Menu Close


A research team led by the University of Leicester have solved the mystery of a 300 million year-old fossil, which identified that the ancient ‘Tully Monster’ was a vertebrate due to the characteristics of its unique eyes. Tullimonstrum gregarium, colloquially known as the ‘Tully Monster’ was a soft-bodied vertebrate which inhabited in coal quarries in Illinois, Northern America.

A fossil with a striped body, large tail, a pair of stalks terminating in dark, oval-shaped ‘blobs’ and a large elephant trunk-like proboscis at the head end which has a pincer-like claw filled with teeth – it is a complete mystery as to what kind of extinct animal it was.Its alien-like image is known to many Americans as an iconic logo which can be seen on the sides of large U-haul™ trailers.

Photo credit: University of Leicester
Photo credit: University of Leicester

Professor Sarah Gabbott from the University of Leicester’s Department of Geology said: “Since its discovery over 60 years ago scientists have suggested it is a whole parade of completely different creatures ranging from molluscs to worms – but there was no conclusive evidence and so speculation continued.”

The Tully Monster was first found by Mr. Francis Tully in 1958. He took the specimens to the Field Museum of Natural History in Chicago.

Thomas Clements, a PhD student from the University of Leicester and lead author on the paper explains the vital clue the team needed to solve the mystery: “When a fossil has anatomy this bizarre it’s difficult to know where to start, so we decided to look at the most striking feature – the stalked structures with dark blobs.”

In a new study published in Nature, the University of Leicester paleontologists, along with colleagues at the University of Bristol and the University of Texas in Austin, discovered that the dark ‘blobs’ were actually made up of hundreds of thousands of microscopic dark granules, each 50 times smaller than the width of a human hair.

Photo credit: University of Leicester
Photo credit: University of Leicester

The shape and chemical composition of these granules is identical to organelles found in cells called melanosomes; these being responsible for creating and storing the pigment melanin. The team used a new technique call Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) in order to identify the chemical signature of the fossil granules.

Thomas added: “Nearly all animals can produce the pigment melanin. It’s what gives humans the range of skin and hair colours we see today. Melanin is also found in the eyes of many animal groups where it stops light from bouncing around inside the eyeball and allows the formation of a clear visual image”

Identifying fossil melanosomes containing melanin and a lens is the first time it has been conclusively proved that tullimonstrum had eyes on stalks.

Professor Gabbott said: “There were two distinct shapes of melanosomes in Tullimonstrum‘s eyes, some look like microscopic ‘sausages’ and others like microscopic ‘meatballs’. This evidence was crucial because only vertebrates have two different shapes of melanosome, meaning that unlike previous researchers that thought that Tullimonstrum was an invertebrate (animal without a backbone), this is the first unequivocal evidence that Tullimonstrum is a member of the same group of animals as us, the vertebrates.”

RAF Advertisement