The misidentification of a fossilized femur in Richard Brookes’ book, A New and Accurate System of Natural History (1763), as a human scrotum was to have enormous repercussions in the world of paleontology.

The French philosopher and naturalist, Jean-Baptiste Robinet, included an illustration of the fossil in his Considerations philosophiques de la gradiation nturelle des forms (1768) which was clearly drawn from that in Brookes’ book but went further by claiming to be able to identify the musculature in each “testicle pouch” and that the central cavity resembled a urethra. He discounted the idea that the fossil was the petrified bone of a once-living creature, advancing the theory that it was a stand-alone entity created by mineral germs which happened to resemble a male anatomical part. Robinet’s theory was not widely accepted.

In 1824 William Buckland described “an enormous fossil…reptile” in Notice on the Megalosaurus or great Fossil Lizard of Stonesfield, which had been discovered in the slate near the Oxfordshire village. He thought it was “an amphibious animal”, not unsurprisingly as previously discovered fossilized specimens unearthed, including Mary Anning’s Ichthyosaurus and Plesiosaurus and Georges Cuvier’s giant monitor lizard found in Masstricht, were clearly water-dwelling. What Buckland called a Megalosaurus, “great lizard”, is known today as a six-meter long land-dwelling carnivore, a femur from which was Brookes’ Scrotum humanum.

In 1827 Gideon Mantell gave the remains the type species of Megalosaurus bucklandii in recognition of Buckland’s part in bringing it to the attention of the scientific community and Richard Owen in 1842 used Megalosaurus as one of the genera that defined the group Dinosauria. By this time the more perceptive minds began to realise that these creatures were a distinct form of animal rather than just a type of big lizard.

However, this thought posed a significant taxonomical dilemma. Under the Linnaean system the first name given to a specimen has taxonomic priority over later names and, inescapably, not only was Scrotum humanum a valid binomen but it was also the first generic and specific name applied to a non-avian dinosaur. In other words, Scrotum humanum had priority over Megalosaurus bucklandii and future generations of paleontologists were stuck with the uncomfortable fact.

The question of what to do about it rumbled on well into the late twentieth century, even though Brookes had known perfectly well that the Cornish femur was not a petrified scrotum and that the rubric to the illustration was erroneous. However, as the term Scrotum humanum had not been used in scientific literature since 1899, under the rules of the International Code of Zoological Nomenclature (ICZN) it could be termed a nomen oblatum or forgotten name and its priority dropped, a decision described at the time as “perhaps fortunate”.

In 1985, though, the ICZN dropped the nomen oblatum clause and a paleologist by the name of William Serjeant had to make a formal application for the name to be suppressed so that it would not take priority over a name deemed to be more appropriate.

As to the original fossil that caused all the fuss, it disappeared without trace, possibly shortly after Post had written about it. It is unlikely that Brookes and certainly not Robinet had ever seen it.