The Wrongheaded Dinosaur
by Keith M. Parsons
Scientific facts are indisputable, arent they? Humans
have about 60,000 miles of blood vessels. The average depth of the ocean
floor is 13,124 feet. The Earth is 93 million miles from the sun. We believe
these claims because we trust in the process by which they were discovered.
Most of us, and most scientists, see science as a rational process, whereby
a field of competing theories and hypotheses yields one that is best supported
by reason and objective evidence. For such “rationalists,” science is the
model of organized rational activity.
This traditional view has been opposed in recent years by practitioners
of a new field called Science and Technology Studies (STS), who claim that
scientists are mistaken in thinking that their views are shaped mainly
by objective evidence. They regard a notion such as “objectivity” as passé.
Instead, they see nonscientific factors such as personal ambition, vested
social interests, ideology, racism and sexism playing a majoror exclusiverole
in molding scientific opinion. One branch of the STS movement aims to debunk
the notion of a scientific “fact” altogether, claiming that these so-called
“facts” are merely “constructs,” and that they are not “discovered” but
are “created” or constructed from what scientists agree upon as factual.
Now lest the reader too hastily dismiss this “constructivist” claim,
let me point out that some scientific episodes do raise doubts about scientific
objectivity and rationality. One major incident occurred at Carnegie Museum
of Natural History.
From 1934 to 1979, the museum displayed one of its prize dinosaur specimens
with the wrong head, an incident as potentially shocking as if a horse
skeleton were to be topped with a giraffes skull. During those 45 years
the museums great Apatosaurus louisae was displayed with a head that is
now regarded as belonging to Camarasaurusa very different sort of dinosaur.
This error supports the constructivist view. For 45 years Carnegie Museum
of Natural History, and the world, believed in a creature that never existed.
Of course, we now know that the Apatosaurus that was accepted for 45 years
was a construct, a figment of scientific imagination. But if this could
happen at one of the worlds great natural history museums, and, even worse,
be accepted by the whole paleontological community, who is to say that
the worlds museums are not still full of such chimeras? Lets look more
closely at just how Apatosaurus got the wrong head.
The late 19th and early 20th centuries are appropriately called the
“heroic age” of vertebrate paleontology. Great discoveries were announced
regularly, and vertebrate paleontology was an exciting adventure. In the
American West, range wars threatened to erupt as heavily armed fossil hunters
staked out their prize fossil beds. This spirit of fierce competition was
reflected by the museums that sponsored the fossil hunts and by the wealthy
patrons who funded the museums.
In November of 1898 Andrew Carnegie was interested to read that the
fossil remains of a dinosaur regarded as the “worlds most colossal animal”
had been discovered by a collector for the University of Wyoming at Laramie.
Carnegie sent a note and the newspaper clipping to W.H. Holland, director
of Carnegie Museum of Natural History, instructing Holland to buy the dinosaur
for his museum. But no such specimen existed; the University of Wyomings
collector had concealed the fact that he had found only a single leg bone.
In 1899 Carnegie therefore commissioned an expedition to find an appropriately
massive dinosaur.
Amazingly, on July 4 of that same year the expedition discovered the
rarest of paleontological findsan almost complete skeleton of an enormous
sauropod dinosaur, which the curator, J.B. Hatcher, named Diplodocus carnegii
after their benefactor. Carnegie was so delighted at the discovery that
he funded further expeditions, and within a few years a rich fossil site
had been located near Vernal, Utah. Named Carnegie Quarry, it was excavated
for many years by the museums fine field paleontologist Earl Douglass.
The quarry soon yielded a dinosaur even more massive than Diplodocusthe
huge Apatosaurus louisae, named for Carnegies wife, Louise. These two
magnificent specimens now dominate the Dinosaur Hall in Carnegie Museum
of Natural History.
The problem with Apatosaurus was that no skull was found connected to
the end of the neck. A Diplodocus-like skull, however, was found nearby.
Might this skull, catalogued as CM 11162, be the skull of Apatosaurus?
Both Holland and Douglass suspected that it might be. But the weight of
scientific opinion was against them.
CM 11162 was small, not much larger than a horses head, and it had
feeble, peg-like teeth. How could such a structure suffice to feed a giant
like Apatosaurus? It was not known until much later that these sauropods
ground their food in a gizzard, like birds do today. The weak teeth only
had to rake in the food, not chew it. More importantly, paleontologists
came to regard Apatosaurus as closer in overall structure to the larger-headed
Camarasaurus than to Diplodocus. The skull found close to the Carnegies
Apatosaurus looked decidedly like a Diplodocus skull.
Nevertheless, Holland insisted that CM 11162 was the skull of Apatosaurus.
He defended his view in an address to the Paleontological Society of America
in December 1914, but he left the mounted skeleton of Apatosaurus headless.
Why didnt Holland attach a cast of CM 11162 if he thought it was the right
one? Some have suggested that Holland wanted to avoid conflict with Henry
Fairfield Osborn, head of the American Museum of Natural History, who had
dared Holland to mount the Diplodocus-like skull. Holland, though, was
not afraid of controversy. On the contrary, he was a skilled polemicist
who could devastate opponents with a combination of biting sarcasm and
airtight logic.
A more likely explanation is that Earl Douglass continued to make spectacular
discoveries at Carnegie Quarry, and as long as Douglass excavations continued,
there was a chance that he would find an Apatosaurus neck with the skull
attached. Such a find, of course, would settle the dispute once and for
all. But a skeleton of Apatosaurus with the skull in place was never found.
In 1934, after Hollands death, the cast of a skull was placed on the headless
Apatosaurusnot CM 11162, but the skull that is now regarded as that of
a Camarasaurus.
Why was the cast of the Camarasaurus skull attached and who was responsible
for the decision? My research has failed to disclose an answer to the latter
question. Andrey Avinoff, director of Carnegie Museum in 1934, says in
his monthly report for May of that year only that the cast of the skull
“was mounted.” Records do not show who made the decision. However, it is
possible to speculate on what motivated the decision. In 1934, noted paleontologist
C.W. Gilmore came to the Carnegie to study the skeleton of Apatosaurus.
Gilmore did not endorse the Camarasaurus head, but he did assert that Holland
had been wrong in regarding CM 11162 as the correct skull. Further, the
bulk of paleontological opinion still favored an affinity between Apatosaurus
and Camarasaurus.
Probably, though, the strongest motivation for the decision to mount
the Camarasaurus head was not strictly scientific. The display of a headless
Apatosaurus no doubt had been a perennial source of embarrassment to the
museum. Unlike the Venus de Milo, Apatosaurus did not gain charm by being
displayed with parts missing. The Camarasaurus skull, meanwhile, was most
impressive. It was massive with big, strong teeth, an appropriate skull
for a monster like Apatosaurus. Thus, the decision was likely motivated
by a desire to impress the public.
So the Camarasaurus skull remained on Apatosaurus louisae until the
1970s, when Apatosaurus attracted the attention of J.S. McIntosh, the worlds
leading expert on sauropod dinosaurs. He reexamined all the evidence, including
the letters written by Earl Douglass describing his discoveries at the
Carnegie Quarry. McIntosh came to the conclusion that CM 11162, the Diplodocus-like
skull favored by Holland, was in fact the correct skull of Apatosaurus.
In 1978 McIntosh and Carnegie Museum paleontologist David Berman co-authored
the definitive monograph establishing that Apatosaurus did indeed have
a Diplodocus-like skull. By thoroughly examining the postcranial anatomy
of Apatosaurus and Diplodocus, Berman and McIntosh showed that Apatosaurus
bore a much greater anatomical affinity to Diplodocus than to Camarasaurus.
They also argued that CM 11162 had just the sort of modifications of the
Diplodocus skull design that one would expect to find in a more massive
creature such as Apatosaurus. Further, they included a detailed historical
account of the Apatosaurus discoveries, showing that various mistakes and
confusions had led to the incorrect belief that Apatosaurus was similar
to Camarasaurus. Their argument quickly convinced the paleontological community.
Carnegie Museum of Natural History agreed, and on October 20, 1979,
a ceremony was held in which the wrong skull was removed and a cast of
CM 11162 was attached. CM 11162 itself, the most complete Apatosaurus skull
ever found, was too precious to be mounted and rests in a display case
in Dinosaur Hall. That is how Apatosaurus finally got the right head, or
perhaps we should say it finally got the head we now think is right.
When Carnegie Museum changed the head on its type specimen, which is
the scientific example against which all other members of the species must
be compared, other natural history museums were forced to change the heads
on their own displays of Apatosaurus.
What lessons can we draw about the nature of science from the infamous
Wrongheaded Dinosaur Incident? It is clear that science does not always
proceed in a completely rational manner. Social influences certainly play
a role, maybe even a larger role than most rationalists would like to admit.
Nevertheless, reason and evidence, the traditional “scientific” factors,
also molded and shaped every step of our story. The desire to impress the
public and end the embarrassment of a headless Apatosaurus may have motivated
the decision in 1934 to mount the Camarasaurus head. However, at the time
the weight of scientific opinion, including that of leading authorities,
did not oppose such a mounting. Further, just as rationalists expect, over
the long run (45 years in this case) the evidence did win out. Berman and
McIntoshs study finally produced the conclusive evidence and argument
that, for the paleontological community, placed the issue beyond controversy.
Science is complex and multifaceted, a process not reducible to any
stereotype. Like all human endeavors, science is subject to social influences
at every level.But to a greater degree than the vast majority of human
enterprises, science uses objective methods and standards that limit the
effects of bias and elevate scientific hypotheses to a high level of reliability.
The best established scientific claimsthat blood circulates, that germs
cause disease, that evolution has occurred, that atoms can be split, that
DNA is the genetic material and that the universe is expandingshould not
be called “constructs.” To attempt to debunk these great discoveries, among
the crowning glories of human achievement, is to demean reason and ultimately
humanity itself.
Keith M. Parsons investigated the wrongheaded dinosaur incident while
completing a Ph.D. in the Department of History and Philosophy of Science
at the University of Pittsburgh. Parsons is a Carnegie Museum of Natural
History research associate.
