Amphicoelias
Name:
Amphicoelias
(both sides hollow).
Phonetic: Am-fee-see-le-as.
Named By: Edward Drinker Cope - 1878.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Sauropoda, Diplodocoidea.
Species: A. altus (type).
Diet: Herbivore.
Size: Roughly estimated to be about 25 meters long.
Refer to main text for more details.
Known locations: USA, Colorado.
Time period: Kimmeridgian to Tithonian of the
Jurassic.
Fossil representation: Fragmentary and isolated
remains, original fossils are now lost.
For
one hundred and forty years Amphicoelias was
regarded by some to have
been one of the largest dinosaurs to ever walk the earth. First named
in 1878 by Edward Drinker Cope, and based upon some truly large
fossils of vertebrae and partial limbs and pubis bones. Three species
were named, A. altus, A.
fragillimus and A. latus. When the
largest fossils belonging to A. fragillimus
compared to fossils of
the dinosaur Diplodocus
and scaled up to match the size of the new
vertebrae, Amphicoelias was regarded to being at
least forty to maybe
even sixty meters long. Then a bizarre thing happened, the large
fossils of Amphicoelias disappeared.
For
the remainder of the nineteenth and throughout the twentieth century,
Amphicoelias was spoken about as an almost mythical
dinosaur genus.
The only evidence that these fossils existed were the drawings
included with the original description, and not from multiple sides
and angles as they usually would have been rendered. It is also
worth remembering that this happened during the Bone Wars, the
great paleontological rivalry between Edward Drinker Cope and Othniel
Charles Marsh as they raced against one another to catalogue as many
fossils as possible. It could be that the missing fossils are
somewhere in a museum storage facility, forgotten about for over a
century.
Throughout
the twentieth century the scientific community steadily learned much
more about dinosaurs, and Amphicoelias existed as
a dubious genus,
very difficult to fact check against. In 1921 one species,
A.
latus which was based upon the description of tail vertebrae
and a
femur (thigh bone) was actually found to actually be from the
dinosaur Camarasaurus.
This left Amphicoelias with the type species
A. altus and the other species A.
fragillimus. Several times it
has been suggested that these two species were one and the same, just
the fossils of A. fragillimus were of a larger
individual. Most of
the previous forty to sixty meter length estimates were because of the
A. fragillimus fossils.
Some
researchers however began to note that the drawing of the fossil
vertebra of A. fragillimus was actually less like
a diplodocid
sauropod, but more like a rebbachisaurid sauropod. The
rebbachisaurid sauropods are usually treated as a sub group of
diplodocids, related to them but morphologically different. No one
knew about rebbachisaurid sauropods when Amphicoelias
was named, it
was only in the latter half of the twentieth century that they began to
be discovered. In 2018 Kenneth Carpenter formalised the
assessment, and moved A. fragillimus into its
own genus, as the
rebbachisaurid sauropod Maraapunisaurus
fragillimus. Comparing the
known material of Maraapunisaurus fragillimus to
more complete
rebbachisaurid sauropod genera such as Limaysaurus
and adjusting for
size has led to estimates of a little over thirty meters long, not
forty to sixty for Maraapunisaurus fragillimus.
This
leaves A. altus as the only valid species, one
that is definitively
a diplodocid sauropod dinosaur. Comparing what we know about the size
of the original fossils of A. altus, we know
that the individual
dinosaur that left these fossils was probably around twenty-five meters
long. This means that while Amphicoelias was a
big dinosaur, it was
certainly within the known size scope of the diplodocid sauropod
dinosaurs.
Because of the lack of surviving fossil material we still don’t know much about the Amphicoelias genus. But as a diplodocid sauropod dinosaur we can infer that it would have been a large twenty-five long herbivore, using its long neck to either reach food growing up in trees or sweeping over wide expanses of low growing plants. Many other types of sauropod dinosaurs shared its environment as well as smaller ornithopod dinosaurs and also stegosaurs too. Some large predators such as Allosaurus would have also been present.
Further reading
- On the Vertebrata of the Dakota Epoch of Colorado, Edward Drinker
Cope - 1878a.
- Camarasaurus, Amphicoelias
and other sauropods of Cope, H.
F. Osborn & C. C. Mook - 1921.
- New remains of Amphicoelias Cope
(Dinosauria: Sauropoda) from
the Upper Jurassic of Montana and diplodocoid phylogeny, J. A.
Wilson & M. Smith - 1996.
- Biggest of the big: a critical re-evaluation of the mega-sauropod
Amphicoelias fragillimus." In Foster, J.R. and
Lucas, S.G.,
eds, K. Carpenter - 2006.
- A new basal diplodocid species, Amphicoelias
brontodiplodocus,
from the Morrison Formation, Big Horn Basin, Wyoming, with
taxonomic reevaluation of Diplodocus, Apatosaurus,
and other
genera, H. Galiano & R. Albersdorfer - 2010.
- Maraapunisaurus fragillimus, N.G. (formerly Amphicoelias
fragillimus), a basal Rebbachisaurid from the Morrison
Formation (Upper
Jurassic) of Colorado. - Geology of the Intermountain West. 5: 227–244.
- K. Carpenter - 2018.
----------------------------------------------------------------------------
Random favourites
 |
 |
 |
 |