vacantlook
04-02-2004, 12:24 PM
Fossil Arm Bone Reveals First Walkers
http://dsc.discovery.com/news/afp/20040329/gallery/armbone_zoom.jpg
April 2, 2004 — An ancient fossil revealed that early fish did not grow legs to colonize the land as previously thought, but to prop themselves up underwater 370 million years ago, according to scientists.
The fossil of a Devonian-era tetrapod's arm bone, discovered in Pennsylvania, reflects an intermediate stage in the evolution of sea creatures to land, according to an article in the journal Science.
The humerus suggests that the first limbs evolved on fish to hold themselves up and to raise their heads, characteristics of land animals, according to study leader Neil Shubin of the University of Chicago.
Fish with such limbs lived in slow, shallow rivers well before vertebrates walked onto land, the study said.
The unique form of the fossil suggests the variety was among the earliest animals who could explain the mysterious footprints seen on some river beds, said the study.
The transition of animals from water to land happened in the Devonian, 360 to 370 million years ago.
In an accompanying article, Jennifer Clack of the University Museum of Zoology in Cambridge, U.K., wrote: "From this humerus, the investigators infer some of the anatomical and functional changes that took place in the tetrapod lineage during the Devonian era, and these changes in turn suggest some possible routes by which terrestriality was attained."
Source Link (http://dsc.discovery.com/news/afp/20040329/armbone.html)
http://dsc.discovery.com/news/afp/20040329/gallery/armbone_zoom.jpg
April 2, 2004 — An ancient fossil revealed that early fish did not grow legs to colonize the land as previously thought, but to prop themselves up underwater 370 million years ago, according to scientists.
The fossil of a Devonian-era tetrapod's arm bone, discovered in Pennsylvania, reflects an intermediate stage in the evolution of sea creatures to land, according to an article in the journal Science.
The humerus suggests that the first limbs evolved on fish to hold themselves up and to raise their heads, characteristics of land animals, according to study leader Neil Shubin of the University of Chicago.
Fish with such limbs lived in slow, shallow rivers well before vertebrates walked onto land, the study said.
The unique form of the fossil suggests the variety was among the earliest animals who could explain the mysterious footprints seen on some river beds, said the study.
The transition of animals from water to land happened in the Devonian, 360 to 370 million years ago.
In an accompanying article, Jennifer Clack of the University Museum of Zoology in Cambridge, U.K., wrote: "From this humerus, the investigators infer some of the anatomical and functional changes that took place in the tetrapod lineage during the Devonian era, and these changes in turn suggest some possible routes by which terrestriality was attained."
Source Link (http://dsc.discovery.com/news/afp/20040329/armbone.html)