Pterosaur

(TEAR-O-saur) (winged lizard)

The flying reptiles are not dinosaurs or birds, though the three lines do have a common ancestor in the Triassic.  They were the first vertebrates to fly and ruled the skies during the Jurassic and Cretaceous.

First found in 1784, it took 17 years for a scientist to realize the animal’s anatomy dictated it had wings.  It was believed they could not actually flap their wings to take off.  That belief was not widely contested until recent studies that show most, if not all, Pterosaurs were good flyers like birds and not just gliders.  On the ground, they probably walked on all fours like bats.  Scientists are still speculating on how these animals became airborne, flew, landed, and caught prey.

The heads of Pterosaurs have a variety of shapes.  Though usually long and slender they could also be short and thick.  The jaws could be straight or curved, toothless, have sharp teeth for catching fish or insects, flat teeth to crush shells, or extremely long bristle-like teeth to filter feed.  Many have crests on their snout or the back of the skull.

Unlike dinosaurs and birds, Pterosaurs did not stand upright.  This trait keeps them outside the dinosaurian line.  They did have large brains and good eyesight.  A few specimens show a fuzzy covering like fur on their bodies.

Suborder Rhamphorhynchoidea

These are the first pterosaurs to appear, Triassic.  Most were small, had fingers usable for climbing, had teeth, and long tails.  They did not have boney head crests, but a few had crest made of keratin.  They disappeared at the end of the Jurassic.

Suborder Pterodactyloidea

(TEAR-uh-DAC-tul) (wing finger)

These Pterosaurs descended from the Rhamphorhynchoidea and are common in the Cretaceous.  They all had short tails.  The largest flying reptiles are in this group.  Pterodactyls ranged in size from 10 inch to 40 foot wingspreads.  That is the difference between a robin and a small airplane.

Wings

The membrane wing of a Pterosaur is stretched between the body, the arm, and an extremely elongated fourth finger.  Hair-thin fibers stiffened the membrane and kept it from flopping like a sail in the wind.

Bird wings are primarily made but with the addition of feathers.  The number of bones in their arm is reduced.  Most birds no longer have multiple fingers.  Scientist believe the last joint is their last remaining finger.

The only flying mammal is the bat.  They have a membrane wing like the Pterosaur.  Three of their fingers are elongated and form ribs in the wing.  The others are used for grasping.

Bones

The bones of Pterosaurs, like birds and dinosaurs, are hollow and lightly built.  It is possible, like dinosaurs, they could pump air into the bones to give their blood supply additional oxygen.

Cretaceous Pterosaurs found in Texas

Coloborhynchus wadleighi: Early Cretaceous.  The only evidence of this animal comes from a well preserved snout, which is long and toothed, the top is crested.  Found in the Pawpaw Formation near Dallas Texas in 1993.

Quetzalcoatlus northropi: Late Cretaceous. The largest Pterosaur.  First found 1971.

Quetzalcoatlus northropi - reconstructed wing

(kwet-zel-KWAT-lus NORTH-ro-PI)

Period: Upper Cretaceous, Javelina Formation

Location: Big Bend National Park, Texas

Collection: Dallas Museum of Natural History

Size: ? mm long

Click the picture for more photos!

Quetzalcoatlus northropi - femur

Period: Upper Cretaceous, Boquillas formation

Location: near Terlingua Texas

Collection: Ken Barns, cast by the Bonehead Club

Found by: Kim Knight of the Bonehead Club

Size: 14 1/2" x 2 1/8" wide shaft

Click the picture for more photos!

Found in Big Bend State Park in 1971 by Doug Lawson, Quetzalcoatlus northropi is the largest animal ever to fly.  It has a wingspan of 35 to 40 feet, wider than an F-16 fighter plane.  Their 7 foot body sported a 7 foot head, a 10 foot neck, and 7 foot legs.  Considering this animal is larger than a small aircraft, it probably weighed well under 800 pounds.  The name comes from the Aztec flying serpent god and Northrop Corporation who build aircraft.

Like birds and Theropods, these animals have hollow bones to reduce weight.  The largest of Quetzalcoatlus’ wing bones are no thicker than ¼ inch, the thinnest are like eggshells.  It is possible that these animals were so light that a slight breeze could lift them like a kite.

No complete heads of Quetzalcoatlus have been found.  The mount that hangs in the Texas Memorial Museum used a scaled up version of a closely related animal.  Dr. Wann Langston, Doug Lawson’s teacher, advised, helped design, and supervised the construction.  He also acted as advisor to Paul MacCready who built and flew a remote control model Quetzalcoatlus in the 1980’s.

The fossils are found in large river flood planes, so the animal probably hunted there also.  Many theories of its eating habits have been postulated.  Did this huge creature pluck fish from the waters surface, probe for mollusks and crustaceans with its beak, or feed on carrion like a vulture?

Recent discoveries of incomplete Pterosaurs in Romania and Spain may have a wingspan 3 feet wider than the Quetzalcoatlus.