Fossil Friday: Oligokyphus

Species: Oligokyphus sp. (Oh-lee-goh-kai-fus)

What it means: Small curved animal

Other species: Oligokyphus triserialis (type), O. major, and O. lufengensis

Where I live: Arizona in the U.S.A.- The Kayenta formation

When to find me: The Early Jurassic period, about 196 million years ago.

My favorite food: Plants! I’m an herbivore.

My neighborhood: The Kayenta formation used to be a tropical floodplain, a bit like African savannah today- but no grass or flowers. Ferns cover the open plains, dotted with islands of spiky cycad groves. Rivers crisscross the land with lush tree ferns, ginkgo trees, and conifers. Every year during the wet season the plains turn into a flooded marsh, but the hottest months bring no rain, and the rivers shrink until the plains are almost as dry as the great desert that lies to the north.

A few of my neighbors: I’m surrounded by meat-eating dinosaurs like Dilophosaurus, Kayentavenator, and Coelophysis, and plant-eating dinosaurs like Sarahsaurus (an early sauropod), Scelidosaurus, and Scutellosaurus (armored dinosaurs). I have to be careful not to get stepped on, or end up as lunch for crocodile cousins that prowl the rivers and the dry land. In the sky, flying pterosaurs with long tails keep an eye out for insects like beetles, dragonflies, an ancient cousin of the moth, and something called a snakefly. While frogs and turtles swim with the fish in the river.

Fun Facts:

  • I may look like a bit like a weasel, but I’m not a mammal at all! I’m part of a mammal-ish group of creatures called cynodonts. I have three brothers and sisters in the Oligokyphus family (or Oligokyphus genus, technically). The species are O. triserialis, O. major, and O. lufengensis. No one is really sure which one I am because so few fossils were found, so no one gave me a species name.
  • Even though there are only a ton of teeth and a few tiny jaw fragments found in the Kayenta formation, I was actually the first Oligokyphus found, and the rest are based on my teeth!
  • The words in my name are Greek! From oligos (small) + kyphos (hump, or curved back).

Fossil Finds:

Numerous fragmentary remains of teeth, head, and the rest of the body are known from China (Lufeng formation), Great Britain (Windsor Hill Quarry, Pant Quarry), Germany (Exter Formation), and North America (Kayenta Formation in the U.S.A., McCoy Brook Formation in Canada). Of the Kayenta Formation, only a few isolated teeth and jaw fragments have been found of an indeterminate species.


Jenkins, F. & Crompton, Alfred & DOWNS, WILLIAM. (1984). Mesozoic Mammals from Arizona: New Evidence on Mammalian Evolution. Science (New York, N.Y.). 222. 1233-5. 10.1126/science.222.4629.1233.

Luo, Zhe-Xi & Sun, Ailin. (1994). Oligokyphus (Cynodontia: Tritylodontidae) from the Lower Lufeng Formation (Lower Jurassic) of Yunnan, China. Journal of Vertebrate Paleontology – J VERTEBRATE PALEONTOL. 13. 477-482. 10.1080/02724634.1994.10011526.

Fedak, Tim & Sues, Hans-Dieter & Olsen, Paul. (2015). First record of the tritylodontid cynodont Oligokyphus and cynodont postcranial bones from the McCoy Brook Formation of Nova Scotia, Canada. Canadian Journal of Earth Sciences. 52. 150313143816000. 10.1139/cjes-2014-0220.

The Liassic therapsid Oligokyphus.‭ ‬-‭ ‬British Museum‭ (‬Natural History‭)‬,‭ ‬London‭ ‬1-149.‭ ‬-‭ ‬W.‭ ‬Kühne‭ ‬-‭ ‬1956

Hans-Dieter Sues (1985) First record of the tritylodontid Oligokyphus (Synapsida) from the Lower Jurassic of western North America, Journal of Vertebrate Paleontology, 5:4, 328-335, DOI: 10.1080/02724634.1985.10011869

These two websites were a huge help in knowing where to start when finding research material and basic information.

“Oligokyphus.” Prehistoric wildlife,

“Microdocodon, Oligokyphus, Tritylodon, and Kayentatherium.” Reptile Evolution,

6 thoughts on “Fossil Friday: Oligokyphus

  1. This may be a bit unpopular l, but I think you should Oligokyphus’s type species over an undescribed species. If you add it in soon, try to base it off of the type species, O. triserialis (the creature might be named Olga). I don’t like the idea of basing something off of a species that still needs an official scientific name. That’s just my opinion. What do you think?


    1. Hi Angel, thank you for stopping by! And thank you for the thoughtful feedback. 🙂

      The drawing is based off the type species of O. triserialis. Aside from size, there aren’t really any differences in the different species that would be obvious enough to make a difference for this style of reconstruction, so really the only differences may be color pattern and size when other species of Oligokyphus show up on the site.

      I may do the same with Scelidosaurus because it’s a similar story there. Except with Scelidosaurs there is only one known species thus far, just not enough fossil material found to determine if it’s a different one, seeing as they’re on completely different continents. Those continents were connected at one time, yes, but you can find different species just on one side of a state vs. the other side. So not very much space is needed for species to deviate from each other.

      Ultimately I’m going with the data I found. If all my sources choose to say it’s an indeterminate species vs. simply assigning it to one until further notice, then I will do the same.

      You do make a good point though, so I think I’ll make a small change and at least mention the type species somewhere, clarify that there are more than one, and we don’t know which one this one is. 🙂


      1. I would like you to do a Scelidosaurus post later, since the only named species of it lived in what is now England.


        1. I will be including Scelidosaurus with the Kayenta formation creatures, since the remains found are generally agreed to be from Scelidosaurus and there is only one known species. If further material is found and a new species is determined, then I will update the post when we have that data.

          There are many incomplete fossils, and going by formation can prove difficult, but I want to include as complete a picture as I can (and have fun, and ultimately I Want to draw Scelidosaurus), so I won’t be leaving out any taxa from any formation so long as there is enough information to at least try to draw it.

          Liked by 1 person

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