Box #15 in our count down is Asteracanthus…

Asteracanthus: the “Star Spine”

Asteracanthus is one of those critters that range a large time span and many places across the globe from United States to Europe, from Iran to Morocco…But the most complete specimen is known from the Solnhofen formation of Late Jurassic Germany. It looks like a shark, but is about as close a relative as an animal can be without actually being a shark. The biggest clue to what it actually is are its teeth and the spines in front of each dorsal (top) fin. Most sharks have teeth that are all similar in shape, but this critter is a Hybodontiform.

The Greek hybos means humped, and the Greek dontus means tooth, so you can probably guess what makes them so unusual. Since most of their skeletons are made of cartilage- the stuff that gives our nose and ears their structure- most of these creatures are only known by differences in their teeth and fin spines. But the Solnhofen Asteracanthus preserved the entire body in the soft sea bottom.

Asteracanthus is among the largest of its kind, and grew to about 9ft (3m) long. Paleontologists propose that it preferred the deeper water of the open ocean rather than shallower seas, mostly staying close to the sea bed. Since most of the group are considered slow swimmers compared to most sharks, perhaps it was an ambush predator. The modern zebra shark (or leopard shark) uses a similar hunting strategy and grows to about the same size.

For most of the day they rest on the sea floor, always aware of larger predators, and at night they hunt for clams, crabs, fish, and shrimp. Perhaps Asteracanthus could also prey upon ammonites and weird critters like Clausocaris, which basically look just like the brainbots in the movie Megamind. Bulbous carapace body about the size of your hand, large compound eyes that take up most of that body, and long, dangling shrimp legs.

Learning more about creatures like Asteracanthus can lead us to surprising places, like finding out about the very alien-looking Clausocaris! It all works together to bring these animals to life in our imaginations, and provides a stage for the dinosaurs and other prehistoric creatures that lived alongside them.