joint, but not nearly to the degree found in Diplodocus.
In living species, the position of the head relative to the neck
is often determined by the animal's feeding habits. Hence the hor-
izontal head and the vertical neck in Diplodocus imply that its neck
was held nearly vertically during feeding. Since the neck is very
long, Diplodocus must have been feeding at very high levels—twenty
or thirty feet above the ground. Not many clams are found living
at such heights. More likely the Diplodocus searched the upper
reaches of Jurassic trees for select vegetarian morsels. With its
sharply tapered snout, Diplodocus could probe deeply in among the
branches, choosing its menu with more care and delicacy than the
big-toothed Camarasaurus or Brachiosaurus could.
Diplodocus's head—neck anatomy simply contradicts those tra-
ditional restorations of the beast portrayed as feeding exclusively
on ground level with its long neck outstretched. Why evolve a
twenty-foot neck at all if feeding was done exclusively on the
ground? Diplodocus had short front legs, so a six-foot neck would
have sufficed quite nicely for ground feeding. Ostriches are long-
necked ground feeders, but they have very different problems—
they are very long-legged and require their long neck just to reach
the ground.
The most troublesome part of a Diplodocus's head is not its
GIZZARD STONES AND BRONTOSAUR MENUS I 139
Diplodocus nostrils were in a whale-type position—on the forehead between
the eyes.
teeth but its whalelike nostrils. Most air-breathing vertebrates have
their nostrils at the tip of the snout. Air is drawn in through the
nostrils, passes through a tube in the snout, and is then drawn
downward through a hole in the roof of the mouth into the wind-
pipe. The windpipe lies just behind the base of the tongue. But
whales do it differently. Whale nostrils—their blowholes—are lo-
cated way back on the skull right above the eyes. When a whale
exhales after a deep dive, a geyser of humid air is blown nearly
directly upward from its forehead. (Sperm whales have a long tube
running through their fleshy snout from the blowhole in the skull,
so, rather exceptionally, sperm whales blow from the front of the
snout.) Nostrils in the whale position seem an obvious advantage
for a swimming air-breather. The typical whale can inhale and ex-
hale from its blowhole without danger of ramming water into its
nostrils. And nostrils at the tip of the snout would be more vul-
nerable to the rush of water caused when the head plunges back
below the ocean's surface.
Diplodocus had nostrils in the whale position—just in front of
and above the eyes. If you are inclined to believe the water-living
theory, the interpretation of Diplodocus's nostrils is obvious: The
140 i THE HABITAT OF THE DINOSAURS
Did Diplodocus have an elephant-style trunk? Modern
elephants have bony nostrils located in the forehead position.
beast used its skull as a combination snorkel-periscope to simul-
taneously breathe and look around while only the forehead was
exposed above the level of the water.
An alternative explanation is however possible. There is one
type of forehead structure found among living species that matches
the Diplodocus's—the foreheads of mammals with trunks. Ele-
phants have nostrils located exactly in the Diplodocus position, be-
tween the eyes on the forehead. Tapirs—short-legged relatives of
horses—possess nostrils located halfway between the elephant po-
sition and the usual mammal location at the end of the snout. Ta-
pirs have trunks of moderate length. A trunk is actually a highly
GIZZARD STONES AND BRONTOSAUR MENUS | 141
modified set of upper lip muscles that surround the fleshy nostrils
and wrap around to form a mobile muscular tube. Usually the fleshy
nostril—the hole in the skin through which the breath passes—is
located in the flesh that more or less directly covers the bony nos-
tril hole in the skull. But in a trunk the fleshy nostril is carried at
the end of the mobile tube. In fossil mammal skulls, a trunk can
be hypothesized if the bony nostril is located in the elephant or
tapir position, and the skull bones around the nostril show attach-
ment sites for the modified lip muscles.
I find the similarity between a Diplodocus's forehead and an
elephant's thoroughly unsettling. Could Diplodocus have been a di-
nosaur equipped with a proboscis? A horrendously heterodox
thought, but not a new one. The possibility of trunked dinosaurs
has been raised in paleontological journals on and off for half a
century. There are all sorts of evolutionary problems generated by
this theory. First of all, to produce a trunk, evolution requires a
start with a set of muscular lips. Nearly all mammals possess a
complex set of lip and face muscles, so evolving a trunk from any
given mammal ancestor poses no great difficulty. But reptiles pos-
sess hardly any lips at all. Lizards have thin muscular bands run-
ning along the inner edges of their lips—just enough muscular tissue
to flare the lips a bit to bare the teeth. But lizards don't have enough
lip muscle to pucker, suck, flare the nostrils, or wiggle the nose.
Crocs are even more lipless. The muscular lip band found in liz-
ards is gone entirely in crocs, which have only a thin, scaly layer
of skin over the gums. These thin croc lips are so tightly con-
nected to the jaw and skull bones that they can't move at all. The
thin band of the lizard lip hangs down enough to hide the teeth
when the mouth is closed. But the croc lips hide nothing; its up-
per teeth are visible sticking down out of the gums even when its
mouth is closed. Crocs have achieved the ultimate tight-lipped
condition. The croc jawbone curves upward at the rear, which ac-
counts for a smile the animal seems to have frozen on its face. In
point of fact, crocs can't smile at all.
What sort of lips did dinosaurs have? Primitive brontosaur
relatives, like Massospondylus, possessed bony gums just as mod-
ern lizards do. On the fossil gumline along the outer edge of the
upper and lower jaw there is a gently beveled edge which must
have been the attachment site for thin, muscular, lizard-style lips.
142 | THE HABITAT OF THE DINOSAURS
Crocodile lips. Croc facial skin is thin and tightly fixed to the skull bones, so
there are no movable lips along the gum line. Tooth shape shown at right.
Lips require blood for nutrition and nerve fibers to carry sensory
information to the brain. Massopondylus shows a series of holes in
the jawbones precisely where the lips would lie in life. Through
these holes passed the requisite blood vessels and nerve tracts. An
identical pattern of holes can be found in the jawbones of living
lizard species. So Massospondylus, the brontosaur uncle, was
equipped with a little bit of lip, and primitive dinosaurs of the
Triassic Period were all similarly lizard-lipped. The predatory di-
nosaurs, Allosaurus, Ceratosaurus, and the tyrannosaurs, retained this
lizard-lipped condition into the later periods. Therefore Tyranno-
saurus can be restored accurately with a sneer on its face or in the
act of baring its teeth.
It is not totally impossible that evolution could convert the
lips of Massospondylus into a big complex system of elephantlike
face muscles, complete with proboscis. If Diplodocus really walked
around with a trunk hanging from its forehead, some evidence of
big proboscis muscles attaching to the skull bones near the edges
of the bony nostril would have to be found. I can't find any such
marks. But the Diplodocus's lips were definitely different from those
of lizards—the gum lines along its jawbones were not beveled, and
the holes for blood vessels and nerves did not make an evenly
GIZZARD STONES AND BRONTOSAUR MENUS | 143
spaced row like the one in lizards. Diplodocus's lips were different
from those of crocs, too. In the tight-lipped crocs, the skull bone
beneath the thin scaly lip tissue is pitted and grooved so that the
horny skin can attach very firmly to this roughened bone surface.
Diplodocus's jawbones were quite smooth compared to crocs'.
It's very unclear how Diplodocus's lips were attached to its skull,
but the possibility of a proboscis must be explored by more ana-
tomical research. Alternative explanations for the locations of Di-
plodocus's nostrils should also be explored—were they perhaps
adaptations for tooting and honking? Primitive dinosaurs close to
the brontosaurs, such as Massospondylus, may have snorted. The
bony nostril hole is quite capacious in these early species and must
have housed a series of pockets and compartments structured from
skin, cartilage, and nasal lining. Compartments of soft, nonbony
tissue in horses' skulls amplify their snorts and whinnies. Perhaps
Massospondylus's nostrils performed the same functions. Stout-
toothed brontosaurs like Camarasaurus and Bracbiosaurus had truly
gigantic bony nostrils, so large that the eye sockets appear small
by comparison. The bony nostril hole on each side of the skull is
so enlarged in these species that only a tiny strip of bone separates
the right from the left orifice. In life, these gigantic apertures were
filled by some form of enlarged nasal device. The nasal organ was
sufficiently large to spread over the snout bones, because the mark
left by the soft-tissue nose can be seen on the top surface of the
fossil snout. What important biological function required such a
huge nose? The Camarasaurus's bony nostril vaguely resembles a
Tyrannosaur lips.
Tyrannosaurus, like
Massospondylus and
other primitive
dinosaurs, had a lizard-
style lip band along the
gum line. A row of
bony lip holes in the
skull and jaws shows
how blood vessels and
nerves reached the
movable lips.
144 | THE HABITAT OF THE DINOSAURS
tapir's, and therefore the possibility of a short proboscis cannot be
dismissed. Or the nostril hole may have housed resonating cham-
bers to provide its owner's voice with a rich and varied timbre.
If brontosaurs in general possessed nasal adaptations for bel-
lowing out Jurassic songs, perhaps, just perhaps, Diplodocus's fore-
head nostrils were part of its nasal symphony. Diplodocus had small
nostrils but probably evolved from an ancestor with gigantic bony
nostrils like those of Camarasaurus. If Diplodocus's ancestors had
been nose-honkers, roofing over the narial tissue would have al-
tered the tone—probably making it brassier.
Brontosaur faces and noses are still full of mystery. Right now,
fossil tongues are the exciting topic in paleontology. The tongue
itself doesn't fossilize, but the tongue bones in the throat do—and
tongue muscles leave their marks where they attach to skull and
jaws. But too few researchers are studying lips and their evolu-
tion. Someday someone will win his or her place in the history of
science by solving the mystery of brontosaur noses and lips. When
I'm asked by students what they should study, I always reply, "Think
lips."
Diplodocus nostrils as
nose flutes. Primitive
brontosaurs—like
Camarasaurus and
Bracbiosaurus—had
huge bony nostrils that
must have been
covered with a fleshy
chamber. The big
chamber may have
been used to amplify
sound. In Diplodocus
the nasal chamber is
roofed over by the
snout bones, so that
the sound produced
would have been
brassier than that of a
camarasaur or
brachiosaur.
GIZZARD STONES AND BRONTOSAUR MENUS | 145
7
THE CASE OF THE
DUCKBILL'S HAND
On the fourth floor of the American Museum of Natural His-
tory in New York, in a square glass case, stands the nearly
complete, mummified carcass of a twenty-foot duckbill dinosaur.
That mummy is famous worldwide for its hands.
In the early days of paleontology, the scientists of Europe and
they would reveal a scaly hide. Up to 1900 only a few small patches
of skin marks had been recovered from European dinosaurs and
none from American. The Late Cretaceous delta beds of the
American West changed all that. Expeditions from the American
Museum to the Red Deer River in Alberta uncovered complete
duckbill skeletons, including enormous patches of skin impressed
in the sandstone around the ribcage, tail, and neck. The skin's
substance itself was of course not preserved—it had rotted away
after the duckbill had been entombed by a sudden influx of sand.
But sand and mud had infiltrated the duckbill's body cavities while
the dried hide still separated the animal's insides from the sur-
rounding sediment. Consequently, when the sandstone was care-
fully chipped away, the surface of the vanished skin acted as a
separation layer, so the stone faithfully recorded the living skin's
texture. The American Museum's technicians—probably the best
in the world at the time—erected twenty-foot slabs of sandstone
in their exhibit hall, displaying the Alberta duckbill skeletons as
146 | THE HABITAT OF THE DINOSAURS
Web-propelled swimmers,
like modern ducks, had
long, widely spread toes.
Duckbills supposedly
paddled with their webbed
feet. But both forepaws and
hind paws had very short
toes that did not spread
much, not a good design for
fast swimming.
they had lain, half-embedded in rock, still partially clothed in their
skin texture.
Even more spectacular mummies subsequently came from
Wyoming's Lance Creek beds. The Alberta skeletons lay on their
sides,
their skin impressions flattened by the overlying rock bod-
ies—producing a two-dimensional appearance. The Wyoming
mummies however were nearly entire bodies, preserved lying on
their backs, their chests expanded as if in a last gasp for breath,
both fore and hind feet extended outward in an agonized pose.
Impressions of skin covered each carcass on all sides. So lifelike
do these three-dimensional mummies look, it is easily possible to
imagine driving across a dried-up lake and happening upon just
such a carcass, victim of a drought, sprawled with its collapsed belly
pointing upward, legs contorted into unnatural angles by the con-
traction of sun-dried skin. Something about these contortions of
death, so eloquently preserved in sand, drives home the message:
This twenty-foot carcass was once alive, with full, pulsating mus-
cles filling out the now cadaverous torso.
Duckbill dinosaur skulls and skeletons had entered the annals
of science during the 1880s. The broad, ducklike muzzles sug-
gested in a vague way some sort of mud-grubbing habits. But when
the hands of the recently arrived three-dimensional mummy were
finally cleaned, they caused a sensation. The skin impressions con-
tinued down the wrist, and between the duckbill's fingers. The
conclusion was obvious—the duckbill's feet were webbed! The
concept of aquatic duckbills, up till then an ill-defined theory,
crystallized into a solid scientific "fact"—duckbills had webbed feet,
duckbills swam. From that moment on, nearly every popular and
scientific account of duckbill dinosaurs portrayed them paddling
through lakes and rivers. The exhibits in the New York Museum
depicted crested duckbills rushing into the water, with huge wad-
dling strides; the caption read: "Escape to the Swamps." And once
the aquatic theory became "fact," all the quirks of the duckbill's
anatomy were forced into supporting the notion of an aquatic mode
of life. The hollow crests of some duckbills were even hypothe-
sized as air reservoirs adapted for prolonged diving.
A more careful consideration of the duckbill mummy's webbed
paddle raises important heretical doubts about its aquatic role. If
three-ton duckbills paddled at fair speed through the swamp waters
of their Cretaceous delta home, they would require a paddle of