Critter of the Month: Hybodus

Meet Chum. He would love to go for a swim with you, especially if you have any treats! 🙂


The shark cruised the turquoise water, sunlight rippling through the waves to the soft sand below. A small school of silvery fish stirred up a cloud in the warm, shallow waters by the reef, but the shark turned away from them.

He felt muffled clicks and whistles through the water behind him, the ripple of movement against his scales, and he swam faster. There were more than one.

Swift and streamlined as torpedoes, the creatures quickly caught up, and the shark zigged around a rock jutting up from the sea floor and through the jagged branches of a floating log. In the salty brine flowing past him he tasted cool, sweet water, and with a thrust of his tail he followed it. Soon the water clouded with silt and sand, littered with leaves.

A sharp pain stabbed into his tail, and he bolted upward to jab his dorsal spines against one of the sea reptiles that pursued him. The dolphin-like creature whistled, its long, thin snout grinning with teeth before it spun out of reach of the sharp spines.

The fresh water filled him like a meal too large, and he felt heavy. The dizzying clicks of his pursuers rippled against his sides from every direction, and they rammed into his sides and belly as they dove and spun around him. If he tried to jab them with his spines or snap at them, they just disappeared into the dark, murky water as quickly as they appeared.

His belly touched the slime of rotting leaves and mud, and he swam forward until he found a dark hollow in the rock that jutted out from the riverbank. Hard jaws snapped out from the gloom, and the shark flicked away. Right back to his pursuers. The faintest ripple in the water warned him of a swipe from a heavy tail, and he spun around again. He swam into the hole, around the snapping beak and past the hard rock it hid under. Deep into the bank of rotting grasses and weeds. The shark could feel the larger creatures chirping through the water, poking their long snouts closer, but the muddy rock between them moved.

The snapping beak struck out at the offenders, and they backed away. They dove and poked their toothy snouts into the sanctuary, but the snapping beak was too quick. It darted out and under its rock again before the creatures could react.

At last, the writhing movement of water calmed to nothing but the flow of the current, and slow, hidden fish in the gloom.

Longer still, the rock moved again. It slowly pulled out of its gloomy den with strong strokes of its flippers. The shark followed, the tip of a fin just close enough to feel the jagged, hard top of a turtle’s shell. The shark and the turtle swam side by side, the filtered sunlight like twilight in the murky river.

Making progress…

It’s good to be back! I feel almost like my normal self again, and back in the swing with my various creative endeavors. 😀

Oh boy, did I bite off a chunk this time! I thought a prehistoric shark would be pretty simple, but I took a close look at the fossils and I did a double take. Am I missing something, or are those fins a very different shape than what you normally see in reconstructions?

Fisch: Hybodus hauffiensis
Fisch: Hybodus hauffiensis; Holzmaden, Schwäb. Alb, Baden-Württemb. B:ca. 34cm.;
Hybodus fraasi, picture not mine. Wikipedia commons.

So I hunted for as many research papers as I could find. Maybe all the artists are reconstructing Hybodus based on a research paper from a real expert, or simply looking at modern sharks. There’s a lot of comparison to modern day Port Jackson Sharks floating around the internet…

I can see why. With spines in front of each dorsal fin, similar silhouette, and two different kinds of teeth (Sharp in front, flat crushing plate in back), the two critters are superficially similar to each other. Port Jackson sharks were my first go-to reference too!

But I found a research paper that cautions against comparing Hybodus to Port Jackson sharks, or any modern shark, too closely.

“there is no anatomical or paleontological evidence to support a relationship between Hybodus and any particular Recent sharks.” (Maisey, John G.)

That is a quote from this paper , Anatomical Revision of the Fossil Shark Hybodus fraasi. This paper and another gem that was actually awesome enough to have a detailed description and skeletal diagrams inside, were my primary references that finally helped me nail down this critter. That research paper was The Anatomy and Interrelationships of Mesozoic Hybodont Sharks, Maisey, John G. These two papers were truly invaluable in figuring out what the crazy scientific terminology all meant, and accurately interpreting what I was seeing in the fossils.

For example, something I thought was a spike along the side fins was actually the shark’s scapula, or shoulder blade. 😀

In other news, I think I can definitely keep this up in the coming months. 😀

The Critter of the Month will continue on the first of each month. That way I can focus on picture-book progress and other projects the rest of the month. 🙂


Next month I hope to be able to show you some good progress on what I’ve been working on while I’ve been with Babysaurus. 😀 Oh, and speaking of Babysaurus, here he is when he was just a few days old. 🙂 Crazy to think he’s already more than two months!


Baby Peter, just a few days old.


See you on October 1st!

19 thoughts on “Critter of the Month: Hybodus

    1. Thank you very much, and thank you for sharing! I enjoyed reading your post. I also speculate that they might’ve been able to transition between water salinity, so I have Chum swim up a river channel as he tries to lose his pursuers in the brackish murk. 🙂

      Liked by 1 person

  1. Woahh, he’s so cool! You really did a good job on the lighting! The background and texture are also great–I really like how you got the shimmery effect of the light shining through the water. Each critter gets more detailed and realistic!

    I also really like the short story. I think you gave very vivid description using very few words, and yet you also left room for the reader’s imagination. I like the way you incorporated the description into the story. It was also cool how you were able to make it so the reader could “feel” what Chum was feeling–I didn’t realize how sensitive underwater critters are to vibrations in the water. 🙂

    And Chum found a friend, yay! It took me several reads to realize that the turtle revealed at the very end was also the same “beak” and “hard jaws” mentioned throughout the story, and that it was backing off Chum’s pursuers from under its “rock,” or shell. But I’m probably just a slow reader, and I’m guessing flash fiction is supposed to be ambiguous. I also noticed just a couple of repetitive words (i.e. side), but besides that it looks great!

    I think Chum just might be my favorite sea critter in the shop! Great job on him. 😀


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