Ashley: The cannibal Xiphactinus

 If you're following me on the twitters I'm sure you all know about my absolute and undying love for the giant ugly predatory fish from Kansas, Xiphactinus audax. We spend a lot of time in normal years in Kansas during the spring and fall (when the weather and bugs aren't too miserable) and we tend to find a good number of at least partial skeletons, some exceeding 18 feet in length.

Random Xiphactinus verts in the wild

It's easy to think of them as just another boring fossil, as if they were the hadrosaurs of the ocean, but every once in a while something about them makes them interesting.Sometimes because they are found inside something interesting, other times because something interesting is found in them.

Xiphactinus as stomach contents of a large shark, Cretoxyrhina
Photo taken at University of Kansas Natural History Museum

Xiphactinus is well know for its gluttony. The famous "Fish Within a Fish" at the Sternberg Museum of Natural History, where a 13 foot long Xiphactinus semi-successfully ingested a nearly 6 foot long Gillicus is a prime example of this. I claim it to be semi-successful as the Gillicus is completely articulated and not digested, indicating that trying to swallow this meal likely killed the Xiphactinus. Other times smaller remains of a fishy meal in the body cavity of a Xiphactinus are found, we see this in a little less than half of our specimens.

Photo courtesy of Mike Everhart www.oceansofkansas.com

Fast forward to the spring of 2018. I was scouting the lower Niobrara Chalk in Gove County, Kansas. The chalk is defined stratigraphically by 23 distinctive easily traced (usually) bentonite layers laid out by Hattin in his 1982 work. These outcrops were around Hattin's Marker Unit 6, so the upper limit of where I could possibly find my dream fish , an articulated specimen of the ram-snouted Martinichthys ziphoides. No luck on that front however I did find this fine pile of bone eroding out, seemingly face-first. A small pile of bones is always a good sign!

The bones are the kinda grey things on the yellow chalk

Unfortunately it looked like it was headed into the base of a big cliff. After initial evaluation, we decided to GPS and cover up the site to protect it until we could come back at a later date. That date came the next spring.After a long morning of removing overbruden, we were relieved to see the fish had actually folded in half back on itself about 4 feet from the erosional edge and the balk half pointed back out that direction. We didn't have a tail fin, but we also didn't have to move a mountain of rock chasing this Xiphactinus either. I gave it the nickname "Ashley" after one of my trivia teammates (remember when we could go to bars and do that? Wear a mask and maybe we can soon).

Can you see the digsite?

One of the strange things we noticed while exposing the bones in the field was a large bulky bone near the belly. It looked like a cliethrum, one of the bones that the pectoral fin hangs off of. The skeleton itself was mildly disarticulated in parts, and any Xiphactinus will have 2 of them, so maybe this was just a bit of Ashley that was pulled off the carcass when scavengers like the shark Squalicorax came to strip off all the flesh.

Typical Kansas fish dig

Preparation showed the skeleton was in much better condition than we had imagines, with decent articulation and a beautiful pelvic fin. It also showed both cliethra that were supposed to be present on a Xiphactinus wee in fact there in place. So what does that mean with our now THIRD cliethrum?

2 very nice looking jackets all cleaned up

One way to be sure is to prepare it as well. Free from all of its matrix two things were readily apparent: One: the acid-etched texture of the surface of the bone meaning it was stomach contents and Two: based on the shape, it also belonged to Xiphactinus.

The smoking gun, so to speak. Acid-etched Xiphactinus cliethrum

With that shocking knowledge in hand with al of the bad things Xiphactinus could be (common, boring ugly, a lot of work to dig up and prepare) we can also add cannibalism to that ever growing list.

Fall Xiphactinus Surprise

Let's go to Kansas they said. We'll find some marine reptiles they said. It'll be fun they said. Boy, were they wrong!

October is tarantula migration season

Doing fieldwork in Kansas at the end of October is pretty rare for us, but we lucked out with the weather and spent a few days hitting outcrops we hadn't been on in a few years. It's important for them to go through an erosive "refresh cycle" so that we can find new stuff on the same ground. In just the first day we found the remains of a partial Pteranodon sternbergi and a few cool small fish. Mike and Jacob were working on excavating Pteranodon #6 of the year and I was finishing up jacketing a nice Ichthyodectes ctenodon specimen and had a little time to kill, so I wandered off to the south a little bit to scout for some cool treasures. I had been over the area just a few yeas before, so I was expecting something small.

The chin

Curator at digsite for scale

That's when I accidentally found the biggest fish of my career laying on its left side. I nicknamed it "Nia". She's a Xiphactinus audax over 17 feet long when whole, with pectoral fins each 2 feet long.

There was a serious lack of overburden at first

Luckily overburden wasn't a big problem at first, with an average of about 4 inches (100mm) of chalk over the specimen. Digging in though, the articulated strand of ribs, spines and vertebrae were pointed straight into the outcrop wall.

Expanding the digsite

The Niobrara sea was chock full of predators ready and willing to scavenge a dead animal, and they didn't pay Nia any respect either. We discovered a half dozen shed Squalicorax falcatus teeth in the head area, lost while taking chunks of meat off the carcass. Unfortunately (or mercifully, depending on how you see it) the body was bitten off about 5 feet from the start of the dig.

Jacob driving a chalk-splitting chisel under the big jacket

How the specimen flipped in the field

Jacketing was a bit tough and we anticipated some problems with a huge flat jacket in soft weathered chalk. We feared a collapse (like that one other Xiphactinus I found a few years back that I nicknamed "Bea Arthur") so we did everything possible to try to get the specimen out safely. It still fell out, but to our amazement, almost all the bones remained in place in the jacket!

Show prepped main jacket

The rest of the jaws will go back in place later

Show prepping took a long time because of how soft the bones were. I got it into the "pretty enough" stage and now Nia is in storage, waiting for her turn to be turned into a spectacular panel mount.

Cap'n Chuck Rises: A Teaser

Like many places, progress on various projects here ebbs and flows. Sadly, the Pete III Daspletosaurus restoration project has been temporarily put on hold so we can address more pressing matters. In this case, it's Cap'n Chuck (RMDRC 06-009), a fairly complete and extremely well preserved Platecarpus tympaniticus specimen that I discovered one cold October day in 2006. A recap of the early part of the project can be found by clicking here. Once prepared the specimen sat in drawers in my office for years.

Squalicorax bites on the top of the skull

That's a nice set of ribs

Recently the powers that be have decided that we should restore and mold the skeleton to replace the smaller Platecarpus planifrons skeleton in our cast catalog. Comparing it to the lower chalk mosasaur, Cap'n Chuck has a nearly identical skull length, more gracile lower jaws and wider top of the skull, however its postcranial skeleton is radically different in proportions. Humerei and vertebrae are nearly twice as big. The ribs are surprisingly uncrushed, preserving their original round cross section as well as curvature. In fact they are so well preserved we can even with some degree of certainty determine which ones belong on the left or right side (nearly imossible to do on typically crushed ribs).

Lower jaws, slender and displaying symmetrical tooth replacement

Nearly complete axis showing beefiness

The differences really are amazing. A few years back, Takuya Konishi split Platecarpus planifrons into its own genus: Plesioplatecarpus. I was very skeptical of this split for a long while, but now after comparing the low chalk mosasaur against its upper chalk relative, I'm really beginning to see his point.