Color Vision Discovered in 300 Mya Fish

According to Dr. Gengo Tanaka, the fossil below was found about 50 years ago.

“I have a friend [who owns a] fossil shop,” he wrote in an email. “I bought this specimen from him.”

Dr. Tanaka explained that his friend attributed the fossil find to his father, who discovered it in a quarry five decades ago.

It’s a small fish known as Acanthodes bridge, and it is thought to have lived in shallow waters 300 million years ago in what is now Kansas.

 

Acanthodes bridge - Tanaka, et al

[image of fossilized Acanthodes bridge, courtesy of the Natural History Museum, London]

 

It might be a little fish, but it is providing enormous and exciting information about the evolution of color vision.

In their recent paper, Dr. Gengo Tanaka of Kumamoto UniversityProfessor Andrew Parker of the Natural History Museum, London and 13 other scientists describe evidence of color vision 100 million years earlier than previously known.  They are the first to record fossil rods and cones—the cells responsible for enabling sight.

“The soft tissue of eyes are usually the first to decompose when an animal dies, and before they are fossilized. In our fish, however,” wrote Professor Parker,  “the soft tissue was preserved before burial (by sediment) and turning to rock. The original organic material has been altered (but in some cases not too much), although remains relatively soft.”

Using SEM (scanning electron microscope) and TEM (transmission electron microscopy), the scientists studied the fossil eyes in more depth.  They compared rods and cones of 509 retinal cells, obtained from the fossil itself and from existing freshwater fish.  Cones within the eye are the key to color vision, although they assert that the discovery of opsins in the fossil record would provide “conclusive evidence” for such vision.

“Cone cells are those responsible for colour vision in extant animals,” Professor Parker further explained. “They contain the opsins that react to different wavelengths of light.”

When asked if he expected to find color vision in this fossil, Dr. Tanaka wrote, “I have discovered fossilized rod and cones in several Cenozoic fishes. So, I expected that we could discover fossilized rod and cone cells in other specimens.”

Similarly, Professor Parker wrote, “I would expect to find colour vision in the geological record at some point, but I did not expect when.”

Acanthodes bridge - eye detail

 

[details of Acanthodes bridge, courtesy of the Natural History Museum, London; a: Complete dorsoventrally compressed specimen, b: details of the head region, c: details of right eye]

“We were a team interested in the emergence and history of vision, when Gengo [Tanaka] found the fossil fish,” he continued, describing how it came to pass that these 15 scientists collaborated on the paper.

But why would color vision be significant for a species such as Acanthodes bridge?

“That such ancient fish had colour vision tells us that the type of ecologies and behaviours that exist today, where light plays a major role, were also in place 300 million years ago. For the fish, they could distinguish predators and prey with greater accuracy and in some cases crack the camouflage of these animals.”

“This is the first time that colour vision has been identified in any extinct animal, regardless of geological age,” he wrote. “It suggests that our modern behavioural system, or way of living, where colour plays a major role, has been in place over at least 300 million years.”

“This can explain,” he continued, “why things have changed little over that period: predators and prey have changed form in some ways, but the balance of the different types of animals and plants living together has remained similar.  Triceratops has been replaced with rhinos, ichthyosaurs replaced by dolphins, but their roles in the ecosystem are similar. That they saw in the same way helps us to understand this.”

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An enormous thank you to Chloe Kemberry, Dr. Gengo Tanaka and Dr. Andrew Parker!  What a great pleasure connecting with you about such an exciting discovery!

Paper referenced:

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Recent mammoth-related news and what is coming up next on this blog

Recent mammoth-related buzz in the news:

1. A paper in the journal Nature proposes that the diet of woolly mammoths (and other herbivores of that time) may have caused their extinction:
Fifty thousand years of Arctic vegetation and megafaunal diet:

http://www.nature.com/nature/journal/v506/n7486/full/nature12921.html

http://www.npr.org/blogs/thesalt/2014/02/05/272094425/woolly-mammoths-taste-for-flowers-may-have-been-their-undoing

Not all paleontologists agree.  As noted in the NPR post above, at least one does not:

Daniel Fisher, a paleontologist at the University of Michigan, says the new work…does show that both vanished around the same time. But he also studies mammoth poop. And it makes great fertilizer. So maybe it was the other way around: the flowers needed the mammoths’ poop to grow, so when the mammoths started to disappear …

“It becomes difficult to sort out what part of it is cause, and what part of it is effect,” Fisher says. He also points out that present-day elephants can survive just fine on grass and shrubs.

2. A large mammoth tusk was discovered at a construction site in Seattle, WA.  The landowner very generously donated this to the Burke Museum:

 https://www.burkemuseum.org/info/press_browse/SLU_mammoth_PR

http://www.seattlepi.com/local/komo/article/Construction-crew-finds-ancient-mammoth-tusk-in-5226137.php

3. Members of a family in Wichita, KS found a mammoth bone in the Arkansas River:

http://www.kansas.com/2014/02/23/3307661/wichita-family-finds-bone-from.html

4. An article in the New York Times describes in depth the possibility of recreating a mammoth:

**Many thanks to Ellen G., who was the first to let me know about this article, and to Ron G., who was among the others who did!

5.   A new paper suggests that mammoths were not stampeded over cliffs by Neanderthals at La Cotte de St. Brelade in Jersey (an island off of the coast of France):

A new view from La Cotte de St Brelade, Jersey:

http://antiquity.ac.uk/ant/088/ant0880013.htm

http://www.theguardian.com/science/2014/feb/28/neanderthals-driving-mammoths-cliff-jersey

From the article above:

Researchers have found that the plateau that ends at the cliff edge was so rocky and uneven that mammoths and other weighty beasts would never have ventured up there. Even if the creatures had clambered so high, the Neanderthals would have had to chase them down a steep dip and back up the other side long before the animals reached the cliff edge and plunged to their doom.

“I can’t imagine a way in which Neanderthals would have been able to force mammoths down this slope and then up again before they even got to the edge of the headland,” said Beccy Scott, an archaeologist at the British Museum. “And they’re unlikely to have got up there in the first place.”

Coming up in the near future on Mostly Mammoths, Mummies and Museums:

1.  A discussion with Asier Larramendi and Rubén Molina about research, paleoart, science and their exciting company, Eofauna: http://eofauna.com/en

2. An interview with paleontologist, Ronald Richards, about the fascinating mastodon and mammoth exhibit currently available at the Indiana State Museum:  http://www.indianamuseum.org/

3. A look at the 6th International Conference on Mammoths and their Relatives–this year in Greece–with PhD student, Evangelos Vlachos, who is one of the organizers of the event: http://www.mammothconference.com/