Upload
norman-pooler
View
223
Download
3
Tags:
Embed Size (px)
Citation preview
by William T. Kratz
historical research of the whale
fossil records related species
geographic distribution
whale evolution video
In 1693 John Ray classified whales as mammals
In 1859 Charles Darwin believes that whales have similarities to the black bear
In 1883 William Flower suggested whales evolved from ungulates
Philip D. Gingerich Ph.D. researched whale fossils in Pakistan and Egypt from1970s through 1990s
Hans Thewissen led the team that reconstructed the skeleton of the first land mammal ancestor of the whale
Indohyus Pakicetus Ambulocetus
natans Rodhocetus Basilosaurus Dorudon
Indohyus literally means India’s Pig
Fossil founded by Indian geologist Ranga Rao
Skeleton assembled by Hans Thewissen
Fossil dates back 60 mya Even toed ungulate Size of a modern house cat Chemical tests on teeth and bone
analysis revealed that Indohyus spent much of its time wadding in water as a hippo would
Bone structure around the ear revealed unique similarities to that of the modern whale
First Archaeocete Evolved 52 mya Founded by Philip Gingerich in
1983 in Pakistan Pakicetus was about the size of a
wolf Primarily was a land mammal but
spent much time in the water. Had sharp teeth of a carnivore Like Indohyus, had similar bone
structure around ear to that of modern whales
Ambulocetus “walking whale” was found in 1992 by Thewissen
Fossil dates back 49 mya 3 meters in length, hind legs were
well adapted for swimming Skeleton suggests that it hunted
like a crocodilian Ambulocetus had no external ear,
probably kept head close to ground to detect vibrations of land prey
Anatomy of spinal column-swam with tail going up and down
Had an adaptation in the nose that enabled it to swallow underwater, and its periotic bones had a structure like those of whales, enabling it to hear well underwater
49-43 mya in Pakistan by Stromer 1908
Lumbar vertebrae-neural spines higher, more developed tail for swimming
Sacral vertebrae not fused- more flexibility, body developed for swimming
Femur was a third shorter than that of the Ambulocetus’
Skull elongated Ears pushed further back Smaller eyes First ancestor to be more water
orientated that land
Basilosaurus “regal lizard” First skeletal parts found in
Louisiana and Alabama in the 1830’s
Fossil dates back 35-40 mya Could grow up to 20 meters First ancestor that was all aquatic Complete set of hind limb bones
and a pelvis, but very small Formation of blow hole-single
large nostril to the top of the head
First to have tail fluke- due to structure of vertebral proportions
Dorudon was founded by Gingerich in 1994
Fossil dates back 33-40 mya Found in North America, India,
and Pakistan Originally thought to be an
intermediate Basilosarus, ranging from 4-5 meters
Carnivorous, feeding on small fish and mollusks
Looked very similar to modern whales, but lacked the melon organ
Also a completely water orientated mammal.
Distribution of Basilosaurus and Dorudon widely spread vs. Ambulocetus and Rodhocetus restricted to one area in India, Pakistan region
http://www.youtube.com/watch?v=lUuUEo84YlY&feature=related
WHALE EVOLUTION ANIMATION