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Will a 333-Million-Year-Old Bone Change Our Perspective on Evolution?

The origin of terrestrial tetrapods was a key event in vertebrate evolution, yet how and when it occurred remains obscure due to scarce fossil evidence. (Image: Via North Queensland Register)
The origin of terrestrial tetrapods was a key event in vertebrate evolution, yet how and when it occurred remains obscure due to scarce fossil evidence. (Image: Via North Queensland Register)

How much do we really know about evolution? It seems over the last few years there have been more and more findings that disprove how we got to where we are.

A 333-million-year-old broken bone is causing fossil scientists to reconsider the evolution of land-dwelling vertebrate animals, says a team of palaeontologists, including QUT evolutionary biologist Dr. Matthew Phillips, and colleagues at Monash University and Queensland Museum, wrote the Queensland University of Technology (QUT).

According to QUT, Analysis of a fractured and partially healed radius (front-leg bone) from Ossinodus pueri, a large, primitive, four-legged (tetrapod), salamander-like animal found in Queensland pushes back the date for the origin of demonstrably terrestrial vertebrates by 2 million years, said Dr. Phillips, a researcher in the Vertebrate Evolution Group at QUT’s School of Earth, Environmental and Biological Sciences.

“Its age raises the possibility that the first animals to emerge from the water to live on land were large tetrapods in Gondwana in the southern hemisphere, rather than smaller species in Europe, Dr Phillips said, who is the lead author of the study published in PLOS One.

“The evolution of land-dwelling tetrapods from fish is a pivotal phase in the history of vertebrates because it called for huge physical changes, such as weight-bearing skeletons and dependence on air-breathing.”

Dr. Phillips told the North Queensland Register: “The break was most plausibly caused by a fall on land because such force would be difficult to achieve with the cushioning effect of water.”

The researchers had found two more features that provide evidence the tetrapod had spent substantial time on land.

“The internal bone structure was consistent with remodeling during life in accordance with forces generated by walking on land,” and “evidence of blood vessels that enter the bone at low angles, potentially reducing stress concentrations in bones supporting body weight on land.”

The more man looks for answers, the more questions we find. Will we ever find the proof we are looking for? Most likely not.

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