Scientists in 2005 were only just starting to
recognise the astonishing size reached by pterosaurs, those
flying reptiles which lived alongside the dinosaurs of the
Mesozoic era (248-65 million years ago).
Recent discoveries in the Americas suggested
that some had wingspans of eighteen metres (sixty feet). But
there was nothing ugly about the way they moved through the air,
according to Dr David Martill of the University of Portsmouth.
Their ability to utilise air currents, thermals and ground effects
would astonish aeroplane designers, according to him. Pterosaurs
were beautifully engineered.
Their skeletons were exceedingly light: their
bones were very thin and hollow, and those hollows were filled
with an air-sack system. They had also lost their reptilian scales
and their wing membrane was exceptionally thin. All of this meant
that there wasn't that much weight to get off the ground, and so
they probably flew really rather well.
The oldest pterosaur fossils date back to 220
million years and by now scientists had identified several different
forms - some with teeth, some without; and some sporting elaborate
head crests. With their membranous wings attached to their legs there
was something bat-like about them, and their long beaks were similar
to those of some bird species - but scientists were stressing that
they shared no line of descent to any creatures living now.
Indeed, there was still a great deal of debate about
where exactly they should be placed in the evolution of life forms
on Earth. Dr Martill told the British Association's Festival of
Science in Dublin that new discoveries would help to solve this
riddle - and perhaps reveal just how big these beasts managed to
Pterosaur trackways found in Mexico not too long
beforehand suggested that the animals could achieve a wingspan of
eighteen metres. Existing Romanian and Brazilian fossils also showed
a wingspan of between thirteen to fourteen metres (42-45 feet). Compare
this to today's biggest flying bird, the wandering albatross, which
has a wingspan of about 3.5m (11.5 feet).
One of the reasons they were so big may have been
because they just kept on growing. Humans get to their teenage years
and then stop growing; but if a pterosaur kept on growing then the
older it got, the bigger it got. They would be rare at their biggest
size of course, because the older they would get, the more chance
there was of them being eaten or being involved in an accident.
There is evidence from rare fossil eggs containing
pterosaur embryos which suggests that the creatures could fly soon
after hatching. If this was the case then it was a remarkable
achievement because the wings would have had to have grown from just
a few tens of centimetres in length to several metres without
interrupting the animals' flying capability.
This would be something along the lines of an aircraft
engineer trying to convert a Eurofighter into a jumbo jet while it
was still flying.