Name:
Brontosaurus
(Thunder lizard).
Phonetic: Bron-toe-sor-us.
Named By: Othniel Charles Marsh - 1879.
Synonyms: Apatosaurus excelsus, Elosaurus,
Eobrontosaurus.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropoda, Diplodocidae, Apatosaurinae.
Species: B. excelsus
(type), B. parvus, B. yahnahpin.
Diet: Herbivore.
Size: B. excelsus and B.
parvus estimated to be
about 22 meters long. B. yahnahpin
estimated to be about 21
meters long.
Known locations: USA - Morrison Formation
deposits in Wyoming and Utah.
Time period: Kimmeridgian of the Jurassic.
Fossil representation: Several individuals including
some fossils of juveniles.
The turbulent history of
Brontosaurus
For
well over one hundred years there was a great question asked amongst
dinosaur enthusiasts; is Brontosaurus actually Apatosaurus?
Well
this all began in a period of American paleontological history dubbed
the ‘bone wars’, a fierce rivalry between two men named Edward
Drinker Cope and Othniel Charles Marsh. Both men named a great many
prehistoric animals in an effort to outdo one another, and much of
their work was rushed meaning that later palaeontologists had to revise
their work in more detail.
During
this time Marsh would name what would become two of the most famous
dinosaurs of all time, Apatosaurus in 1877,
and Brontosaurus in
1879. Not much else was really heard about these dinosaurs until
1903 when Elmer S. Riggs, a palaeontologist noted for his work
on sauropod dinosaurs came to the conclusion that Brontosaurus
was so
similar to Apatosaurus that it should become a
synonym. However,
when the first skeleton of Apatosaurus was mounted
in the American
Museum of Natural History in 1905, it bore the name Brontosaurus
as
this had been picked out by Henry Fairfield Osborn (who in 1905
would also name Tyrannosaurus).
This
one mounted skeleton is the reason why so much controversy would exist
for this dinosaur for over a hundred years. As far as science was
concerned, Brontosaurus did not exist except as a
synonym to
Apatosaurus, but the wider public only really
heard about
Brontosaurus, after all, Brontosaurus
was the name on the display.
From that point on Brontosaurus would get star
billing in almost every
popular science book about dinosaurs that was marketed towards children
and the general public, as well as appear in later films featuring
dinosaurs.
Aside
from the naming confusion the mounted skeleton was not perfect. The
skull was still unknown, so a man named Adam Hermann sculpted one
based upon a dinosaur named Morosaurus, today
listed as a synonym to
Camarasaurus.
The first clue to the true form of the skull came when
the first Apatosaurus skull was found in 1909
by Earl Douglas,
and it was immediately apparent that Apatosaurus
had a similar skull
to the sauropod dinosaur Diplodocus.
By extension this would mean
that the Brontosaurus display would need to have a
new skull, and
this was the opinion of Douglas and the then museum curator William
H. Holland. However Henry Fairfield Osborn disagreed with this
identification because the skull was found disarticulated from other
remains. Later the mounted skeleton was left headless until 1934
when after Holland’s death, a cast of a Camarasaurus
skull was added
to it, once again giving it a box like had, something that would be
repeatedly copied in all paleoart for Brontosaurus.
It
was not until a 1975 study by John Stanton McIntosh and David
Berman re-describing the skull and jaws of Apatosaurus
and Diplodocus
was published that things would really get moving for more accurate
reconstructions. Specifically, many skulls of Apatosaurus
had been
known for a long time, they had just mistakenly been added into the
Diplodocus genus on the basis of superficial
similarities. McIntosh
and Berman also noted that Holland was correct in his interpretation
that the Brontosaurus mount had the wrong skull
form. In October
1979, the first true Apatosaurus skull was
mounted upon an
Apatosaurus skeleton. In 1995 the original Brontosaurus
mount
from 1905 in the American Museum of Natural History finally got a
skull revision to be like that of Apatosaurus,
and was also now named
as Apatosaurus excelsus, and not Brontosaurus
excelsus. In 2011
the first Apatosaurus skull still articulated to
the cervical
(neck) vertebrae was described.
It
took the best part of a century to reveal the true shape and form of
Apatosaurus, and for most of this time the
majority of
palaeontologists agreed with the opinion of Elmer S, Riggs from
1903 that Brontosaurus should be a synonym to
Apatosaurus. One
notable exception however was Robert T. Bakker, who in 1998
argued that Apatosaurus and Brontosaurus
are actually different enough
to merit keeping Brontosaurus as a separate genus.
It would not be
until 2015 however that an extremely in-depth study conducted by
Emanuel Tschopp, Octavio Mateus and Roger Benson would reveal one of
the most ground breaking conclusions for over one hundred years.
Using a statistical analysis of fossil specimens attributed to various
different Apatosaurus species, they found that
fossils once
attributed as the Brontosaurus type species B.
excelsus, could
indeed be classed as different enough to resurrect it as a valid
genus. They also concluded that the genera Elosaurus
and
Eobrontosaurus are actually synonymous with Brontosaurus.
Brontosaurus
the dinosaur
When
first presented to the public Brontosaurus was a
fairly generic
sauropod
dinosaur with four legs, long neck, long tail and a robust
almost box-like head. Thanks to over one hundred years of study
conducted upon Diplodocus and Apatosaurus,
we now have a much better
idea of what Brontosaurus would have been like.
For a start the skull
of Brontosaurus would have been quite elongated and
not at all like
Camarasaurus, which by the way is a very different
kind of sauropod
often referred to as a macronarian.
Brontosaurus
is what is known as a member of the Diplodocidae due to its superficial
similarity to Diplodocus. The Diplodocidae can be
further broken down
into the Diplodocinae for members closer to Diplodocus
and the
Apatosaurinae which is for members closer to Apatosaurus
and are
usually more robustly built than diplodocines. Because of its
similarity to Apatosaurus, Brontosaurus
can have its classification
refined to that as an apatosaurine diplodocid sauropod dinosaur.
Brontosaurus
used to be given a tail that was fairly short and generic, but we now
know that Brontosaurus would have had a whip-like
tail. Brontosaurus
may have been able to crack this whip-tail to produce loud bangs.
This may have been for signalling to others, used in dominance
contests (the loudest sound belonging to the fittest/most powerful
individual) to even deterring predatory dinosaurs such as
Allosaurus,
Torvosaurus
or Ceratosaurus,
or perhaps even a
combination of all of the above.
Classic
depictions of Brontosaurus usually show it
wallowing around in swamps
and lakes, often so submerged that only the head is above the water.
This goes back to thinking going back to the nineteenth century that
sauropods were so huge and heavy that they would need to use water
buoyancy to take the load of their bodies off their legs and while they
did this they would feed upon underwater plants while using their long
necks to reach the surface of the water to breathe. This is not a bad
idea, it’s just the wrong idea.
For
a start the buoyancy is achieved by the water exerting pressure upon
body. The water pressure exerted upon the lungs of an animal the
size of Brontosaurus completely submerged in the
water would be so
great that breathing would be at best difficult, at worst near
impossible, even if the head was out of the water. There is also
the simple fact that the overwhelming majority of sauropods fossils
come from what are dry inland areas such as plains and even sparse
forests, some of which would have been several hundred feet above sea
level back in the late Jurassic. Brontosaurus was
certainly a
dinosaur that preferred dryer inland areas, only approaching bodies
of water to drink.
Brontosaurus
is one of a great many sauropod genera known from the famous Morrison
Formation of North America, though some have speculated that there
may be ‘too many’ sauropod genera and some may represent synonyms
to others. Indeed, just as many have wanted Brontosaurus
to be
separated from Apatosaurus, there are others who
still credit it as
synonymous with Apatosaurus. Aside from
Diplodocus, Apatosaurus and
Camarasaurus already mentioned, other sauropods
that Brontosaurus may
have come into contact with at some time or another include
Brachiosaurus,
Haplocanthosaurus,
Supersaurus,
Galeamopus,
Barosaurus
and the colossal Amphicoelias
amongst others.
Brontosaurus would have likely encountered other
famous names such as
Stegosaurus,
Camptosaurus,
Ornitholestes,
Dryosaurus
and
Mymoorapelta,
as well as larger predatory dinosaurs such as
Allosaurus, Ceratosaurus, Torvosaurus
and Saurophaganax.
Further reading
- Notice of new Jurassic reptiles. - American Journal of Science and
Arts 18:501-505. - O. C. Marsh - 1879.
- Elosaurus parvus: a new genus and species of the
Sauropoda. - Annals
of Carnegie Museum 1:490-499. - O. A. Peterson & C. W. Gilmore
- 1902.
- Structure and Relationships of Opisthocoelian Dinosaurs. Part I,
Apatosaurus Marsh. - Publications of the Field
Columbian Museum
Geographical Series 2 (4): 165–196. - Elmer S. Riggs - 1903.
- Osteology of Apatosaurus, with special references
to specimens in the
Carnegie Museum. - Memoirs of the Carnegie Museum 11 (4): 1–136. - C.
W. Gilmore - 1936.
- Description of the Palate and Lower Jaw of the Sauropod Dinosaur
Diplodocus (Reptilia: Saurischia) with Remarks on
the Nature of the
Skull of Apatosaurus. - Journal of Paleontology 49
(1): 187–199. - J.
S. McIntoshh & D. S. Berman - 1975.
- A new species of sauropod, Apatosaurus yahnahpin.
- Wyoming
Geological Association Field Conference 1994:123-134. - J. Filla
& P. Redman - 1994.
- Apatosaurus yahnahpin: a preliminary description
of a new species of
diplodocid dinosaur from the Late Jurassic Morrison Formation
(Kimmeridgian-Portlandian) and Cloverly Formation (Aptian-Albian) of
the western United States. - M�moires de la Soci�t� G�ologique de
France (Nouvelle S�rie) 139 (Ecosyst�mes Continentaux du M�sozoique):
87-93. - J. A. Filla, P. D. Redman - 1994.
- Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in
Wyoming and Colorado, by Robert T. Bakker. In, Lower and Middle
Cretaceous Terrestrial Ecosystems. - New Mexico Museum of Natural
History and Science Bulletin, 14: 67–77. - S.G. Lucas, J.I. Kirkland,
& J.W. Estep (eds.). - 1998.
- A specimen-level phylogenetic analysis and taxonomic revision of
Diplodocidae (Dinosauria, Sauropoda). - PeerJ 3: e857.
- Emanuel Tschopp, Octavio Mateus & Roger Benson -
2015. - P. M. Barrett, G. W. Storrs, M. T. Young & L. M.
Witmer - 2011.
- A specimen-level phylogenetic analysis and taxonomic revision of
Diplodocidae (Dinosauria, Sauropoda). - PeerJ 3:e857. -
E. Tschopp, O. Mateus & R. B. J. Benson -
2015