#agathaumas

#RETROVEMBER2025: 3. Agathaumas sphenocerus

A large ceratopsid dinosaur which may be related to Triceratops. This dinosaur is heavily armored, much more than its relatives. This must be a result of its more sluggish nature as it would rather stand its ground than flee from danger. Size varies from individuals, but some grow to be larger than Triceratops.

Regaliceratops peterhewsi for @a-dinosaur-a-day's Draw Dino's Daily

I always associate Regaliceratops with Charles R. Knight's Agathaumas painting.

Agathaumas is likely synonymous with Triceratops, making it a Chasmosaurine, but due to the limited fossil remains he painted it with a large nose horn, smaller brow horns, and prominent frill epiossifications, as well as a back covered in large scales. Regaliceratops is a Chasmosaurine with a nasal horn larger than its brow horns and prominent frill epiossifications (albeit much less prickly looking) and with its close relation to Triceratops may also have bore similarly large scales upon its back.

Celebrating The Lost World, 100 years later!

On February 8th, 1925, the first major film featuring dinosaurs was presented to the public for the first time. The Lost World, an adaptation of Sir Arthur Conan Doyle’s 1912 novel of the same name, featured the stop-motion saurians of Willis O’Brian (who’d later work on King Kong) who pioneered special effects in cinematography. The animals seen in the film, while outdated anatomically, move rather dynamically: running around, gruesomely attacking each other to the bewilderment and excitement of 1920s audiences. To this day, The Lost World has some of the most adaptations of any dinosaur media.

The Dynamo V. Aga storyboard for my passion project Saurian Archipelago has been completed! Feel free to give thoughts, I'm proud with how this all came out! It took about 3 weeks to make everything, with 135 pictures.

The Dynamosaurus and Agathaumas are behemoth dinosaurs in an isolated archipelago ecosystem, both standing as natural enemies, what force and danger do they pose when they're in eachother' sights?!

It's been a century since the first adaptation of Sir Arthur Conan Doyle's original novel. This movie holds a special place for me as the first silent film and vintage monster movie I ever saw.

I first learned about the movie from a museum exhibit on Charles R. Knight, and it's easy to see why it was highlighted. More than any other dinosaur film this feels like one of his paintings in motion. Willis O' Brian set the standard for active dinosaurs in film: Sauropods stampede across dry land, while theropods leap onto and grapple their prey. He and his protege Ray Harryhausen would expand on and refine this dynamic portrayal throughout their careers, going against the contemporary scientists' and even Charles R. Knight's characterization of dinosaurs as sluggish, ungainly animals.

Sadly O' Brien's later work did not carry on the Lost World's depiction of dinosaurs as living animals rather than perpetually bloodthirsty monsters. Much of the movie's extensive stop motion is dedicated to dinosaurs going about their business, living in families, hunting or browsing, only occasionally interacting with our human leads. Very few films have the ambition to depict a full on prehistoric ecosystem. It's by no means devoid of sensationalism: the carnivores have a habit of attacking other animals with food already available or losing their meals like klutzes. Still, it took a long time for other films to even differentiate herbivorous dinosaurs from meat eaters.

Even modern dinosaur movies could learn a thing or two about how The Lost World treats its herbivores: while they rarely start fights, they are more than capable of finishing them. Instead of passive meals, the prey animals are often able to repel and even kill their predators, fighting back with a vicious desperation rarely see in movies but all too common in the natural world. This more balanced approach is a breath of fresh air compared to the theropod fixation common in modern palaeomedia.

Modern big budget dinosaur movies could also learn from The Lost World's restraint. The problem with using Tyrannosaurus rex as the baseline Big Theropod is there is nowhere to escalate without pulling things out of your ass (see the Jurassic World movies). T. rex was essentially the final boss of non-avian theropods; while a few other theropods may have matched or slightly exceeded it in length, none were as heavily built, none had such a strong bite, and none combined it with the Tyrannosaurids' impressive suite of senses and intelligence. Tyrannosaurus was described only 20 years prior to the Lost World film, which opts to use the more established Allosaurus as the main saurian antagonist, but highlights the more impressive newcomer during a few key scenes. I often wish T. rex could have remained this seldom seen novelty rather than becoming a tired old measuring stick.

Most relevant to my usual focus, The Lost World is—to my knowledge—the first film to depict a giant monster rampaging through a city. The Brontosaur's frenzied escape from London prefigures much of King Kong's final act (though with a less tragic end), and O' Brien's miniature work holds up pretty well. Even now the large sauropod stands out compared to the giant apes, theropods, and other more fanciful usual suspects.

I've talked about The Lost World (1925) a few times on this blog, partly due to it being the very first feature length film depicting dinosaurs, and partly due to how effective it is as a snapshot of dinosaurs during the early 1900s.

Anyone who has seen the film will note that there are actually two species of ceratopsians portrayed. The first is the more famous Triceratops, as seen in the photo above on the left.

The one on the right resembles a Triceratops, but looks a little...different. The nasal horn is a lot longer, the frill exhibiting more spikes, and it's hide more heavily armoured.

As you might've guessed, this isn't Triceratops. In fact...it's a dinosaur that may not have even existed.

Meet Agathaumas sylvestris ("marvelous forest-dweller"), one of the oldest described ceratopsians ever recorded. In fact, it was "discovered" before ceratopsians were even properly described.

The original partial remains (AMNH 4000) were discovered in 1873 by Fielding Bradford Meek and Henry Martyn Bannister near Black Butte and Bitter Creek in Wyoming. They were eventually sent to the famous paleontologist Edward Drinker Cope who initially described it as a hadrosaur due to how fragmentary the fossils were. It wasn't until his rival Othniel Marsh described Triceratops did Cope recognize it as a ceratopsian in 1889.

And here's where things get...interesting.

As anybody interested in paleontological topics should know, Cope and Marsh were locked in a fierce rivalry called the Bone Wars, where the two competed to find the most specimens and describe the most species. In a series of publications ("The horned dinosauria of the Laramie" from the American Naturalist) Cope initially didn't recognize the name "ceratopsid" as a proper family name (believing that the namesake Ceratops wasn't related), and even argued for his own classification: Agathaumids. Furthermore, he grouped 4 other of his discoveries together in this family: Monoclonius, Dysganus, Manospondylus, and Claorhynchus.

Despite his efforts, Cope's gambit ultimately failed when in 1907, Agathaumas's validity was challenged by John Bell Hatcher. Due to the fragmentary nature of the fossils, it was later reclassified as a pseudonym for Monoclonius. This isn't anything unique for species described in the Bone Wars due to the rush to name new animals. And to rub salt in the wound, all of the members of the Agathaumids were considered to be nomen dubium (doubtful name) while Marsh's name Ceratopsids was chosen as the classification for the group (The Ceratopsia).

Armor for Agathaumas – Incertae Sedis (wordpress.com)

So where does that leave Agathaumas and the original remains? Nowadays, while the remains are still considered a holotype, it's widely considered to be a centrosaur. The painting by Charles R. Knight as seen from above came from the species Agathaumas sphenocerus, later reclassified as a species of Monoclonius, which is now believed to have been described from specimens of Styracosaurus and Centrosaurus. The reconstruction would later be used for the animal's depiction in the 1925 The Lost World. The genus as a whole is now typically regarded as synonym for Marsh's dinosaur, Triceratops (in a bit of irony).

So while now considered nomen dubium, Agathaumas is still rather interesting due to how a once notable dinosaur fell victim to science marching on, and how it got caught in the center of a notorious rivalry.

A big thanks to the I Know Dino podcast for covering this. Feel free to check them out cause they have a lot of good material for dinosaur enthusiasts. Also feel free to check out any of the articles cited in the post if you want some additional reading, and this great video by E.D.G.E from YouTube.