Information Pikaia gracilens is an extinct animal known from the Middle Cambrian and perhaps swam much like an fossil found near Mount Pika in the Burgess Shale of British Columbia. It was discovered by Charles Walcott and was first described by him in 1911. Based on the obvious and regular segmentation of the body, Walcott classified it as a Polychaete worm. It resembles a living chordate commonly known as the Lancelet eel.
During his re-examination of the Burgess Shale fauna in 1979, Paleontologist Simon Conway Morris placed P. gracilens in the making it perhaps the oldest known ancestor of modern vertebrates, because it seemed to have a very primitive, proto-chordates,notochord.
Averaging about 1 1/2 inches in length(5 cm), Pikaia swam above the seafloor using its body and an expanded tail fin. Pikaia may have filtered particles from the water as it swam along. Only 60 specimens have been found to date. (information taken from Wikipedia:http://en.wikipedia.org/wiki/Pikaia)
When Pikaia’s fossils were first discovered in the early 1900s, scientists wrote it off as a worm. But in the 1970s, Pikaia was reexamined. Scientists noticed that the rod running along its back resembled a backbone-like structure. Furthermore, the markings on the sides of its body were unusually shaped: they formed V-shapes (pointing towards the head). This zigzag shape is not seen in arthropod segments, but is the typical shape of chordate muscle bundles. Pikaia was probably a chordate — the same group that includes fish, dinosaurs, and humans!
As you can see, the fossil of a Pikaia is extremely similar to a Zebrafish embryo. They have the same body structure and shape. This can suggest that the zebrafish is a descendant from the ancient Pikaia.
Pikaia:
Click below for an animation interpretation on how Pikaia used to live under the water
Click below for a more detailed animation
[[http://www.phleschbubble.com/album/movies/pikaia.mov|]]
http://www.phleschbubble.com/album/pikaia.htm
Information
Pikaia gracilens is an extinct animal known from the Middle Cambrian and perhaps swam much like an fossil found near Mount Pika in the Burgess Shale of British Columbia. It was discovered by Charles Walcott and was first described by him in 1911. Based on the obvious and regular segmentation of the body, Walcott classified it as a Polychaete worm. It resembles a living chordate commonly known as the Lancelet eel.
During his re-examination of the Burgess Shale fauna in 1979, Paleontologist Simon Conway Morris placed P. gracilens in the making it perhaps the oldest known ancestor of modern vertebrates, because it seemed to have a very primitive, proto-chordates,notochord.
Averaging about 1 1/2 inches in length(5 cm), Pikaia swam above the seafloor using its body and an expanded tail fin. Pikaia may have filtered particles from the water as it swam along. Only 60 specimens have been found to date.
(information taken from Wikipedia: http://en.wikipedia.org/wiki/Pikaia)
When Pikaia’s fossils were first discovered in the early 1900s, scientists wrote it off as a worm. But in the 1970s, Pikaia was reexamined. Scientists noticed that the rod running along its back resembled a backbone-like structure. Furthermore, the markings on the sides of its body were unusually shaped: they formed V-shapes (pointing towards the head). This zigzag shape is not seen in arthropod segments, but is the typical shape of chordate muscle bundles. Pikaia was probably a chordate — the same group that includes fish, dinosaurs, and humans!
As you can see, the fossil of a Pikaia is extremely similar to a Zebrafish embryo. They have the same body structure and shape. This can suggest that the zebrafish is a descendant from the ancient Pikaia.
http://evolution.berkeley.edu/evolibrary/article/_0_0/cambrian_11
The Pikaia belogns to the Chordate family in the tress of life of the animal kingdom.
Click here to return to previous page