Flying Reptiles, Starting Dinosaurs

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Natural Sciences 360 Legacy of Life Lecture 14
Dr. Stuart S. Sumida
The Diversity of Extinct Flying Reptiles
Examples of Convergent Evolution Starting
Dinosaurs
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• Remember, were studying AMNIOTES.
• Defined by
• EMBRYOLOGICAL FEATURES amnion, chorion,
  allantois, yolk sac.
• ANATOMICAL FEATURES lack of an intertemporal
  bone.
• ALSO, FUNCTIONAL FEATURES
• Costal breathing (inhaling using movement of the
  ribs).
• Active exhalation using movement of ribs to push
  air out.

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ARCHOSAURIA
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• ARCHOSAURS ARE DIAPSID REPTILES
• ARCHOSAURIA INCLUDES
• Crocodylomorpha
• Pterosauria
• Dinosasuria
• Aves (Birds)

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Crocodylomorpha Pterosauria Eoraptor
Herrerasauridae Saurischia Ornithischia
Archosauria
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Crocodylomorpha Pterosauria Eoraptor
Herrerasauridae Saurischia Ornithischia
Archosauria
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PTEROSAURIA Flying Reptiles of the
Mesozoic They are the closest relatives of
dinosaurs, but they are not actually
dinosaurs. They used elongate 4th finger to
support a wing. The wing DID NOT attach to the
leg.
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Rhamphorhynchus sp.
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Reconstruction of the pterosaur Eudimorphodon in
pronograde, bipedal walking.
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TERMS FOR POSTURE Pronograde backbone parallel
to ground Orthograde backbone perpendicular to
ground BIPEDAL and QUADRUPEDAL are not postural
terms.
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Pterydactylus
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Reconstruction of Pteranodon
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Reconstruction of Pteranodon
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Some pterodactyloids had wildly developed
skulls. This one, Pterodaustro (Upper Cretaceous
of Argentina) had numerous teeth that probably
probably functioned similar to whale baleen.
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Comparative wing structure in flying vertebrates
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Two hypotheses of wing reconstruction in
Pteranodon.
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The largest of the Late Cretaceous pterosaurs
were probably so large they were restricted to
being gliders only. Quetzalcoatlus northropi had
a wingspan of approximately 11-13 meters.
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Humerus of Quetzalcoatlus northropi over ½
meter long.
Humerus (young?) Q. northropi about 0.25 meter
long.
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Quetzalcoatlus northropi had a wingspan of
approximately 11-13 meters.
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DINOSAURIA
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Crocodylomorpha Pterosauria Eoraptor
Herrerasauridae Saurischia Ornithischia
Dinosauria
Archosauria
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THE MOST PRIMITIVE DINOSAURS
Crocodylomorpha Pterosauria Eoraptor
Herrerasauridae Saurischia Ornithischia
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• Eoraptor lunensis (Dawn Raptor)
• From the Upper Triassic of Argentina.
• Thought to be amongst the most primitive of
  dinosaurs.
• Its hip is like that of dinosaurs it has a
  perforate acetabulum. (A hole in the hip
  socket.)

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Eoraptor lunensis (Dawn Raptor)
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Eoraptor
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CT Scan of Eoraptor skull.
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A perforate acetabulum
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Eoraptor Reconstruction
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Eoraptor Reconstruction
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Crocodylomorpha Pterosauria Eoraptor
Herrerasauridae Saurischia Ornithischia
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Herrerasauridae Upper Triassic of Argentina 2
4.5 meters long. Long, low skull that is as
long as the femur. 24 presacral vertebrae and
the vertebrae are relatively shorter than more
primitive forms.
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Herrerasaurus ischigualastensis
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Stereo-pair view of Herrerasaurus
ischigualastensis skull.
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Herrerasaurus ischigualastensis
Skull, specimen drawing. Long, low skull that
is as long as the femur.
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Herrerasaurus ischigualastensis
Skull reconstruction
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Herrerasaurus ischigualastensis Reconstruction
24 presacral vertebrae and the vertebrae are
relatively shorter than more primitive forms.
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Herrerasaurus ischigualastensis
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Herrerasaurus ischigualastensis
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Dinosaurian groups more derived than Herrerasaurs
may be divided into two groups based on hip
construction
SAURISCHIAN ORNITHISCHIAN
(Note position of pubis.)