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| Pterosaurs |
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| Draft 104 |
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| Pterosaurs were the first
vertebrates to evolve flight. Their wings were formed by a sophisticated
membrane of skin stretching from the thorax to a
dramatically lengthened fourth finger. Earlier species had long,
fully-toothed jaws and long tails, while later forms had a highly reduced
tail, and some lacked teeth. There is no fossil evidence of feathers, but
pterosaurs were unique among reptiles in that at least some of them were
covered with hair,
similar but not
homologous to mammalian
hair. Pterosaur hair is not true hair; it is a form of extremely thin
fiberous "scales". Although in some cases fibers in the wing membrane have
been mistaken for hair, some fossils such as those of
Sordes pilosus
(the "hairy demon") do show the unmistakable imprints of hair on the head
and body, not unlike modern-day bats, an interesting example of
convergent evolution. The presence of hair (and the demands of flight)
imply that pterosaurs were warm-blooded ('endothermic'). |
http://species.wikipedia.org/wiki/Pterosauria
http://www005.upp.so-net.ne.jp/JurassicGallery/page16.htm
Many pictures |
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| "Winged lizards" |
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Kingdom Animalia (animals)
Phylum Chordata (chordates)
Subphylum Vertebrata (vertebrates)
Superclass Tetrapoda (four-legged animals)
Class
Diapsids - these include all the reptiles (except turtles) and
birds. They are distinguished by having two holes in the rear upper part of
their skulls and two holes behind the eyes.
Sublass Archosauria - this group includes dinosaurs, crocodilians,
pterosaurs, birds, etc.
Order Order Pterosauria - flying reptiles. There are two type of
pterosaurs:
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| Pterosaur Encyclopedia. P. 66. This
the oldest known pterosaurs occur in three distinct evolutionary lines:
Eudimorphodontidae, Dimorphodontidae and Rhamphorhynchidae. Triassic
pterosaurs are, as far as we know them, completely developed and have all
the typical skeletal characters of the order. They are not
Pro-pterosaurs or forerunners of the pterosaurs and also not missing links
between pterosaurs and their ancestor. We must therefore accept that
the evolution history of pterosaurs goes back much further into the past
that was formerly believed. Perhaps they originated the lower
Triassic, possibly even in the Permian, thus in the Paleozoic Era. Certainly
no fossil have so far been found that could be interpreted as ancestor of
the pterosaur or proto-petrosaurs. |
Pterosaurs were an order of flying
reptiles that lived during the time of the dinosaurs. They ranged
in size from a few inches to over forty feet. They had hollow bones, were
lightly built, and had small bodies. They had large brains and good
eyesight. Some pterosaurs had fur and some had light-weight, bony crests on
their heads that may have acted as a rudder when flying, or it may have been
a sexual characteristic.
Pterosaurs were excellent flyers and could flap their wings and fly
with great power. Their wings were covered by a
leathery membrane. This thin but tough membrane stretched between its body,
the top of its legs and its elongated fourth fingers, forming the structure
of the wing. Claws protruded from the other fingers.
Fossils do not reveal their color, but their lifestyle and diet was
similar to modern day eagles and many had fur. This suggests that they
may have been brown, white or gold. The crests may have been quite
colorful.
Most ate fish, but some of the smaller species may have eaten
insects. Although they dominated the skies for over 165 million years,
they became extinct at same time as their dinosaurs.
Pterosaurs could flap their wings and fly
with power, but the largest ones (like
Quetzalcoatlus, which had a wingspan up to 36 feet or 11 m wide)
probably relied on updrafts (rising warm air) and breezes to help in flying.
WHEN PTEROSAURS
LIVED
Pterosaurs lived during the
Mesozoic Era, the Age of Reptiles. The primitive types of pterosaurs (rhamphorhynchoids)
appeared during the Triassic, and died out at the end of the Jurassic
period. More advanced pterosaurs (pterodactyloids) appeared late in the
Jurassic period and died out during the Cretaceous, about 65 million years
ago, during the K-T extinction (65 mya).
DIET
Pterosaurs were carnivores; they ate fish (which they caught at the surface
of the oceans), mollusks, crabs, perhaps plankton (for some species),
insects, and scavenged dead animals on land.
LOCOMOTION
Pterosaurs flew long distances using large, light-weight wings.
CLASSIFICATION
Pterosaurs were reptiles, but not dinosaurs. By definition, all dinosaurs
were
diapsid reptiles with an upright stance. Pterosaurs probably had a
semi-upright stance. There is a small minority of paleontologists who think
that the pterosaurs' stance could have been upright and that pterosaurs
should therefore be included in the clade of dinosaurs (being derived
theropods). Either way, dinosaurs and pterosaurs are certainly closely
related.
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| Ranging from the size of a sparrow to the size of an airplane, the
pterosaurs (Greek for "wing lizards") ruled the skies in the Jurassic and
Cretaceous, and included the largest vertebrate ever known to fly: the late
Cretaceous Quetzalcoatlus. The appearance of flight in pterosaurs was
separate from the evolution of flight in
birds
and
bats; pterosaurs are not closely related to either birds or bats, and
thus provide a classic example of convergent evolution.
It was once
thought that pterosaurs were not well adapted for active flight and relied
largely on gliding and on the wind to stay in the air. However, based on
analyses of pterosaur skeletal features (including work done by Berkeley's
own Kevin
Padian), it is now thought that all but the largest pterosaurs could
sustain powered flight. Pterosaurs had hollow bones, large brains with
well-developed optic lobes, and several crests on their bones to which
flight muscles attached. All of this is consistent with powered flapping
flight.
The largest pterosaur (Quetzalcoatlus, wonderfully named for the
Aztec winged serpent god) had a wing span from eleven to twelve meters long
(about forty feet). The wing's main support was an amazingly elongated
fourth digit in the hand. Fibers in the wing membrane added structural
support and stiffness. At least some pterosaurs may have had some sort of
hair-like body covering, which could very well mean that they were
endothermic.
Pterosaurs had a diverse range of head types, as you can tell from the
pictures below. Their ability to fly probably allowed them to evolve into
many niches, taking advantage of many different food sources, which would
explain the range of skull morphology seen.
Pterosaurs consist of two main types (they do form a single (monophyletic)
group, though): the "rhamphorhynchoids," more properly termed the basal
Pterosauria, which had long tails, and their descendants the "pterodactyloids,"
which had shorter tails. Why is the term "rhamphorhynchoid" an invalid one?
Since the later Pterosauria (the"pterodactyloids") are the descendants of
the basal Pterosauria, "rhamphorhynchoid" is a paraphyletic term,
which phylogenetic researchers shy away from using. The basal Pterosauria
(including Rhamphorhynchus, pictured at the top of this page) first
appeared in the Late Triassic and all went extinct at the end of the
Jurassic. The more derived pterosaurs (including Pteranodon,
below) that were the descendants of this group appear first in Late Jurassic
rocks, and the last of them
died out at
the end of the Cretaceous. Below is a mounted skeleton of Pteranodon
ingens on display at the UCMP. Click on the picture to view an
enlargement. |
Pterosaurs were an order of flying
reptiles that lived during the time of the dinosaurs. The pterosaurs ranged
in size from a few inches to over 40 feet. They had hollow bones, were
lightly built, and had small bodies. They had large brains and good
eyesight. They flew long distances using large, light-weight wings.
Some pterosaurs had fur on their bodies, and some (like
Pteranodon) had light-weight, bony crests on their heads that may have acted
as a rudder when flying, or may have been a sexual characteristic.
Pterosaur wings were covered by a
leathery membrane. This thin but tough membrane stretched between its body,
the top of its legs and its elongated fourth fingers, forming the structure
of the wing. Claws protruded from the other fingers. Pterosaurs could flap their wings and fly
with power, but the largest ones (like
Quetzalcoatlus, which had a wingspan up to 36 feet or 11 m wide)
probably relied on updrafts (rising warm air) and breezes to help in flying.
Pterosaurs lived during the Mesozoic Era, the Age of Reptiles. The primitive
types of pterosaurs (rhamphorhynchoids) appeared during the Triassic, and
died out at the end of the Jurassic period. More advanced pterosaurs (pterodactyloids)
appeared late in the Jurassic period and died out during the Cretaceous,
about 65 million years ago, during the K-T extinction (65 mya).
Pterosaurs were carnivores; they ate fish (which they caught at the surface
of the oceans), mollusks, crabs, perhaps plankton (for some species),
insects, and scavenged dead animals on land.
Pterosaurs were reptiles, but not dinosaurs. By definition, all dinosaurs
were diapsid reptiles with an upright stance. Pterosaurs probably had a
semi-upright stance. There is a small minority of paleontologists who think
that the pterosaurs' stance could have been upright and that pterosaurs
should therefore be included in the clade of dinosaurs (being derived
theropods). Either way, dinosaurs and pterosaurs are certainly closely
related.
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Their "wings" consisted
of skin, which was stretched by the strongly extended fourth finger and
on the height of the thigh was again fastened to the body. They developed
approximately 70 million years before the oldest well-known bird, the
Archaeopteryx. To the numerous forms belong
the largest flying organisms, which ever existed. Later the fall of the
group began, the last members became extinct toward end of the Mesozoic. Fossils
have been found worldwide except for Antarctica. One differentiates between two
subordinations. The oldest and most primitive forms are summarized
under the designation Rhamphorhynchoidea, while the Pterodactyloidea
covers the more modern Flugsaurier. |
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Classification of pterosaurs has traditionally been difficult, because
there were many gaps in the
fossil record. Many new discoveries are now filling in these gaps and
giving us a better picture of the evolution of pterosaurs. Traditionally,
they are organized into two suborders:
Rhamphorhynchoidea (Plieninger, 1901): The early, or basal pterosaurs.
They flew by flapping their wings, and had long tails and short wing
metacarpals. They were small, and their fingers were still adapted to
climbing. They appeared in the late Triassic period, and lasted until the
late Jurassic.
Pterodactyloidea (Plieninger, 1901): The more advanced pterosaurs.
They flew by soaring, with short tails and long wing
metacarpals. They appeared in the middle Jurassic
period, and lasted until the
Cretaceous-Tertiary extinction event wiped them out at the end of the
Cretaceous.
However, the Rhamphorhynchoidea are a
paraphyletic group, so with the increasing use of
cladistics it has fallen out of favor.
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