tonocetids) and used their eyes to look sideways, not just upwards like
ambulocetids and pakicetids.
Protocetid ears are similar to those of remingtonocetids (figure 43):
they show aquatic adaptations such as the enlarged mandibular foramen
and the partial release of the petrosal from the skull, but these structures
are not as perfected as they are in modern whales. It is likely that pro-
tocetids used their eyes and ears to hunt large prey and that most of that
hunting took place below the water-line.
Brain. The deserts of Egypt have yielded a trove of casts of the inside of
the braincase (endocasts) for basilosaurids,21 and CT scans have revealed
the shape of that cavity in remingtonocetids (figure 35). In Kutch, we
found endocasts for the protocetid Indocetus. 22 Like all early whales, it
has long olfactory tracts. There are also the beginnings of a rete mira-
bile, the network of veins that surrounds the brain (discussed in chapter
2). The retia (plural of rete) are largest on the left and right side of the
brain, and there are none covering the top (dorsal) surface. In modern
bowhead whales, the location of retia is similar.
In these Eocene endocasts, the front part of the brain (cerebrum in
figure 35) is distinct from the back part (cerebellum). The relative
dimensions of cerebrum and cerebellum are similar to those of land
mammals and Remingtonocetus: the cerebrum is larger and higher than
the cerebellum. It is different in basilosaurids. There, the cerebellum is
much larger and higher, towering over the cerebrum. The surface of the
cerebellar casts suggest that this space in basilosaurids is mostly covered
with retia, greatly enlarged over their condition in protocetids, but it is
still likely that the cerebellum makes up a greater portion of the volume
of the brain than in other Eocene whales. In modern mammals, the cer-
ebellum is involved in fine motor coordination, but we do not know
whether there was a significant change in motor coordination between
protocetids and basilosaurids.
The surface of the brain of all Eocene whales is relatively smooth, a
condition called lissencephaly. In general, mammal brains that are larger
(have higher EQs, see chapter 2) also have a brain surface with more
Whales Conquer the World | 169
and deeper grooves (sulci), and that relates in some broad way to how
much brainpower they have. Eocene whale brains are different from
modern odontocetes and mysticetes in that regard. That pattern—
smooth brains in Eocene forms and convoluted brains in their modern
relatives—is actually found in many mammal groups. In evolution,
brain size and degree of convolution increased over the past fifty million
years independently in different mammal groups.23
Unfortunately, it is at present impossible to determine what these early
whales did with those brains. Brain organization in modern whales is very
different from that in other mammals, and it is possible that this is related
to increased cognitive skills and behavioral complexity.24 However, we
cannot know whether these organizational patterns occurred in Eocene
whales. Their brains were certainly a lot smaller than in the modern forms.
Walking and Swimming. Protocetids such as Maiacetus had a robust
vertebral column and short limbs.25 Nearly all swimming mammals have
short limbs. Sea lions, which propel themselves with their hands (figure
20), have short forelimbs and large, wing-like hands that can be forced
through the water with powerful shoulder muscles.26 Seals swim by
means of pelvic oscillation. They have giant feet planted on very short
thighs, and shins that allow powerful strokes in swimming. Maiacetus
has short limbs, but its hands and feet are not large. Principal component
analysis, a powerful mathematical method to study similarity in shape,
has been used to study limb and trunk proportions of swimmers.27
Maiacetus turned out to be most similar in skeletal proportions to the
giant freshwater otter Pteronura, which is a caudal undulator (figure 20).
Indeed, the tail of protocetids is very interesting. The proportions of
the vertebrae near the root of the fluke change abruptly in mammals
with flukes (whales, dugongs) but not in those without flukes (otters,
manatees; figure 12). Indeed, in Maiacetus, most known tail vertebrae
are wider than they are high, but the thirteenth tail vertebra is higher
than it is wide. In Dorudon, the thirteenth caudal vertebra is the ball
vertebra and is located where the fluke hinged, and the height-width
proportions of the vertebrae change here.28 That suggests that Maiace-
tus had a fluke, and might mean that swimming using the modern means
of fluke-driven caudal oscillation originated in the family Protocetidae.
Whereas the limb bones of Pakicetus and Ambulocetus are pachyos-
totic, this is not the case in protocetids. In Pakicetus and Ambulocetus,
the extra bone is probably used as ballast to keep the animal underwater,
which makes sense for hunting from ambush. In protocetids and Basilo-
170 | Chapter 12
saurus, the ribs are somewhat pachyostotic,29 and these heavy ribs may
have functioned as a stabilizer, as explained in chapter 2.
The limbs of protocetids had fully mobile joints, with well-developed
fingers and toes, tipped by short hooves. Protocetids were certainly able
to get around on land, although they were not fast or strong. The verte-
bral column of protocetids presents a puzzle. Nearly all mammals have
seven neck vertebrae, and the number of thoracic and lumbar vertebrae
adds up to the same number. Thus, the vast majority of mammals have
twenty-six vertebrae in front of the sacrum (cervical + thoracic + lum-
bar vertebrae, together called the presacral vertebrae),30 as pointed out
in chapter 4. In fact, relatively stable numbers of presacral vertebrae
occur in birds and reptiles too. The number of presacral vertebrae is also
twenty-six in Eocene artiodactyls31 and in most protocetids. However,
in both Ambulocetus and Kutchicetus, the numbers are higher (thirty-
one and thirty, respectively), and things get really out of hand in basilo-
saurids ( Basilosaurus, forty-two; Dorudon, forty-one). Excess presacral
vertebrae indicate that whales made a f
undamental change in mamma-
lian design, and the question is whether the number was increased twice
in early whale evolution (in ambulocetids/remingtonocetids as well as in
basilosaurids), or whether it was increased just once, with some pro-
tocetids reversing to the ancestral numbers.
Habitat and Life History. Pakicetids and ambulocetids were closely
tied to freshwater, and remingtonocetids are common in muddy back-
bays. Protocetid fossils are often found in deposits indicative of clear,
warm, and bright waters (figure 30).32 Such seas sustain ecosystems
with diverse life-forms, and protocetids were probably the top predator
of these systems. Although most protocetid fossils have been found in
such near-shore but open marine environments, it is likely that they also
inhabited the surface waters of the deeper oceans. Those environments
do not easily fossilize, and less is known about diversity there. It is pos-
sible that the oceans teemed with cetacean life soon after protocetids
appeared on the scene.
Still, it is also clear that protocetids retained ties to the land. If seals
and sea lions are a modern analogue for protocetids, it could be that
functions related to reproduction required a stable substrate. Of course,
those functions—mating, birthing, and nursing—do not fossilize easily.
In general, fetuses and newborns have bones that are soft and fossilize
poorly. A small whale inside a larger whale’s body was discovered for the
Eocene whale Maiacetus— a remarkably beautiful specimen. The head of
Whales Conquer the World | 171
the small one is facing toward the tail of the larger individual, and it has
been interpreted as a fetus inside the mother’s body.33 However, the
smaller individual is located where the mother’s heart and stomach used
to be, not where her uterus was. Modern baleen whale fetuses are com-
monly found in the chest cavity after the death of the mother, when rot-
ting gases in the abdomen propel the dead fetus forward, through the
diaphragm and into the chest. Furthermore, the skeleton of the little
whale is incomplete; its entire back half is missing. Is it possible that the
adult killed a small free-swimming specimen, biting it into two pieces
and swallowing one part. The bones of the small specimen are so unde-
fined that one cannot determine whether these two are even the same
species. There are ways to study this further: bodies of fetuses are physi-
ologically part of their mother’s body, so if the isotopic signature of the
small specimen matches that of the adult one, the mother–fetus relation
seems more plausible; but that work has not been carried out yet.
protocetids and history
The first protocetid was discovered in 1904 in the desert of Egypt.34 The
site where it was found is now gone: the city of Cairo has expanded over
it. That specimen was a skull. It was named Protocetus atavus, Latin for
“before-whale grandfather.” It was immediately recognized as a possible
link to land mammals, and for nearly a century it defined what people
thought an ancestral whale would look like. But it was just a skull, and
scientists did not realize how different protocetids really are from mod-
ern whales. The skull survived more than forty million years of burial in
Africa, but not four decades of being housed in a natural-history museum
in Stuttgart, Germany: it was destroyed during bombing in World War II.
Protocetids are fascinating whales—the first ones to disperse across
the planet, adopt the fast-hunting strategies that many modern whales
still use, and reach unprecedented levels of diversity, both in numbers of
species and in morphology. Having said that, they cannot help me
understand what the ancestors of whales, the critters before pakicetids,
looked like, and they cannot solve the riddle of the relation to hippos.
For that, I need to study artiodactyls—old ones, and preferably from
India or Pakistan, since that is where cetaceans originated. Again, I am
confronted with the fact that I have to focus away from marine rocks
and start digging in rocks that have terrestrial animals.
Chapter 13
From Embryos to Evolution
a dolphin with legs
Tokyo, Japan, June 7, 2008. No living cetacean has legs that stick out
of its body. Except for one, and I am in Japan to see it: a dolphin with
hind limbs. I have seen pictures of the animal on the Internet, showing
two triangular fins emerging from the body near the slit where the gen-
itals lie hidden. The animal made headlines around the world, and my
Japanese colleagues offered to take me to see it.
The dolphin’s capture is controversial. Tadasu Yamada, who studies
whales at Japan’s National Museum of Nature, tells me that the dolphin
was caught by dolphin hunters from the village of Taiji, about 300 km
west of Tokyo.1 These hunters are infamous for their practice of scaring
groups of dolphins into narrow coves with loud sounds, and then killing
them, apparently for food. This one dolphin looked different, and the
hunters kept it alive, housing it in a nearby marine park. They call it
Haruka, which means “coming from ancient times,” a reference to the
evolutionary origin of hind limbs.
I visit Tadasu in his office in Tokyo with Jim Mead, the curator of
marine mammals at the Smithsonian Institution in Washington, D.C.
Both of these senior anatomists delight in anatomical trivia, launching
with gusto over lunch into a detailed discussion of the anal tonsils of
cetaceans—where they are, what they’re for.
After they exhaust that topic, Jim says to me: “Back in the sixties, I
worked east of Tokyo, in Chiba Prefecture. There was a whaling station
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174 | Chapter 13
in Chiba, and we would stay there and study the beaked whales they
pulled up, Berardius. ”
Berardius is the Latin name for a species of beaked whale that lives
in very deep water. This whale is enormous and eerie, with big eyes—
something like a monstrous Flipper crossed with a giant squid.
We talk about our past experiences studying whales in Japan. Japan
is a big whaling country, but whaling is regulated by a group called the
International Whaling Commission (IWC). Japan exploits a loophole in
the IWC regulations, allowing scientific whaling, and kills thousands of
whales in the name of research. But few scientists—including Japanese
scientists—are impressed with this research.
Any nation can join the IWC and have a vote. The meetings are often
aggressive, with whaling nations such as Japan, Norway, and Iceland
going head to head with conservation-minded nations like Australia
and New Zealand. The four-legged dolphin is an example of scientific
research on the coattails of hunting, but it’s a very unusual one. We talk
about how to get access to it. Yamada had emailed me that the Japanese
scientists at the Taiji whale museum wanted Jim and me to give short
presentations, explaining what they could do scientifically with the ani-
mal. I was excited, and had called Frank Fish about the possibility of
experiments. Frank got excited, too. Two days later, I received word
from Tadasu that the whole thing had fallen through. The administra-
tors running the aquarium wanted nothing to do with outsiders. There
would be no talks, and we would only be allowed to see the animal in
the tank, as if we were tourists, with no special access. I ask him why.
“They want to keep the animal alive as long as possible, and breed it.
They have put her in a tank and want nothing done with her.”
I hadn’t planned any invasive or damaging experiments, mainly just
filming the animal. But I can see that this is not simple.
“Have they CT-scanned the animal?” I ask.
“No, they really limit all handling. They have made clear that they
only will allow access to the specimen to people who openly support the
drive hunt.”
That counts me out, because I do not. “How can we help other scien-
tists get access? I presume that they only want Japanese to study the
animal.”
“No, foreigners are fine, as long as they support the drive hunt.”
Studying Haruka has become a political act.
The three of us meet three more Japanese, and together we fly to
The Walking Whales Page 26