Field Museum

Tully Monster Mystery

After 50 years of research and mystery, scientists finally pulled together enough evidence to solve the Tully Monster Mystery! 

Mystery Solved! 

 An invertebrate is an animal that does not have a backbone or spine, examples can include: insects, crabs, lobsters, snails, octopuses, and worms. Here are some examples of invertebrates from the Field Museum’s collections!

What is an invertebrate?

A vertebrate is an animal that does have a backbone or spine. Examples can include fish, mammals, birds, reptiles, and amphibians. Here are some examples of invertebrates from the Field Museum’s collections!

What is a vertebrate?

In this activity, try to label recognizable parts of this creature that for decades puzzled scientists, the Tully Monster! Can you identify: The body? The eye-bar? The proboscis (long trunk)? The fins? Try your hand and use the key at the end of the slideshow in the next activity to check your answers!  

Tully Monster ID 

Here are some of the fossils in the Field Museum collections that scientists used to study the Tully Monster. Can you think about why it might be hard to reconstruct what a creature looked like from its fossils?

Tully Monster Fossils

Here are the parts of the Tully Monster in a labelled diagram. Were you able to find these parts in the last exercise? What made it difficult to identify these body parts?

Tully Monster ID Key

This creature puzzled scientists for decades! Is it a vertebrate? Is it an invertebrate? Work your way through this kit to find out!

To give students additional opportunity to explore Mazon Creek fossils, consider renting the “300 Million Years Ago in Illinois” Experience Box from the 

Life Science

Science

Vertebrate Slideshow

Cephalopods are marine invertebrates including squid, octopus, and many others. 

Looking at this artist's reconstruction of two cephalopods from the Silurian period over 400 million years ago, do you think any parts of these creatures' bodies are hard? Why or why not? 

Gastropods include creatures like snails and slugs. Have you ever seen a shell like this one? What purpose to you think a shell might serve for this creature?

What do you think this creature looked like when it was alive? 

Gastropods come in many shapes and sizes! Snails are an example of a common gastropod. 

What similarities or differences do you notice between this animal and others in this slideshow? 

This specimen is a holotype, meaning it is the name bearer for the species. Other unidentified specimen would be compared with this one to determine whether they belong to the same species. 

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Millipede - Brachoria sheari 

How many legs does this creature have? What other creatures can you think of with this many legs? 

What parts of this creature look hard? Remember that invertebrates are animals that do not have spines. What do you think this creature uses instead of a spine? 

This scorpion species is endemic to Madagascar, meaning it is not found anywhere else in the world.

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Scorpion - Tityobuthus mccarteri 

Observe the scale in the bottom right hand side of the image - This image is very, very zoomed in. Do you see anything in this image that you have never noticed before when looking at ants? Why might that be helpful for researchers who study ants?

Ants are widespread, with over 10,000 known species around the world. They possess compound eyes and antennae, and body sections of abdomen and thorax. They have large heads with strong jaws. 

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Ant - Myrmica fracticornis

Bryozoans are microscopic invertebrate animals that live in colonies in hard structures they build. This fossil is the exoskeleton, or support structure of a bryozoan colony that lived during the Silurian period. Do you notice other species using exoskeletons for support in this slideshow?

Bryozoans are colonial animals that live in both freshwater and seawater. A colony is composed of hundreds of very tiny individuals, each of which has a special organ that filters small food particles from the water. Bryozoan colonies are attached to the seafloor or to other organisms.  Fan and bush-shaped colonies like this bryozoan may have functioned as bafflers.

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Museums

Tully Monster Mystery

What is an invertebrate?

Silurian Cephalopod