- small brain, eyes, ears and nasal opening that connects with pharynx - mouth contains tooth-like formations made of keratin - all are marine - most are bottom-dwelling scavengers that feed on worms and sick or dead fish - have rows of slime glands that secrete slime that may repel other scavengers when a hagfish is feeding Dr. B. Holly Smith working at the base of the tail at a Basilosaurus excavation in Wadi Hitan, Egypt. The location of the nasal opening underwent a transition, from the tip of the snout in (An), to midway between the tip of the snout and the skull in Basilosaurus, to the very top of the head in modern whales. Dorudon lacked the elongated vertebrae of Basilosaurus and was much smaller (about 4-5 meters in length). In development, the nose opening shifts from the tip of the snout (arrow in left embryo) to its position on top of the head. The transition from land to water is documented by a series of intermediate fossils, many … The tympanic bulla of Basilotritus uheni shares basilosaurid synapomorphies but possesses unusual traits inherited from protocetids. Even though all modern cetaceans are obligate aquatic mammals, early cetaceans were amphibious, and their ancestors were terrestrial artiodactyls, similar to small deer. Dorudon’s dentition was similar to Basilosaurus’s; its cranium, compared to the skulls of Basilosaurus and the previous whales, was somewhat vaulted (Kellogg 1936). They do have two nasal passages underneath the skin, but the septum does not rise all the way to the surface. The Wadi Al Hitan Basilosaurus isis specimen with stomach contents described here is known by its map number, WH 10001. Dolphins and whales can also use their blowhole to create sounds. Recent research shows that there were a large number of experimental methods of feeding, including the origin of filter feeding long before the origin of baleen. Compare it with the blue whale skull above, there is really a whole lot of soft tissue over the opening of the nasal cavity. This all seems to suggest that Basilosaurus had a big, fleshy nose. Cetacean Evolution (Whales, Dolphins, Porpoises) ... protocetid, Rodhocetus, there are . The nasal cavities (or chambers) of Ankylosaurus were elongated and separated by a septum at the midline, which divided the inside of the snout into two mirrored halves. . Basilosaurus has a possible record in New Zealand. The neck of archaeocetes was still longer and much more flexible than those of modern whales. . Mysticetes have two nasal openings, or blowholes, at the surface of their skin. The septum had two openings, including the choanae (internal nostrils). Materials and methods. The first whales lacked such an adaptation. They do have two nasal passages underneath the skin, but the septum does not rise all the way to the surface. Neck. In modern cetaceans, the nasal opening is called the blowhole, and it is located on the forehead, allowing the animal to surface and breathe while in a horizontal position in the water . sp., comes from the late middle Eocene (Bartonian) of Ukraine. It is the earliest dated record of a cetacean from Eastern Europe. . We are particularly interested in this part of the skeleton because this is where the reduced hind limbs, feet, and toes ... Evolution of nasal opening in whales Hearing in whales. Mysticetes have two nasal openings, or blowholes, at the surface of their skin. As you can see, the first cetaceans and cetacean ancestors were found in India and Pakistan. Although there is no shortage of guidebooks that focus on cetacean species, Whales, Dolphins, and Porpoises: A Natural History and Species Guide gives homage to the diversity of this taxonomic group through its large page size, ample species-specific illustrations, and efficiently organized authoritative text. Sinuses and nasal chambers in the snout may have been for heat and water Dolphins and whales can also use their blowhole to create sounds. The skeleton as a whole does not have a museum number because most parts of the skeleton were not collected. Basilosaurus 40-35 MYA is enormous and nearly a full cetacean. By about 40 million years ago however, cetaceans such as Basilosaurus were living all around the world. The blowhole is even more dorsal in comparison though, and the hind flippers are all but internal. Basilosaurus contains three species from the late middle and early late Eocene: B. cetoides is known from the southeastern United States, B. isis is known from Egypt and Jordan, and B. hussaini is known from Pakistan (Uhen, 1998). . Basilosaurus has a nose hole set farther back than a typical land mammal or pinniped, and if you take a look at the front of the skull, it has a substantially large nose hole opening. Its broad muzzle indicates it was a non-selective browser. Cetaceans (whales, dolphins, and porpoises) are an order of mammals that originated about 50 million years ago in the Eocene epoch. Shastasaurus has one of the most specialised mouths of all known ichthyosaurs in that the jaws are both short and toothless. This toothless adaptation is also seen in the similar Shonisaurus although this ichthyosaur has comparatively longer jaws. Why Shastasaurus should …