swered, it will provide unique insights into how it lived, what ene-
mies it feared. This mangled carcass can in fact help test the widely
believed theory that brontosaurs were swamp dwellers, sloshing
around lakes and rivers up to their armpits to keep their imprac-
ticable bulk buoyed up by the tepid waters. If that theory is true,
then this Camarasaurus very likely died in its favorite watery hab-
itat. Can that idea be tested? Very easily. If the body sank in an
aqueous grave, it should be resting on the type of sediment laid
down on lake or stream bottoms.
Along this limestone outcrop where the bones are eroding out,
there is only this one carcass—scattered vertebrae from the neck
THE CASE OF THE BRONTOSAURUS: FINDING THE BODY
105
How sediment was
laid down at Como
and back, a shoulder blade, a thigh bone—all the right size to fit
together and make one skeleton. The bones aren't jumbled on top
of each other. They lie close together in a layer one bone deep.
Clearly this body fell apart, ligaments rotted, knee detached from
thigh, neck vertebrae separated from one another. Such rotting of
the ligaments could have happened underwater while the body lay
in the muck. Crayfish, turtles, and other bottom scavengers would
have crawled over it, tugging and biting at every shred of flesh. Or
it could have happened on land, where dryshod predators could have
pulled the meat and gristle apart. Which scenario is correct?
The surrounding rock of the bone layer is a dark gray mud-
stone containing little streaks of sand grains here and there. No
distinct layers, though; no fine horizontal bedding. And that is a
clue. Mud settling through standing water—a pond or swamp—
usually deposits clear-cut layers, one piled on top of the other, be-
cause the flow of mud particles is almost never constant. Usually,
the flow of mud into the lake varies with rainfall and flooding. A
spring flood sweeps coarser sand into the pond, the sand sinks, a
106
THE HABITAT OF THE DINOSAURS
layer is formed. Gentle showers wash fine mud into the pond, the
mud sinks on top of the sand, another layer. Such layers of mud
undisturbed often form delicate sheets, because the fine clay par-
ticles which compose them are in the shape of microscopic plates
that lie flat on top of each other. The lack of layering thus suggests
this body didn't lie on a deep lake bottom. Very deep lakes usu-
ally possess bottom mud with very clearly defined layering.
Protruding from under the bones is the limestone of the Cam
Bench. Why does this layer stick out from the eroded bank? Ob-
viously because it's harder than the bone-bearing layer above it.
But why is the lower layer harder? Because it's a limestone—and
limestone resists erosion in this dry Wyoming climate. But this is
not an ordinary limestone. Most limestones form underwater, when
lime (calcium carbonate) precipitates out of solution. This lime-
stone is made up of little balls, from pinhead size to golfball size,
packed together, jammed onto each other.
A closer look at these broken lime balls reveals that some have
a tiny grain of sand at the core, others a few mud streaks. Such
lime balls can form in gently agitated warm water—the action of
the waves rocks small particles as they clothe themselves with layer
after layer of lime. But these aqueous lime balls, called ooids ("oh-
oyds"), are usually all of nearly one size, not at all like these in the
Cam Bench, where pin-sized balls lie adjacent to others a hundred
times bigger. Furthermore, ooids usually show internal layering,
like an onion. These lime balls below the skeleton don't. Instead,
the Cam Bench lime balls look like the ones called kunkar that
grow in well-drained soil today in tropical India. So the camara-
saur could have died on dry land.
Now, do such irregular lime balls as these grow anywhere to-
day—and if they do, in what kind of habitat? An answer to that
question might tell us where this one dinosaur body lays, and
therefore where it lived and died. Soil scientists in Australia and
India have found exactly the right thing. In tropical soils where
the particles are well drained for most of the year, a trench dug
into the soil layers will reveal a zone of lime balls a foot or so
beneath the surface. Lime in solution washes down from the soil's
surface during the rains. As the water dribbles and oozes down-
ward, some lime drops out of solution and tiny lime pellets form,
growing bigger each year. In many tropical landscapes these lime
THE CASE OF THE BRONTOSAURUS: FINDING THE BODY I 107
Death of a camarasaur. Adult camarasaurs were too big to fear most
predators—the camarasaur's fifteen-ton bulk was immune to attack by the
average one-ton Allosaurus, But when sickness weakened their resistance,
even a full-grown camarasaur could fall victim to the steak-knife teeth of the
dinosaurian hunters.
balls lack internal layering—just like the ones under the fossil di-
nosaur. Aussie soil scientists call this type of lime ball "kunkar."
If the lime balls under the skeleton are truly kunkar, that would
be grounds for considerable excitement. Kunkar nodules would
prove that this soil was originally not swampy and wet, because
swampy soil water is usually acid and dissolves lime balls as quickly
108 | THE HABITAT OF THE DINOSAURS
as they form. In such acid soil a conspicuous kunkar layer never
forms. If brontosaurs died on kunkar-growing soil, it means they
probably lived on dry, firm ground, and not in swamps at all.
Layers of lime balls growing today in Indian soils have one
characteristic signature: the balls get bigger toward the top of the
layers, because the top balls receive more lime from the water
THE CASE OF THE BRONTOSAURUS: FINDING THE BODY I 109
percolating downward. A trench hacked into this limestone out-
crop exposes unweathered rock, and the balls do indeed get big-
ger toward the top! It certainly looks as if this particular brontosaur
died on a land surface, just above a layer of irregular-sized lime
balls growing in the soil.
Could we prove, however, that this was a land death? What's
on trial here is not a murder suspect, but a suspect theory. Tra-
ditional theory maintains that the big dinosaurs were water crea-
tures—and old theories are tough antagonists in court. The scientific
establishment tends to believe that old, accepted views are correct
unless shown to be wrong beyond any reasonable doubt.
Here at Como we need the equivalent of the spent bullet,
lodged in the carcass, that can be securely traced to the murder
weapon. We need to find one more independent piece of evi-
dence that this multi-ton giant met its end on land. Further inves-
tigation around the eroding carcass reveals that some of the bones
are scarred by deep, knifelike wounds. These could be teeth marks
of the predator that killed the brontosaur or of the scavengers t
hat
stripped the body after death. In the dust a gleaming piece of tooth
enamel catches the sun: a tooth, four inches long, pointed, sharp-
edged, with sawlike serrations along front and back. Not the Ca-
marasaurus's tooth—the victim was a vegetarian. The tooth is from
a big Ceratosaurus, a bipedal predator.
The Ceratosaurus tooth is the spent bullet. This predator's tooth
clearly broke off as the flesh-eater bit into the brontosaur. At the
base of the tooth, where the root should be, is a deep pit where
the root had been dissolved by the Ceratosaurus gums. We hu-
mans think of tooth loss as a tragedy, because once gone, our adult
molars leave nothing but a hole in our jaw. But Ceratosaurus and
all the other dinosaurs had an endless supply of teeth forming at
each socket. As a new tooth grew in the socket, its pointed tip
pushed out the old tooth. The new tooth grew upward as its root
grew longer—the old tooth's root was dissolved to make room for
the new. An X-ray of a ceratosaur jaw reveals four or five teeth,
all in a row from top to bottom, each growing upward, pushing
the one ahead.
Fractured edges around the root remnants of the ceratosaur
tooth show that it broke off during life; the big predator was bit-
ing into something hard enough to break the tooth off its jaw.
110 I THE HABITAT OF THE DINOSAURS
How new teeth grow out
and push old teeth from
their sockets (shown is the
predator Ceratosaurus)
There is another Ceratosaurus tooth, and another. All three
are the right size to come from the same animal, and all three broke
off during life. This is the killer—or at least a beast that bit into
the dinosaur carcass after death. And Ceratosaurus was a land
predator, not a swimming meat-eater like the crocodile. Ceratosau-
rus hunted for prey on land, either killing the young and weak
brontosaurs or searching for brontosaurs that had died of other
causes. So broken ceratosaur teeth supply our sought-for clue. The
case for death on land is solid.
If a brontosaur carcass lay on a pond bottom or floated on a
lake surface, it wouldn't attract land predators, it would attract
crocodiles, which swarm over any available meat. Crocs shed their
teeth just as dinosaurs did, and when crocs bite into a big carcass,
a few teeth usually detach and stick embedded in the body. If our
brontosaur carcass had ever been in water for a long time, we would
THE CASE OF THE BRONTOSAURUS: FINDING THE BODY | 111
expect to find some croc teeth with it. But in digging around the
site for five days, not one croc tooth turns up. A few feet above
the lime-pellet bench there is a stream deposit full of broken and
shed crocodile teeth mixed with clamshells and turtle bones. This
deposit clearly preserves the record of water-living predators and
their victims, a record which is absent in the case of our Camara-
saurus.
The case is looking good—the vegetarian Camarasaurus died
on land and was chewed up by a Ceratosaurus. But now a compli-
cation. The plot thickens when the shed teeth of a second big
predator, Allosaurus, a very different species, turn up among the
Camarasaurus bones. And then yet another predator's teeth—this
time a very small killer, Coelurus, only the size of a very big tur-
key.
A moment's reflection produces a clear solution to this case.
In land ecosystems today, a big carcass is an enormous amount of
protein waiting to be used by any and all predators. Whether a big
water buffalo dies of disease or from a lion's attack, the sight and
smell of the dead hulk will attract lions, hyenas, jackals, and vul-
tures from a wide radius. After the biggest, most aggressive flesh-
eaters have eaten their fill, the smaller jackals and foxes nip in to
tear off their share. And thus one buffalo carcass gets chewed and
pulled apart by successive crews of large and small predators.
Only one more piece of evidence of how the Cam Bench
brontosaur died and was preserved is necessary to complete the
case. The chewed-apart Camarasaurus carcass had somehow to be
covered by a layer of sediment. But the layer of rock entombing
the skeleton is unambiguous at this point. It was deposited as a
blanket of mud when a turbid sheet of water inundated the flood-
plain. Floodplains are special places. They can remain dry and grow
a rich carpet of bushes, young trees, ferns, and ground pines for
half a year, ten years, or as much as a thousand years. It's during
these intervals that the kunkar lime balls form in the soil below
their surface. But floodplains get their layers of sediment when
neighboring rivers and streams overflow. The floodwaters that have
been rushing through river and stream channels slow down dra-
matically when they spill over and spread across the flat lowland.
Homeowners in Cincinnati and other floodplain cities today know
firsthand how such sheets of floodwater can bury even large ob-
112 | THE HABITAT OF THE DINOSAURS
jects in mud—sometimes objects as large as a station wagon or a
one-story house can disappear in a few days. Our Camarasaurus
carcass, chewed and pulled apart, was gently and thoroughly cov-
ered by just such a mud deluge. Then the floodwaters receded.
The new layer of mud dried out. Plants began to germinate, ferns
sprouted. A new soil surface developed atop the new blanket of
mud, supporting the very same type of plants that had fed the cam-
arasaur during its lifetime. Once again, kunkar nodules began to
grow below the surface and among the camarasaur bones.
But other arguments are possible here. The Russians have
given a name to this type of paleontology, "taphonomy," coined
from the Greek word for "burial" and the word for "laws." Ta-
phonomy is when a paleontologist reconstructs the corpse's burial
so it can reveal how and where it lived. It is important not to be
fooled by first impressions. A fossil body's location may not be
where the death occurred. Fossilization can be misleading. A dead
brontosaur like the Camarasaurus lying on a floodplain probably
means the death occurred on land. But maybe a flood washed the
body from a river onto the land. It could happen.
Worse yet, there's the possibility the body was dragged from
a watery death site by the actual killer. Meat is meat and in short
supply in most habitats. So a land predator, such as a lion, might
pounce on a crocodile in shallow water if the croc were unwary.
Without the least concern for whether it were messing up a po-
tential fossil, it would drag the dead croc hundreds of yards from
the shore to some secure spot on dry ground where the big cat
could enjoy its scale-wrapped dinner in comfort. Large land-hunt-
ing dinosaurs could have done the same, dragging aquatic prey into
their terrestrial habitat.
Taphonomy is therefore a science requiring subtlety, broad
knowledge, and a good eye for detail. The diligent carcass sleuth
mus
t be alert for signs that the dead body has been moved from
water to land, or vice versa. Crocodiles are usually as hungry as
lions and nearly as crafty. A big croc will wait in the reed-choked
shallows for an unwary zebra to come and drink. In a minute the
zebra disappears beneath the river's surface. And an unwary pa-
leontologist, excavating the scene a million years later, might be
similarly ambushed—he might conclude that the zebra was aquatic
because he found its mangled bones buried in river sand.
THE CASE OF THE BRONTOSAURUS: FINDING THE BODY | 113
Rivers are moreover terrible deceivers. When modern rivers
overflow, they wash all sorts of living and dead matter off the
floodplain into the river channel. Consequently, sediment buries
dead squirrels, unfortunate cows caught in the flood, lawn furni-
ture, shopping carts, and other terrestrial debris, along with the
fish bones and clamshells that belong there. If hundreds of dino-
saur skeletons from a single species are found preserved in river-
channel sediment, could it safely be concluded that the species was
water-loving? Not at all. Big floods along the Missouri wash
114 | THE HABITAT OF THE DINOSAURS
hundreds of Hereford steers into the rivers, where they eventu-
ally become buried in sandbars. Does that prove Herefords are an
aquatic species? Dinosaurs of all kinds have been found in stream-
and river-laid sandstones—predators like Allosaurus, armored steg-
osaurs, and giant brontosaurs. A few years ago, a young Canadian
paleontologist was misled into concluding that duckbill and horned
dinosaurs were aquatic because in Alberta their skeletons are con-
centrated within the river sandstones. But Mesozoic rivers were as
deceptive as modern ones. Dinosaurs in rivers prove nothing con-
clusively.
If rivers can't be trusted, where can paleontologists turn for a
truthful account of the brontosaur's habitat preference? Lake bot-
toms and floodplains are the most trustworthy locales. Some fish
and crocs do get washed and dragged up onto plains, and some
zebras and lions do get washed or dragged into lakes. But, on av-
erage, lake-bottom mud preserves mostly water creatures, and
Robert T Bakker Page 11
