After a glance at pterosaur origins and taxonomy — "our Hypothetical Pterosaur Ancestors are small animals, perhaps only 200-300 mm long from their snouts to tail tips" — Witton turns to anatomy, looking first on skeletons and then at what can be inferred about pterosaur "soft bits".
"In concert with features indicative of an active locomotory style and the capacity for rapid growth, pycnofibers strongly indicate that pterosaurs were probably hot-blooded, active homeotherms."
In his discussion of flight he argues, against some previous theories, that pterosaurs had densities comparable to modern birds and bats and used quadrupedal take-off:
"rather than only using seabird and shorebird flight styles, pterosaurs were also flap-gliders, continental soarers, aerial predators, and sometimes even heavyset, short-burst fliers"
He also discusses their terrestrial, arboreal and aquatic locomotion.
"Pteraichnus and other pterosaur tracks demonstrated that much of what had been hypothesized about pterosaur gaits and postures from bones alone was largely incorrect. Notions of pterosaur bipedality were the first to be dismissed. All known pterosaur trackways indicate that they habitually walked and ran on four limbs."
And we can infer something about ecology and ethology. "The idea that pterosaur crests were prominent, visually communicative structures relates to suggestions that the animals spent at least some of their time in large groups or flocks." There is evidence from fossil insects that pterosaurs preyed on them; conversely, some groups of insect species have been proposed as specialist pterosaur parasites. And so forth.
And there's a chapter on "the rise and fall of the pterosaur empire".
"We are left, then, with no clear indication of why pterosaur diversity dwindled so dangerously low in the Late Cretaceous. It is notable that all pterosaurs, not just those of the Cretaceous, seem to have been evolutionarily conservative."
This takes up about a hundred pages; another hundred and sixty pages are devoted to sixteen chapters on individual pterosaur taxa: Anurognathidae, Campylognathoidids, Rhamphorhynchidae, etc. I skimmed over most of the anatomical and paleontological detail in this:
"The nasoantorbital fenestrae and temporal openings of pteranodontians are relatively small, but their orbits are large and positioned high in the skull. While Muzquizopteryz and some Nyctosaurus lack headcrests, all Pteranodon and some adult Nyctosaurus bear supraoccipital crests, the largest of which have bases extending from the posterodorsal region of the skull to immediately anterior of their orbits. ..."
"The discovery of Germanodactylus represented the state of dsungaripteroid research. The first specimen of this pterosaur, a disarticulated skeleton from the Late Jurassic Solnhafen Limestone (Tithonian; 151-145 Ma), was initially described and referred to Pterodactylus kochi by Felix Plieninger (1901). Soon after, Carl Wiman (1925) decided that this specimen warranted its own species, Pterodactylus cristatus. The eminent Chinese paleontologist C.C. Young thought that specific distinction from P. kochi was not enough however, and created a new genus for the specimen, Germanodactylus. ..."
But I enjoyed the fascinating insights into locomotion and behaviour and ecology that can be inferred from that detail, with Witton prepared to engage in restrained speculation:
"Perhaps the most intriguing part of ctenochasmatoid paleoecology is the function of their unusual teeth and probable wading habits. Differences in their cranial morphology likely reflect varied dietary preferences and foraging strategies, suggesting niche partitioning akin to that of modern wading birds. ... The long necks may reflect adaptations to searching for small prey, enabling them to sweep their jaws around in search of food without expending energy to move their bodies."
Pterosaurs is wonderfully illustrated, with perhaps half of it taken up by maps showing fossil locations, colour photographs of key fossils, and glorious colour artistic reconstructions, including some full-page ones of pterosaurs in action in different environments.
"Gnarly skulls, chunky teeth, and tough skeletons suggest that dsungaripteroids, like the Lower Cretaceous Dsungaripterus weii shown here, were hardier beasts than other pterosaurs, and correspondingly better candidates for appearing on the front cover of rock music albums."
Its density and depth will deter some, but Pterosaurs can work for lay readers, if they have a general background in the biological sciences and are prepared to skip over the more involved technical material.
May 2016
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