When it comes to trying to impress the opposite sex, men are often unable to resist showing off.
A 160 million-year-old fossil dubbed 'Mrs T' has revealed that dinosaurs were just the same.
Male pterodactyls used their spectacular giant head crests to woo the ladies, scientists believe.
While female reptiles had no decorative markings on their heads, the males sported impressive plumes of feathers, sometimes five times the size of their skull, which they used to show off to prospective mates.
It had previously proved impossible to say whether the remains of the reptiles, which lived alongside dinosaurs between 220 and 65 million years ago, were male or female, and 'sexing' them has foxed experts for more than 100 years.
The evidence comes from Mrs T, the nickname given to a female pterosaur preserved together with the egg she was about to lay.
Pterosaurs - favourites of Hollywood filmmakers - were flying reptiles that lived alongside the dinosaurs, some of which grew as large as light aircraft.
Mrs T was a 160million-year-old Darwinopterus pterosaur whose skeletal remains were uncovered in Liaoning Province, north-east China.
Because she was found with her egg, scientists know that she must have been female.
The pterosaur had relatively large hips to accommodate the passage of eggs, but no head crest.
Other Darwinopterus specimens, now known to be male, have smaller hips and well-developed crests. Scientists believe these were probably used to ward off rivals or attract mates.
Dr David Unwin, from the University of Leicester, whose team describe the find in the journal Science, said: 'Pterosaurs, flying reptiles, also known as pterodactyls, dominated the skies in the Mesozoic Era, the age of dinosaurs, 220 to 65million years ago.
'Many pterosaurs have head crests. In the most spectacular cases these can reach five times the height of the skull.
'Scientists have long suspected that these crests were used for some kind of display or signalling and may have been confined to males, while females were crestless.
'But, in the absence of any direct evidence for gender this idea remained speculative and crested and crestless forms were often separated into completely different species.
'The fossil we have discovered, an individual of Darwinopterus, is preserved together with an egg showing that it must be female. This type of discovery, in which gender can be determined with certainty, is extremely rare in the fossil record, and the first to be reported for pterosaurs.'
Future pterosaur fossil finds in which the skull or hips are preserved can now help scientists to 'sex' the creatures.
Dr Unwin added: 'Gender is one of the most fundamental of biological attributes, but extremely difficult to pinpoint with any certainty in the fossil record.
'Being able to sex pterosaurs is a major step forward. Finally, we have a good explanation for pterosaur head crests, a problem that has puzzled scientists for more than 100 years.
'Now, we can exploit our knowledge of pterosaur gender to research entirely new areas such as population structure and behaviour. We can also play matchmaker for pterosaurs bringing back together long separated males and females in the single species to which they both belong.'
Mrs T is thought to have been laid to rest in the Jurassic mud that preserved her bones by a tragic accident.
She was killed suddenly in a traumatic event that broke her left forearm - perhaps a storm, or one of the volcanic eruptions that were common in northern China at this time.
Unlike those of modern birds, her egg was small with a soft shell.
This was not surprising, since a small, soft egg would require less investment in terms of materials and energy, said Dr Unwin.
Such economy would have offered active pterosaurs an evolutionary advantage and may have been an important factor in the evolution of giant species, like the 32.8ft (10m) wingspan Quetzalcoatlus.
**Courtesy of the Daily Mail.
See also: The original paper published tomorrow in Science.
