The Rosetta Stone of Evolution from the Sea

Discovered in rock formed from late Devonian river sediments on Ellesmere Island, in northern Canada, the Tiktaalik roseae was an important discovery in learning how animals emerged from the sea. Believed to be 375 million years old, the fossil represented an important intermediate step in the exodus from the ocean that eventually formed land animals.

"Exquisite specimens of Tiktaalik roseae discovered several years ago continue to function as a rosetta stone for understanding the emergence of quadripeds on land," said H. Richard Lane, program director in the National Science Foundation (NSF)'s Division of Earth Sciences.

The creature, a large aquatic predator discovered in 2004, is believed to have existed on the bottom in shallow water for times, and out of the water for short periods. According to the research, Tiktaalik roseae has features of the skull, neck, ribs and appendages that are shared with the earliest limbed animals (tetrapods), as well as fishlike features such as scales and fin rays.

And according to the paleontologists behind the new study, the mosaic features make it a textbook example of a transitional fossil.

"The braincase, palate and gill arches of Tiktaalik help reveal the pattern of evolutionary change in this part of the skeleton," said Jason Downs, a scientist at the Academy of Natural Sciences and lead author of this week's paper. "We see that cranial features once associated with land-living animals were in fact the first adaptations for life in shallow water."

The research points to the flattening of the skull and lengthening of the snout as examples of the transitional evolution taking place.

According to Ted Daeschler at the Academy of Natural Sciences in Philadelphia, who co-led the team who discovered the Tiktaalik roseae in 2004, "The gradual evolutionary transition from fish to tetrapod, and the transition from aquatic to terrestrial lifestyles required much more than the evolution of limbs. The head of these animals was becoming more solidly constructed and, at the same time, more mobile with respect to the body across this transition."

"We used to think of this transition of the neck and skull as a rapid event, largely because we lacked information about the intermediate animals," said Neil Shubin of the University of Chicago, who co-led the team that discovered Tiktaalik roseae. "Tiktaalik neatly fills this morphological gap, and helps to resolve the timing of this complex transition."

Posted by Josh Hill.

http://www.eurekalert.org/pub_releases/2008-10/nsf-doe101508.php

Comments

[rayceeya]

The really interesting thing is that this is a ray finned fish instead of a lobe finned fish.

It's always been thought that lobe finned fish similar to the Coelacanth are the ancestors of all tetrapods. Now it appears that the classic four legged "Darwin Fish" may have been a ray fin.

[Andrew]

Somebody call Adnan Oktar, there's $7.5 trillion to be made!

[Inginious]

And this is considered "transitional" evolution because the snout is longer and the head is flat!?
come on!
Hypothetically speaking, assume 1000 years have passed and the platypus has been extinct. Would scientist assume that this animal is considered transitional evolution? Would this be their "Missing Link"?
Stupid evolutionist know nothing! case in point:
scientists have had this "BELIEF" that animals at the bottom of the ocean would have to be lonely creatures with minimal movement... haha, guess what? you are wrong again. (see: http://gizmodo.com/5060158/worlds-deepest-fish-filmed-for-the-first-time)
Science is awesome and i've been studying it for years due to my field and There has not been one single evidence that proves this belief. it's a nice belief and be really awesome if it were true :(