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Fossil sheds new light on sea-to-land transition
An illustration of Tiktaalik roseae, which looked like a cross between a crocodile and a fish. The species appeared to have used rear fins in the way limbs are used.
WASHINGTON - A 375-million-year-old fossil has shed new light on the theory of evolution, challenging the widespread view that large hind appendages first appeared after vertebrates transitioned from the water to land.
A report in the Proceedings Of The National Academy Of Sciences on Monday said the well-preserved pelvis and partial pelvic fin of a Tiktaalik roseae - which looked like a cross between a crocodile and a fish - indicated hind legs actually began as hind fins.
First discovered in 2004, Tiktaalik roseae are the best-known transitional species which bridged the leap between fish and land-dwelling tetrapods.
Studies of the species had previously indicated that the creature grew up to 2.7m in length and hunted in shallow freshwater environments. It was equipped with gills, scales and fins but also had tetrapod-like characteristics such as a mobile neck, ribcage and lungs. The species also had large forefins, with shoulders, elbows and partial wrists.
However, analysis of fossils recovered from a dig site in northern Canada in 2004 revealed a fuller picture of the hind quarters of the creature for the first time.
Scientists found a pelvic girdle, a prominent ball and socket hip joint and a highly mobile femur which extended beneath the body.
Said one of the report's co-authors, Dr Edward Daeschler: "Tiktaalik was a combination of primitive and advanced features...They appear to have used the fin in a way that's more suggestive of the way a limb gets used."
AGENCE FRANCE-PRESSE
An illustration of Tiktaalik roseae, which looked like a cross between a crocodile and a fish. The species appeared to have used rear fins in the way limbs are used.
WASHINGTON - A 375-million-year-old fossil has shed new light on the theory of evolution, challenging the widespread view that large hind appendages first appeared after vertebrates transitioned from the water to land.
A report in the Proceedings Of The National Academy Of Sciences on Monday said the well-preserved pelvis and partial pelvic fin of a Tiktaalik roseae - which looked like a cross between a crocodile and a fish - indicated hind legs actually began as hind fins.
First discovered in 2004, Tiktaalik roseae are the best-known transitional species which bridged the leap between fish and land-dwelling tetrapods.
Studies of the species had previously indicated that the creature grew up to 2.7m in length and hunted in shallow freshwater environments. It was equipped with gills, scales and fins but also had tetrapod-like characteristics such as a mobile neck, ribcage and lungs. The species also had large forefins, with shoulders, elbows and partial wrists.
However, analysis of fossils recovered from a dig site in northern Canada in 2004 revealed a fuller picture of the hind quarters of the creature for the first time.
Scientists found a pelvic girdle, a prominent ball and socket hip joint and a highly mobile femur which extended beneath the body.
Said one of the report's co-authors, Dr Edward Daeschler: "Tiktaalik was a combination of primitive and advanced features...They appear to have used the fin in a way that's more suggestive of the way a limb gets used."
AGENCE FRANCE-PRESSE
