Research shows Jaws didn't kill his cousin

Research shows Jaws didn't kill his cousin
A fossil of a jawless fish. Credit: Emma Randle, University of Manchester

New research suggests our jawed ancestors weren't responsible for the demise of their jawless cousins as had been assumed. Instead Dr Robert Sansom from The University of Manchester believes rising sea levels are more likely to blame. His research has been published in the journal Proceedings of the Royal Society B.

He says: "When our jawed vertebrate ancestors overtook their jawless relatives 400 million years ago, it seems that it might not have been through direct competition but instead the inability of our jawless cousins to adapt to changing environmental conditions."

In this research, Dr Sansom, PhD student Emma Randle and Phil Donoghue from the University of Bristol studied the patterns of diversity of fossil . These boney fish with a tank like construction (ostracoderms) were dominant and diverse in ancient seas. The team found that patterns of ostracoderm diversity were correlated with changing environmental and geological conditions; the fish were strongly reliant on the availability of shallow water seas and ecosystems.

Dr Sansom says: "Our research suggests the dependence of these armoured fish on shallow environments is likely to be a factor behind their demise and eventual extinction in the Devonian period when sea levels rose."

The findings also suggest the jawless could have existed earlier than previously thought.

Dr Sansom explains: "Understanding the relationship between biodiversity and changing conditions at this time reveals a long missing fossil record for our jawless cousins. It is possible that they could have radiated and evolved up to 20 million years before their first known occurrences as fossils."

He continues: "As such, using biological and geological data helps us understand an important evolutionary event and reconstruct our own origins as ."


Explore further

Unusual anal fin offers new insight into evolution

More information: "Discriminating Signal from noise in the fossil record of early vertebrates reveals cryptic evolutionary history" Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2014.2245
Citation: Research shows Jaws didn't kill his cousin (2014, December 16) retrieved 20 June 2019 from https://phys.org/news/2014-12-jaws-didnt-cousin.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
0 shares

Feedback to editors

User comments

Dec 16, 2014
SO we know that many times in past the sea level went up and down for meters!
We also know for sure the the temperature also has been higher and lower (for much more than the cataclysmic ones predicted today).
However, now it is a by product of human activities that are doing this terrible damage to the planet that we were not able to witness a thing.
And then I am tagged as "denier" a derogatory term associated to with the ones that deny holocaust.
Great science!

Dec 17, 2014
@wasp

"When our jawed vertebrate ancestors overtook their jawless relatives 400 million years ago--"

The earth of 400 million years ago was a very different place than the earth of the last few million years. Pay attention.

Dec 17, 2014
@ Vitvet
I am a geologist, with MSc and a PhD in Australia.
Just 60000 years go when (supposedly) the first humans arrived in Australia Fraser island (I bet you never heard about it! It is the largest sandy island in the world) was underneath the sea level.
So what are you trying to say when you cite "last few million years"?
During the last few million years the sea has gone up and down and many glaciation have occurred therefore the temperature as oscillated quite dramatically as well.
So, make your point!
Or READ more about the last "few" million years...

Dec 17, 2014
@wasp171

Reviewing your comments on other threads it is hard to believe you have the education you claim. The article is about what was happening circa 400 million years ago. Wouldn't you agree the earth was a much different then?

Dec 17, 2014
Well i've certainly heard of Fraser Island, lived in Maryborough 40 years ago and spent lots of time on the place over many years. It isn't even a million years old and it was connected to the mainland until the seas rose after the last ice age i.e. it wasn't under the sea when humans arrived but part of the coastline.

Dec 17, 2014
I wonder if vibratory resonance could active a dormant dna and produce jawlessness?
The difference between krill and shrimp is jaws.
The Ancient Chinese have lion statues without jaws. Where would that idea come from?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more