Pterosaurs, Pterodactyls, and Pteranodons

Triassic to Cretaceous Flying Reptiles 65-200 Million Years Old

The smallest flying reptile was the size of a sparrow, the largest had a 60 foot, or 18-meter wingspan, and some walked on all fours.

Flying lizards once darkened the skies of most continents. Of course, that was during the late Triassic to the end of the Cretaceous period (from 228 to 65 million years ago). Known as pterosaurs (“flying reptiles”), they were one of three vertebrate groups who learned to take wing, including birds and bats. The earlier species of pterosaurs had long tails and jaws full of teeth. The later species had shorter tails and few, if any teeth.

What are Pterosaurs?

The group Pterosauria included the well-known pterodactyls with a wingspan of 50 to 75 centimeters, or 20 to 30 inches, and pteranodons which were 1.8 meters, or six feet long, with a wingspan of 7.5 m, or 25 feet. Pterosaurs are sometimes referred to as “flying dinosaurs,” which label is incorrect as pterosaurs were only distantly related to dinosaurs.

Pterosaurs and dinosaurs were part of a larger group of reptiles known as archosauria “ruling lizards,” which included crocodiles, birds, and dinosaurs and appeared in the early Triassic Period. Some pterosaurs have been found with hair, not mammal-like hair, not feathers, but a different type of hair covering the head and body, similar to bats. This suggests that pterosaurs were endothermic (“warm-blooded”).

Birds were not descended from pterosaurs, although they had similar features such as hollow bones filled with air to make them lightweight. Birds are thought, however, to have been more descended from the dinosaurs. The size of pterosaurs varied greatly, probably more so than modern birds– from the size of a sparrow to that of an airplane The pterosaurs had amazing flying skills for such large creatures which lacked the strong breast muscles of birds. Scientists note that a pterosaur the size of a giraffe could have merely jumped from all fours to take to the air. .

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One of the largest species of pterosaur was the Quetzalcoatlus northropi, named after the Aztec feathered-serpent god and found in Texas. The Quetzalcoatlus had a wing-span of between eleven and twelve meters or about forty feet. A pterosaur discovered in Mexico had a wingspan of 18 meters or 60 feet. In comparison, the bird with the largest wingspan today is the Wandering Albatross which has a wingspan measuring about 3.15 meters, or about 10 feet.



Pterosaur Flight

Pterosaurs had thin skin membranes strung over the extended fingers of the wings, similar to bats. They had a long fourth finger which extended their wing (but still only three toes on the feet). Their brains were farther developed than dinosaurs of the same size. They had exceptional sight and could receive sensory stimuli from their wings to assist in navigating and hunting.

Some pterosaurs had very long, extended areas on the back of their heads. The pteranodon was one pterosaur who had this unusual crest which extended far backward. Pterosaur trackways (“footprints”) have been found indicating that some pterosaurs walked on all fours, using their short back legs and short ends of their wings to move along the ground.

Some pterosaurs with longer back legs are thought to have been bipedal and capable of running like the modern bird, the Road-Runner. Scientists speculate that while some pterosaurs could have taken off from a standing position or with a few flaps of their huge wings, others may have taken advantage of heights to leap into the winds.

Pterosaurs became extinct during the Cretaceous-Tertiary extinction event when half of plants and animals, including dinosaurs and pterosaurs, vanished from the earth. Their place in the skies was replaced by the many species of birds, who, today, are thought to be a living remnant of the dinosaurs.

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Sources:

  • New World Encyclopedia. “Pterosaur,” available at newworldencyclopedia.org Accessed 26 Feb 2010
  • Fox, Stuart. “How Giant Pterosaurs Took Flight: Biomechanics suggests that a giraffe-size pterosaur could have jumped from all fours to get off the ground” Scientific American (May 2009) available at scientificamerican.com/article.cfm?id=how-pterosaurs-first-took-flight Accessed 26 Feb 2010
  • Pursglove, Paul. The Pterosaur Database available at pterosaur.co.uk Accessed 26 Feb 2010

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