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“Modern cetaceans represent a bizarre mixture of traits, many of which are thought to be specializations that enable an obligately aquatic lifestyle. Some of the characteristic features of extant cetaceans are indicated in illustrations of the delphinid odontocete Tursiops truncatus (bottlenose dolphin), top and middle, and the balaenopterid mysticete Balaenoptera musculus (blue whale). Many of the specializations that make a whale look like a whale are evolutionary losses (e.g., hindlimbs, external ears, hair, teeth) in combination with structures that are uniquely evolved within Mammalia (e.g., dorsal fin, blowhole, melon, baleen, extremely ‘‘telescoped’’ and asymmetrical skull, pleated throat pouch). Artwork is by Carl Buell.”
A phylogenetic blueprint for a modern whale. Gatesy J, Geisler JH, Chang J, Buell C, Berta A, Meredith RW, Springer MS, McGowen MR. Mol Phylogenet Evol. 2012 Oct 26. pii: S1055-7903(12)00418-6 (pdf)
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Grampus griseus by Edward Drinker Cope (1876) proceedings of the Academy of Natural Science of Philadelphia (vol 28)
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this is an amazing photo set! Enjoy!
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Skeleton Necklaces!
Wanted to try out some different species… had a lot of fun with these! They are available for sale through my Facebook page, and will be on my Etsy page in the near future. $20 plus shipping!
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cetacea size comparison
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lagenorhynchus obliquidens - Pacific white-sided dolphin by *odontocete
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The natural history of North Carolina by BioDivLibrary on Flickr.
Raleigh,Reprinted by authority of the Trustees of the Public libraries,1911.
biodiversitylibrary.org/page/29160501 -
GETTING A LEG UP ON WHALE AND DOLPHIN EVOLUTION
NEW ANALYSIS SHEDS LIGHT ON ORIGIN OF CETACEANS
via AMNH (2009)
When the ancestors of living cetaceans—whales, dolphins and porpoises—first dipped their toes into water, a series of evolutionary changes were sparked that ultimately nestled these swimming mammals into the larger hoofed animal group. But what happened first, a change from a plant-based diet to a carnivorous diet, or the loss of their ability to walk?
A new paper published this week in PLoS One resolves this debate using a massive data set of the morphology, behavior, and genetics of living and fossil relatives. Cetacean ancestors probably moved into water before changing their diet (and their teeth) to include carnivory; Indohyus, a 48-million year-old semi-aquatic herbivore, and hippos fall closest to cetaceans when the evolutionary relationships of the larger group are reconstructed.
“If you only had living taxa to figure out relationships within this group of animals, you would miss a large amount of diversity and part of the picture of what is going on,” says Michelle Spaulding, lead author of the study and a graduate student affiliated with the American Museum of Natural History. “Indohyus is interesting because this fossil combines an herbivore’s dentition with adaptations such as ear bones that are adapted for hearing under water and are traditionally associated with whales only.”
The origin of whales, dolphins, and porpoises—with their highly modified legs and lack of hair—has long been a quandary for mammalogists. About 60 years ago, researchers first suggested that cetaceans were related to plant-eating ungulates, specifically to even-toed, artiodactyl mammals like sheep, antelope and pigs. In other words, carnivorous killer whales and fish-eating dolphins were argued to fit close to the herbivorous hoofed animal group. More recent genetic research found that among artiodactyls, hippos are the cetaceans’ closest living relatives…
(read more: American Mus. of Nat. Hist.) (image: Carl Buell)
Posted on February 15, 2012 via fauna with 193 notes
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Meet Odobenocetops (literally “walrus-faced whale”). Yes, it’s a freak, but that’s why we love it. This genus of dolphin with its own family (Odobenocetopsidae) forms a sister group with Monodontidae, which houses both narwhals (Monodon monoceros) and beluga whales (Delphinapterus leucas), which is part of what makes them so bizarre. Both Odobenocetops and the narwhal have tusks evolved from incisors, but the beluga whale does not. This means tusks would have evolved separately and independently in both. What’s more, is that the only male Odobenocetops found has profoundly uneven tusks. This is interesting because only one incisor normally becomes a tusk in narwhals, so these are two rare instances of asymmetry evolving convergently in related species, which only makes it more spectacular. Also astonishing is how different these dolphins were from their cousins. For one, they have flattened skulls and lacked the bulbous melons (which gives dolphins their rounded foreheads) of other toothed whales which are involved in echolocation. To compensate, their eyes are set comparatively high on the head and face forward, giving them binocular vision, kinda like us. These features suggest that it was likely a bottom feeder, evolving convergently with walruses (Odobenus rosmarus), and sucking small shelled invertebrates from the sea bed and prying them out with powerful tongues. Odobenocetops may have used its tusks to help dig up food, as walruses were once believed to.
Posted on January 5, 2012 via with 251 notes
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n46_w1150 by BioDivLibrary on Flickr.
Via Flickr:
Voyage dans l’Amérique Méridionale. v.9.
Paris :Pitois-Levrault,1835-47.
biodiversitylibrary.org/item/50740
