A lot of mistakes have been made when it comes to distinguishing between male and female dinosaurs, new research suggests.
Debate over whether palaeontologists have been accurately identifying the sex of dinosaur fossils has been rumbling on for many years.
Despite previous claims of success, new research led by academics at Queen Mary University of London has proven it is indeed very difficult to spot the difference.
The team analysed the skulls of modern-day gharials, an endangered crocodilian species, to see how possible it is to distinguish males and females based only on fossil records.
Male gharials are larger than females and have a fleshy growth at the end of their snout known as a ghara.
The ghara is made from soft tissue, which wouldn't fossilise well, but it is supported by a bony hollow near the nostrils which can be seen in their skulls.
By studying 106 gharial specimens in museums across the world, the researchers found that, aside from the presence of the narial fossa in males, it was almost impossible to tell the sexes apart.
Dr David Hone of Queen Mary University of London said: "Like dinosaurs, gharials are large, slow growing reptiles that lay eggs, which makes them a good model for studying extinct dinosaur species.
"Our research shows that even with prior knowledge of the sex of the specimen, it can still be difficult to tell male and female gharials apart.
"With most dinosaurs we don't have anywhere near that size of the data set used for this study, and we don't know the sex of the animals, so we'd expect this task to be much harder."
There are many species where males and females have distinctive attributes that set the sexes apart - such as a deer's antlers and a peacock's bright tail feathers.
This is known as sexual dimorphism and is very common within the animal kingdom. It is expected dinosaurs would have been the same, but it is far too difficult to tell from the skeleton alone.
Dr Hone said: "Some animals show extraordinarily high levels of sexual dimorphism, for example huge size differences between males and females.
"Gharials sit somewhere in the middle as they do possess these large narial fossa that can help with identification.
"Our study suggests that unless the differences between the dinosaurs are really striking, or there is a clear feature like the fossa, we will struggle to tell a male and female dinosaur apart using our existing dinosaur skeletons."
The research also challenges previous studies which suggested there were differences between the sexes in popular dinosaur species such as the Tyrannosaurus rex, and led to common misconceptions amongst the general public.
"Many years ago, a scientific paper suggested that female T. rex are bigger than males. However, this was based on records from 25 broken specimens and our results show this level of data just isn't good enough to be able to make this conclusion," Dr Hone added.
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