Anomalocaris

The Anomalocaris is a stand-alone fossil that can be donated to the museum in.

Upon donation or selecting "Tell me more about this!", Blathers the curator will say:

"Anomalocaris lived in the water long before the dinosaurs and are known for their, er, "distinctive" look. Flat bodies over three feet in length, bulging eyes like a... dragonfly, antennae like shrimp tails... They looked so peculiar that people originally thought they were multiple fossils stacked on top of each other! As a delightful side note, "anomalocaris" means "abnormal shrimp." Obviously this animal has a certain reputation in the scientific community!"

In Real Life
From shortly after the Cambrian explosion, Anomalocaris is believed to be one of the earliest apex predators. It reached up to a meter in length, making it one of the largest animals of the time. They are classified as radiodonts, which are believed to be close relatives of arthropods.