April 16, 2005

FOSSILIZED remains of ancient whales have been found in the United States, Egypt, Nigeria and India. However, more discoveries involving ancient whales have been made in Pakistan than in any of the countries mentioned.

It was generally thought that whales originated in Egypt. But the discoveries made in our provinces indicate, rather strongly, that the whales’ origins could well be in what is now called Pakistan. Several whales dating back to the Eocene Epoch — about 55 million years to 38 million years before present — have been found in the marine and non-marine deposits of the country. These deposits may be described as fossiliferous, having the best whale fossils anywhere in the world.

The discovery of ancient whales in Pakistan goes back to 1958, when Dehm and Ottingen found the dental remains of two archaeocetes (whales living during the Eocene Epoch). Called Gandekasia and Ichthyolestes, these animals were found in transitional marine beds on top of the Kuldana Formation (a rock unit) in Kala Chitta Hills, Attock District, Punjab.

Between 1979 and 2000, the Geological Survey of Pakistan, in collaboration with the University of Michigan and Howard University of the US, found fossils of as many as 14 genera of extinct whales from NWFP, Punjab and Balochistan in rocks dating back to the period between 52 and 40 million years before present. The rocks were both continental and marine in nature.

The oldest known whale fossils in the country, however, came from the Kohat and Attock districts of northern Pakistan, in 52-million-year-old sediments deposited by ancient rivers. A wolf-sized early whale, known as Pakicetus, represented by upper and lower teeth, was found in Chorlaki, Kohat District, NWFP, by a team of the Geological Survey of Pakistan and University of Michigan in 1979.

In the early 80s, the jaws and ear bones of the same genus were found by another team, comprising scientists from the Geological Survey of Pakistan and Howard University, from the Kala Chitta Hills. At both places, the Pakicetus lived with land mammals, such as rodents, tillodonts, artiodactyls, perissodactyls and proboscideans, suggesting that the early cetaceans lived on land.

In 1991-1992 palaeontologists of the Geological Survey of Pakistan and Howard University found a partial skeleton, consisting of a skull, teeth, femur, vertebrae and fore and hind limbs, of a 50-million-year-old cetacean (scientific name for whales, dolphins, and porpoises). It was named Ambulocetus, or walking whale, which was found from the Kala Chitta Hills in shallow marine bed of silt and mudstone in an area measuring about two square metres. The same bed contained impressions of leaves and marine molluscs, suggesting that the specimen was buried in shallow sea.

It had a long snout, like dolphins, and measured about 10 feet from snout to tail. The bones of its hands and feet indicated that it could move on land as well as in water. On the basis of the size of its fossilized bones, the weight of this archaeocete was estimated to be between 600 and 700 pounds. Of the four cetaceans found in Kala Chitta Hills, Pakicetus was the oldest and was found in a continental deposit, while the rest came from marine deposits.

A rich collection of cetaceans has also been found from the Eocene marine deposits of the Sulaiman Range. In their continued search, scientists of the Geological Survey of Pakistan and University of Michigan discovered as many as 10 genera of ancient whales, dating back to the middle-Eocene time (48 million years before present), from marine sediments of the Punjabi and Balochi parts of the Range.

In 1992 three archaeocetes — called Rodhocetus, Remingtonocetus, and Indocetus — were found to the west of Taunsa Sharif, D.G. Khan District, in a 48-million-year-old Domanda Formation. The Rodhocetus had a short neck, reduced femur and unfused sacral vertebrae. Unfused sacral vertebrae gave flexibility to its back and tail for efficient tail-powered swimming, which is the hallmark of whales that came later. In the other mammals these vertebrae are, however, fused and hold the pelvis together.

The Remingtonocetus is represented by partial cranial, right dentition, vertebrae and several ribs. In the meantime, long neck, long hind limbs, a rigid sacrum and robust tail of the Indocetus has been encountered in the same area.

Skulls and skeletons of three more whales were found in the Takra area, west of D.G. Khan, in 1994. These were Takracetus, Dalanistes and Gaviacetus. The Takracetus is represented by a partial cranium in three parts, and a cervical and thorax vertebrae. In the case of Dalanistes, much of the skull, long neck, robust fused sacrum and hind limbs remained. The Gaviacetus was represented by the cranium, with associated post-cranial elements.

In 1996 the same team found the vertebrae of the largest archaeocete, the Basilosaurus, in about 40-million-year-old rocks of Drazinda Formation, west of Taunsa Sharif. This is the youngest and the largest ancient whale found so far in Pakistan.

In 1999-2000 skulls, vertebrae, ankle bones and fore and hind limbs of four more genera of ancient whales were found in the Balochi part of Sulaiman Range, near Drug and Karkna areas of Loralai Division. These genera are Andrewsiphus, Remingtonocetus, Qaiserocetus and Rodhocetus. Of these, Qaiserocetus was a new find for Pakistan while the remaining three had already been reported from either Pakistan or India. These discoveries strongly suggest that Pakistan is rich in ancient whales.

The fossil record of ancient whales can only grow if more discoveries are made in the country. The discoveries can play a key role in understanding the early history of whales. They can also prove that Pakistan, and not Egypt, was the area from where whales originated.

Discoveries made in Pakistan have been reported in prestigious international and national journals, like Science and Nature. This has put Pakistan firmly on the world’s palaeontology map.

Meanwhile, whales are perhaps the most fascinating animals that live in almost all oceans and big rivers of the world. Though they resemble fish — particularly in their appearance, habitat and food — whales are not fish, but mammals.

They possess mammalian characteristics. They are warm-blooded vertebrates that breathe air with lungs and give birth to babies that feed on milk. On the basis of these characteristics, Carl Linnaeus, a Swedish biologist, described them as mammals in 1758. Furthermore, the anatomy and behaviour of the living whales and the bones and teeth of fossilized whales show, rather conclusively, that they are mammals.

Among the mammals which have adapted to aquatic life, whales are more suited to existence under water. Other marine mammals such as pinnipeds (flesh-eating mammals like seals) and serenians (plant-eating mammals such as sea cows) return to land to breed and bask on reefs. However, the whale spends its whole life in water.

When a whale needs oxygen, it comes to the surface, jumps high up in the air and stores oxygen in its muscles before diving down. It can stay under water for 40 to 60 minutes.

Whales are very friendly towards humans and are considered to be one of the intelligent mammals. Its intelligence can be equated perhaps to that of monkeys and apes — members of the highest order of mammals. Modern whales can be divided into two categories. These are Odontocetes, toothed whales with one blowhole at the top of their heads, and Mystecetes, toothless whales with two blowholes. Whales breathe air through these blowholes.

There are 38 genera and 76 species of modern whales. Of these, 66 species belong to the odontocetes group, which includes dolphins and porpoises. The largest of all toothed whales is the sperm whale, which is about 65ft long and weighs about 70tons.

Today the world’s largest and heaviest animal is the toothless blue whale. Its length is between 90-100ft and it can weigh anywhere from 160 to 200tons.

Modern whales are carnivores, that is, they eat flesh. Their food ranges from small invertebrates to fish and other whales. A blue whale consumes about 2.25tons of food everyday. They exist in almost all oceans, from the equator to the poles. In winter, they migrate from the poles to warm waters for breeding. But in the summers, they return.

In Pakistan there is a toothed whale (dolphin) which is present in the Indus. The local name for Indus dolphin is “Bulhan”. It is mainly confined to Taunsa, Chashma, Guddu and Sukkur barrages.

Bodies of toothless whales are found regularly near the beaches along the Indian Ocean. The carcass of a 15-metre-long blue whale was found near the Makran coast, Balochistan, in the mid-80s. Its skeleton is on display in the exhibition halls of the Pakistan Museum of Natural History, Islamabad.

The writer is a former deputy director of the Geological Survey of Pakistan

Whale of a debate
THERE IS considerable debate among scientists over the ancestry of whales. The evolutionists among them contend that modern whales descended from terrestrial animals having hind legs, known as Mesonychids. The creationists, however, dismiss all this as mere speculation.

Led by E.J. Slijper, the creationists point towards the supposed lack of transitional forms in the whales’ fossil record as proof that evolutionists are wrong. They also claim that the evolutionists’ theories had allowed for a large number of changes, by selection and mutation, within a period of only about 20 million years. This, they say, is next to impossible.

In the following paragraphs, Sci-tech World presents excerpts from a paper by Raymond Sutera, entitled “The origin of whales and the power of independent evidence” which presents the evolutionists’ case:

“The palaeontological evidence comes from studying the fossil sequence from terrestrial mammals through more and more whale-like forms until the appearance of modern whales… .

“Sinonyx: We start with Sinonyx, a wolf-sized mesonychid (a primitive ungulate belonging to the order Condylarthra) from the late Paleocene, that is about 60 million years ago. The characters that link Sinonyx to the whales, thus indicating that they are relatives, include an elongated muzzle, an enlarged jugular foramen, and a short basicranium (Zhou and others 1995). The tooth count was the primitive mammalian number (44)... . The molars were very narrow shearing teeth, especially in the lower jaw, but they possessed multiple cusps. The elongation of the muzzle is often associated with hunting fish. All fish-hunting whales, as well as dolphins, have elongated muzzles. These features were atypical of mesonychids, indicating that Sinonyx was already developing the adaptations that later became the basis of the whales’ specialized way of life.

“Pakicetus: The next fossil in the sequence is the oldest cetacean and the first known archaeocete. It is from the early Eocene of Pakistan, about 52 million years ago (Gingerich and others 1983). Although it is known only from fragmentary skull remains, those remains are very diagnostic and they are definitely intermediate between Sinonyx and later whales. This is especially the case for teeth.

“The upper and lower molars, which have multiple cusps, are still similar to those of Sinonyx, but the premolars have become simple triangular teeth composed of a single cusp serrated on its front and back edges. The teeth of later whales show even more simplification into simple serrated triangles, like those of carnivorous sharks, indicating that Pakicetus’s teeth were adapted to hunting fish.

“A well-preserved cranium showed that Pakicetus was definitely a cetacean with a narrow braincase, a high, narrow sagittal crest, and prominent lambdoidal crests. Gingerich and others (1983) reconstructed a composite skull that was about 35 centimetres long.

“Ambulocetus: In the same area that Pakicetus was found, but in sediments about 120 metres higher, Thewissen and colleagues (1994) discovered Ambulocetus natans... in 1992. Dating from the early to middle Eocene, about 50 million years ago, Ambulocetus is a truly amazing fossil. It was clearly a cetacean, but it also had functional legs and a skeleton that still allowed some degree of terrestrial walking. The conclusion that Ambulocetus could walk by using the hind limbs is supported by its having a large, stout femur.

“Rodhocetus: In the middle Eocene (about 46 million years ago) Rodhocetus took all of these changes even further, yet still retained a number of primitive terrestrial features (Gingerich and others 1994). It is the earliest archaeocete of which all of the thoracic, lumbar, and sacral vertebrae have been preserved. The lumbar vertebrae had higher neural spines than in earlier whales. The size of these extensions on top of the vertebrae where muscles are attached indicate that Rodhocetus had developed a powerful tail for swimming.

“The pelvis of Rodhocetus was smaller than that of its predecessors, but it was still connected to the sacral vertebrae, meaning that Rodhocetus could still walk on land to some degree. However, the ilium of the pelvis was short compared to that of the mesonychids, making for a less powerful muscular thrust from the hip during walking, and the femur was about one-thirds shorter than Ambulocetus’s, so Rodhocetus probably could not get around as well on land as its predecessors (Gingerich and others 1994).

“Overall, Rodhocetus showed improvements over earlier whales by virtue of its deep, slim thorax, longer head, greater vertebral flexibility, and expanded tail-related musculature. The increase in flexibility and strength in the back and tail with the accompanying decrease in the strength and size of the limbs indicated that it was a good tail-swimmer with a reduced ability to walk on land.

“Basilosaurus: The particularly well-known fossil whale, Basilosaurus, represents the next evolutionary grade in whale evolution (Gingerich 1994). It lived during the late Eocene and latest part of the middle-Eocene (35-45 million years ago). Basilosaurus was a long, thin, serpentine animal that was originally thought to have been the remains of a sea serpent, hence its name which actually means “king lizard”.

“Its extreme body length (about 15 metres) appears to be due to a feature unique among whales; its 67 vertebrae are so long compared to other whales of the time and to modern whales that it probably represents a specialization that sets it apart from the lineage that gave rise to modern whales.

“What makes Basilosaurus a particularly interesting whale, however, is the distinctive anatomy of its hind limbs (Gingerich and others 1990). It had a nearly complete pelvic girdle and set of hind limb bones. The limbs were too small for effective propulsion, less than 60 cm long on this 15-metre-long animal, and the pelvic girdle was completely isolated from the spine so that weight-bearing was impossible. Reconstructions of the animal have placed its legs external to the body — a configuration that would represent an important intermediate form in whale evolution.

“Further evidence that Basilosaurus spent most of its time in the water comes from another important change in the skull. This animal had a large single nostril that had migrated a short distance back to a point corresponding to the back third of the dental array. The movement from the forward extreme of the snout to a position nearer the top of the head is characteristic of only those mammals that live in marine or aquatic environments.

“Clearly, even if we look only at the palaeontological evidence, the creationist claim of ‘No fossil intermediates’ is wrong. In fact, in the case of whales, we have several examples, beautifully arranged in morphological and chronological order.

“In summarizing the palaeontological evidence, we have noted the consistent changes that indicate a series of adaptations from more terrestrial to more aquatic environments as we move from the most ancestral to the most recent species. These changes affect the shape of the skull, the shape of the teeth, the position of the nostrils, the size and structure of both the fore limbs and the hind limbs, the size and shape of the tail, and the structure of the middle ear as it relates to directional hearing underwater.

“The palaeontological evidence records a history of increasing adaptation to life under water — not just to any way of life in water, but to life as lived by contemporary whales.”

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