"The skull of a Purussaurus, one of the biggest crocodiles to have ever lived," reads a Facebook post from October 4.
The post, which has been shared more than 600 times, shows a photo of a man leaning over a huge animal skull.
Purussaurus is a large prehistoric crocodilian that lived in South America millions of years ago.
The same photo was shared in similar posts here and here on Facebook and here on Twitter.
Some social media users appeared to believe the skull belonged to a real-life creature.
"Wow, that's pretty awesome, imagine those being around today," one person commented.
"It can literally swallow a small car if it still lives," another wrote.
However, the photo had been shared in a misleading context.
A reverse image search of the photo found a similar image published here on the website of a British firm called Crawley Creatures.
The firm specialises in "moulding, sculpting, machining, electronics design, engineering and art working", according to its website.
The image is captioned "Deinosuchus skull", referring to an extinct giant relative of alligators in North America.
Below is a screenshot comparison between the photo in the misleading posts (left) and the image published by Crawley Creatures (right).
A spokesman for Crawley Creatures said the image in the misleading posts showed one of the firm's props.
"The skull was made by Crawley Creatures Ltd. pre. 2009. It was made for the Prehistoric Park TV series," the firm's director Jez Gibson-Harris told AFP.
He said that the man in the picture was a technician working for the company.
AFP has previously debunked posts presenting film props as real-life creatures, including a 'werewolf' and a giant ape.