In spite of the spectacular discovery of a longer time range of the existance of Hybodus, it, just as the dinosaurs, pterosaurs and most marine reptiles, went extinct at the big K-T extintion-event. But not all hybodontids suffered that much from the extinction and some made it through to the Cenozoic. Fossils of the giant hybodontid Ptychodus were found in Paleocene strata of 61.7 million years old. But finally it seemed the succesful line of hybodontids had ended, until, in Early-Miocene strata in Sri-Lanka, the fossils of a close relative of Hybodus himself (even within the Hybodontidae) were uncovered: Miosynechodus.
You might have been wondering what a relatively modern-looking turtle and these ancient hybodont sharks might have been doing in the same image. The turtle is Miocaretta, a close relative of the extant genus Caretta. Just as in Miosynechodus, its name clarifies it’s indeed from Miocene strata, not a strange time for an extinct loggerhead. It is not the only animal found at the place with modern relatives. The fossil site also revealed fossils of Hemipristis serra, an extinct weasel shark, Miodugong, a Miocene dugong, and Miotestudo, another Miocene turtle with modern relatives.
In the large amount of fossils from invertebrates, bony fish, sharks, turtles and marine mammals one particular animal jumped out. They were the fossils of Miosynechodus. It was most surprising to see this ancient survivor living amongst the many nearly-modern animals. Just like Hybodus, Miosynechodus is a hybodontid, a member of a long-lived group of primitive sharks. Hybodontids likely originated out of Ctenacanthids and probably gave rise to the modern Euselachii (which includes most, if not all, modern sharks, and possibly also rays).
Unfortunately due to the cartilage skeletons of sharks, many of their remains vanish over time… Although there was too little information on the fossils of Miosynechodus, it’s likely all fossils found were teeth (and maybe a fin-spike, or two). All known information on the diet of Miosynechodus is that it likely hunted small animals such as small fish and maybe crustacians or even smaller organisms floating in the water. I was unable to find much information on the creature, even though I scanned the whole internet. My interpretations on the creature’s appearance, size and lifestyle are therefore extremely speculative, mostly based on Hybodus itself. This lack of information has one advantage: this is the first ever drawing of Miosynechodus to be published on the internet.
The last thing I want to remind you guys of is to keep in mind sharks are becoming increasingly threatened. Fishing for fins in the shark-fin soup, as well as sharks getting stuck in the nets of fishermen and many other things causes the shark population to drastically decrease. Are money and trophies worth more than seeing these creatures swimming in the wild and interacting with nature, just as they've done for 400 million years? Please support the sharks and other fish and don't help to disrupt the cycle. Please think before you eat, buy or catch.
So I guess you guys now know where the turtle in my avatar comes from!
I hope you guys enjoyed another obscure species being portrayed for the first time on the internet. As always comments, feedback and critiques are appreciated much!
And now I wish you all a good… well, that’s hard to tell… I’ll just wish you a happy next 24 hours!
P.S. First Miosynechodus AND Miocaretta in DA!!!