western interior seaway


Fossil Fish Skull (Xiphanctinus audax, Cretaceous) -  Niobrara Formation, Kansas

This sinister looking skull once belonged to a predatory fish that dominated the Western Interior Seaway known as Xiphactinus which was much longer than any bony fish of today. The beast is represented here by just a skull and some post-cranial material, but the point gets across nonetheless.

“Toto, I’ve a feeling we’re not in Kansas anymore.”

This scene represents a moment in time 83 million years ago, in what is now the state of Kansas, which was covered by a body of water known as the Western Interior Seaway and populated by diverse, prehistoric marine life. In this diorama near Dinosaurs in Their Time, an agile marine reptile, Dolichorhynchops bonneri, dives after the penguin-like bird, Hesperornis regalis.

I was surprised to see that Hesperornis could be almost as big as the average human, wich also puts it around the same size as a female Pteranodon (minus the latter’s wingspan). Following recent research on pterosaurian competence underwater, here’s a female Pteranodon being harassed by two much more agile Hesperornis into giving up on her fish.

It’s Shark Week!

Scientific name: Cretolamna appendiculata
Diet: Fish, small marine reptiles
Projected Natural Lifespan: 30 years
Length: 3.6 meters (12 feet)
Locality: Throughout North America, 
Exhibit: Western Interior Seaway, Aquarium

Cretolamna is a medium-sized shark, with species known from sites worldwide, ranging from the early Cretaceous to the Miocene. Unlike many fossil sharks, whole body fossils are preserved of it, providing a unique glimpse into its appearance. Its body is fairly elongated, and it bears a resemblance to living mako sharks. Its teeth are broad-based and have two short cusps at the base surrounding the longer, narrower crown, indicating a diet of fairly large prey. Cretolamna is thought to be ancestral to later giant lamniform sharks such as Carcharocles.

At Huxley
Cretolamna can be found in the Cretaceous section of the Aquarium, in the Western Interior Seaway hall. 

Notable Behavior
Our Cretolamna are pretty active and high-energy sharks, and quite fast-swimming. Like modern mako sharks, they have rete mirabilia that allow them to conserve heat and sustain a higher body temperature than the surrounding water, which undoubtedly boosts their activity. They did bump into the walls a bit when they were younger, but this has gotten a lot better over the years - in part due to visual markers delineating the wall (as seen above). And as a result, they eat more often - we feed them at least four times a week, more than most of our other chondrichthyans. When feeding, they swim up to bite from below, like several modern sharks. Combined with their speed, sometimes this leads to them leaping clear out of the water! 

Keeper Notes
They’re pretty tolerant of people, and show a notable curiosity in the divers that feed them and clean up the tank, even going so far as to rub against them. So far they’ve never bitten anyone, though our divers wear armored wetsuits just in case.

Ending yet another hiatus with some huge Beach Lizards. Tylosaurus pembinensis and Deinosuchus rugosus, the two biggest shark-snackers of the Western Interior Seaway during the Santonian and Campanian.

Serves also a little preview to a project I’m working on, more on that later.

[Also Brand-new Commission prices are up here, if you are interested.]

Animal of the Week: Big Blue the Mosasaurus


Mosasaurus hoffmanni*


Mosasaurs are an infamous group of marine lizards. Thought to be closely related to snakes and monitor lizards, mosasaurs are long, streamlined, and well-adapted for an aquatic existence, with paddle-shaped limbs and fluked tails. Mosasaurus is the biggest of the lot; some fossil specimens can reach an excess of 50 feet! Big Blue is currently 30 feet - which is still a good size. Mosasaurs are active warm-blooded predators, known to prey on fish and other marine reptiles. As well as the many conical teeth that line the dental margins of the mouth, they have a second row of teeth on the palate, useful for dragging prey further into the throat. Mosasaurus itself is especially robust. Discovered in 1764, it’s become among the most infamous marine reptiles, mostly due to being so big.


Take the stairs down from the aquarium’s Western Interior Seaway hall to the viewing room to see the Trench of the Mosasaur. Gaze into the massive sea pen we’ve built for her, suitable for an animal of her size. On weekday mornings, you can hop on a boat and watch us feed her deep in the sea pen.

Fun Facts

Mosasaurs have a good sense of hearing, and especially tune into repetitive low-frequency sounds (like the sounds of splashing prey). We found that hard rock music is quite effective at drawing her to the boat for feeding, better than the scent of chum even! Recommend songs for Big Blue’s Spotify playlist in our Ask box. We’re always looking to keep her interested in the latest in hard rock fads!

Personality & History

Big Blue is our second mosasaur ever produced by our facility’s geneticists. She bears genome version 1.0, as version 0.9′s mosasaur had passed during artificial gestation. The successful birth of a large marine predator brought an extensive set of architectural and procedural development for our aquarium. She was at first raised in a tank in the Western Interior Seaway hall, part of which is now occupied by our Eonatator. Knowing that she’d outgrow the facility, consultants from the now-defunct Free Willy-Keiko Foundation were flown in to oversee her care as a juvenile and the construction of a much bigger abode.

At 5m, we introduced her into her permanent home: a custom-built sea pen with hydrophone deterrents to dissuade her from venturing close to the thick mesh walls. She’s acclimated quite well, giving us hope for when our megatooth sharks graduate to a full sea pen.

Big Blue is quite inquisitive, often displaying interest in visitors when she swings by the underwater viewing window. If she bumps a viewing boat, consider it a friendly nudge. She has yet to attack a human-navigated vessel, preferring big smelly hunks of meat over cold hard metal - but the boats have a scent-based repellent as well as a number of trade-secret deterrents to stymie her curiosity.

She is not without her own set of challenges that the Huxley keepers & aquarists must keep careful attention to! Big Blue is prone to an undescribed genus of Australian marine parasite (similar to sea lice, our taxonomists have found) that cause her superficial injuries to the skin and tongue. After calling her into a shallow, protected medical pool, a specialized dive team descend and carefully remove any “mosasaur lice” found from our custom bio-scanners. The dedicated 8-person team have earned her affection. Er. As much as a mosasaur can display affection, rather. Toleration might be a better word for it.

We promise it’s nothing to worry about! Our vets are working on a topical remedy as well as the possibility of introducing a larger stock of live fish into the pen to combat the population of these little buggers.


The top image is a picture of a cross-bedding formation. The rocks in the cliff have horizontal layers that were formed in a flowing fluid.

The top picture is in Zion National Park, Utah. A long time ago, when dinosaurs roamed the Earth and the sea levels were much higher, the entire center of North America was underwater. The Western Interior Seaway was where sea monsters of incredible size and ferocity lurked beneath the waters.

Paleontologists still find new dinosaur fossils in the Western Interior Seaway all the time.

The bottom image is also of cross-bedding. On Mars.

A few years ago we were searching for liquid water on Mars. Now we have geological proof that Mars was once a water world, rivers flowed across its surface.

Perhaps it’s time we sent some paleontologists to dig for fossils?

(Image credit: Rygel, M.C. and NASA respectively)

Dakotaraptor steini

Source: Me! I drew it! Yay! I don’t usually draw things! 

Name: Dakotaraptor steini

Name Meaning: Dakota Thief

First Described: 2015 

Described By: DePalma et al. 

ClassificationDinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Maniraptora, Pennaraptora, Paraves, Eumaniraptora, Dromaeosauroidea, Dromaeosauridae, Eudromaeosauria

Dakotaraptor is a new dromaeosaurid from Hell Creek that has been in the rumor mill a long time.  It’s a very large dromaeosaurid, from Hell Creek - we don’t have many of those, only Utahraptor, Achillobator, and Austroraptor in addition to Dakotaraptor - with quill knobs on its arms. As we all know from Velociraptor, this is direct evidence of heavily used pennaceous feathers, making the phylogenetic certainty of these complex integumentary structures on dromaeosaurs of all sizes even stronger. In short, it is now especially inexcusable that the raptors in Jurassic World don’t have feathers. Come on, guys. Stop the madness. Also, that one tumblr user who insists that Utahraptor didn’t have feathers is… somehow even more wrong now. He was already 100% wrong before. We live in a glorious, wondrous, amazing world. 

Source: @ewilloughby (Emily Willoughby; directly from the paper. What a gorgeous reconstruction!) 

Dakotaraptor itself is known from arm and leg bones, as well as some tail vertebrae, and teeth. Based on these remains, its size was estimated to be between 5 and 5.5 meters long, meaning only Utahraptor actually exceeded Dakotaraptor in size. This is impressive, but what is even more startling is the size of it’s characteristic sickle claw: it appeared to have been about 16 cm long, and 24 cm along the dorsal curve. It is proportionally larger than the claw of Deinonychus; it is about 29% of the length of the femur, whereas Deinonychus’ is about 23%. It is similar to that of Utahraptor, but more robust. The quill knobs on the arm are completely, without a doubt, quill knobs, similar to those found on Velociraptor, Archeopteryx, and Microraptor, and were points where the secondary remiges (so the VERY LONG very complex pennaceous feathers) could attach. Not all birds even have quill knobs; they are indicative of heavy use of the feathers themselves and Dakotaraptor probably had about 15 of them (Velociraptor had 14, Archaeopteryx 12, and Microraptor 18). 

Source: RJ Palmer, of @saurian-game fame 

When analyzed for cladistic relationships, it was found to be a sister taxa (meaning, really closely related) of Dromaeosaurus. However, there are some problems with this. First off, they don’t actually include Acheroraptor in their analysis, which leaves me with some questions. First off, how do we not know that Acheroraptor isn’t a juvenile Dakotaraptor? Acheroraptor is only known from skull bones, but Dakotaraptorisn’t known from any. I do not know if you can definitevly say they’re different genera at this time, especially since the only dromaeosaurid teeth found in Hell Creek so far have belonged to one genus - Acheroraptor. I’m giving it the benefit of the doubt for now, but I really demand some new analyses. After all, the authors of this paper are… the people who are still insisting that Nanotyrannus is separate from Tyrannosaurus rex. And look, I made an ADAD entry on Nanotyrannus, but solely for completion purposes, and I really do not think its a separate genus, but rather an ontogenic state of Tyrannosaurus. The authors are fans of over-splitting, and I’m really looking forward to other people’s analyses and statements about whether or not Dakotaraptor and Acheroraptor are the same thing (and, thus, Acheroraptor would take priority). 

Source: @ryuukibart

Dakotaraptor was most similar in proportion to smaller, more agile dromaeosaurids, such as Deinonychus and Dromaeosaurus, rather than other big raptors like Utahraptor and Achillobator. The size of its “raptor claw” indicates heavy use, even more so than normal in dromaeosaurs. It was found in the Upper Hell Creek Formation, very close to the Cretaceous-Palogene Boundary, making it one of the youngest known dromaeosaurs, living in the Maastrichtian age of the Late Cretaceous, about 66 million years ago. It is known from a few specimens, including a “gracile morphotype” which is… interesting… given the taxonomic confusion regarding this animal… they say that its sexual dimorphism but I’m concerned on multiple levels. There’s a lot of iffy taxonomic stuff going on in this paper that has me cringing. And the bulk of its basis for new-genus-ness is its size. I am… Sigh. At least we know it was huge and we know it had feathers. 

Source: @spinosaurus-the-fisher! He made two versions. I refused to pick one. We all get two. 

It lived in one of the most famous prehistoric ecosystems, alongside such dinosaurs as Tyrannosaurus rex, Triceratops, Alamosaurus, Torosaurus, Edmontosaurus, Ankylosaurus, Pachycephalosaurus, Thescelosaurus, Ornithomimosaurus, Troodon, Edmontonia, Dracorex, Sphaerotholus, Stygimoloch, Leptoceratops, Tatankaceratops, Struthiomimus, Anzu, Acheroraptor, Avisaurus, Cimolopteryx, Brodavis, and Potamornis. This was a forested environment, in a warm and humid subtropical climate, alongside the Western Interior Seaway. It probably competed with juvenile Tyrannosaurus for food given their similar sizes. It had very long forelimbs with robust bone structure that could have been used to protect eggs when brooding, or even the famous hypothesized attack method of dromaeosaurs with flapping of wings to help with holding onto prey. Also, they could have been used for mating display, territorial behavior, and shielding the young. 

Source: @spookydunsparce!

Dakotaraptor and Utahraptor, though similar in size, had different anatomies and thus probably filled different ecological niches and evolved their large sizes for different reasons (though, of course, new material from Utahraptor [the so-called “Utahraptor Block” has yet to be described). It seems that Utahraptor was not very good at pursuit capabilities - meaning, not very fast. Dakotaraptor, on the other hand, had proportions similar to smaller dromaeosaurs, and probably would have been at least a little bit faster and able to pursue animals for food. It was a medium sized predator, in addition, allowing it to feed on food not really pursued by either the large predators of Hell Creek or the small. More research definitely needs to be done on this dinosaur, and I really want that classification issue to be resolved, and for people to look at it who aren’t proponents of Nanotyrannus, but, for now, it’s still truly wonderful to have evidence of substantial feathers on large dromaeosaurs. 

Source: @mei-longart!

Source for text: 

DePalma, R. A.,D. A. Burnham, L. D. Martin, P. L. Larson, R. T. Bakker. 2015. The first giant raptor (Theropoda: Dromaosauridae) from the Hell Creek Formation. University of Kansas Paleontological Contributions 14: 1-16. 

Today’s shout out goes to the Saurian Developer Xane, at https://twitter.com/XaneFeather (tumbler @featheryraptor, though he doesn’t use it). Thank you for telling me about this wonderful discovery, Xane!

Hagryphus giganteus

By Ashley Patch on @apatchsketches

Name: Hagryphus giganteus 

Name Meaning: Ha’s griffin

First Described: 2005

Described By: Zanno & Sampson

ClassificationDinosauria, Saurischia, Eusaurischia, Theropoda, Neotheropoda, Averostra, Tetanurae, Orionides, Avetheropoda, Coelurosauria, Tyrannoraptora, Maniraptoriformes, Maniraptora, Pennaraptora, Oviraptorosauria, Caenagnathoidea, Caenagnathidae

Hagryphus was another oviraptorosaur from the Kaiparowits Formation in the Grand Staircase-Escalante National Monument in Utah. It lived in the Campanian age of the Late Cretaceous, about 75.95 million years ago. It is only known from scattered remains but it was a particularly large oviraptorosaur, about 3 meters long. It lived near the Western Interior Seaway, in an floodplain with large channels and wetland peat swamps, ponds and lakes, and boarderd around by highands. It lived in a wet and humid climate alongside many other types of dinosaurs: dromaeosaurids, Talos, Ornithomimus, Albertosaurus, Teratophoneus, ankylosaurids, Parasaurolophus, Gryposaurus, Utahceratops, Nasutoceratops, and Kosmoceratops. 



Shout out goes to virtualdeveloper!