Pronunciation: ed-MAR-kuh
Meaning: Belonging to Edmark
Author/s: Bakker et al. (1992)
Synonyms: None known
First Discovery: Wyoming, USA
Discovery Chart Position: #367
Edmarka rex
When Robert Bakker and his team pulled bones from Wyoming's famous Como Bluff in the earliest 1990s, they knew they had discovered something enormous. A partial skeleton, including a piece of skull, ribs and a shoulder girdle, was enough to suggest they belonged to a theropod rivalling Tyrannosaurus rex in size, and a new king was crowned—Edmarka rex, truly the apex predator of the Late Jurassic Morrison Formation. To Bakker, this creature represented the ceiling for predator size: any larger, and the biomechanics of land-based hunting might break down entirely. Yet in the end, it wasn't the biomechanics of hunting that broke down, but the name itself.
Despite their impressive size and subtle quirks, later studies concluded that the bones belonged not to theropod royalty, but fell within the accepted variation of Torvosaurus tanneri, a megalosaur already known from the Morrison Formation. The name Edmarka was dismissed and slipped quietly into synonymy, remembered more as a flash of Bakker's flair than as a lasting addition to the dinosaur canon. And it wasn’t alone. Other colourful monikers, like the informal-but-catchy "Brontoraptor"—the Thunder Plunderer—from the same area have likewise been folded into Torvosaurus.
However, simply declaring "they're the same" doesn’t quite cut it in the digital age. Fossils deserve more than a quick eyeballing; they demand detailed redescriptions, careful anatomical comparisons, and ideally CT scans to probe their internal structures. Only then can palaeontologists be confident about whether a specimen truly belongs to an established genus or merits a name of its own. And that hasn't happened. Yet.
Despite their impressive size and subtle quirks, later studies concluded that the bones belonged not to theropod royalty, but fell within the accepted variation of Torvosaurus tanneri, a megalosaur already known from the Morrison Formation. The name Edmarka was dismissed and slipped quietly into synonymy, remembered more as a flash of Bakker's flair than as a lasting addition to the dinosaur canon. And it wasn’t alone. Other colourful monikers, like the informal-but-catchy "Brontoraptor"—the Thunder Plunderer—from the same area have likewise been folded into Torvosaurus.
However, simply declaring "they're the same" doesn’t quite cut it in the digital age. Fossils deserve more than a quick eyeballing; they demand detailed redescriptions, careful anatomical comparisons, and ideally CT scans to probe their internal structures. Only then can palaeontologists be confident about whether a specimen truly belongs to an established genus or merits a name of its own. And that hasn't happened. Yet.
(Edmark's King)Etymology
Edmarka honours scientist Bill Edmark.
The species epithet, rex, means "king" in Latin.
Before being officially named, it was affectionately known as "Terminator".
Discovery
The type remains of Edmarka were discovered in the Morrison Formation at Nail Quarry, Como Bluff, Albany county, Wyoming, USA, by Robert T. Bakker and D. Kralis in 1990-1991.
The holotype (CPS 1002) is a cheek bone. Given their discovery in the same 3m x 2m square, CPS 1005 (ribs) and CPS 1006 (a left shoulder girdle) likely belong to the same individual. Referred material includes CPS 1003 (a shoulder bone known as a coracoid) from the holotype site and CPS 401 (six back ribs) found by Siegwarth and Filla at Louise Quarry in 1989. In a 2025 GSA abstract, Justice Duncan and Scott Persons united GPM/TATE 0050 (a pubis and partial ischium) and GPM/TATE 0012 (a nearly complete pelvis, both thighs, a shin and a calf, a left shoulder blade, several tail vertebrae and chevrons, informally referred to as "Brontoraptor") from Nail Quarry. They found no traits sufficient to distinguish these specimens from Edmarka rex, and assigned them there, based mainly on equally robust shoulder blades. Furthermore, they highlighted an extensive suite of characters that differ from Torvosaurus tanneri.
