Named By: E. Tschopp, O. Mateus & R. B. J. Benson - 2015.
Synonyms: Diplodocus hayi.
Classification: Chordata, Reptilia, Dinosauria, Saurischia, Sauropoda, Diplodocidae, Diplodocinae.
Species: G. hayi (type), G. pabsti.
Size: Holotype individual roughly about 27 meters long based upon 1.44 meter femur, 0.98 meter fibula and scaled to standard diplodocine diplodocid sauropod proportions.
Known locations: USA, Morrison Formation deposits in Colorado and Wyoming.
Time period: Kimmerigian of the Jurassic.
Fossil representation: Skulls and partial post cranial fossils from several individuals.
history of Galeamopus goes all the way back to
1902 when the
first fossils were discovered in the US state of Wyoming. In 1906
the fossils were assigned to the Diplodocus
genus, but in 1924
they were given their own species D. hayi,
upon the basis that
they were clearly different to other Diplodocus
type species. For
almost a century afterwards, D. hayi was held
as a valid species of
Diplodocus, but then in 2015 everything
changed. A study
conducted by Emanuel Tschopp, Octávio Mateus and Roger Benson focused
upon spotting key differences between fossils assigned to both genera.
What they found was the specimens of Diplodocus hayi
clear autapomorphies that distinguish it as distinct from other
Diplodocus species, enough to make it a separate
genus which now
bears the name Galeamopus. However, while this
revision was big
news in itself, it was overshadowed by an even bigger story, when
this same study also concluded that Brontosaurus
was actually separate
making Brontosaurus a scientifically valid genus
for the first time since 1903.
At this point it should be obvious that Galeamopus was what is known as a diplodocid sauropod, but this can be refined further to calling it a diplodocine due to its closer similarity to Diplodocus. Diplodocine members of the Diplodocidae are noted as being more gracile (lightly built) than their apatosaurine (closer to Apatosaurus) cousins. Galeamopus also certainly had a whip-like tail that may have been capable of producing loud cracking sounds. It is also possible that Galeamopus had a series of short keratinous spines running down the length of its body as these have been seen in some other species of diplodocid sauropods.
- A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). - PeerJ 3:e857. - E. Tschopp, O. Mateus & R. B. J. Benson - 2015.
- Osteology of Galeamopus pabsti sp. nov. (Sauropoda: Diplodocidae), with implications for neurocentral closure timing, and the cervico-dorsal transition in diplodocids. - PeerJ. 5. - Emanuel Tschopp & Octávio Mateus - 2017.