David M. Unwin

The best dinosaur book I’ve ever read. (OK, I know very well pterosaurs aren’t dinosaurs, but close enough for most purposes; besides if I said it was the best diapsid clade book I’ve ever read nobody would pay attention).


I’m supposed to know something about vertebrate paleontology (not that much, my own field was invertebrate paleoecology) but at least more than average. The trouble is a variant of the Red Queen Hypothesis; you have to keep learning as fast as you can just to break even and if you want to get ahead you have to learn even faster. Thus a lot of my vertebrate paleontology knowledge comes from Romer’s Vertebrate Paleontology, and now everything I learned out of that book is wrong. It’s wonderful.


At any rate, the 40-year old view of pterosaurs is that they were clumsy fliers (sometimes it was doubted that they could fly at all, and were just gliders), and that they were absolutely helpless on the ground. Thanks to the discovery of exquisitely preserved fossils in Brazil, Kazakhstan, and China, it’s now know that pterosaur wings were vastly more sophisticated than simple flaps of skin. The mystery was how an animal that depended entirely on a single finger to support its wing could actually develop any flight power. The answer turns out that the wing was a lot stronger than thought because of internal stiffening fibers and muscles. The muscles within the wing were presumably able to change the shape of local areas on the wing, and casts of pterosaur brains support this – the muscle control area is much larger than in similar reptiles. It’s also know now that a mysterious bone (a modified wrist bone) controlled a flap of skin on the leading edge of the wing (the propatagium, if you’re in to that sort of thing), allowing it to act like leading-edge slats on high performance aircraft. Similarly, the tailed pterosaurs (rhamphorhynchoids) had a extensive “wing” connecting the hind legs but not attached to the tail. The tailless pterosaurs (pterodactyloids) did not have the trailing “wing”, but did have webbed hind feet that could aid in maneuver. Pterosaur fossils are found hundreds of miles from the nearest paleoland, showing an albatross-like capability for sustained ocean flight.


Pterosaurs also had “hair”. “Hair” is in quotes there because it’s definitely not mammalian hair; it grows from the epidermis instead of the dermis and individual hairs are not hollow like they are in mammals. They had extensively pneumatized bones, like birds, suggesting an efficient breathing system (I have one question about this; author David Unwin says pterosaurs could not have functioned with the lung-inflation system of lizards or crocodiles. This is certainly true for lizards, which use rib motion to breathe, but crocodiles have a hepatic piston which is as effective as the mammalian diaphragm and bats fly just fine). Finally, the pterodactyloid pterosaurs seem to have been able to walk just fine; they probably looked rather odd doing it, but the wing finger folded backwards to allow the “hand” to make contact with the ground. This is one of the cases where once you know what you’re looking for they’re all over the place; pterosaur tracks were first noticed in 1957 but nobody had any idea what they were until the last few years; now there are full fledged pterosaur trackways, not only foot and handprints but peck marks where wading pterosaurs probed for marine invertebrates. They seem to have been able to run – that’s how they took off, building up speed on four legs, switching to two while the wings unfolded, and jumping with the hind feet to get airborne.


The organization and content of the book strike a near-perfect balance between technical details and fine drawings and references, and pretty pictures, making it just as interesting to the six-year old dinosaur fanatic and those with more advanced interests. There a full and double-page color plates, and Unwin has a dry sense of humor – the illustration of a pterosaur on its way to being fossilized in Solnhofen lagoon is: “It’s not pining, it’s passed on. This Pterodactylus is no more. It has ceased to be. It’s expired and gone to meet its maker. This is a late Pterodactylus*. It’s a stiff. Bereft of life, it rests in peace. It’s rung down the curtain and joined the choir invisible. This is an ex-Pterodactylus”.


*Not true; it’s Jurassic. A late Pterodactylus would be Cretaceous.… (más)

Being something of an omnivorous reader, I came across a story on National Geographic online about how giant Pterosaurs took flight by a leap from all fours. Since I was a child I’ve been fascinated by dinosaurs (yes, yes I know, quibblers, pterosaurs aren’t dinosaurs), so of course this story caught my eye. With it was a striking scale illustration of a man, a giraffe and a giant pterosaur called a Hatzegopteryx. What a beast! And it flew! With my curiosity piqued, it was time to look into these creatures further.

I turned to David Unwin’s The Pterosaurs from Deep Time, the most up-to-date work on these remarkable creatures. Unwin, the curator of the Humboldt Natural History Museum in Berlin, has created an excellent source for anyone interested in these creatures. It’s not a species-by-species breakdown, but an examination of pterosaurs as a whole. As such it’s great, but a few points really stood out for me.

Unwin’s explanation of how pterosaurs (or anything for that matter) become fossilized is fantastic. It really drives home the sheer improbability that any animal’s remains would be preserved to the present day. Conditions must be so finely tuned as to be almost impossible-which would account for the enormous gaps we have in the fossil record. For instance, almost all the pterosaur species we know about lived in coastal areas or near lakes and lagoons. What of the rest of the world? So far, we really don’t know. This means we don’t really know about their origins, as the most primitive types of pterosaurs seem to burst out fully-formed, like Minerva. Unwin conjectures that the earliest pterosaurs were gliders who eventually became flappers, then flyers, but we haven’t and are unlikely to find these primitive pterosaurs, as the arboreal environment they would have emerged in is not conductive to fossilization of such fragile animals.

In 2004 the first pterosaur eggs were discovered which answered the question of why there weren’t any songbird-sized pterosaurs. The answer was that from the moment of birth, pterosaurs could fly and take care of themselves. As they grew, they filled a different niche in the ecology. So, instead of smaller species and larger species existing side-by-side, there were older and younger pterosaurs eating different things, a rather unusual arrangement, very unlike that of birds or bats today.

The case of active versus passive flying is addressed in the eighth chapter. Unwin makes a strong case for pterosaurs being active flyers, and in some ways, even better than flyers than birds or bats are today. More remarkable fossils show the structure of the flight membranes, or patagia, which could be tensed and relaxed as needed, a complex action requiring quite a bit of brain-power. Even the largest of the flyers, the pteranodontia and azhdarchidae (of which the Hatzegopteryx was a member), flapped some in flight, though they probably spent most of the time as soarers like albatrosses today.

The Pterosaurs from Deep Time is beautifully illustrated, with color paintings of many of the described creatures. It’s written in a readable style for non-experts (like myself) and is actually quite funny in a few parts (the beginning of the postscript is hilarious). Anyone interested in the prehistoric world will profit from reading this.… (más)