Orthoceras: Early Squid

Orthoceras was an extinct genus of cephalopod, a family that includes modern-day squid, octopi, and cuttlefish. It lived for a long period of time from the lower Ordovician Period until the Triassic Period. It is possible they could have lived longer, but fossil records have thus been dated to encompass between 500 million years ago and 190 million years ago. Orthoceras shells have been well-preserved in sea beds, often clustering together due to the motion of ocean currents. Fossilized orthoceras shells have been unearthed in Morocco, the Alps, and Iowa.

Unlike the soft-bodied squids of today's oceans, orthoceras had a long, conical shell that housed much of its body. This cone could range in length from a few inches to a giant six feet and helped the orthoceras move by acting as its siphon. Water was taken in through the base of the cone and then expelled out the back, causing jet propulsion. Also, the cone could be filled with air or water, acting as a buoyancy chamber. This would allow orthoceras to control its depth in the water more effectively. The cones of orthoceras preserve their color very well in the limestone deposits in which they are commonly found. Vibrant, gem-like colors of green and blue are common in these cones. The many tentacles of orthoceras were left free so it could grasp small prey items drifting in the currents, including fish and other cephalopods. Coupled with its jet-propulsion method of movement, it is likely that orthoceras could have been a very effective hunter of fast-moving prey.

Like squid and octopi in today's oceans, orthoceras was undoubtedly one of the more intelligent forms of life living in the oceans. Much of this intelligence stems from a cephalopod's use of its many tentacles, much in the same way that we use our fingers to grasp objects and manipulate the environment. Modern-day squid have well-developed brains that are much larger than creatures it shares the ocean with such as fish, gastropods (snails and slugs), and bivalves (clams). If orthoceras resembled squid today, then they would have had well-developed and large eyes. These are especially light sensitive which would allow orthoceras to locate prey in dark or deep water in the Paleozoic seas.

Orthoceras eventually went extinct in the Triassic Period. This is probably due to the catastrophic changes the Earth was undergoing toward the end of the Permian Period when many ecosystems were wiped out due to sweeping changes in the global climate.