Pterosaurs: Flying Reptiles of the Mesozoic Darren Naish University of Southampton
Pterosaurs: winged diapsid rep les of the Mesozoic, membranous wings supported by super-enlarged 4th finger. Toothed & toothless species.
Known since late 1700s; ‘Ptero-dactyle’ named by George Cuvier in 1809.
The pterosaur wing Main spar supported by super-enlarged, thickened 4th finger and associated 4th metacarpal with roller-like distal end. Unique, rod-like bone at the wrist - the pteroid – controls posi on and shape of membrane between shoulder and wrist. Three small, clawed fingers in most (but not all) species.
Pteroid is some mes incredibly long: in Nyctosaurus, more than 50% length of radius Pterosaurs in popular mythology: typically called ‘pterodactyls’, they are scaly, dull-coloured, bat-winged monsters with prehensile feet Pterosaurs: not scaly, but hairy Sordes Excep onal fossils show that pterosaur bodies were covered in hair-like fibres known as pycnofibres. Best known for Jurassic Sordes from Central Asia, but pycnofibres now known from numerous Triassic, Jurassic and Cretaceous Species from across the family tree. Pterosaurs had fuzzy coats, probably for insula on.
Fibres on top of skull of Sordes
Fibres on side of body of anurognathid Jeholopterus The extent of the main part of the wing membrane has been controversial Distal part universally agree to be narrow and slender (= high-aspect), but proximal part argued to be broad, and to incorporate some/all hindlimb, by some, and narrow and a aching to body by others. Fossils show that brachiopatagium did a ach to hindlimb, being most extensive in non- pterodactyloids.
Brachiopatagium a aching to bia in Cretaceous azhdarchoid
Brachiopatagium a aching to ankle (perhaps to long 5th toe) in Jurassic rhamphorhynchid Sordes Pterosaur wing membranes were internally complex The ‘darkwing’ Rhamphorhynchus specimen, examined under UV light, reveals the presence of a massive, looping blood vessel system, a layer of subparallel suppor ng fibres, and a layer with a mesh-like network of connected ssue strands.
These features suggest that (while thin) the membrane was robust, internally supported, perhaps used in thermoregula on (or even respira on). Frey, E., Tischlinger, H., Buchy, M.-C. & Mar ll, D. M. 2003. New specimens of Pterosauria (Rep lia) with so parts with implica ons for pterosaurian anatomy and locomo on. In Buffetaut, E. & Mazin, J.-M. (eds) Evolu on and Palaeobiology of Pterosaurs. Geological Society Special Publica on 217. The Geological Society of London, pp. 233-266. Skeletal pneuma city: pterosaurs, like birds and other saurischian dinosaurs, had pneuma c bones. Air-filled sacs connected to the lungs were distributed throughout the body, and occupied most of the skeleton. Demonstrated by pneuma c foramina and hollow bones. Pneuma c foramina (pf) and hollow bones here illustrated for ornithocheiroid Anhanguera. So - ssue pneuma city: when skeletal pneuma city is present, a series of air-filled sacs connected (by tubes called diver cula) to the lungs are also present. Pterosaurs had air-sacs throughout the body cavity, also extending along the length of wing and wing-finger.
Distribu on of air-sacs in Cretaceous ornithocheiroid Anhanguera
Pneuma city present in earliest pterosaurs: was it a primi ve feature for the group, shared with dinosaurs? Or did it evolve independently? This remains unknown and controversial. What are pterosaurs? They are undoubted members of Neodiapsida, and almost certainly members of Archosauromorpha. But where within this clade do their affini es lie? S ll somewhat controversial. Hypothesis 1. Pterosaurs are crown-archosaurs (they have an antorbital fenestra), and share a list of characters with dinosaurs (hinge-like ankle, long neck): there is a pterosaur + dinosaur clade within crown-Archosauria. Hypothesis 2, 3 and 4. Pterosaurs are only convergently similar to dinosaurs, are outside of crown-Archosauria, and (1) are protorosaurs, (2) are close to drepanosaurs, or (3) are close to Archosauria, but not part of it.
Specialists are s ll arguing over these compe ng hypotheses and pterosaur affini es have yet to be resolved A quick history of pterosaurs Pterosaurs appear in Late Triassic, persist to end of Late Cretaceous. All early pterosaurs (non-pterodactyloids or “rhamphorhynchoids”) are small predators of small animals. Pterodactyloids evolved in Middle Jurassic: possessed combined nostril + antorbital fenestra (termed nasoantorbital fenestra or NAOF). Evolve giant size (wingspans of c 10 m) and several lineages evolve toothlessness. Pterodactyloids dominate Cretaceous: include oceanic, fish-ea ng ornithocheiroids, strongly terrestrial dsungaripteroids and azhdarchoids. Only ornithocheiroids and azhdarchoids persist to very end of Late Cretaceous. A quick history of pterosaurs Pterosaurs appear in Late Triassic, persist to end of Late Cretaceous. All early pterosaurs (non-pterodactyloids or “rhamphorhynchoids”) are small predators of small animals. Pterodactyloids evolved in Middle Jurassic: possessed combined nostril + antorbital fenestra (termed nasoantorbital fenestra or NAOF). Evolve giant size (wingspans of c 10 m) and several lineages evolve toothlessness. Pterodactyloids dominate Cretaceous: include oceanic, fish-ea ng ornithocheiroids, strongly terrestrial dsungaripteroids and azhdarchoids. Only ornithocheiroids and azhdarchoids persist to very end of Late Cretaceous. Non-pterodactyloids (= ‘rhamphorhynchoids’) mostly Triassic and Jurassic, but some lineages persisted into Cretaceous. Generally small (wingspans less than 1 m), generally long-tailed. Short metacarpus, long 5th toes. Curved claws suggest good at climbing. Short hindlimbs. Probably poor terrestrial abili es.
Anurognathids: ny size, wide mouths, flexible interphalangeal joints in wing finger Dimorphodon