In all mammals, this bone, the astragalus or talus (Fig. Gingerich PD, Smith BH, Simons EL. What is one way Scientists know that Maiacetus lived in the ocean? Although Richard Harlan came up with the name Basilosaurus, it was the famous English naturalist Richard Owen who recognized that this prehistoric creature was actually a whale. Skulls and skeletons are known for a single raoellid: Indohyus (Thewissen et al. Counter current heat exchange evidence is also found for the tongue and the testes of dolphins. Thewissen JGM, Bajpai S. Dental morphology of the Remingtonocetidae (Cetacea, Mammalia). Basilosaurus was an unfamiliar, long snake like animal. The position of the eyes, osteosclerosis of the limb bones, sedimentological data, and stable isotope data are consistent, and all suggest that pakicetids were waders in shallow freshwater. Now, cetacean origin is one of the best known examples of macroevolution documented in the fossil record. Although not positioned at the tip of the snout like more primitive whales (e.g. Oxygen in the molecules that make up the teeth comes from the drinking water and food that the animal ingests. "Eocene Antarctica: a window into the earliest history of modern whales". That this evolutionary process is repeated in a way during ontogeny became obvious through external observations on embryos and fetuses (Kukenthal 1893). As a result, the skeleton of Indohyus shown in Fig. Skeletal evidence indicates that Basilosaurus could perceive the direction of origin for underwater sounds. iPad. Archaeocete whales have been found from early to middle Eocene (52-42 Ma) deposits in Africa and North America but are best known from Pakistan and India. It is like a recipe to show who is related to who. (D) Pelvis and femur of the juvenile male specimen figured in C. (E) Another pelvis and femur from an adult specimen (B. mysticetus, 98B5) for comparison. 2006). Isotopic records from early whales and sea cows: contrasting patterns of ecological transition. In life, the peg like front teeth were used to seize prey and the rear triangular teeth were used to dispatch and process prey. In spite of this, some species retain a few hairs on their face and in others the fetus has whiskers (Fig. 2004;34:1222. 27). have come from the common ancestor. Because its long, narrow skull so closely resembled that of Mosasaurus, Basilosaurus was initially and incorrectly "diagnosed" as a marine reptile of the Mesozoic Era and given its deceptive name (Greek for "king lizard") by the naturalist Richard Harlan. This is the oldest whale genus with evidence for flukes, although flukes may have occurred in early whales for which the tail is unknown. Get 5 free video unlocks on our app with code GOMOBILE, _______________________________ Where is the nasal opening in 1997; Bajpai and Thewissen 1998; Gingerich et al. The teeth in the tip of the snout are roughly similar to those of modern fish-eating toothed whales, although the teeth are extremely robust and deeply rooted. Archaeocetes are important because they represent the earliest radiation of cetaceans and because they include the ancestors of the two modern suborders of cetaceans, the Mysticeti (baleen whales) and Odontoceti (toothed . Gingerich PD, Haq M, Zalmout IS, Khan IH, Malkani MS. Protocetids are a diverse group, with approximately 15 genera described. Evo Edu Outreach 2, 272288 (2009). At the same time, a long rost rum with narrow jaws develops. While hunting in these deep and murky waters, they use short, powerful, ultrasonic echolocation clicks to find, follow, and catch . Study a DNAs of different groups searching for hidden relationships and also the time when species diverged from their ancestors. Thewissen, J.G.M., Cooper, L.N., George, J.C. et al. However, the rest of Basilosaurus hearing adaptations indicate it was fully marine, and thus any retention of adaptations for hearing airborne sound was probably vestigial. This is the oldest whale genus with evidence for flukes, although flukes may have occurred in early whales for which the tail is unknown. (1990) proposed. Little is known about the diet and feeding morphology of protocetid cetaceans, but, there too, variation appears to be common. His current research is on trait-based community dynamics in vertebrates, Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. 14). 2004;430:7768. They appear to have lived side by side roughly 34 to 40 million years ago. Once cetacean hindlimbs were no longer needed, it could have taken millions of years before they were lost entirely, with a protracted period of highly reduced hindlimbs. Size: Complete skeletons of Basilosaurus indicate that it measured at least 17 meters (56 feet) in length. For instance, cetaceans and sirenians lack (nearly all) body hair, whereas pinnipeds have dense fur. 2006. Isotopic records from early whales and sea cows: contrasting patterns of ecological transition. By reading a z leveled books best pizza sauce at whole foods reading a z leveled books best pizza sauce at whole foods This feature disappeared entirely in later whales and is today retained only by the distantly related marine mammals known as pinnipeds. Both remingtonocetids and protocetids are found in the same areas of India, Eye size in cetaceans and extinct marine reptiles (ichthyosaurs; modified from Thewissen and Nummela (2008), University of California Press). In spite of this, cetaceans are mammals. J Vert Pal. Stromerius nidensis was described in 2007 and dated to the late Eocene of Egypt; it is the only species classified in subfamily Stromeriinae. This is unlike modern (odontocete) cetaceans in which the teeth along the tooth row are all very similar (a condition called homodonty). 1990;229:1547. chemistry dealing with chemical compounds and processes in living plants and animals. From Milan Klima, Development of the Cetacean Nasal Skull 1999 Springer. In 1845, a man named Albert Koch perpetrated one of the most notorious hoaxes in the history of paleontology, reassembling a bunch of Basilosaurus bones into a fraudulent "sea monster" named Hydrarchos ("ruler of the waves"). Discover fascinating details about this enormous marine mammal. Cranial anatomy of Pakicetidae (Cetacea, Mammalia). It contains a small group of species, most of which are only known from teeth and jaws (Thewissen et al. It would be reasonable to infer from this fact that Basilosaurus was native to North America exclusively, but fossil specimens of this whale have been discovered as far afield as Egypt and Jordan. Their jaws were powerful,[9] with a dentition easily distinguishable from that of other archaeocetes: they lack upper third molars and the upper molars lack protocones, trigon basins, and lingual third roots. Proc Natl Acad Sci USA. As archaeocetes, Basilosaurids lacked the telescoping skull of present whales. In: Thewissen JGM, Nummela S, editors. This work was supported by grants from the Indian Department of Science and Technology (to Sunil Bajpai) and the US National Science Foundation (to J. G. M. Thewissen). Use specific examples of known genes (e.g., \beta globin and other genes) when making your list. 1990. They write new content and verify and edit content received from contributors. From Land to Water: the Origin of Whales, Dolphins, and Porpoises, https://doi.org/10.1007/s12052-009-0135-2, http://www.neoucom.edu/audience/about/departments/anatomy/AnatFaculty/media, www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/whales/Pakicetid.html, http://www.neoucom.edu/DEPTS/ANAT/publ.html, http://www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/index.html, www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/whales/Remi.html, https://creativecommons.org/licenses/by/2.0. But the animals, known as toothed whales, also produce other sounds for social . Toothed whales can use vocal registers like humans to communicate and hunt. 13). 2007, 2004). BioSci. B.T. It would be reasonable to infer from this fact that Basilosaurus was native to North America exclusively, but fossil specimens of this whale have been discovered as far afield as Egypt and Jordan. Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve, form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end, form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle, the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores. In: Thewissen JGM, Nummela S, editors. Reproductive biology and phylogeny of Cetacea. Although echolocation and filter feeding are important evolutionary themes of odontocetes and mysticetes, respectively, both of these suborders are diverse, feeding on different prey and using different hunting techniques. Hand and foot of the protocetid Rodhocetus (modified from Gingerich et al. 2001, 2007). 1994), it is now generally accepted that protocetids lacked a fluke (Gingerich et al. Madar SI, Thewissen JGM, Hussain ST. Additional holotype remains of Ambulocetus natans (Cetacea, Ambulocetidae), and their implications for locomotion in early whales. Hulbert RC Jr, Petkewich RM, Bishop GA, Burky D, Aleshire DP. Evolution: Education and Outreach Article Am Mus Nov. 2005;3480:165. 1998). The name "King Lizard" is misleading in not one, but two, ways: Not only was Basilosaurus a whale rather than a reptile, but it wasn't even close to being the king of the whales; later cetaceans were much more formidable. Basilosaurids occurred worldwide during most of their history, and important fossils have been recovered in Egypt and the southern United States. New York: Plenum; 1998. p. 35378. Thewissen JGM, Fish FE. biogen senior engineer ii salary. Anatmia - latin kifejezsek (alapszvetek), John David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine, BIO 101 - How Populations Evolve, Part 2 (2), Plant Biology Exam 2- Evidence for Evolution. The larger bones of the extremities of mammals are usually hollow, and the cavity in them is filled with bone marrow. Like other mammals and unlike other vertebrates, they nurse their young; they have three ear bones that are involved in sound transmission (hammer, anvil, and stirrup), and their lower jaws consist of a single bone (the dentary). In the Northern Hemisphere, fossils of basilosaurids are abundant, while records in the Southern Hemisphere are scarce and, in some cases (i.e., Antarctica), doubtful. Basilosaurids are like most mammals in that there are only three phalanges per finger, whereas in modern cetaceans this number is commonly increased. report the skeleton of a stem toothed whale, from the Oligocene of South Carolina, with intermediate locomotor adaptations between modern toothed whales and the earliest pelagic whales. Berkeley: Univ Calif Press; 2008. p. 25786. 1999; Gatesy and O'Leary 2001). Geisler JH, Theodor JM, Uhen MD, Foss SE. However, the hind limbs are greatly reduced in size and the pelvis is not attached to the vertebral column, making the hind limbs unsuitable to support the body weight of these whales. Eg: when we looking at the whales's anatomy, we can see that they evolved from an ancien 4 legged land mammal. Buffrenil, V. Whales breathed with more ease when they no longer had to lift a snout above water. 2004. ____ Do both have multi-chambered stomachs? In Hippopotamus, for instance, the marrow cavity makes up 55% of the total thickness of the femur. Gingerich PD, Ul-Haq M, Khan IH, Zalmout I. Eocene stratigraphy and archaeocete whales (Mammalia, Cetacea) of Drug Lahar in the eastern Sulaiman Range, Balochistan (Pakistan). 2001b; Buchholtz 1998). We thank Ajay Thakore and the Gujarat Mining Development Corporation for assistance with fieldwork in Gujarat, and Mr. Bhatti of Bhuj for help with logistics. basilosaurid, any member of the family Basilosauridae, an early group of whales that lived from the middle Eocene to the late Oligocene Epoch (about 41 million to 23 million years ago). They were too large to have hauled themselves out of the water, and they possessed forelimbs that were too specialized for swimming to have supported them on land. 1900;23:32731. Department of Anatomy and Neurobiology, Northeastern Ohio Universities College of Medicine, Rootstown, OH, 44272, USA, School of Biomedical Sciences, Kent State University, Kent, OH, 44242, USA, Department of Wildlife Management, North Slope Borough, Box 69, Barrow, AK, 99723, USA, Department of Earth Sciences, Indian Institute of Technology, Roorkee, 247 667, Uttarakhand, India, You can also search for this author in In the early 19th century, when the fossil remains of Basilosaurus were being studied by American paleontologists, there was a great deal of interest in giant marine reptiles like Mosasaurus and Pliosaurus (which had recently been discovered in Europe). Gingerich PD, Arif M, Clyde WC. The purpleblue color is fossilized bone in this image taken with a polarized light microscope with a gypsum filter. Tr Ecol Evol. 2007). Unlike earlier archaeocetes, which all had 11 teeth per half jaw (44 teeth in all), basilosaurids had lost one tooth in each upper jaw, bringing their total number to 42. In hunting behavior, Ambulocetus may have been similar to a modern crocodile, and, externally, Ambulocetus may have looked like a crocodile (http://www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/index.html). A modern gray whale can emerge from the water, inhale and resubmerge without stopping or tilting its snout to breathe. Gingerich PD, Raza SM, Arif M, Anwar M, Zhou X. ______________________ The closest match, so far, of whale DNA to Further evidence of the aquatic habitat for Indohyus comes from the chemical composition of its teeth. Both are missing a (C) The pelvis is attached to the femur with a synovial joint, and a small cartilaginous tibia is also present (B. mysticetus, 06B4; Lucas 1900; Struthers 1893). Fossils of ambulocetids can be classified in three genera, and remains of these have been found in Northern Pakistan and northwestern India. Basilosaurids are known from all the New World and the Old World and probably lived in all seas between 41 and 35 million years ago. This early whale has short and powerful legs, with five fingers in the hand and four toes in the foot. The thickness of the wall is more or less constant all around the ear in most mammals, but this is not the case in cetaceans, where the internal wall is much thicker than the external wall. Zeuglodon) is a genus of primitive whale from the Late Eocene. statement and The availability of rich new food sources has been proposed as a reason for the cetacean entry into the water, but this is unlikely, given that cetacean ancestors already lived in very shallow freshwater. Deciphering whale origins with molecules and fossils. Science. One of the first identified prehistoric whales, Basilosaurus, the "king lizard," has been a part of American culture for literally hundreds of years, especially in the southeastern U.S. It's unusual for two states to share the same official fossil; it's even rarer for these two states to border each other. Scientists are still trying to understand what exactly these differences mean, but they must have affected function of the animals in a major way. Nummela S, Thewissen JGM, Bajpai S, Hussain ST, Kumar K. Eocene evolution of whale hearing. 4), has a hinge joint, called a trochlea, where it articulates with the tibia (shin bone). another animal is to ? Thewissen). The sediments at Locality 62 can inform us about the environment in which pakicetid whales lived (Aslan and Thewissen 1997) and in which more than 60% of the fossils are pakicetids (Thewissen et al. (Image from Thewissen et al. Its overall body shape is so unlike those of other whales that it was initially thought to be a marine reptile; hence the name Basilosaurus, which means king lizard. The teeth towards the back of the mouth have multiple large serration-like cusps. Also unlike earlier cetaceans, the nasal opening is not at the tip of the snout (Thewissen and Bajpai 2001b). The emergence of whales, evolutionary patterns in the origin of Cetacea. A type of Basilosaurid ancient whale. Coen Elemans was . A new middle Eocene protocetid whale (Mammalia: Cetacea: Archaeoceti) and associated biota from Georgia. Indohyus pertains to the Artiodactyla, which is indicated best by the shape of one of the bones in the ankle. Thewissen JGM, Hussain ST, Arif M. Fossil evidence for the origin of aquatic locomotion in archaeocete whales. Protocetids are usually found in near-shore marine deposits, often associated with carbonate platforms such as reefs (Williams 1998). Thewissen). Copyright The Pandas Thumb and original authors Content provided under Creative Commons BY-NC-ND License 4.0. 1990. The reduced connections, plus the development of air-filled sinuses around the middle ear, helped isolate the inner ear from bone-conducted sound waves. with a long rostrum and nasal opening retracted to a position above the first premolars. They are more similar to a wolf with a long nose and tail (Thewissen et al. There are no external hind limbs in normal modern cetaceans, although, very rarely, an anomalous individual with such limbs is born (Fig. Strauss, Bob. 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. The typical species were around 18 meters/60 feet in length in life, and had serrated, triangular teeth with two roots, and had a second pair of small, possibly functional flippers. Dorudon atrox in turn was a prey item for the larger basilosaurid . J Pal. Morphological support for a close relationship between hippos and whales. Eg: the nasal opening of the basilosaurid whale shows that this animal is an intermediate species between land mammal and modern whale. Writing before the discovery of Ambulocetus, Fish predicted that the swimming mode of modern cetaceans (moving the fluke through the water in the dorsoventral plane) was preceded by a swimming mode that included dorsoventral sweeps of the feet aided by a long tail, similar to otters. It always stays near water, and when in danger from a predator, Hyemoschus jumps in the water and scurries to safety fully submerged. The early evolution of Cetacea (whales, dolphins, and porpoises). Provided by the Springer Nature SharedIt content-sharing initiative. 2006). In spite of the variation in body size, all modern Cetacea are relatively similar in shape: they have a horizontal tail fluke used in swimming; their forelimbs are flippers; there are no external hind limbs; their neck is short, and their body is streamlined. Basilosaurus drazindai and Basiloterus hussaini, new Archaeoceti (Mammalia, Cetacea) from the middle Eocene Drazinda Formation, with a revised interpretation of ages of whale-bearing strata in the Khirthar Group of the Sulaiman Range, Punjab (Pakistan). The organ of balance is located in the petrosal, a bone attached to the ectotympanic. Then wait for the post B.T's wife drove him to the clinic when his wheezing was unresponsive to fluticasone/salmeterol (Advair) and ipratropium bromide (Atrovent) inhalers, he was unable to lie down, and he began to use accessory muscles to breathe. Together with other basilosaurid whales, Basilosaurus is frequently referred to as a transitional form between the four-legged . Domning. Paleo-scientists actually mistook this species for a juvenile Basilosaurus. Clementz MT, Goswami A, Gingerich PD, Koch PL. New York: Plenum; 1998. p. 23567. 2006;26:74659. In Eocene Basilosaurus-bearing fossil sites in Egypt, many fossils of the smaller basilosaurid Dorudon bear large puncture marks, which are potentially caused by the teeth of Basilosaurus. Embryos of the pantropical spotted dolphin (Stenella attenuata) covering approximately weeks 4 to 9 of embryonic development. The phylogenetic relations among groups are best expressed by a cladogram, and classifications cannot accurately reflect phylogenetic relationships anyway (because an ancestor species would have to include all its descendant species). Pakicetids are related to artiodactyls, as was shown by the cladistic analysis (Gatesy and O'Leary 2001; Geisler et al. 1990). 2001;21:34766. 1994;263:2102. The skeleton of the raoellid artiodactyl Indohyus. Dorudon was once mistaken for its much larger cousin, Basilosaurus. Sharks, whales, and dolphins share similar features such as body shape and the position of fins. The first occurs in the genus Basilosaurus which had a snake-like body with a maximum length of approximately 17m long. police officer relieved of duty. Retrieved from https://www.thoughtco.com/facts-about-basilosaurus-king-lizard-whale-1093325. The transition from land to water is documented by a series of intermediate fossils, many of which are known from India and Pakistan. This suggests the snout is only weakly attached to the skull. ThoughtCo. Nasal Drift in Early Whales Whales breathed with more ease when they no longer had to lift a snout above water. Eg: whales and hippos evolved from a common ancestor. 1995a, b; Fig. 20). bell-shaped curve that results when the values of a trait in a population are plotted against their frequency. Three species of Basilosaurus are known, and specimens have been discovered in fossil sites in the southeastern United States (Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, and Tennessee), England, Egypt, Jordan, and Pakistan, indicating that Basilosaurus inhabited the Northern Atlantic Ocean, Tethys Sea, and the Paratethys Sea (the precursor to the Mediterranean Sea). Some dolphins can exceed speeds of 50 km/h, a feat accomplished by thrusting the flukes while adjusting attack angle with their flippers [].These movements are driven by robust axial musculature anchored to a relatively rigid torso consisting of numerous short . Although the pelvis was characterized by a reduced ilium (the bone that connects to the sacrum, which forms the base of the vertebral column, in terrestrial animals), it possessed a proportionally large pubis. This implies that pakicetids ate different food and processed it differently from raoellids and that they had different sense organs. This is a clear indication that this prehistoric whale spent most of its life near the water's surface since its hollow backbone would have crumpled from the intense water pressure deep beneath the waves. 21), and Georgiacetus from North America (Hulbert et al. Nature. 1997; Williams 1998; Geisler et al. [12] They were characterized by elongated distal thoracic vertebrae, lumbar, and proximal sacrococcygeal. These may The new find of aquatic behaviors in raoellids suggests that these animals used the water as a refuge against danger. common ancestor with. They were probably the first fully aquatic cetaceans. Diet: The skull of Basilosaurus is superficially crocodilian in shape, exhibits large jaw muscle attachment areas, and a fearsome set of teeth with canine-shaped incisors in front, and flattened, serrated triangular molars in back. Discuss and make a list of some of the reasons why it would be informative for a geneticist to determine the amount of a gene product. another animal is to ? Contr Mus Pal Univ Michigan. Fetus of the pantropical dolphin (LACM 94389, Stenella attenuata) with whiskers along the rostrum. The more similar the DNAs are, the closer related the organisms are. Conclusive paleontological evidence shows the way in which the nasal openings were moved in the course of phylogeny (see Kellogg 1928; Slijper 1962; Gaskin 1976; Oelschlager 1978, 1987, 1990; Moore 1981). _____________ ____________Mammals Geisler JH, Saunders AE, Luo Z-X. Bringing Georgia's Natural History to Georgians, GA Paleo Research by Paul F. 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All of the basilosaurids share some common features despite significant variations in size. Cour Forsch Inst Senckenberg. With the origin of protocetids, cetaceans spread across the globe. The Bowhead whale specimens were collected under NMFS marine mammal collection permit 814-1899. O'Leary MA, Uhen MD. Diagram showing the relationships among cetaceans and their land relatives. Modern representatives of artiodactyls include pigs, hippos, camels, deer, sheep, cattle, and giraffe, and, of these, hippos are thought to be the closest living relatives of cetaceans (Nikaido et al. To see earlier posts, select the Archives at the top of this page. Nikaido M, Rooney AP, Okada N. Phylogenetic relationships among cetartiodactyls based on insertions of short and long interspersed elements: hippopotamuses are the closest extant relatives of whales. Thewissen JGM, Cohn MJ, Stevens LS, Bajpai S, Heyning J, Horton WE Jr. Developmental basis for hind limb loss in dolphins and the origin of the cetacean body plan. Basal fully aquatic whales, the basilosaurids are worldwide known from Bartonian-Priabonian localities, indicating that this group was widely distributed during the late middle Eocene. Basilosaurus is characterized by extremely elongate vertebrae (three times as long as those in most other basilosaurids, relative to vertebral width), a very high degree of flexibility in the vertebral column, a high number of vertebrae, and an incredibly elongate body form in general. In: Thewissen JGM, editor. The bones of Indohyus were found high in the Himalaya mountains near the border between Pakistan and India. 1999;25:53456. The changing cetacean body plan during the first ten million years of cetacean evolution. 2001a;75:4635. 2001a). Comparing things that are similar and different. A 50-mL graduated cylinder contains 20.0 mL of water. In development, the nose opening shifts from the tip of the snout (arrow in left embryo) to its position on top of the head. _______________________________ Where is the nasal opening in Basilosaurus (a.k.a. Even though all modern cetaceans are obligate aquatic mammals, early cetaceans were amphibious, and their ancestors were terrestrial artiodactyls, similar to small deer. They lived during the middle to the early late Eocene and are known from all continents, including Antarctica. ____ Do both have multi-chambered stomachs? In this case, it is hippos. One feature that is a strong indicator of this relationship is the shape of one of the bones of the ear. Raoellids are only known from Pakistan and western India and are restricted to the lower and middle Eocene, approximately between 55 and 45 million years ago. Write C++ statements that do the following: The scientific name is always the Genus + species. Locomotion: Although Basilosaurus has rudimentary hindlimbs, they were useless for any sort of terrestrial locomotion. The emergence of whales, evolutionary patterns in the origin of Cetacea. 2007). Notice the similarities between hippos and whales. In an if/else statement, the if part executes its statement or block if the expression is __________, and the else part executes its statement or block if the expression is __________. Nummela S, Hussain ST, Thewissen JGM. Well-developed muscle attachments on bones of the hindlimbs suggest that they were functioning (and not completely vestigial), and they have been interpreted as clasper-like structures for mating (vestigial hindlimbs in boa constrictors serve such a purpose). Bones shown here are derived from several individuals and were found scrambled with many other bones near the border area between Pakistan and India by geologist A. Ranga Rao ( J.G.M. 8), the marrow cavity of the femur (the thighbone) makes up more than 60% of the total thickness of the bone, and the bony walls, called cortex, are thin. Another surprising feature in the skeleton of Indohyus was found in the bones of its extremities. "10 Facts About Basilosaurus." Both raoellids and pakicetids had aquatic adaptations, wading and walking in freshwater streams.
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