A university lecturer had to change a long-standing presentation on the world's first documented dinosaur fossil - after students complained that it contained a picture of testicles.
A 400-year-old illustration of the fragment of Megalosaurus leg bone was shown in a lecture to third year students at the University of Portsmouth as part of a course on the history of palaeontology.
It was displayed along with its original name from the 18th century 'Scrotum Humanum', given to it because of its uncanny resemblance to male genitalia.
But the lecturer then used a photo of actual testicles to compare the ancient femur bone to, prompting at least two complaints from shocked students.
The image has now been removed from the presentation to prevent future offence.
The decision to change the lecture was revealed in the university's response to a Freedom of Information request regarding student complaints.
The response stated: 'The very first dinosaur that was described 'scientifically' was named Humanum scrotum (it was very fashionable in Georgian and earlier times to compare natural objects to parts of the human body, especially genitalia) because of its resemblance to a scrotum.
'An image of a mammalian scrotum was included in the presentation for comparison with the bone until several complaints were received requesting its removal. The image was removed from the presentation.'
Dr Anthony Butcher, palaeontology course leader at Portsmouth University, whose colleague was forced to make the change, said the complaints had been received in the last couple of years.
He said the lecture was given to final year students as part of the BSc in Palaeontology course and explored the history of fossil discovery.
'There's a long history of people finding things and not knowing what they were,' he said today. 'This (fossil) was from a time when palaeontology wasn't a science and was the first dinosaur bone ever recorded. It's a part of history.
'It looks like a certain part of the human anatomy.'
Dr Butcher said it was the subsequent picture of 'mammalian' genitalia that caused offence.
'It's a palaeontology course. There's a lot of biology in it. Was the image necessary? It was there as a comparison, it wasn't gratuitous.'
Dr Butcher declined to identify the lecturer who have the talk and said he did not know which mammal the offending testicles belonged to.
Scrotum Humanum - the head of a femur bone belonging to a dinosaur later named Megalosaurus - is widely believed to be the first ever recorded dinosaur fossil.
It was found in an Oxfordshire quarry in 1676 and given to Robert Plot, Professor of Chemistry at the University of Oxford and first curator of the Ashmolean Museum.
Plot published a picture of it the same year in his book, Natural History of Oxfordshire, which was then used in a book by Richard Brookes in 1763.
Brookes called it ‘Scrotum Humanum’, apparently comparing its appearance to a pair of ‘human testicles’. The dinosaur was renamed in the 19th century.