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Description

A classic duel from the old motion picture age, a Tyrannosaurus rex (12 meters) clashing with an Agathaumas sphenocerus (9 meters), Wyoming, 67 mya.

Now, let’s see how many people won’t bother to read past this first paragraph and make unsubstantiated assumptions.

Basically, this is a “what if” scenario, humoring the idea that this ceratopsian chimera was real and a part of the late Maastrichtian megafauna of Laramidia, alongside Triceratops and Torosaurus.

If you don’t know, Agathaumas sphenocerus was a ceratopsian that seemingly had it all, a long nose horn, brow horns and a large spiky frill, combining all the best traits of its various cousins, like Triceratops and Styracosaurus. Its popularity spiked with Charles R. Knight’s iconic illustration of the animal, which showed its impressive headgear. Agathaumas became a staple in old dinosaur textbooks and stop motion movies, like The Lost World (1925), where it was depicted fighting a T. rex. Its distinctive visage also undoubtedly inspired generations of cheap cartoon depictions of ceratopsians that were mash-ups of Triceratops and Styracosaurus, in the same vein as how Pteranodon and Rhamphorhynchus frequently get merged into one generic “pterodactyl”.

Unfortunately, this magnificent dinosaur never actually existed; it was a chasmosaur/centrosaur chimera before they became a thing on Saturday Morning. The large holotype specimen (9 meters) was dug up in the Lance Formation of Wyoming and named by Edward Drinker Cope in 1872, it’s only made up of partial postcranial remains, consisting of hip bones, hip vertebrae and ribs, making it the first-named ceratopsian. Unfortunately, the giant ceratopsians of the Campanian and Maastrichtian tend to vary very little in terms of postcranial anatomy, making it difficult for workers to identify individual specimens on a taxonomic level without a skull for them to examine, which doomed the validity of Agathaumas from the start.

Skull material attributed to the genus was eventually found, showing a large nasal horn and possible brow horns, which inspired Knight’s legendary chimera. But the skull material ultimately proved to belong to Monoclonius, which has also been rendered a nomen dubium, as all of its material has been sunk into Centrosaurus and Styracosaurus, while the Agathaumas holotype is more than likely just a Triceratops, the first one to be discovered at that.

With the loss of its validity, Agathaumas eventually faded into obscurity as stop-motion dinosaurs entered the age of color films, with Monoclonius enjoying some limelight in features like Dinosaur! (1985), before being phased out as well following its loss of validity and becoming a synonym of Centrosaurus.

Description

A classic duel from the old motion picture age, a Tyrannosaurus rex (12 meters) clashing with an Agathaumas sphenocerus (9 meters), Wyoming, 67 mya.

Now, let’s see how many people won’t bother to read past this first paragraph and make unsubstantiated assumptions.

Basically, this is a “what if” scenario, humoring the idea that this ceratopsian chimera was real and a part of the late Maastrichtian megafauna of Laramidia, alongside Triceratops and Torosaurus.

If you don’t know, Agathaumas sphenocerus was a ceratopsian that seemingly had it all, a long nose horn, brow horns and a large spiky frill, combining all the best traits of its various cousins, like Triceratops and Styracosaurus. Its popularity spiked with Charles R. Knight’s iconic illustration of the animal, which showed its impressive headgear. Agathaumas became a staple in old dinosaur textbooks and stop motion movies, like The Lost World (1925), where it was depicted fighting a T. rex. Its distinctive visage also undoubtedly inspired generations of cheap cartoon depictions of ceratopsians that were mash-ups of Triceratops and Styracosaurus, in the same vein as how Pteranodon and Rhamphorhynchus frequently get merged into one generic “pterodactyl”.

Unfortunately, this magnificent dinosaur never actually existed; it was a chasmosaur/centrosaur chimera before they became a thing on Saturday Morning. The large holotype specimen (9 meters) was dug up in the Lance Formation of Wyoming and named by Edward Drinker Cope in 1872, it’s only made up of partial postcranial remains, consisting of hip bones, hip vertebrae and ribs, making it the first-named ceratopsian. Unfortunately, the giant ceratopsians of the Campanian and Maastrichtian tend to vary very little in terms of postcranial anatomy, making it difficult for workers to identify individual specimens on a taxonomic level without a skull for them to examine, which doomed the validity of Agathaumas from the start.

Skull material attributed to the genus was eventually found, showing a large nasal horn and possible brow horns, which inspired Knight’s legendary chimera. But the skull material ultimately proved to belong to Monoclonius, which has also been rendered a nomen dubium, as all of its material has been sunk into Centrosaurus and Styracosaurus, while the Agathaumas holotype is more than likely just a Triceratops, the first one to be discovered at that.

With the loss of its validity, Agathaumas eventually faded into obscurity as stop-motion dinosaurs entered the age of color films, with Monoclonius enjoying some limelight in features like Dinosaur! (1985), before being phased out as well following its loss of validity and becoming a synonym of Centrosaurus.