Other features are even more impressive indicators of the land ancestry of cetaceans. He appears anxious and says that he is short of breath. Fossil cetaceans are the pakicetid Ichthyolestes (red), the remingtonocetid Remingtonocetus (orange), the protocetid Indocetus (yellow), and the basilosaurid Dorudon (purple). Contr Mus Pal Univ Michigan. Science. Rains came only a few times per year, but they were torrential. It also exposes the inside of the middle ear, which is filled with sediment here. "During vocal fry, the vocal folds are only open for a very short . In some species, pelvis, femur, and tibia are present (Figs. 2004;430:7768. For other protocetids, a diet of smaller fish has been suggested (O'Leary and Uhen 1999). 1990. The hindlimbs are tiny, and the pelvis lacked any bony connection to the vertebral column (and must have floated in the muscles of the belly), indicating that these elements could not support any weight out of water. 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. Frank Fish (1996) discussed the evolution of different swimming modes in mammals (Fig. Ambulocetid fossils are approximately 49 million years old (middle Eocene). However, unlike earlier, more primitive whales, many of the joints in the ankle and foot are fused and others have limited mobility. Evolution and Development 9:278-289. While toothed whales generally have one hole, baleens are split into two. and then the comments to load (may take many seconds). A good example is the giant killer whale Leviathan (Livyatan), which lived about 25 million years later (during the Miocene epoch), weighed as much as 50 tons, and made a worthy opponent for the contemporaneous prehistoric shark Megalodon. [3][4] The group is noted to be a paraphyletic assemblage of stem group whales[5] from which the monophyletic Neoceti are derived. So first that shark whales and the dolphins. Unlike modern whales, basilosaurids possessed small hindlimbs with well defined femur, lower leg and feet. In most mammals, its walls are made of a bone called the ectotympanic, as is the case in artiodactyls and cetaceans. The former species were larger and had larger eyes (Fig. Here we document new remains of basilosaurid whale from early middle Eocene (Lutetian) of Wadi El-Rayan Group of the Fayum Depression, Egypt. Now, cetacean origin is one of the best known examples of macroevolution documented in the fossil record. The organ of balance is located in the petrosal, a bone attached to the ectotympanic. 2001; www.neoucom.edu/DEPTS/ANAT/Thewissen/whale_origins/whales/Pakicetid.html). 21), and Georgiacetus from North America (Hulbert et al. This could then lead to overstimulation of the semicircular canals, especially in acrobatic animals. CAS It exchanges heat, ions, or gases between vessel walls so that the two bloodstreams within the rete maintain a gradient with respect to temperature, or concentration of gases or solutes. Cetacean fossils have been recorded from middle and late Eocene deposits on Seymour Island since the beginning of the twentieth century and include fully aquatic Basilosauridae and stem Neoceti. Numbers are used to refer to individual specimens. 20). In spite of this, cetaceans are mammals. Molecular biology came to the rescue, identifying genetic similarities between cetaceans and artiodactyls (English: even-toed ungulates) that were not present in other mammals. In spite of our advances in understanding of the pattern of cetacean origins, it remains unclear which process caused this pattern: Why did cetaceans enter the oceans? Archaeocetes is the common name for a group of primitive whales that lived in the Eocene Period (55-34 million years). As such, these teeth are not suitable for crushing food. The transition from land to water is documented by a series of intermediate fossils, many of which are known from India and Pakistan. Journal of Vertebrate Paleontology 26:355-370. Studies the geographic distribution of different species. Both are missing a Basilosaurids occurred worldwide during most of their history, and important fossils have been recovered in Egypt and the southern United States. Locomotor evolution in the earliest cetaceans: functional model, modern analogues, and paleontological evidence. In the forelimb, basilosaurids resemble modern cetaceans, in that their elbow joint is not separately mobile and their hand webbed with individual digits not recognizable (Uhen 2004). with a long rostrum and nasal opening retracted to a position above the first premolars. 7). A point of similarity among protocetids is the position and size of the eyes, which differentiates them from earlier cetaceans (Nummela et al. Bone histology of the archaeocetes (Mammalia: Cetacea). Nummela S, Hussain ST, Thewissen JGM. The transition from raoellid to pakicetid and thus from artiodactyl to cetacean was a remarkable event that included the wholesale rebuilding of the skull and its food-processing equipment. Write C++ statements that do the following: The scientific name is always the Genus + species. 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. 1997;23:48290. The hammer provides a scale. 5 consists of bones of a number of different individuals. Ann Rev Ecol Syst. In general, the diameter of these tubes, the semicircular canals, scales with body size (Spoor and Thewissen 2008), but the canals are extremely reduced in modern cetaceans. de., Ricqles, A. There are several recent reviews of the evolution of odontocetes and mysticetes (Fordyce and Muizon 2001; Bianucci and Landini 2007). Gingerich PD, Raza SM, Arif M, Anwar M, Zhou X. These results suggest that Indohyus was aquatic and thus that cetaceans originated from aquatic ancestors. Am Zool. 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). _______________________________ Where is the nasal opening in [3] While they were unable to support body weight on land, they might have assisted as claspers during copulation. The first embryo shows forelimbs but not hind limbs (in most mammals forelimbs develop before hind limbs). Just like raoellids and all cetaceans, pakicetids have an involucrum, the thickened inner lip on the tympanic bone (Fig. Instead it is located further posterior on the snout, foreshadowing the formation of the blowhole of later whales (Fig. Humans and chimpanzees share a recent common ancestor. 1st ed. Article Creationists have moved the goal posts to other questions which I will attempt to address as an addition to my original posting since they require graphics and comments do not allow for pictures to be included. The emergence of whales, evolutionary patterns in the origin of Cetacea. 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). Gatesy J, O'Leary MA. Such an analysis results in a cladogram, and our study (Thewissen et al. Boessenecker et al. These creatures are known from multiple well preserved skeletons. Gingerich PD, Arif M, Bhatti MA, Anwar M, Sanders WJ. 2007). Peters, S.E., Antar, M.S.M., Zalmout, I.S., and Gingerich, P.D. Toothed whales, the odontocetes, have access to rich marine food resources down to depths of 2000 m and achieve a biomass turnover larger than that of human fisheries combined ().The key to this success is their ability to locate, track, and capture fast-moving prey underwater in complete darkness at depths of, routinely, >100 m using echolocation, a feat that critically depends on the . The three voice registers of a bottlenose dolphin in sequence. Clementz, M.T., Goswami, A., Gingerich, P.D., and P.L. While every effort has been made to follow citation style rules, there may be some discrepancies. 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. (2001), Nature), Fossiliferous area of H-GSP Locality 62, the richest locality for pakicetid cetaceans. Experts are tested by Chegg as specialists in their subject area. 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. Blowholes help to distinguish modern forms of whales. A 147-g piece of metal has a density of 7.00 g/mL. The comment should have a gray vertical bar to the left of the commenter's avatar. a Outline ellipses and regression of body size (on x-axis, as 10-log in grams) against semicircular canal radius (on y-axis, as 10-log in mm) for modern land mammals (maroon) and modern cetaceans (blue). Eg: when we looking at the whales's anatomy, we can see that they evolved from an ancien 4 legged land mammal. Sensory Abilities: Land mammals (including humans) can hear underwater, but they cannot tell which direction the sound comes from because sound waves travel through the bones of the skull and arrive at both inner ears at the same time. Good introductions to the evolutionary history of odontocetes and mysticetes have been published (Fordyce and Muizon 2001; Bianucci and Landini 2007). In addition, the part of pakicetid skulls behind the eyes (orbits) and the joints for the lower jaw (mandibular fossa) is very narrow (Fig. Two isotopes, forms of elements that are chemically identical but have heavier atoms because of excess neutrons in the nucleus, are common in nature: Oxygen-16 and Oxygen-18 (where the number reflects the mass of the atom). 2001b;5:103749. Age: 34-40 million years old, Eocene Epoch. You can find out more about our use, change your default settings, and withdraw your consent at any time with effect for the future by visiting Cookies Settings, which can also be found in the footer of the site. Geisler JH, Theodor JM, Uhen MD, Foss SE. Thewissen JGM, Williams EM. Aslan A, Thewissen JGM. Fig 1. The study of differences and similarities between living things. Fordyce E, Muizon Cd. Cranial anatomy of Pakicetidae (Cetacea, Mammalia). The morphology of the sense organs suggests that hearing was important for Remingtonocetus but that vision was not. At the time, of course, no one knew that these petrified artifacts were actually the bones of a long-extinct prehistoric whale. Unlike modern cetaceans, the skull of Basilosaurus has bony external ear canals, suggesting that it may have retained some form of highly reduced external ear. Basilosauridae is a paraphyletic family of extinct cetaceans that lived during the late middle to the early late Eocene, known from all continents. 4). (Image from Thewissen et al. Figure3 is such a diagram for early cetaceans. 11). 2007). The intermediate fossil of the Basilosaurid whale contains a nasal hole at _____. This wear pattern has been correlated to fish eating (O'Leary and Uhen 1999). Basilosaurids occurred worldwide during most of their history, and important fossils have been recovered in Egypt and the southern United States. Llanocetus denticrenatus was discovered in the latest Eocene sediments of Seymour Island, Antarctica and current research puts it as the earliest known Mysticeti or baleen whale. The phylogeny among fossil animals can be determined by coding their morphology and having a computer program determine the greatest similarities in significant characters. "10 Facts About Basilosaurus." This helps the animal walk on the bottom of rivers, where the extra bone mass serves as ballast. The lower jaw of Basilosaurus has a very large hole (mandibular foramen) with thin walls, which in modern toothed whales houses a large pad. Little is known about the diet and feeding morphology of protocetid cetaceans, but, there too, variation appears to be common. another animal is to ? In the latter case, the heat exchange is used to reduce the temperature of the testes. Oxygen-16 is by far the more common isotope (over 99% in nature), but the ratio between Oxygen-16 and Oxygen-18 varies in different environments, and animals living in water have a different ratio compared to animals living on land (Roe et al. Thewissen). J Pal. A remarkable video of this behavior is posted on www.youtube.com and is called Eagle versus Water Chevrotain (chevrotain is the French name for African mouse deer). Thewissen JGM, Fish FE. 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). The bony wall is broken in this specimen, showing the thickness of the wall (medial tympanic wall). The evolutionary history of cetaceans - whales, dolphins, and porpoises - started with the rise of Archaeoceti, a paraphyletic group of stem cetaceans, in the ancient Tethys seaway during the early Eocene more than 50 million years ago (Bajpai and Gingerich 1998).The earliest archaeocetes - pakicetids, ambulocetids, remingtonocetids - were amphibious species from Eocene sediments of fluvial . The limb proportions (relative length of the thighs, feet, and hands, etc.) Madar SI, Thewissen JGM, Hussain ST. Additional holotype remains of Ambulocetus natans (Cetacea, Ambulocetidae), and their implications for locomotion in early whales. 1st ed. Carnegie Institute of Washington Publication, vol. 1999; Gatesy and O'Leary 2001). Edward Babinski has some good pages. Adam Li / NOAA/NMFS/SWFSC. That this evolutionary process is repeated in a way during ontogeny became obvious through external observations on embryos and fetuses (Kukenthal 1893). The emergence of whales: evolutionary patterns in the origin of Cetacea. Notice the similarities between hippos and whales. Instead it is located further posterior on the snout, foreshadowing the formation of the blowhole of later whales (Fig. Summarizing, pakicetids inherited the aquatic lifestyle from their raoellid ancestors. In spite of this, some species retain a few hairs on their face and in others the fetus has whiskers (Fig. However, under closer examination, scientists . It contains a small group of species, most of which are only known from teeth and jaws (Thewissen et al. Study a DNAs of different groups searching for hidden relationships and also the time when species diverged from their ancestors. A new middle Eocene protocetid whale (Mammalia: Cetacea: Archaeoceti) and associated biota from Georgia. Heads vary in size but share a basic layout; front teeth are peg like and distinctly banana shaped when found loose, only the tip is enameled. Internally, there are pelvic or hind limb remnants in all species, which provide origin for the muscles to the genitals. View the full answer. Whales, dolphins, and porpoises together constitute the Cetacea (English: cetaceans). Based on the difference in time between the perception of a sound wave in each ear, Basilosaurus could likely determine the direction of origin of incoming sound. coat of fur. J Pal. In Artiocetus and Rodhocetus, the limbs are short; the hand had five fingers, and the foot had four toes, and the foot was much larger than the hand, somewhat similar to Ambulocetus. In growth it was similar to today's Killer whales, but Basilosaurus was muchlenthier than killer whales(twice the size of the killer whale).There was a co-existence between this huge c. The emergence of whales: evolutionary patterns in the origin of Cetacea. The intermediate fossil of the Basilosaurid whale contains a nasal hole at ________. 2007;290:71633. Humans and chimpanzees share a recent common ancestor. Nasal Drift in Early Whales Whales breathed with more ease when they no longer had to lift a snout above water. Strauss, Bob. Dorudon atrox in turn was a prey item for the larger basilosaurid . In our view, classifications of animals above the species level are mostly vehicles for communication between scientists, and communication is greatly hampered by classifications that are not stable: changing the content of Cetacea by including Indohyus leads to instability of Cetacea. 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. 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. ThoughtCo. 1900;23:32731. Isotopic approaches to understanding the terrestrial to marine transition of the earliest cetaceans. Discover fascinating details about this enormous marine mammal. Although the first fossils for this group were discovered before World War II, these were so fragmentary that they were not recognized as cetaceans. Like all arachaeocetes, they lacked the telescoping skull of modern whales. Hulbert RC Jr. Postcranial osteology of the North American middle Eocene protocetid Georgiacetus. 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. The earliest dorudontines were the earliest basilosaurids, with long skulls and relatively short bodies. The skeletons of Ambulocetus (top) and Pakicetus (bottom), J.G.M. In the second embryo, hind limbs have started to form, but their development ceases and they slowly disappear as the embryo grows (third and fourth embryos). It appears most likely that Ambulocetus was an ambush predator, attacking prey that came close to it but not pursuing it over long distances. 16), roughly the size of a large male sea lion. Pakicetids have teeth with cusps (the elevated bumps on a tooth) that are high, separated by deep valleys from other cusps (Fig. Structural adaptations of early archaeocete long bones. Odontocetes and mysticetes conquered nearly all of the oceans: they include coastal and off-shore forms, arctic and tropical waters, shallow water, deep sea, and riverine forms. First, identify the closest match of whale DNA to another animal. Comparing things that are similar and different. 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. Hind flippers present in a single anomalous dolphin housed at the Taiji Whale Museum, Diagram showing the approximate location of the pelvis and hind limb of a male bowhead whale (Balaena mysticetus) in (A) lateral view and (B) dorsal view. It may seem odd that a 47-million-year-old artiodactyl that looks like a tiny deer is aquatic, but this behavior is reminiscent of one species of modern artiodactyl. Cross section of the femur (thighbone) of Indohyus (RR 42). 22). Externally, pakicetids look nothing like a modern cetacean. The feet are much larger than the hands. Modified from Spoor et al. Whales originated from aquatic artiodactyls in the Eocene epoch of India. Preliminary evaluation of Kuldana paleosols and implications for interpreting vertebrate fossil assemblages, Kuldana Formation, Northern Pakistan. What is one way Scientists know that Maiacetus lived in the ocean? The branching of the cetacean groups on this cladogram is consistent with most recent work (Thewissen et al. What is one way Scientists know that Maiacetus lived in the ocean? Provided by the Springer Nature SharedIt content-sharing initiative. The proportions of the vertebrae at the tip of the tail suggest that Basilosaurus had small tail flukes. of the skeleton of Ambulocetus are similar to those of river otters (Thewissen and Fish 1997). The tail made up as much as three-quarters of the total body length of Basilosaurus. Paleobiology. Comparative biochemistry and molecular biology. This changed in the early 1990s, when paleontologists unearthed the first of a series of fossil cetaceans, mostly in India and Pakistan, documenting the transition from land to water in detail in the Eocene Period (which lasted from approximately 54 to 34 million years ago). The presence of basilosaurids in . Basilosaurids, however, were the first widespread truly aquatic group of whales. Terms and Conditions, While early reports on protocetid skeletons proposed that a fluke was present (Gingerich et al. 24). Another surprising feature in the skeleton of Indohyus was found in the bones of its extremities. As a result, the skeleton of Indohyus shown in Fig. In modern dolphins, on the other hand, it is located on the top of the head, above the eyes. Unlike all modern cetaceans, Basilosaurus also retained external hindlimbs with a functional knee and toes. Kellogg R. A review of the Archaeoceti. On the other hand, whereas the main propulsive organ of cetaceans and sirenians is the tail, sea lions swim with their forelimbs, and seals with their hind limbs. Taxa that have more branches of the diagram in common are more closely related. In addition, the hind limbs may have been used as claspers to help guide the long bodies of the males and females into position for mating. The nostrils migrated upward toward the top of their . 1997). Protocetids such as Babiacetus have heavy jaws (Fig. Roe LJ, Thewissen JGM, Quade J, O'Neil JR, Bajpai S, Sahni A, et al. Land locomotion must have been slow since the semicircular canals were small (Spoor et al. In life, the peg like front teeth were used to seize prey and the rear triangular teeth were used to dispatch and process prey. One feature that is a strong indicator of this relationship is the shape of one of the bones of the ear. This suggests that the diet of remingtonocetids is different from that of earlier cetaceans. 1st ed. Isotopic records from early whales and sea cows: contrasting patterns of ecological transition. In India and Pakistan, protocetids are found in the same areas as remingtonocetids (Gingerich et al. It was not until 2001 that skeletons of these whales were discovered (Thewissen et al. 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. Cetaceans are unrelated to other marine mammals, the sirenians (manatees and dugongs) and the pinnipeds (seals, sea lions, walruses). It is possible that these relatives are also closely related to hippopotamids, which would make molecular and morphological phylogenies consistent. 1: Georgia's Oldest Fossils; Archaeocyathids, At 513 Million Years Old, 8: Suwannee Current, Gulf Trough, & Bridgeboro Limestone, 9: The Clayton Formation Report; By Hank Josey, 12: Basilosaurids; The First Modern Whales, 13: Ziggy and The Museum of Arts & Sciences, Macon, GA, 18: Miocene Epoch; 23.3 to 5.3 Million Years Ago, 19: Pliocene Epoch; 5.3 to 2.5 Million years Ago, 20: The Ice Ages; Pleistocene & Holocene Epochs, *NEW* 20K: Pleistocene Vertebrates from Coastal Georgia. It has been suggested that early cetaceans ate fish (O'Leary and Uhen 1999). Similar to earlier archaeocetes and unlike most later cetaceans, basilosaurids retained a heterodont dentition, with clear morphological differences between incisors, canines, premolars, and molars (Uhen 2004). 1998; Hulbert 1998). Write each sum in sigma notation. 2006;103:84148. 2007, 2004). Hand and foot of the protocetid Rodhocetus (modified from Gingerich et al. We hope that a detailed understanding of evolutionary patterns will allow us to determine the processes that drove cetacean evolution. 6 (RR 208). Relative height of the mandibular foramen (mandibular foramen height divided by height of the mandible at the last tooth) in fossil cetaceans and modern odontocetes. Basilosaurids are usually referred to as archaeocetes, the ancient whales, but in modern classifications they are members of the Pelagiceti, the fully aquatic whales. b A reconstruction of inner ear of modern bowhead whale, showing semicircular canals above, broken stapes (yellow), and the cochlea below. Many skeletons of Indohyus were washed together, and the bones are jumbled. VIDEO ANSWER:Hello. 1st ed. These may It's unusual for two states to share the same official fossil; it's even rarer for these two states to border each other. J Anat Physiol. another animal is to ? Pakicetids also have tooth wear that is highly unusual, with large polished areas on their enamel, caused by tooth-to-tooth contact. They are all . Variation in the skeleton behind the skull is hard to assess because these bones are only known in a few species, specifically Rodhocetus and Artiocetus from Pakistan (Gingerich et al. ______________________ The closest match, so far, of whale DNA to https://doi.org/10.1007/s12052-009-0135-2, DOI: https://doi.org/10.1007/s12052-009-0135-2. This form of locomotion is anguilliform, or eel-like; in the case of Basilosaurus, this movement would have been up-down, rather than side to side as in eels and other anguilliform fishes. Pakicetids are the earliest cetaceans and had a pelvis that was similar to most terrestrial mammals (composite of H-GSP 30395, 30213). Thewissen JGM, Hussain ST, Arif M. Fossil evidence for the origin of aquatic locomotion in archaeocete whales. Whales breathed with more ease when they no longer had to lift a snout above water. With the origin of protocetids, cetaceans spread across the globe. While hunting in these deep and murky waters, they use short, powerful, ultrasonic echolocation clicks to find, follow, and catch . _____________ ____________Mammals There are no external hind limbs in normal modern cetaceans, although, very rarely, an anomalous individual with such limbs is born (Fig. This eye position occurs in aquatic mammals such as hippopotamus. However, the first basilosaurid specimenBasilosaurus, whose Latin name is translated king lizardwas originally classified as a lizard when it was first described. The great length of the vertebral column of basilosaurids can be attributed to the increase in the number of lumbar vertebrae in the taxon but also by the increase in length of each individual vertebra. Buchholtz EA. Cetacea includes one of the largest species of animal ever, the blue whale (27m in length, 136,000kg) but also has some very small modern representatives, e.g., the vaquita (1.4m in length, 42kg). The changing cetacean body plan during the first ten million years of cetacean evolution. New York: Plenum; 1998. p. 32552. RR 209 has the back of the palate with the region for the eyes; RR 210 is the braincase; RR 207 and 208 are a nearly complete skull, just lacking the region of the incisors, Detail of the ear region of a skull in Fig. 's symptoms. 2005). They were, however, very small and did not articulate with the vertebral column, which also lack true sacral vertebrae. . Deciphering whale origins with molecules and fossils. 2006). 2006). 1995a, b; Fig. Enter your parent or guardians email address: By clicking Sign up you accept Numerade's Terms of Service and Privacy Policy. 1998). Composite skeletons of the pakicetid cetaceans Pakicetus (left) and Ichthyolestes (right). The kekenodontines consist of the single genus Kekenodon, which was only poorly known and is the only basilosaurid dating from the Oligocene Epoch. Cetaceans are so different from land mammals that it was difficult to find significant similarities in the anatomy between cetaceans and land mammals. 2001b;293:223942. In: Thewissen JGM, editor. Modern whales emerge Mysticetes and Odontocetes (33-28 mya) The ancestors of toothed and baleen whales diverged as the world's climate rapidly cooled and opened up new opportunities for basilosaurid diets. List five independent nursing interventions that may help relieve B.T. 2002). Bianucci G, Landini W. Fossil history. 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. 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.