa from about 155 to 150 million
years ago during the late Jurassic period. They grew to about 30 feet long
and 5,000 lbs. The Allosaurus largest may have been up to about 40
feet long. They had large heads and large teeth for ripping and devouring
flesh. Imagine fleeing from several Allosaurus - some paleontologists
think they hunted in packs.
Diplodocus was a huge herbivore that lived in western
North America about 154 to 150 million years ago during the end of the
Jurassic Period when gigantic dinosaurs were common. Indeed, Diplodocus
could grow up to 115 feet long with a 20 foot neck counterbalanced by an
extremely long tail which contained 80 vertebrae. It would have weighed in
excess of 30,000 lbs.
Brachiosaurus was a large dinosaur with a very long neck
that lived in western North America about 154-153 million years ago during
the Jurassic. It was an herbivorous browser that could graze vegetation 30
feet high. It was 85 feet long and weighed almost 40 tons. Recent research
leads some to believe Brachiosaurus may have been warm-blooded.
Brachiosaurus was discovered in Colorado in the Morrison
Formation of North America. The Morrison Formation consists of layered
deposits of Late Jurassic sedimentary rock, which extends through many
states in western United States where many fossilized dinosaur remains have
been preserved and discovered.
Brontosaurus was another huge herbivorous dinosaur
that lived from around 154 to 150 million years ago during the Jurassic
Period. Fossils have been found in Colorado, Wyoming, Oklahoma and Utah.
Various Brontosaurus species grew to as long as 70 feet and weighed from 20
to 35 tons. The ever popular Brontosaurus has been featured in movies, children's cartoons,
and even a US postage stamp where the Postal Service chose to use the name
Brontosaurus over its more scientifically correct replacement Apatosaurus.
Stegosaurus was a herbivore that lived during the Jurassic
period around 155 to 150 million years ago in western North America and
Europe. It could grow up to 30 feet long, 14 feet high to the top of its
bony plates and could weigh more than 3 tons. Seventeen bone plates
resembling giant 2.5 foot tall triangular teeth in two rows extending along
Stegosaurus's back would have made it appear more formidable, may have been
protective armor, and may have also absorbed and dissipated heat. Spikes
near the end of its tail could damage when swinging its tail on attacking
Amphicoelias was a herbivorous dinosaur that lived in
North America around 150 million years ago during the Late Jurassic. It may
have been the largest dinosaur ever. Amphicoelias may have grown as
long as from 130 to 200 feet and weighed 135 tons!
The illustration by Carl Dahlgren from an 1892 issue of
''Californian Magazine'' is based on insufficient information. The neck
would not have been curled and the tail would have been elevated and
somewhat straight and level being used for balance. It's understandable that
no one at that time perceived such huge animals would elevate extended
appendages so far.
Compsognathus longipes lived in Europe about 150
million years ago during the late Jurassic. They were very small dinosaurs,
about the size of a chicken or turkey and walked on two legs. Remains have
been found with lizards in their stomachs. They probably ate other
vertebrates and insects. It's been suggested Compsognathus longipes
might be related to Archaeopteryx which appear similar in some
respects and have been discovered in the same deposits.
One of the first dinosaur fossils to be discovered and one
of the most popular. Iguanodons lived in North America, Europe and Asia from
the late Jurassic Period to the late Cretaceous Period between 140 and 110
million years ago. They grew as large as 40 feet long and weighed up to 4
tons. Iguanodons were herbivores. They had bony beaks, toothless in the
front to nip off plants and teeth for chewing similar to sloths. They had
fingers! Scientists call them "digits". Iguanadon laid eggs and probably
cared for their young.
This dinosaur ran on two legs. Bipedal dinosaurs (motivating
on two legs), is not a recent theory. This sketch of an Iguanodon was
published in 1921. However, Iguanodons might have become more quadrupedal as they
grew and aged. The Iguanodon thumb spike was originally thought to
grow on the
animal's snout, similar to a rhinoceros. It was likely used to break seeds
and other foods and as a weapon against predators like Tyrannosaurus rex, or
Hypsilophodon lived in England about 120 million
years ago during the Early Cretaceous period. They had sharp beaks, ate
plants, grew to about 6 feet long and weighed about 45 lbs. This image of
Hypsilophodon from the late 19th century is based on the misconception
at the time that they climbed trees. They were, however, very agile and were
able to run on two hind legs.
Claosaurus was a duck-billed dinosaur (hadrosaurid)
that lived in North America from about 80 to 70 million years ago during the
Late Cretaceous Period. It was a herbivore that grew to about 12 to 16 feet
long and weighed about 1,000 lbs.
Hadrosaurus was a duck-billed dinosaur that lived in
New Jersey during the late Cretaceous, which ended in mass extinction 65
million years ago. It ate plants and could walk on its hind legs. A
Hadrosaurus found in 1858 in New Jersey was the first nearly complete
skeleton found and mounted and. It is the New Jersey State dinosaur.
Triceratops is a commonly known dinosaur and depicted
in countless animations often defending itself against Tyrannosaurus rex.
Triceratops (Greek for "three-horned face") were herbivores that
lived in North America during Cretaceous Period around 68 to 65 million
years ago. They had a horn on the snout, two 3 ft horns above each eye, a
large bony frill behind the skull, and robust, pillar like legs. They grew
from 25 to 30 feet long, 9 to 10 feet tall and weighed from 6 to 12 tons.
The largest skull discovered was 8 feet long. The frills and horns were
traditionally believed to be defensive weapons against predators. Some think
their purpose may have been for courtship and dominance displays, similar to
today's goats and deer.
Torosaurus was a quadrupedal (walked on 4 legs)
herbivore that lived in what is now the Great Plains of North America from
Texas and New Mexico to Canada around 66 million years ago during Late
Cretaceous. It grew to 30 feet long, weighed 13,000 lbs and its huge
frilled skull, lined with holes, largest of any land animal, was as long as
8.5 ft. It had a sharp beak similar to Triceratops for biting off tough
plants. Some paleontologists have suggested Torosaurus is a mature
form of Triceratops, while others have concluded they are closely related,
but separate species.
"Tyrannos" and "sauros" are Greek for "tyrant," and
"lizard". "Rex" is Latin for "king". Fitting for a 15,000 lb predatory
dinosaur needing to continuously feed on flesh to sustain its life. For 2
million years, Tyrannosaurus rex, mad with hunger, hunted down and
devoured everything it could find in western North America until the
Cretaceous´ - Paleocene extinction event 65 million years ago. It was 40 feet
long and 13 feet tall at the hips. It had huge powerful legs and a huge tail
to balance its massive 5 foot long skull all held horizontally - perfect for
chasing down and catching fleeing pray. Many of the antiquarian
illustrations show incorrect posture, understandable for the times.