was a very large muscle in Remingtonocetus and Andrewsiphius. Mas-
seter attaches to the outside of the jaw and to the jugal arch, formed
partly by the cheekbone. The jugal arch is tiny in Remingtonocetus, sug-
gesting that masseter was small. This is strange because, in most mam-
mals, medial pterygoid and masseter are similar in size as they work
together closing the jaw. As in other mammals, the throat anatomy of
Remingtonocetus combined the functions of chewing, swallowing, and
breathing, but the interplay of these is poorly understood in this fossil
whale—but clearly different from Ambulocetus.
114 | Chapter 8
Brain and Smell. The skull of the Remingtonocetus specimen in figure
29 is an unusually well-preserved fossil, and it was possible to CT scan
the specimen and study the outside as well as the inside cavities of the
skull, such as the nasal cavity and the braincase. A sophisticated scanner
took about a thousand scans, covering every half-millimeter of the spec-
imen (figure 35). A special computer program reads those slices and
puts them together, so that pieces can be left off or added again, making
virtual removal of parts possible. In figure 35, the skull is left off, and
just the cavities inside it are shown—a virtual endocast (as described in
chapter 2). The CT scans show that the brain was small, and on its sides
are large areas that were probably bunches of veins, as in the modern
whales discussed in chapter 2. As in all mammals, the outside of the
brain consists of two large parts: the cerebrum in the front, and the
smaller cerebellum in the back; both can be seen in the virtual endocast
of figure 35. Very unusual is the canal that emerges from underneath the
cerebrum in the front and reaches toward the nasal cavity. In life, the
nerves going to the nose (cranial nerve I) would have run in this canal,
but usually this nerve is not as long as it is in Remingtonocetus. The
contact of the canal with the nasal cavity does indicate that Reming-
tonocetus had a sense of smell. However, it is not clear why it is as long
as it is. At present, it seems most likely that the external anatomy of the
skull affected skull architecture and thereby internal anatomy: the posi-
tion of the masticatory muscles on the outside of the skull in this area
required that the internal structures be elongated.
Vision and Hearing. The position of the eyes is unusual in reming-
tonocetids. They face laterally underneath a dome-shaped forehead in
Remingtonocetus, Dalanistes, and Attockicetus and are not perched on
top of the head. The eyes in Andrewsiphius and Kutchicetus also face
laterally, but are closer together on top of the head, more like Ambuloce-
tus. 13 The small sockets for the eyes suggest that the remingtonocetids
had poor vision. These animals lived in muddy water and a swampy
environment, so probably there was not much to see. In contrast, the
ears are enormous: the two large tympanic bones that surround the mid-
dle ear cavity project prominently from the base of the skull. Of course,
being whales, these bones do have an involucrum. Another indication
that hearing is important is that the mandibular foramen is nearly as
large as the full depth of the jaw (figure 25), similar to modern toothed
whales, but bigger than in Ambulocetus. Some of the specimens from
Kutch include ear ossicles, and they look very much like those of modern
The Otter Whale | 115
Middle ear cavity
Cavities inside a Remingtonocetus skull
Dorsal view
IITR-SB 2770
Tract for olfactory nerve
Petrosal
Cribriform plate
Cranial cavity
(bone that
(area where olfactory Nasal cavity
(for brain)
houses inner ear)
nerves cross from nose
Nasal
to cranial cavity)
Opening
Impression of
Impression of cerebrum
5 cm
cerebel um
Tracks for optic nerves
Lateral view
figure 35. Internal anatomy of the skull of Remingtonocetus (IITR-SB 2770) as
reconstructed from CT scans. The cranial cavity (where the brain is located) is green, the
nasal cavity with its sinuses is blue, and the middle ear cavity is red. The bone that
houses the organs of hearing and balance (yellow) is called the petrosal (see chapter 11).
After S. Bajpai, S., J. G. M. Thewissen, and R.W. Conley, “Cranial Anatomy of Middle
Eocene Remingtonocetus (Cetacea, Mammalia),” Journal of Paleontology 85 (2011):
703–18. Used with permission of the Paleontological Society.
whales, and unlike Pakicetus. Clearly, hearing is an organ system that is
undergoing fast evolutionary change, and this is discussed in chapter 11.
Walking and Swimming. Among modern mammals, the skeleton of
remingtonocetids is most similar to that of otters, suggesting that these
whales were probably agile hunters. In Frank Fish’s concept of the evo-
lution of otter locomotion (figure 20), Kutchicetus would have matched
the giant freshwater otter Pteronura, swimming with its powerful tail,
possibly aided by paddling with the hind limbs (since the feet are not
known in Kutchicetus, we cannot be sure). The vertebral skeleton for
Remingtonocetus shows that it had a relatively stiff back, possibly more
stiff than Kutchicetus, and it is possible that the species was a pelvic pad-
dler;14 but since neither tail nor feet are known for Remingtonocetus,
locomotor inferences are speculative. In general, remingtonocetids were
probably adept swimmers, but land locomotion must have been clumsy.15
Life History and Habitat. Remingtonocetids in Kutch are known from
nearly all fossil sites there: the algal reef of Rato Nala, the seagrass
116 | Chapter 8
meadow of Vaghapadar, the muddy storm-swept beach at Godhatad,
Panandhro’s swamp, and the dried-up sea arm near Dhedidi (figure 30).
Remingtonocetus is common at all localities, and thus apparently not
picky about its particular environment. Andrewsiphius and Kutchice-
tus, on the other hand, are rare at the localities open to the ocean (Rato
Nala and Vaghapadar) but common at the localities that have muddier
water
and restricted flow, like Panandhro and Dhedidi. They appear to
have been muddy-water specialists.
building a beast out of bones
It pleased me that Carl Buell did not make up the feet of Kutchicetus.
We do not know enough about those feet to guess at their shape. On the
other hand, I do not have a problem with Carl giving the animal brown
fur, even though I have no idea what color it really was and can only
make an educated guess that the animal had fur at all. Reconstructions
are useful because they give an interested audience an intuitive feel for
an animal—what it looked like and how it lived. Laypeople are unlikely
to notice such details as how many toes there are, so artistic license in
those areas does not violate the trust between scientist, artist, and reader.
Of course, there is always some level of conjecture in reconstructions. If
zebras were extinct and horses were not, it would be straightforward to
draw a zebra’s body shape accurately from its bones, but it is unlikely
that any artist would get the color pattern right.
There is much disagreement among paleontologists about how far
you can go in reconstructing an animal known from some bones only.
In whale artistry, Pakicetus became a household concept in paleontol-
ogy labs when it was described in the early 1980s. At that point, only a
lower jaw, a braincase, and a few isolated teeth were known, but the
cover of the prestigious weekly Science showed the animal jumping out
of the water, with head, body, feet, and tail drawn in detail. Although
the paper that described the animal was explicit about what was known,
those nuances were lost in the many spin-offs based on the Science
cover, including in reams of popular books and illustrations at natural-
history museums. Such excesses of artistic license have not gone unno-
ticed in the creationist community, and have been exposed as examples
of evolutionists making things up based on “a few scraps of bone.”16
Chapter 9
The Ocean Is a Desert
forensic paleontology
In the Del Rio, a Bar in Ann Arbor, Michigan, fall of 1992. My friend
Lois Roe and I are graduate students talking shop at a bar. She went
to Pakistan to collect fossil fish from the time that the Himalayas were
rising, around fifteen to five million years ago, but they did not find
many fossils. Now she is exploring questions that are less dependent on
having many fossils, to get the most out of the samples she does
have. She now works with a professor who knows very little about
fish but a lot about the chemistry of rock and bones—an isotope geo-
chemist.
Isotope geochemistry is a hot field of research, and can tackle some
remarkable problems. It studies the subtle differences between different
forms (isotopes) of the same chemical element. Oxygen, for instance,
occurs most commonly in one form, 16O, where the 16 indicates the
weight of the oxygen atom. In nature, there is also a heavier isotope,
18O, which carries two extra neutrons in its nucleus. Both isotopes react
identically with other elements. For instance, H 16O is a water molecule
2
with a 16O as its oxygen, and this is what most water molecules in nature
are. However, there is also a little bit of H 18O in the world. These are
2
stable isotopes, meaning that they do not decay: once around they do
not change, and they do not produce radioactivity. This is different from
radiogenic isotopes, like those of uranium.
117
118 | Chapter 9
“In nature, 18O makes up about 0.2 percent of the oxygen. There is
no chemical difference, but the isotopes differ in their physical proper-
ties,” Lois explains, while I sip my beer.
“Like what?”
“They fractionate according to their physical properties.”
“What is fractionation?” I know nothing about isotope geochemis-
try, but I am not self-conscious about that with Lois.
“Physical processes will preferentially work with one of the isotopes.
For instance, evaporation favors the lighter isotope—this can be used to
track water through a system. I want to use this for my thesis work.”
“Oh. Because the water molecules with 18O are heavier, they evapo-
rate less easily than those with 16O, hence water vapor contains less
H 18O than the water in the ocean.” It is now dawning on me what she
2
means. If you can measure the ratio between 18O and 16O in water, you
can determine whether the water you have came from water vapor or
from the ocean. Since all freshwater eventually comes from precipita-
tion, the difference holds for all freshwater too.
I say, “Those differences in the ratios must be tiny, and the weight
difference between the isotopes is tiny too. Can you really measure
that?”
“Sure, you use a mass spectrometer.”
I know about the large machine in one of the labs across the street
from the paleontology building. It vaguely reminds me of the top half of
an enormous suit of armor, with two large metallic arms holding strange
weapons stretching out of a larger irregular torso and head. The machine
shoots out molecules from the hands of the knight, through its arms and
into the chest, where they are deflected to different areas depending on
their weight, and are counted when they crash somewhere inside the
armor. The machine counts all those crashed oxygen atoms, and then
determines the ratio of the isotopes.
“Cool, but what is that going to tell you about your fish?”
“Atmospheric water is fractionated as it moves up the Himalayas.
The heavier isotope gets more and more rare because it rains out. There-
fore, by measuring the isotope values, you can determine what the alti-
tude was where the water sample was collected. Of course, you need to
know the local geology, and the—”
“But you don’t have water samples, you just have fossil fish bones.
Where do you get the water?”
“The fish have drunk the water that they swam in, and used the oxy-
gen in the water to build their bones. Bones are made out of apatite,
The Ocean Is a Desert | 119
which contains oxygen. Because the isotopes are chemically not different,
you can measure the isotopes in the bones and determine the isotopes of
the water they swam in.”
“Wow. So the isotopes track the drinking water, and you can see
what an animal drank, twenty million years after it died, and thus you
can determine where in a river a fish lived: in the low plains, or the high
mountain streams.”
“The differences between different kinds of freshwater are relatively
small, and they also depend on other things, such as in which drainage
basin you are. Much larger differences that are easier to measure exist
in other systems, between freshwater and seawater, for instance.”
“Hmm, so you could determine whether an animal drank freshwater
or seawater without measuring salt content, by just looking at the stable
oxygen isotopes in the bones of that animal.” I finish my beer and con-
sider that someone could determine where the water in it came from by
studying the isotopes in my body tissues. So if I got all my fluids from
beer at the Del Rio here, they could determine that from a sample of my
blood or my bones. Forensic bar science, so to speak. The thought is
mildly disturbing, but I can see the scientific potential.
The conversation stays with me as we both leave Michigan, and as my
research focuses more and more on fossil whales. Years later, with draw-
ers well stocked with teeth of Ambulocetus and Pakicetus, I call her up.
“Lois, we’re finding all these fossil whales in Pakistan. The pakicetids
only come from freshwater rocks, the ambulocetids from coastal sedi-
ments. I think that these whales are making the transition from land to
water right where I work in Pakistan.”
“Yes, I have read your papers,” Lois says matter-of-factly.
“Modern whales ingest seawater, and they had land ancestors that
presumably drank freshwater. Could we analyze the bones and teeth of
those fossil whales and determine what they were drinking, and deter-
The Walking Whales Page 18
