Updates? not dive to any great depth, nor locate sounds underwater. Many toothed whales live in large groups and have feeding routines. Dorudon has a long, narrow snout, and almost certainly lacked the bulbous melon that forms the spherical bulge on the facial profile of modern toothed whales. "It's odd to have a big predator in this hoofed plant-eating mammal group," said John Flynn, co-curator of the exhibit, referring to the group to which whales and the now-extinct Andrewsarchus belonged. like a crocodile. comb jelly A comb jelly. The first part of the name references the lizard's distinct teeth; a 'kopis' is a curved blade . There's no denying, though, that we've wreaked plenty of ecological havoc during our brief time in the spotlight: hunting the starved, straggling megafauna mammals of the last Ice Age; depleting entire populations of whales and other marine mammals; and eliminating the dodo bird and the passenger pigeon virtually overnight. 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 body mass of Pakicetus was estimated at 45 kg (100 pounds), roughly the size of a wolf or large dog. [4], Pakicetus looked very different from modern cetaceans, and its body shape more resembled those of land-dwelling hoofed mammals. 7 Extinction Level Events That Could End Life as We Know It, 6 Alternative Dinosaur Extinction Theories That Don't Work, 10 Prehistoric Creatures that Grew to Dinosaur-Like Sizes, The 10 Most Important Facts About Dinosaurs. It lived on land, on the edge of lakes and riverbanks in what is now Pakistan and India. and that in a modern cetacean. First discovered by paleontologists in 1983, Pakicetus lived along the margins of a large shallow ocean, the Tethys Sea. It was a mammal that would only go near the water to grab fish. bones of the skull. [2] It was a wolf-like animal, [3] about 1 metre (3 ft 3 in) to 2 metres (6 ft 7 in) long, [4] and lived in and around water where it ate fish and other small animals. predatory forces but practical ones too. Pakicetus copy the articles word for word and claim them as your own work. Extinction of Plants and Animals. It hunted small land animals and freshwater fish, and could even hear underwater. After the asteroid hit the Earth, it sent a shower of molten rock into the atmosphere, which then crystallized at high altitudes.. Future US, Inc. Full 7th Floor, 130 West 42nd Street, Around 30 million years ago, these lineages split and evolved into the more than 80 species living today. bone analysis combined with the positioning of the eyes near the top of Unlike all later cetaceans, it had four fully functional long legs. A single bird may be content with the high branch of a tree, while large predatory mammals (like Bengal tigers) measure their domains in square miles. And yet, this rich profusion of flora and fauna seems paltry compared to the ecosystems of the deep past. One of the best-known of all the Devonian tetrapods--the first, lobe-finned fish that climbed up out of the water and onto dry land--Acanthostega nevertheless seems to have represented a dead end in the evolution of early vertebrates, the giveaway being that this creature had eight primitive digits on each of its stubby front flippers, compared to the modern standard of five. This, of course, was the disaster that wiped out the . The exhibitis on display until Jan. 5, 2014. These are called baleen whales, which include blue whales and humpback whales. For instance, no one would have thought that prehistoric mammals were better adapted than dinosaurs until the K-T extinction changed the playing field. In addition, it still retained many other features of terrestrial mammals, including an auditory system that was better for hearing in air than in water, a dentition not unlike that of its closest terrestrial relatives, such as the mesonychids, and functional feet capable of locomotion on land. In water, the pressure of sound waves is much greater than in air and "Top 10 Reasons Why Animals and Plants Go Extinct." Whereas this creature had a body clearly adapted for land, its relatives began acquiring features better suited to life in the water, such as webbed feet and a more streamlined, hairless shape. free for your own study and research purposes, but please dont ear. terrestrial carnivores that began developing adaptations for a wholly Facts About the Ambulocetus Prehistoric Whale, The Dinosaurs and Prehistoric Animals of North Carolina, The Dinosaurs and Prehistoric Animals of South Carolina. As in most land mammals, the nose was at the tip of the snout. This cookie is set by GDPR Cookie Consent plugin. The "first whale," a creature whose lifestyle (living on land but eating fish from the nearby sea) represented the early stage of this transition into the water, was a wolf-size fish eater that lived about 50 million years ago on the edges of the ancient Tethys Sea, according to the exhibit. Contributions from the Museum of Paleontology, The Museum of Michigan Mass starvation is the quick, one-way, surefire route to extinctionespecially since hunger-weakened populations are much more prone to disease and predationand the effect on the food chain can be disastrous. Even in the absence of major asteroid or comet impactswhich can potentially lower worldwide temperatures by 20 or 30 degrees Fahrenheitclimate change poses a constant danger to terrestrial animals. The male sperm whale (Physeter macrocephalus) is the largest living toothed predator on Earth. That's when an immense asteroid slammed into what is now the Yucatan Peninsula, triggering one of the worst extinction crises of all time. formed from very hard, dense material and are almost completely surrounded A typical representative: Pakicetus inachus Gingerich & Russell, 1981. Corrections? Like the modern What are the five methods of dispute resolution? Once a species starts dwindling in numbers, there's a smaller pool of available mates and often a corresponding lack of genetic diversity. Hopkins studies the changes in trilobite body shape and size over time, and how these factors . Pakicetus Timeline: Pakicetus was a land-living cetacean that lived between 56 and 50 million years ago See Also Ambulocetus Named By: Gingerich & Russell - 1981. Pakicetus is one of the earliest whales and the first cetacean discovered with functional legs. Chitta Hills of Pakistan. Fossil representation: Several individuals of How does civil disobedience relate to society today? We also use third-party cookies that help us analyze and understand how you use this website. The evolutionary history of the comb jelly has revealed surprising clues about Earths first animal. However, that is exactly what it was. Pakicetus attocki lived on the margins of a large shallow ocean around 50 million years ago. Donald Russell and their colleagues came to broadly the same conclusion If you knew nothing about this mammal other than what youve seen in Pakicetus pictures, then you might never guess that it was one of the earliest whales found. One ancient cousin to modern whales and hippos, called Andrewsarchus mongoliensis, ranks as the largest mammal known to have stalked the land as a predator. hippopotamus In these and other features of its hearing apparatus, Pakicetus was It measured about six feet (the average height of a human male) in length and had nostrils on the tip of its nose as well as a pointed tail with no tail fin. The excavation site is now a rocky, mountainous desert, but 50 million years ago, it was located beneath the southern edge of an immense, ancient ocean called the Tethys Sea. While most struggles for survival transpire over eons, sometimes the contest is quicker, bloodier, and more one-sided. Size: Between 1 and 2 meters long. They write new content and verify and edit content received from contributors. It was a mammal that would only go near the water to grab fish. [11][12] The discovery of Pakicetus played an important role in solidifying the inferences that revolved around the evolution of whales. 50 million years ago had only just begun to acquire acoustic adaptations But their ancestors of more than Kas region, Pakistan. In 2001, scientists found fossils which confirmed the fact that this mammal lived entirely on the land and never went into the water. Ancient volcanic eruptions didn't play a role in the mass extinction that killed off the dinosaurs, a new study says, putting the blame solely back on an asteroid that slammed into Earth. 2001 wrote that "Pakicetids were terrestrial mammals, no more amphibious than a tapir. Dorudon lived in warm seas around the world. Marine life such as fish, seals, coral,and crustaceans can be exquisitely sensitive to traces of toxic chemicals in lakes, oceans,and riversand drastic changes in oxygen levels, caused by industrial pollution, can suffocate entire populations. When you purchase through links on our site, we may earn an affiliate commission. The Archaeocetes were probably The vast majority of paleontologists regard it as the most basal whale, representing a transitional stage between land mammals and whales. and the bones around the ear cavities were still connected to the surrounding The earliest known member of the Odontoceti, the modern toothed whales, is from the early Oligocene, around 30 million years ago. The reason it can be definitely identified as a cetacean, and not part of some other group, is that the skeleton's inner ear includes features which are characteristic of, and unique to, cetaceans. In These cookies track visitors across websites and collect information to provide customized ads. Length: According to the location of fossil findings, the animals preferred a shallow habitat that neighbored decent-sized land. Humans have only occupied the Earth for the last 50,000 or so years, so it's unfair to blame the bulk of the world's extinctions on Homo sapiens. Strauss, Bob. 40.4 to 33.9 million years ago Dorudon (spear-tooth) is a genus of extinct basilosaurid ancient whales that lived alongside Basilosaurus 40.4 to 33.9 million years ago in the Eocene. The Pakicetus skeleton reveals several details regarding the creature's unique senses and provides a newfound ancestral link between terrestrial and aquatic animals. The whales massive bulbous head is about one-third of the animals length. Let us know if you have suggestions to improve this article (requires login). head. Explore the latest news, articles and features, There may be just 800 of these endangered eagles left in the wild, This new version of quantum theory is even stranger than the original, Were starting to understand how viruses trigger chronic conditions. Unlike modern Time Period: First discovered by paleontologists in 1983, Pakicetus lived along the margins of a large shallow ocean, the Tethys Sea. Paleontologists know this because its ears were only adapted for the land and not for the water. adaptation in animals that spend a lot of time in the water. This Just like Indohyus, limb bones of pakicetids are osteosclerotic, also suggestive of aquatic habitat"[8] (since heavy bones provide ballast). Pakicetus was classified as an early cetacean due to characteristic features of the inner ear found only in cetaceans (namely, the large auditory bulla is formed from the ectotympanic bone only). of the skull much more loosely than they do in all other mammals. The basilosaurids, which lived about 34 million to 40 million years ago, had a more familiar shape than their ancestors. The Mysticeti include the baleen whales and their extinct relatives. Dimensions: length - 1,8 m, weight - 30 - 90 kg. As in most land mammals, the nose was at the tip of the snout. halfway stage. Whats more, its eyes, positioned close together on top of the skull, would have allowed Pakicetus to see above water even when submerged. It is the most ancient of presently-known direct ancestors of modern-day whales that lived approximately 48 mln years ago and adjusted to . Hussain - 2009. However, they do know this is exactly what happened. Often, reasons for extinction, especially of prehistoric mammals, fall into many categories such as human involvement or climate change. Cookies collect information about your preferences and your devices and are used to make the site work as you expect it to, to understand how you interact with the site, and to show advertisements that are targeted to your interests. - From Land to Water: the Origin of Whales, Dolphins, and Porpoises - 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. Such muscles are consistent with webbed feet that were used for aquatic locomotion. Sensory Abilities: Pakicetus had a dense and thickened auditory bulla, which is a characteristic of all cetaceans. https://www.thoughtco.com/reasons-animals-go-extinct-3889931 (accessed March 5, 2023). In this scenario it could have focused its attention upon prey that had become trapped in tidal pools at low Why did the dinosaurs go extinct? The exhibit also explores whale biology, and includes a life-size replica of a blue whale heart. Although they had nothing to ponder but this skull, scientists could see that Pakicetus had teeth resembling those of mesonychids, but it was well. I love to write and share science related Stuff Here on my Website. The early dolphins were smaller and believed to have consumed small fish as well as various organisms in the water. These cookies ensure basic functionalities and security features of the website, anonymously. so the left and right auditory regions were not isolated from each other, Strauss, Bob. However, studies from molecular biology placed today's cetaceans within the group of artiodactyls, to which the mesonychids don't belong. "Imagine your hip bones just started to float off your body that is what that is," he said. Pakicetus also exhibited characteristics of its anatomy that link it to modern cetaceans, a group made up of whales, porpoises, and dolphins. Pakicetus is an extinct genus of amphibious cetacean of the family Pakicetidae, which was endemic to Pakistan during the Eocene. Heres how it works. attention upon prey that had become trapped in tidal pools at low Pakicetus [5], Reconstructions of pakicetids that followed the discovery of composite skeletons often depicted them with fur; however, given their relatively close relationships with hippos, they may have had sparse body hair. As human civilization expands relentlessly into the wild, these natural habitats diminish in scopeand their restricted and dwindling populations are more susceptible to other extinction pressures. Pakicetus would have had an advantage in not having Mysticetes. NEW YORK By moving into the water full-time, the ancestors of whales paved the way for their descendants to become behemoths, largely free from gravity's constraints. of the eardrum caused by sound waves are transmitted across the air-filled well-known Early-Middle Eocene Kuldana Formation of Kohat (Pakistan) - I am currently continuing at SunAgri as an R&D engineer. The Marine Reptiles of The Late Cretaceous, Lived around the shores of what is now India and Pakistan. ancestors of the modern cetacean groups the toothed whales and dolphins, Why did the Pakicetus not survive? Pakicetus Facts and Figures. cover a lot of ground to find food, and the rising and falling tides Early Paleogene "Pakicetus is the only cetacean in which the mandibular foramen is small, as is the case in all terrestrial animals. insulates them from background noise conducted through the bones of the Molecular studies P. This website uses cookies to improve your experience while you navigate through the website. - J. G. M. Thewissen & S. T. Hussain - 1993. They also succumbed to a lack of food and predation by early humans. They also claim that its orientation relative to the malleus the second Such an arrangement isolates the cetaceans left and right ears, and When did Pakicetus go extinct? These bristly baleen plates filter, sift, sieve or trap the whales favourite prey from seawater inside their mouths. During the early Eocene times, Philip Gingerich, Other uncategorized cookies are those that are being analyzed and have not been classified into a category as yet. which flourished throughout the Eocene epoch . Original article on LiveScience.com. Whatever the causes, the huge extinction that ended the age of the dinosaur left gaps in ecosystems around . Necessary cookies are absolutely essential for the website to function properly. incus of Pakicetus. (Image credit: Museum of New Zealand Te Papa Tongarewa, 2008). Eocene. Archaeocetes such as Pakecitus had elongated bodies, paddle-like forelimbs Pakicetus attocki . It belongs to the even-toed ungulates with the closest living non-cetacean relative being the hippopotamus. Odontocetes use high frequency vocalizations for echolocation and bio-sonar. of the fossil site indicates that it was a coastal region at the time, L. N. Cooper, J. C. George & S. Bajpai - 2009. discovered fossil ear bones and lower jaw bones of Pakicetus in the Kala (2020, August 27). But even before the move, this lineage was setting size records. Pakicetus is a prehistoric cetacean mammal which lived approximately 50 million years ago during the Early Eocene Period. This 6-foot-tall (1.8 meters) creature lived solely on land, but its relatives began taking to the water and eventually left land completely. 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. Usually, determining which is the "better adapted" species takes thousands, and sometimes millions, of years. Paleontologists know this because its ears were only adapted for the land and not for the water. These leftovers from land are still visible in some modern whales. evidence for the link between artiodactyls and cetaceans. The ossicles in whales are arranged differently Their hips and legs were on the way out. whales, Pakicetus had not yet severed all links with the land. A basilosaurid on display, Dorudon atrox, displays a tiny pelvis and legs detached from its spinal column. [4], It was illustrated on the cover of Science as a semiaquatic, vaguely crocodile-like mammal, diving after fish. Only time will tell. We use cookies on our website to give you the most relevant experience by remembering your preferences and repeat visits. [3] In 2001, fossils of ancient whales were found that featured an ankle bone, the astragalus, with a "double pulley" shape characteristic of artiodactyls. "But if you think about it, some of the other relatives like pigs and peccaries are pretty ferocious and will eat just about anything. Strauss, Bob. The extinction of Homo erectus was a major event in human evolution. had ears Further reading between the equivalent bone in modern cetaceans and that in modern artiodactyls. A relative of the better known Diacodexis , Indohyus has been speculated to be a member of a group of mammals that were possibly related to the mammals whose descendants would eventually go on to become the whales. This stems back to study of Indohyus which revealed that it had bones denser than most terrestrial mammals. This . Species: While it's unusual for disease alone to wipe out a given speciesthe groundwork has to be laid first by starvation, loss of habitat, and/or lack of genetic diversitythe introduction of a particularly lethal virus or bacterium at an inopportune moment can wreak havoc. . Thus, Pakicetus represents a transitional taxon between extinct land mammals and modern cetaceans. "Top 10 Reasons Why Animals and Plants Go Extinct." Whales are mammals, like humans, and their ancestors once lived on land. Pakicetidae ("Pakistani whales") is an extinct mammalian family of carnivorous cetaceans that lived during the Early Eocene to Middle Eocene (55.8 mya40.4 mya) Indo-Pakistan and existed for approximately 15.4 million years. their amplitude much smaller. https://www.britannica.com/animal/Pakicetus, New York Institute of Technology - College of Osteopathic Medicine - Cetacean Family Tree - Pakicetus App. It probably could 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. 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. While every effort has been made to follow citation style rules, there may be some discrepancies. to allow for this. Bob Strauss is a science writer and the author of several books, including "The Big Book of What, How and Why" and "A Field Guide to the Dinosaurs of North America. These species went extinct at the same time as mammoths, as the ice age was ending. known, is a member of the now extinct Archaeoceti suborder of toothed whales Carnivore Paleontologists know this because its ears were only adapted for the land and not for the water. ThoughtCo. Graduated from ENSAT (national agronomic school of Toulouse) in plant sciences in 2018, I pursued a CIFRE doctorate under contract with SunAgri and INRAE in Avignon between 2019 and 2022. Nowadays, there are two varieties of whale. Modern whales evolved from archaic whales such as basilosaurids, which in turn evolved from something like the amphibious ambulocetids, which themselves evolved from . may have had to In 2001, scientists found fossils which confirmed the fact that this mammal lived entirely on the land and never went into the water. Paleontologists arent completely sure at this time. One of the most interesting facts about Pakicetus is that according to scientists, this is the earliest whale theyve found as of yet. Because whales and dolphins use sound to locate food and communicate, The fossils came out of red terrigenous sediments bounded largely by shallow marine deposits typical of coastal environments caused by the Tethys Ocean. The teeth also suggest that Pakicetus had herbivorous and omnivorous ancestors. www.prehistoric-wildlife.com. Based on the detail of the teeth, the molars suggest that the animal could rend and tear flesh. Vibrations What did the first whales look like? This species was the longest-lived relative of our own species, first evolving in Africa around 2 million years ago and then spreading into Asia. [11], Gingerich & Russell 1981 believed Pakicetus to be a mesonychid. bones of Pakicetus indicate dense bone growth, a It looks like a dog-like animal that if it was still alive, would run up to you and lick your hand. As previously mentioned, the Pakicetus' upward-facing eye placement was a significant indication of its habitat. - Journal of Vertebrate Paleontology Analysis Pakicetus (below left), is described as an early ancestor to modern whales. By 25 million years ago, early members of the right whale family appeared. 'Building blocks of life' recovered from asteroid Ryugu are older than the solar system itself, Ancient Roman 'spike defenses' made famous by Julius Caesar found in Germany, Otherworldly 'fairy lantern' plant, presumed extinct, emerges from forest floor in Japan, Watch footage of 1,000 baleen whales in record-breaking feeding frenzy in Antarctica, New Moai statue that 'deified ancestors' found on Easter Island, Lab-grown minibrains will be used as 'biological hardware' to create new biocomputers, scientists propose, The ultimate action-packed science and technology magazine bursting with exciting information about the universe, Subscribe today and save an extra 5% with checkout code 'LOVE5', Engaging articles, amazing illustrations & exclusive interviews, Issues delivered straight to your door or device. Formally known as "Whales: Giants of the Deep," this exhibition traveled to New York from New Zealand, where it was developed by the Museum of New Zealand Te Papa Tongarewa. and along You also have the option to opt-out of these cookies. Assortments of limestone, dolomite, stone mud and other varieties of different coloured sands have been predicted to be a favourable habitat for Pakicetus. The closest living relatives of dolphins today are the even toed ungulates such as camels and cows with the humble hippopotamus being the closest living relative. Kevin Guertin/Wikimedia Commons/CC BY 2.0. Diet: Carnivore. Asia, Pakistan They occur in a wide variety of habitats from fresh water rivers to the deep parts of the ocean. Diet: Members of the rorqual family appeared about 15 million years ago, including the modern genus Megaptera. But of course, it was definitely not a dog- or even related to dogs. Over time, fossils also revealed that Pakicetus had an ear bone with a feature unique to whales and an ankle bone that linked it to artiodactyls, a large order of even-toed hoofed mammals that includes hippos, pigs, sheep, cows, deer, giraffes, antelopes, and even cetaceans, the only aquatic artiodactyls. Description. 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." that worked best when submerged in the water. This indicates that Pakicetus, extinct genus of early cetacean mammals known from fossils discovered in 48.5-million-year-old river delta deposits in present-day Pakistan. This is the first thing most people associate with the word "extinction," and not without reason, since we all know that a meteor impact on the Yucatn Peninsula in Mexico caused the disappearance of the dinosaurs 65 million years ago. They may hunt cooperatively either during the day or night, depending on the species. Archaeoceti, Pakicetidae, Pakicetinae. [4] 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. This cookie is set by GDPR Cookie Consent plugin. ARTIODACTYLs 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. One important feature that links extinct organisms such as Pakicetus and Indohyus to cetaceans is: the shape of a bone in the middle ear New mutations: are random with respect to their effects on fitness Modern day cetaceans are thought to have evolved from ______ - grazing hooved land mammals. tide. Evidence suggests an asteroid impact was the main culprit. may have cut off some areas of the coast, creating islands at high Why Did Crocodiles Survive the K/T Extinction? [3], Based on the sizes of specimens, and to a lesser extent on composite skeletons, species of Pakicetus are thought to have been 1 metre (3ft 3in) to 2 metres (6ft 7in) in length. Wynne was a reporter at The Stamford Advocate. Anatomy: Dorudon, along with other basilosaurids, differed from all modern cetaceans in the shape of its head and teeth. Nov. 2, 2020 A new species of extinct lizard, Kopidosaurus perplexus, has just been described. Chitta Hills of Pakistan. For example, However, you may visit "Cookie Settings" to provide a controlled consent. and small or nonexistent hindlimbs. The large tail of Pakicetus is possibly a specialization for aquatic locomotion, although exactly how is unclear. Planet Earth teems with life and includes thousands of species of vertebrate animals (mammals, reptiles, fish, andbirds); invertebrates (insects, crustaceans, and protozoans); trees, flowers, grasses, and grains; and a bewildering array of bacteria, and algae, plus single-celled organismssome inhabiting scalding deep-sea thermal vents. Pakicetus is a genus of extinct terrestrial carnivorous mammal of the family Pakicetidae which was endemic to Pakistan from the Eocene (55.8 0.240 0.1 million years ago). Subsequent fossils of Pakicetus were also found in Pakistan, hence the generic name Pakicetus. After all, it was about 3 feet long and weighed about 50 pounds. Learn about the mass extinction event 66 million years ago and the evidence for what ended the age of the dinosaurs. discoveries, and its best if you use this information as a jumping off The closest modern relatives of cetaceans Baleen is made out of keratin, the same protein that makes up our fingernails and hair. From the shape of the fossil ossicles, the two scientists deduced that Its also a massive sound generator that helps the whale navigate. deer and their like which are known as artiodactyls. which flourished throughout the Eocene epoch. Another mystery surrounding Pakicetus is why has this animal been found mainly on the Indian subcontinent? It was first discovered in Pakistan and was named by Philip Gingerich and Donald Russell in 1981. Witness the crisis currently facing the world's amphibians, which are falling prey to chytridiomycosis, a fungal infection that ravages the skin of frogs, toads,and salamanders, and causes death within a few weeks, not to mention the Black Death that wiped out a third of Europe's population during the Middle Ages. Which land animal is the closest cousin to dolphins? Our editors will review what youve submitted and determine whether to revise the article. Until the early 1800s, billions of passenger pigeons darkened the skies of the United States in spectacular migratory flocks. The fossil remains of L. denticrenatus have been dated to 34 million years ago. about 30 million years ago Fossil Record Fossils indicate that the earliest known baleen whales lived about 30 million years ago. Thewissen et al. 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.