fossils

Early legs not as diverse as thought

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Franz
Anthony

Editor and Artist
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Julio
Lacerda

Staff Artist and Writer
The limbs of the earliest four-legged vertebrates from 360 million years ago were not as structurally diverse as previously thought.

As stated by Dr Marcello Ruta from the University of Lincoln and Professor Matthew Wills from the University of Bath, the diversity of fish and early tetrapods limbs were equally subtle, despite the vast differences of their overall body plan. It was previously believed that the evolution of early vertebrates with legs – collectively known as tetrapods – also increased the diversity of anatomy within the group.

This is a common assumption about evolution, which states that new features tend to trigger the rapid diversification and anatomical experimentation to fill the previously empty niches. In the case of early tetrapods, this relates to the possibilities of life on land.

According to Wills, legs had to fulfil two new functions: supporting the weight of the animal on land, and helping them to navigate the terrain. This dual requirement likely restrained the variability of early legs, limiting the possibilities of forms they could take.

This finding challenges the long-accepted notion about evolution, which may be crucial to understand other major diversification events. Such an event is also expected to have happened in the early appearance of birds, for example.

Original findings published at Phys.org.

8e6ac47821297aeee8c843e680637dca

Franz
Anthony

Editor and Artist


http://sulc.us/n6sbv
http://www.eartharchives.org/articles/evolutionary-leap-from-fins-to-legs-was-surprisingly-simple/