Skip to comments.Scientists Find Lamprey A 'Living Fossil': 360 Million-year-old Fish Hasn't Evolved Much
Posted on 10/26/2006 11:28:10 AM PDT by aculeus
Scientists from the University of Witwatersrand in Johannesburg, South Africa, and the University of Chicago have uncovered a remarkably well-preserved fossil lamprey from the Devonian period that reveals today's lampreys as "living fossils" since they have remained largely unaltered for 360 million years.
Scientists from the University of Witwatersrand in Johannesburg, South Africa, and the University of Chicago have uncovered a remarkably well-preserved fossil lamprey from the Devonian period that reveals today's lampreys as "living fossils" since they have remained largely unaltered for 360 million years. The scientists describe the new find in the article, "A lamprey from the Devonian of South Africa," to be published in the Oct. 26, 2006, issue of Nature. (Image courtesy of University of Chicago Medical Center) Chicago's Michael Coates, PhD, joined Witwatersrand's Bruce Rubidge, PhD, and graduate student and lead author Rob Gess to describe the new find in the article, "A lamprey from the Devonian of South Africa" to be published in the Oct. 26, 2006, issue of Nature.
"Apart from being the oldest fossil lamprey yet discovered, this fossil shows that lampreys have been parasitic for at least 360 million years," said Rubidge, director of the Bernard Price Institute for Palaeontological Research.
Lampreys are long, eel-like parasites that attach themselves to and feed on other fish. Of the 46,000 known species of vertebrates, lampreys and hagfish are the only surviving jawless vertebrates. Lampreys are the most "primitive" of the vertebrates, meaning that they are the least changed from the first vertebrates. Besides lacking jaws, lampreys have no paired pectoral and pelvic fins, and no scales.
"This fossil changes how we look at lampreys today," said Coates, associate professor of organismal biology and anatomy. "They're very ancient, very primitive animals, yet with highly specialized feeding habits."
It reveals that the anatomical evolution of lampreys is more conservative than scientists thought, Coates added. Although they've gotten slightly longer, they specialized early and successfully and thus appeared to have stayed much the same for the past 360 million years.
"This discovery is a monument to the dedication and passion of [Gess], who has spent many months patiently excavating and unearthing the elusive secrets from the prehistoric past," Rubidge said.
Gess found the new specimen, Priscomyzon riniensis, 18 months ago in an ancient estuary in Grahamstown, South Africa. Preserved showing the underside, the fossil measures less than 2 inches long and reveals a set of 14 teeth surrounding the mouth that is proportionately larger than its descendents today.
"The most striking feature of Priscomyzon is its large oral disc, edged with a soft outer lip, supported by an annular cartilage, and surrounding a circular mouth," the authors wrote. "This is the first clear evidence of a Palaeozoic lamprey with an oral disc."
According to the scientists, this find greatly adds to what was a severely limited lamprey fossil record and, for the first time, places the origin of modern lamprey morphology deep within the Palaeozoic period. It adds essential new detail to the emerging and changing picture of early vertebrate evolution.
Until now, the lamprey fossil record included only those that show a side view but reveal little of the gill basket and feeding apparatus. However, earlier this year, Nature reported on a freshwater lamprey fossil found in the Jehol biota of China (Inner Mongolia) from the Early Cretaceous period (about 125 million years ago).
The newly discovered South African fossil shows that these anatomically specialized fish are "holdovers" from ancient marine ecosystems, Coates said. Obviously exceptional survivors, these animals predate the advent of modern fish and have survived at least four major extinction events.
"There are few representatives of these early branches in vertebrate evolution that are still around today," Coates said, which is why so much scientific attention has been paid to lampreys. Although highly specialized in their own right, these primitive animals are used as surrogate ancestors for comparative research on living jawed vertebrates.
"It gives us a calibration point," Coates said. "We study lampreys because, in many respects, they're so primitive. They never had jaws, they never had [true] teeth, they never had fins, they never had limbs. Lampreys provide a glimpse of conditions early in vertebrate evolutionary history."
Because lampreys do not have bone or any substantial cartilage, they are extremely rare as fossils. This fossil not only reveals a nearly complete soft tissue impression, but it also pushes back their fossil record another 35 million years.
"These are pretty insubstantial animals," Coates said. "Lacking a boney skeleton, they rot down, leaving no hard parts, like a skull or ribs. So if a fossil site is discovered that yields impressions of the delicate remains of these animals, then this site needs to be explored thoroughly for other examples of exceptional preservation."
The scientists will continue to sort through much of the indeterminate material that is emerging from the ongoing dig.
Nearly 50 species of lampreys are found today in temperate rivers and coastal seas. Some species live in fresh water for their entire lives, but most are anadromous, hatching in fresh water, migrating to the ocean to grow and mature, and migrating back to fresh water to spawn and reproduce.
When adult lampreys return to fresh water, they stop feeding during winter and spawn the following spring. Eggs hatch after approximately three weeks and become blind larvae, called ammocoetes. After four to seven years, the ammocoetes metamorphose into juvenile lampreys called macropthalmia, which migrate out to the ocean and become parasitic adult lampreys, living just a year or two and growing up to 2 feet long.
Abundant in the Northeast United States, lampreys have a sucker-like mouth with a ring of cartilage that supports the rim of the mouth. It fastens on to a living fish with its teeth, rasps at the host's soft tissues with its piston-like tongue, produces strands of mucus to trap the food and feeds on the body fluids. A fish attacked by lampreys may be severely injured or even killed.
Copyright © 1995-2006 ScienceDaily LLC
"When all you have to do is suck off of someone else's resources, you don't have to evolve much."
Provided that said resources are always accessible by the equipment you have to access them.
"This also explains why liberals are still around."
On this, we are on the same page.
Gotta run. Thanks for the responses.
It's a chordate.
Only a few of an organisms genes specify its shape. Most of the genes control the detailed composition of proteins. There could have been wholesale changes at the cellular level, but you'd never know it from the fossil record.
That's not wild speculation, either. We observe such low-level divergence occurring in the real world, almost in realtime. Consider the wide variety of bacteria that exist in the world today, all sharing very similar morphologies. If you only knew the shapes, you'd never guess at the extreme variety.
The only really surprising result from this discovery is that an ecological niche has remained so stable for 360,000,000 years.
With the sun going down so early, I thought it was already 8:30.
Well wow. If I had known that I wouldn't have made my comments. NOT!!!
Oh, Lord have mercy! Every time I see that photo, I feel like throwing up. Please, someone---get that woman a burqa!
Ok, I'll warn you now so you can call me names ahead of time - I'm going to post and run, because I can't strand my son at school.
Here's my comment: I've seen in this thread the one common theme I've seen from all evolutionists - no matter what the fossil record shows, it supports evolution.
Think about it. All of these have been proposed on this one thread: 1) If there are changes, that must mean evolution. 2) If there are no changes, that must mean evolution. 3) If this branch didn't change, others must have, so that must mean evolution.
So: None of us were there, and the evidence is approached from a foregone conclusion. My conclusion just happens to be based on God, and whether any will admit it or not, He's better able to do the job than chance.
Flame away, but like I said, I gotta go.
You mean Gerry Garcia?
And, once again, I ask, where is the evidentiary links which support the contention that different species of animals "evolved" from completely different earlier species of animals? The Zoology course I took in college certainly didn't provide such evidence, and noone on any of the threads from FR has either. The most that biologists have been able to say is that they "think" that is what happended, not "we know that is what happened".
That's because the actual fossil records reflects a tree of life that has in fact evolved. Every physics experiment we do likewise supports the conservation of momentum, but that doesn't seem to bother you.
If there were events in the real world that violated evolution--say, a creature that was half mammal, half fish, or fossils occurring out of order in well-dated strata--then the theory evolution would conflict with the evidence. We don't see that in the real fossil record, however.
First of all, I'm not going to call you names. I find the pride and the name-calling more prevalent among the creationists, so I'll leave that to them.
Second, I would like to refine your comment slightly to reflect that state of things more accurately:
You said, "no matter what the fossil record shows, it supports evolution." That's probably how it appears to someone who is dead-set against evolution as a theory. A more accurate version of your statement would be, "short of divine intervention, the only thing that could explain the wide variety that we see in the fossil record would be a process based in evolution. However, since the fossil record is sketchy, we must continue to refine this theory as new data emerges." It's an exciting pursuit, because every once in a while it does get thrown a curve, and it forces the theorists to refine their suppositions and sometimes change them. The pursuit is for a cohesive theory that will account for the variety, and to do that, we must constantly start with the premise that evolution is involved, or else all we have left is divine intervention. Who knows? Maybe God was behind all of it. It's the mechanism that's fascinating.
I was hoping you'd elaborate on your thoughts. I shouldn't have expected as much.
Most people would have seen that my thoughts were very clear.
I hate lampreys. I hate lampreys (and I hate who posted those pictures.)
I hated lampreys from the first time I accidentally saw one in my high school biology book and screamed in class.
Hell is full of lampreys (and leftists. Or maybe I'm just being redundant about parasitic creatures with no backbones.)
Evolution needs to get its stories straight. Constantly revising is not an answer."
This isn't a revision. It's known, for example, that modern sharks have also remained largely unchanged for many millions of years.
"Only a few of an organisms genes specify its shape."
I'd have to just take your word on that, but I suspect it would be in a "this is science's best guess at this point" kind of declaration.
"Most of the genes control the detailed composition of proteins. There could have been wholesale changes at the cellular level, but you'd never know it from the fossil record."
But does this really amount to a hill of beans, when other creatures have changes radically, and wholesale, as one would assume they should. It would make more sense to me, in an evolutionary sense, if the lamprey were extinct or changed significantly. Would it not to you?
This makes the lampray very much more in tune with Earth's long term environment than any other vertebrates species. That, in Darwinian terms means they are the "fittest". All the others were "less fit" ~ that is, they were evolutionary failures!
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