Lecture 16: Pterosaurs Flashcards
Flyers
Started relatively late, requires significant modifications (skeleton, muscles, and motor control/brain)
Three levels of flight
Gliding/parachuting: body surface increases to provide resistance to air
Flying: powered
Soaring: take advantage of air movement
When was air space conquered?
Devonian-395 million years ago. Animals and plants moved on land. First spores used air space for distribution and insects
Why Fly?
Advantages: Larger distance in shorter time. (arctic tern- annual migration route of 30000 km) discovery of new areas. Discovery of new areas, inaccesible over land- colonization by air. Flyers can escape predators, predators can capture their prey.
Flying fish
capable of flying 200m with speeds of up to 50km/h
Flying frogs
Indonesia, membrane between toes
Lizards and geckos
membranes along the side of body, Draco volans-flying lizard from southeast asia. Ribs extend beyond body, air born for about 15m
Flying snake
from south east asia, india and siri lanka, flattens its body to increase air resitance
mammals
Bats, flying squirrels, gliding possums and flying lemurs, fossil record goes back 60 million years
Bats
flying mammals, fossil record of 60 million yrs, four greatly elongated fingers, flying reptiles have one finger, birds have feathers instead
Birds
birds since late jurassic, archaeopteryx lithographica, solnhofen limestone, 140 mya ago
pterosaurs
Flying reptile, appeared at the end of triassic, 213mya , took to the sky over 60 ma before birds
What do flyers have in common?
wings, hollow bones for body weight, some fused joints to reduce flexibility for controlled movement, warm bloodedness for constant high levels of energy
Poor fossil record of flyers
Due to hollow and fragile bones, poor fossilization potential, lithographic limestone of solnhofen offers preservation potential, chalks of Kansas
Solnhofen- Germany,
140 mil years Europe was covered by a tropical sea tethyan sea, quiet lagoon sheltered by barrier
Solnhofen
Quarried for 2000 years, used, used by Romans as building rock, lithography, splitting of rocks into thin slabs reveals fossil content
Why was solnhofen ideal for fossilization?
Lagoon- hypersaline, carcasses fall in and settle down to the seafloor, lack of scavengers destroying carcasses, cover of very fine sediment preserving detail of fossil
What is a pterosaur?
Word means winged lizard. survived over 140 million years, extinction 65 mil year ago, cretaceous/tertiary boundary, not a dinosaur!
Pterosaurs
World wide distribution, early discovery in 18th century, white cliffs of dover, greensand deposits near oxford, solnhofen limestone, chalk deposits of Kansas
Ornithodira created by gauthier
broad groups including: dinosaurs, pterosaurs, birds
Origin of pterosaurs
the first ones already highly specialized flyers, missing link to more primitive forms, no fossil record of ancestors
Possible ancestor
Scleromochlus, 220 million years old; Scotland, Skeletal modifications
2 groups of pterosaurs
Rhamphorhynchoidea - triassic to jurassic -primitve -retain tail, teeth -smaller Pterodactyloidea -more advanced -longer skulls and necks -fused backbones in shoulder region -longer wrist bones -shorter tail and 5. toe
Features of Pterosaurs
Leathery bat-like wing, one greatly elongated finger, a joint at the base of finger so that the wing can be folded in when not flying, 4 joints in the finger, 3 or more short fingers for grasping prey, branches- bearing claws, large openings between nostril and eye, maybe to lighten skull, brains were large and bird like, sharp bill some with teeth on the jaw, teeth were sharp without serration suitable for capturing and killing
