Don't forget Glaucomys Sabrinas
Interesting topic, rosborne.
I wish my intelligent design thread had more science in it. (of course that is really the fault of the ID proponents themselves)
Obviously designed by a creator with a great sense of humor!
Evolution Of Whale Hearing Unfolds In Fossil Record
Arlington, Va. -- An international team of scientists has traced the evolution of hearing in modern cetaceans (whales, dolphins and porpoises). "This study of the early evolution of whales demonstrates the changes that took place in whales' outer and middle ears, required for the transition from a land-based to a marine-based existence," said Rich Lane, director of the National Science Foundation (NSF)'s geology and paleontology program, which funded the research.
The findings are published in the Aug. 12 issue of the journal Nature.
The ear is the most important sense organ for modern toothed whales, say scientists, because these whales locate their prey using echolocation. Directional hearing is critical: A blind such whale could find food without much trouble; a deaf one would starve.
The study documents how hearing in these whales evolved. The research is based on cetacean fossils representing four groups of early whales. The earliest cetaceans, pakicetids (those that swam in ancient seas 50 million years ago), used the same sound transmission system as did land mammals, and so had poor underwater hearing. More recent cetaceans, remingtonocetids and protocetids (those that lived 43-46 million years ago), retained the land-mammal system, but also developed a new sound transmission system.
"The fossils document the ways in which cetacean hearing has changed, starting with ear fossils of whales' land ancestors and ending with the ear of near-modern looking whales," said Hans Thewissen, an anatomist at the Northeastern Ohio Universities College of Medicine (NEOUCOM). Thewissen and NEOUCOM researcher Sirpa Nummela led the study.
The newer system was similar to that of modern whales. The later whales could hear better in water than pakicetids could, and could also hear in air, but hearing in both media was compromised by the existence of two systems. With the advent of basilosauroids (approximately 40 million years ago), the old land-mammal ear disappeared, and the modern cetacean sound transmission system began its development. Although basilosaurids were not echolocators (they lacked the sound-emission equipment of later echolocators), they had taken a major step forward in refining underwater sound reception.
Learning to Listen
How some vertebrates evolved biological sonar
Then, a little more than 30 million years ago, the whale family tree split into two major lineages. One branch, the toothed whales, today includes porpoises, killer whales, and sperm whales. This branch evolved organs to produce high-frequency chirps and inner ear structures to detect them. By 18 million years ago, the ancestors of today's dolphins had an ear structure that suggests that they could echolocate as well as their modern relatives can.
Eocene evolution of whale hearing (Abstract)
Sirpa Nummela, J. G. M. Thewissen, Sunil Bajpai, S. Taseer Hussain and Kishor Kumar
The origin of whales (order Cetacea) is one of the best-documented examples of macroevolutionary change in vertebrates. As the earliest whales became obligately marine, all of their organ systems adapted to the new environment. The fossil record indicates that this evolutionary transition took less than 15 million years, and that different organ systems followed different evolutionary trajectories. Here we document the evolutionary changes that took place in the sound transmission mechanism of the outer and middle ear in early whales. Sound transmission mechanisms change early on in whale evolution and pass through a stage (in pakicetids) in which hearing in both air and water is unsophisticated. This intermediate stage is soon abandoned and is replaced (in remingtonocetids and protocetids) by a sound transmission mechanism similar to that in modern toothed whales. The mechanism of these fossil whales lacks sophistication, and still retains some of the key elements that land mammals use to hear airborne sound.
said Rich Lane, director of the National Science Foundation (NSF)'s geology and paleontology program, which funded the research.
The ear is the most important sense organ for modern toothed whales, say scientists, because these whales locate their prey using echolocation.
Farmerman brought up the example of bats in response to my post regarding sonar in dolphins.
The echolocation of either is so unlikely to have 'evolved a little at a time' .
Keep trying the cheap shots RL
spendi, get your head out of your ass and really try to make some sense. Do
Quote:said Rich Lane, director of the National Science Foundation (NSF)'s geology and paleontology program, which funded the research.
Having placed his reputation on the line by the funding it is only to be expected that Mr Lane will seek to construe the results of the research in a manner which demonstrates how wise he had been to do so as, if his wisdom is so demonstrated, he becomes an obvious candidate for promotion and all that might flow from it.
It is known in the trade as "spin".
e.g.- "International team of scientists" sounds a lot better that "a bunch of skiving freeloaders having a good time at taxpayer's expense on a ship chartered from one of Mr Rich's pals and who's qualifications have been decided upon by various methods not excluding variations on the casting couch and coming to conclusions which only seem not simple and obvious when presented in a language that only insiders can understand.
Quote:The ear is the most important sense organ for modern toothed whales, say scientists, because these whales locate their prey using echolocation.
One can hardly get more simple and obvious and circular than that and it does rather underplay the function of the maw into which the prey is drawn. In seas rich with prey the mouth might well be a much more important sense organ for without it any amount of prey would make no difference.
It does seem a trifle teleological timber.
Have you read the passages in Ulysses where Mr Deasy is depicted cajoling Stephen with ready cash to use his influence with an editor to get a letter of his published in the paper. I hope you don't think such methods stopped evolving in 1904.
You might though because if they didn't it might not suit the case you make so well.
That vaguely reminds me of young Caulfield's essay on Egypt which his tutor found so tiresome.
I thought that the comma after "program" was unnecessary but I'll admit that's a bit picky.
If spin were subject to rigorous verification and peer review you might have a point other than between your ears.