Forgotten Dinosaurs: Agathaumas sylvestris

In 1872, Edward Cope named Agathaumas sylverstris, based on a pelvis and a number of vertebrae discovered in southwest Wyoming. It was technically the first ceratopsian dinosaur to be named and described, but without a skull, Cope had little idea of what the animal looked like.  

The discovery of Triceratops and Monoclonius (=Centrosaurus) fossils would provide a better idea of what sort of animal Agathaumas was. Still, it remains unclear how journalist William Ballou came up with this published description:

“Its ponderous horned skull suggests the appearance of a rhinoceros, and its high, curved back and bulk an elephant. In front was a knife-like beak, on the nose a stout horn, and on the top of the head a pair of large pointed horns, and on the back of the head a row of sharp projections.”

Although not based on any particular fossil evidence, the Ballou description was presumably the basis for Charles Knight's Agathaumas painting (above), which depicts the dinosaur as a sort of spiny uber-Triceratops. Knight’s painting was in turn copied exactly for the Agathaumas that appeared in the 1925 film "The Lost World". 

Today, all fossils referred to Agathaumas are thought to be Triceratops, and the name-bearing holotype is a non-diagnostic nomen dubium

anonymous asked:

Is Brontosaurus considered "real" again? (And could you talk a little about what makes a Dino "real"? I've had people tell me that "triceratops isn't real" because of the torosaurus thing, and I don't quite have the understanding or vocabulary to explain to them why that's not right.)

Of course! In order for a genus/species to be considered valid/”real”, it has to be the first name given to that type of organism. Imagine Palaeontologist A discovers a new dinosaur and names it Palaeofailsaurus. Then a month later, Palaeontologist B uncovers another specimen of the same dinosaur and names it Adinosauradayopteryx. Since Palaeofailsaurus was named first, it is considered valid (assuming no other problems with the paper), and “Adinosauradayopteryx” is considered a junior synonym and invalid.

In the specific cases you mentioned”


  • Is currently considered valid (”real”) again
  • Originally Apatosaurus was discovered and named
  • Soon after Brontosaurus was discovered and named
  • As the two are very closely related and similar in appearance, Brontosaurus was largely considered a junior synonym of Apatosaurus, but as several separate species within the same genus
  • Recent cladistic analyses, however, suggest that the species of traditional Apatosaurus and those of traditional Brontosaurus are more closely related to each other than to the other group
  • Because of this, Brontosaurus is back.


  • Isn’t going anywhere
  • Technically is the junior synonym of Agathaumas, but no one can prove it
  • The validity of Torosaurus is what’s up for debate.
  • It’s possible that Torosaurus is actually the fully adult form of Triceratops.
  • However, Triceratops was named before Torosaurus, so if this is indeed the case Torosaurus goes, not Triceratops.
  • Torosaurus’s validity is still up in the air; I personally don’t feel that there’s enough evidence to definitively say either way.

Hope this helps!

In 1897, artist Charles Knight painted Agathaumas for Cope, creating an imposing beast which blended the long facial horns of Triceratops with the spiked frill of the Styracosaurus. The artwork was later used as basis for a model Agathaumas used in the 1925 film The Lost World.


Agathaumas (“great wonder”) is a dubious genus of a large ceratopsid dinosaur that lived in Wyoming during the Late Cretaceous (late Maastrichtian stage, 66 million years ago). The name comes from Greek, αγαν - ‘much’ and θαυμα - 'wonder’. It is estimated to have been 30 ft long and weighed 6 tons, and was the largest land animal known at the time of its discovery.

It was the first ceratopsian known to science, though relatively little is known about it. The original specimen consisted only of the animal’s hip bones, hip vertebrae and ribs, and because these bones vary little between ceratopsid species, it is usually considered a nomen dubium. It is provisionally considered a synonym of Triceratops, but is difficult to compare to that genus because it is only known from post-cranial remains.