is pakicetus a whale

Was Pakicetus the first whale?

Odd as it may seem, a four-footed land mammal named Pakicetus, living some 50 million years ago in what we know as Pakistan today, bears the title of “first whale.”. Artist’s impression of Pakicetus attocki.

What kind of animal is Pakicetus?

The First Whale: Pakicetus main content. Pakicetus: The First Whale. Straddling the two worlds of land and sea, the wolf-sized animal was a meat eater that sometimes ate fish, according to chemical evidence. Pakicetus also exhibited characteristics of its anatomy that link it to modern cetaceans, a group made up of whales, porpoises, and dolphins.

Were the later descendants of Pakicetus fully aquatic?

The later descendants of Pakicetus were fully aquatic. Modern whales are descended from the archaeocete basilosaurids, a group of toothed whales that had extremely long bodies and tails. The archaeocete basilosaurids appeared later in the Eocene and early Oligocene (34 million to 23 million years ago) and lived in...

Could Pakicetus hear underwater?

Modern whales also transmit sound vibrations to the inner ear using a "fat pad", which allows them to hear directionally underwater. Pakicetus lacked both of these features, indicating that it was unable to dive deeply and that it could not hear well underwater.

How are Pakicetus related to whales?

Pakicetus was a shore-dwelling creature with webbed feet that lived around 49 million years ago. Scientists were able to link Pakicetus to the evolutionary lineage of whales because of its distinct, dense ear bones. Animals like Pakicetus gave rise to the modern-day giants of the deep.

What kind of animal was Pakicetus?

Odd as it may seem, a four-footed land mammal named Pakicetus, living some 50 million years ago in what we know as Pakistan today, bears the title of “first whale.”

Did whales evolved from Pakicetus?

The ancestor of today's whales, the first cetacean, is believed to be Pakicetus, a quadruped measuring 1 to 2 metres long.

What is the closest land animal to a whale?

HipposHippos are the closest living relatives of whales, but they are not the ancestors of whales. Both hippos and whales evolved from four-legged, even-toed, hoofed (ungulate) ancestors that lived on land about 50 million years ago. Modern-day ungulates include hippopotamus, giraffe, deer, pig and cow.

What animal did whales evolve from?

Meet Pakicetus, a goat-sized, four-legged creature that scientists recognise as one of the first cetaceans (the group of marine animals that includes dolphins and whales). How Pakicetus' descendants evolved into whales is one of the most intriguing evolutionary journeys known to science.

Why did whales lose their legs?

In findings to be published this week in the Proceedings of the National Academy of Sciences, scientists say the gradual shrinkage of the whales' hind limbs over 15 million years was the result of slowly accumulated genetic changes that influenced the size of the limbs and that these changes happened sometime late in ...

What are whales related to?

According to molecular evidence, the closest living relatives of whales are, quite surprisingly, the artiodactyls, a group of hoofed mammals that includes deer, cows, sheep, pigs, giraffes, camels and hippos.

Is a dolphin a whale?

It may sound confusing, but all dolphins are simply smaller types of whales. The whale order (Cetacea) is divided into several different families, one of them being Delphinidae (this includes all oceanic dolphin species).

How would you describe Pakicetus?

Pakicetus had a long snout; a typical complement of teeth that included incisors, canines, premolars, and molars; a distinct and flexible neck; and a very long and robust tail. As in most land mammals, the nose was situated at the tip of the snout.

Why can't whales survive on land?

Whales can only survive a few hours on land. They breathe the air just fine. The problem is that their fat holds in too much heat. When the water is not there to absorb the heat, they die.

What is the biggest animal that ever lived?

the blue whaleShare: Far bigger than any dinosaur, the blue whale is the largest known animal to have ever lived. An adult blue whale can grow to a massive 30m long and weigh more than 180,000kg - that's about the same as 40 elephants, 30 Tyrannosaurus Rex or 2,670 average-sized men.

What are the 2 close cousins of whales?

In fact, hippopotamus are actually whales' closest “cousins”, and they're much more closely related than you might guess. Based on their fossil record, scientists have determined that whales are related to land dwelling mammals that lived on Earth between 52 – 47 million years ago.

How would you describe Pakicetus?

Pakicetus had a long snout; a typical complement of teeth that included incisors, canines, premolars, and molars; a distinct and flexible neck; and a very long and robust tail. As in most land mammals, the nose was situated at the tip of the snout.

What is the scientific name for Pakicetus?

PakicetusPakicetus / Scientific name

Were whales ever land animals?

Hippos likely evolved from a group of anthracotheres about 15 million years ago, the first whales evolved over 50 million years ago, and the ancestors of both these groups were terrestrial. These first whales, such as Pakicetus, were typical land animals.

Is Pakicetus extinct?

Pakicetus, extinct genus of early cetacean mammals known from fossils discovered in 48.5-million-year-old river delta deposits in present-day Pakistan. Pakicetus is one of the earliest whales and the first cetacean discovered with functional legs.

What is the evolution of Pakicetus?

It was only over the course of the Eocene epoch that the descendants of Pakicetus began to evolve toward a semi-aquatic, and then fully aquatic, lifestyle, complete with flippers and thick, insulating layers of fat.

What are the descendants of Pakicetus?

If you happened to stumble across the small, dog-sized Pakicetus 50 million years ago, you'd never have guessed that its descendants would one day include giant sperm whales and gray whales.

Where was the Pakicetus found?

One of the odd things about Pakicetus is that its "type fossil" was discovered in Pakistan, not normally a hotbed of paleontology. In fact, thanks to the vagaries of the fossilization process, most of what we know about early whale evolution derives from animals discovered on or near the Indian subcontinent; other examples include Ambulocetus (aka the "walking whale") and Indohyus.

Is Pakicetus a terrestrial or aquatic mammal?

Perhaps because even trained scientists have a hard time accepting a fully terrestrial mammal as the ancestor of all whales, for a while after its discovery in 1983, Pakicetus was described as having a semi-aquatic lifestyle. The discovery of a more complete skeleton in 2001 prompted a reconsideration, and today Pakicetus is deemed to have been fully terrestrial; in the words of one paleontologist, "no more amphibious than a tapir." It was only over the course of the Eocene epoch that the descendants of Pakicetus began to evolve toward a semi-aquatic, and then fully aquatic, lifestyle, complete with flippers and thick, insulating layers of fat.

What is the difference between a pakicetus and a cetacean?

Pakicetus looked very different from modern cetaceans, and its body shape more resembled those of land-dwelling hoofed mammals. Unlike all later cetaceans, it had four fully functional long legs. Pakicetus had a long snout; a typical complement of teeth that included incisors, canines, premolars, and molars; a distinct and flexible neck;

How big is a pakicetus?

Based on the skull sizes of specimens, and to a lesser extent on composite skeletons, species of Pakicetus are thought to have been 1 metre (3 ft 3 in) to 2 metres (6 ft 7 in) in length . Pakicetus looked very different from modern cetaceans, and its body shape more resembled those of land-dwelling hoofed mammals.

What is the skeleton of a pakicetus?

The Pakicetus skeleton reveals several details regarding the creature's unique senses and provides a newfound ancestral link between terrestrial and aquatic animals. As previously mentioned, the Pakicetus' upward-facing eye placement was a significant indication of its habitat. Even more so, however, was its auditory abilities. Like all other cetaceans, Pakicetus had a thickened skull bone known as the auditory bulla, which was specialized for underwater hearing. Cetaceans also all categorically exhibit a large mandibular foramen within the lower jaw, which holds a fat pack and extends towards the ear, both of which are also associated with underwater hearing. " Pakicetus is the only cetacean in which the mandibular foramen is small, as is the case in all terrestrial animals. It thus lacked the fat pad, and sounds reached its eardrum following the external auditory meatus as in terrestrial mammals. Thus the hearing mechanism of Pakicetus is the only known intermediate between that of land mammals and aquatic cetaceans." With both the auditory and visual senses in mind, as well as the typical diet of Pakicetus, one might assume that the creature was able to attack both aquatic and terrestrial prey from a low vantage point.

What is the name of the extinct whale?

Pakicetus is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to Pakistan during the Eocene, about 50 million years ago. It was an animal rather like a wolf, about 1 metre (3 ft 3 in) to 2 metres (6 ft 7 in) long, and lived in and around water where it ate fish and small animals. The vast majority of paleontologists regard it as the most basal whale, representing a transitional stage between land mammals and whales. It belongs to the even-toed ungulates with the closest living non-cetacean relative being the hippopotamus.

What did the teeth on Pakicetus' skull mean?

The first fossil found consisted of an incomplete skull with a skull cap and a broken mandible with some teeth. Based on the detail of the teeth, the molars suggest that the animal could rend and tear flesh. Wear, in the form of scrapes on the molars, indicated that Pakicetus ground its teeth as it chewed its food. Because of the tooth wear, Pakicetus is thought to have eaten fish and small animals. The teeth also suggest that Pakicetus had herbivorous and omnivorous ancestors.

Where are the orbits of cetaceans located?

However, Thewissen et al. 2009 argued that "the orbits ... of these cetaceans were located close together on top of the skull, as is common in aquatic animals that live in water but look at emerged objects. Just like Indohyus, limb bones of pakicetids are osteosclerotic, also suggestive of aquatic habitat" (since heavy bones provide ballast). "This peculiarity could indicate that Pakicetus could stand in water, almost totally immersed, without losing visual contact with the air."

Which cetacean has a large mandibular foramen?

" Pakicetus is the only cetacean in which the mandibular foramen is small, as is the case in all terrestrial animals.

Where did the Pakicetus whales live?

Pakicetus, extinctgenusof early cetaceanmammalsknown from fossilsdiscovered in 48.5-million-year-old river deltadeposits in present-day Pakistan. Pakicetusis one of the earliest whalesand the first cetacean discovered with functional legs. In addition, it still retained many other features of terrestrial mammals, ...

What is the name of the first whale to have legs?

In addition, it still retained many other features. Pakicetus, extinct genus of early cetacean mammals known from fossils discovered in 48.5-million-year-old river delta deposits in present-day Pakistan. Pakicetus is one of the earliest whales and the first cetacean discovered with functional legs. In addition, it still retained many other features.

What is the whale's descendent?

The later descendants of Pakicetuswere fully aquatic. Modern whales are descended from the archaeocete basilosaurids, a group of toothed whalesthat had extremely long bodies and tails. The archaeocete basilosaurids appeared later in the Eocene and early Oligocene(34 million to 23 million years ago) and lived in the Tethys Sea and Atlantic Ocean.

What are the features of a cetacean?

The ancient Greeks recognized that cetaceans breathe air, give birth to live young, produce milk, and have hair —all features of mammals.

Where did whales live during the Eocene?

Whales evolved during the Eocene in the warm, shallow tropical Tethys Sea, which lay sandwiched between the mainland of Asia and Europe to the north and Africa, Arabia, Madagascar, and the Indian subcontinent to the south. Most archaeocetes (first cetaceans) lived in the Tethys or along its margins.

What is a genus?

genus, biological classification ranking between family and species, consisting of structurally or phylogenetically related species or a single isolated species exhibiting unusual differentiation (mono typic genus). The genus name is the first word of a binomial scientific name (the species name is the second word) and is always capitalized.…

What is the term for the dying out of a species?

Extinction, in biology, the dying out or extermination of a species. Extinction occurs when species are diminished because of environmental forces (habitat fragmentation, global change, natural disaster, overexploitation of species for human use) or because of evolutionary changes in their members (genetic inbreeding, poor reproduction, decline in population numbers).…

What does the name Pakicetus mean?

Its name means “Pakistan whale. ”. If you knew nothing about this mammal other than what you’ve seen in Pakicetus pictures, then you might never guess that it was one of the earliest whales found. That’s because it doesn’t look aquatic at all.

When was the Pakicetus first discovered?

It was first discovered in Pakistan and was named by Philip Gingerich and Donald Russell in 1981. Its name means “Pakistan whale.”

What is the earliest whale?

One of the most interesting facts about Pakicetus is that according to scientists, this is the earliest whale they’ve found as of yet. It was a mammal that would only go near the water to grab fish. Paleontologists know this because its ears were only adapted for the land and not for the water.

What is the fossil of Pakicetus?

This fossil material was found in fluvial red sediments, or river-produced deposits colored by material leached from iron ores. This formation is thus a terrestrial or continental deposit. The fossil remains associated with Pakicetus are dominated by land mammals. Non-mammalian remains include other terrestrial remains such as snails, fishes (particularly catfish), turtles, and crocodiles. This evidence indicates a fluvial and continental, rather than a marine environment, as would be expected for a whale or whale-like creature. It is highly significant that the auditory mechanism of Pakicetus was that of a land mammal, rather than that of a whale, since there is no evidence that it could hear directly under water, nor is there any evidence of vascularization of the middle ear to maintain pressure during diving. The authors stated that the teeth resemble those of the mesonychids, which possibly fed on carrion, mollusks, or tough vegetable matter. On the basis of this evidence, the idea was challenged that Pakicetus was anything other than a land mammal, with no relationship to marine mammals. [5]

What was the name of the whale that was discovered in 1983?

In 1983, headlines in newspapers all over the world, based on an article published by Gingerich and coworkers, [4] trumpeted the discovery of a so-called primitive whale which established a link between whales and their hypothetical land-mammal ancestor, the hoofed mammalian carnivore, Mesonyx.

How big is Ambulocetus?

In their Science article, [6] Thewissen and coworkers state that Ambulocetus was about the size of a male sea lion, weighing about 650 lbs. and had a robust radius and ulna (the two bones in the upper forearm).

Where was Ambulocetus found?

It is reported that the fossil of Ambulocetus was found in a silt and mud-stone bed which contained impressions of leaves and abundant Turritella, a marine gastropod. [6] This would suggest that it lived near the seashore, feeding possibly on land animals and/or plants, and perhaps foraging into shallow seas to feed on gastropods and molluscs. They report that the fossil beds are lower-to-middle Eocene beds, and about 120 meters (approximately 390 feet) higher than those in which Pakucetus was found. Berta, in her comments on the paper by Thewissen, et al, gives an age of 52 million years for the sediments in Pakistan where Ambulocetus was found. Thewissen and his coworkers in their paper mention an age of 52 million years for the age of Pakicetus, which they refer to as the "oldest cetacean." Ambulocetus, bearing large forelimbs and hooved hind limbs, was found in strata nearly 400 feet higher than Pakicetus. It therefore cannot be older. Pakicetus is called the oldest cetacean. Yet it is said that Ambulocetus documents transitional modes of locomotion in the evolution of whales. Confused? So are we. It is reported that the teeth resemble those of other archeocetes, which evolutionists believe were either archaic whales or ancestral to whales. The teeth of archeocetes are, however, so similar to mesonychid ungulates, believed to be wolf-like carnivorous mammals, that two of the archeocetes, Gandakasia and Ichthykstes, known only from teeth, were originally classified as mesonychids. [7]

How old is the oldest cetacean?

Thewissen and his coworkers in their paper mention an age of 52 million years for the age of Pakicetus, which they refer to as the "oldest cetacean.". Ambulocetus, bearing large forelimbs and hooved hind limbs, was found in strata nearly 400 feet higher than Pakicetus. It therefore cannot be older.

What newspaper headlines featured the fossil thought to belonged to walking whale?

For example, the Cleveland Plain Dealer featured the report in an article published in that paper January 16, 1994, with the bold headline , "Fossil Thought to Belong to Walking Whale—Creature May Be Missing Link.".

Which animal is closest to Ambulocetus?

A search of texts on mammals for fossils of creatures resembling Ambulocetus failed to produce one closely resembling Ambulocetus, although Allodesmus, an extinct aquatic carnivore believed to have preceded walruses, bears some resemblance. [10]

When did Pakicetus attocki live?

Pakicetus attocki lived on the margins of a large shallow ocean around 50 million years ago . Chemical information from some of these wolf-sized meat-eaters show that they ate fish.

How long ago did the basilosaurid whale live?

These whales were fully aquatic and lived between 34 and 40 million years ago. From a distance, living basilosaurids probably looked very much like modern species. The nostrils, or blowhole, had moved toward the top of the head. The structure of the ear bones suggests that basilosaurids could hear well under water.

How does Ambulocetus hear sound?

It seems Ambulocetus heard sound through its lower jaw bone. Sound passed from the jaw through soft tissues leading to the ear. This small adaptation foreshadows the remarkable sound-receiving system used by modern toothed whales.

What animals left the land?

Eventually they left land altogether—evolving into the fully aquatic whales.

Where did Kutchicetus live?

Kutchicetus minimus, with its small, otterlike skeleton, lived between 43 and 46 million years ago. Like other early whales, Kutchicetus lived in tropical seas. Its fossils are found in sediment that formed in shallow seas sheltered by barrier islands.

When did whales evolve?

Part of the Whales: Giants of the Deep exhibition. The astounding transition came shortly after the rise of modern mammal groups, around 55 million years ago , during a hot period in the Earth’s history.

Can basilosaurids hear under water?

The structure of the ear bones suggests that basilosaurids could hear well under water. Forelimbs became paddlelike flippers, while the hindlimbs were rudimentary. The pelvis had detached from the spinal column, freeing up the lower spine to power greater tail movement.

Where did the Pakicetus get its name?

It’s the geographical gap that makes the “transitional form” argument even less convincing. Pakicetus gets its name from its discovery in Pakistan. Except for Basilosaurus, all the other supposed links in this evolutionary chain are found in that part of the world.

When did whales first appear?

Paleontologists have unveiled the fossilized lower jaw of an ancient whale from India that, they claim, pushes the origin of these marine mammals back before 53.5 million years ago , earlier than previously thought. This primitive species provides new information on the profound evolutionary transformation that turned a group of four-legged land mammals into modern cetaceans--the whales, dolphins, and porpoises inhabiting the ocean today--say the researchers.

How long did it take for a whale to evolve?

Simpson believes that Pakicetus lived 52 million years ago, and modern whales evolved about 2 million years ago, so it took about 50 million years for Pakicetus to evolve into a modern whale.

What is the name of the organism that evolved from mesonychids?

One of these mesonychids evolved into Pakicetus, which evolved into the partly aquatic Ambulocetus, which became the mostly aquatic Rodhocetus, which evolved in one or more steps into the entirely aquatic Basilosaurus which was direct ancestor of modern whales.

Why did mesonychids live in the water?

Mesonychids that lived near rivers or at the edge of the sea waded into the water to catch fish. They found it easier to fish than to hunt on land. And safer, too. The big, dangerous animals that liked to hunt mesonychids could not swim.

What is the order of archaeocete species?

The generally accepted order of the archaeocete species, in terms of both morphological (primitive to advanced) and stratigraphical (lower/older to higher/younger) criteria, is Pakicetus, Ambulocetus, Rodhocetus, Indocetus, Protocetus, and Basilosaurus.

How many problems are there with the whale fairy tale?

This was accepted for years, but in scientific circles today this view of whale evolution is controversial. There are nine major problems with the whale fairy tale. What are these nine problems? We are soglad you asked!

Overview

Pakicetus is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to Pakistan during the Eocene, about 50 million years ago. It was a wolf-like animal, about 1 metre (3 ft 3 in) to 2 metres (6 ft 7 in) long, and lived in and around water where it ate fish and small animals. The vast majority of paleontologists regard it as the most basal whale, representing a transitional stage between land mammals and whales. It belongs to the even-toed ungulates wit…

Description

Palaeobiology

History of discovery

Classification

See also

Notes