|Orthacanthus senckenbergianus life reconstruction by Christopher DiPiazza.|
Orthacanthus doesn't really look like many sharks alive today. Its body was much longer and more slender and it had a shallow, rounded dorsal fin running from the back of its head all the way down to the base of its tail instead of the famous triangle fin we commonly associate with sharks. These physical characteristics gave it the appearance of an eel more than anything else but it was a true shark nonetheless. It also sported a long spike growing up from the base of its skull which may have been a defensive weapon against larger predators. It is this spike that gives the shark its name which translates to "Vertical Spike". There are actually several kinds of living sharks that have spikes, too but all of theirs grow from the base of the dorsal fin, not the skull. Orthacanthus's teeth grew in pairs or "twins". This means that there were two pointy teeth coming out of one root.
When alive Orthacanthus likely was an opportunistic predator and probably hunted the many kinds of other fish as well as amphibians it shared its shallow freshwater environment with. It may also have periodically encountered the giant mammal-like reptile, Dimetrodon, which could have preyed upon it.
|Orthacanthus tooth that shows the twin...wait no sorry this one has three. The triplet style tooth. Sharks always go above and beyond when it comes to teeth evolution.|
That's all for this week! Remember, just because Shark Week is done doesn't mean you can't still be shark crazy the rest of the year! As always feel free to comment below and on facebook!
D. Heyler and C. Poplin. 1989. Systematics and relationships among the Xenacanthiformes (Pisces, Chondrichthyes) in the light of Carboniferous and Permian French materal. Acta Musei Reginaehradecensis S. A.: Scientiae Naturales 22:69-78