Are they fossils of Ediacaran metazoa?

| 26 Comments

In Ediacaran roots extend deeper in time? Joe Meert described enigmatic fossil impressions that could be interpreted as Ediacaran metazoa (multi-celled animals) from strata some 100 million years older than previously known. Now Chris Nedin, a palaeontologist who has worked with Ediacaran and early Cambrian material, has a comprehensive post on his blog Ediacaran titled “770Ma Ediacara (?) Fossils from Kazakhstan (sadly no)”:

Two questions to be asked then. Are these deposits c. 770 million years old? Are these specimens examples of Ediacaran fossils?

I think the answer to the first question is yes, and the answer to the second question is no. I’ll explain below.

Leave comments here or there; Joe has already commented there.

26 Comments

I think I’ve spent too much time in the creationist mines. Seeing a civil, fact filled, discussion trying to ascertain a consensus based on the science was a pleasing surprise - when in fact it is the real standard that should be followed.

The personal attack filled screeds and fact obscuring/ignoring are the true outliers.

The personal attack filled screeds and fact obscuring/ignoring are the true outliers.

Sure, but they don’t go over my head the way that technical stuff can!

Wait, what am I saying?

Sponges and Corals are not metazoa and they are multi-celled animals (I apologize I over react to wrong definitions you were probably just simplifying it I guess).

William said:

Sponges and Corals are not metazoa and they are multi-celled animals (I apologize I over react to wrong definitions you were probably just simplifying it I guess).

Actually, coral and other cnidarians are (eu)metazoans, what with them displaying organized tissue systems and (radial) symmetry.

On the other tentacle, sponges, along with placozoans, are, as you state, multi-cellular animals. Placozoans being living sacs of tissue that creep around for a living, while sponges have “creeping around” on their to-do list.

Stanton said: Actually, coral and other cnidarians are (eu)metazoans, what with them displaying organized tissue systems and (radial) symmetry.

I was wondering about that myself – I thought metazoan was just a fancy term for “animal” – but I was gonna let the biosci pros respond on that.

And of course, sponges have a side job of helping people with housework.

Oh, I almost hate to bring up the old Steve Wright joke: “You know, sponges grow on the bottom of the ocean … did you ever wonder how much deeper it would be if they didn’t?”

The TOL web page http://tolweb.org/Animals/2374 uses “metazoa” as a synonym for “animal”. Is there some disagreement on that?

Henry J said:

The TOL web page http://tolweb.org/Animals/2374 uses “metazoa” as a synonym for “animal”. Is there some disagreement on that?

Well, “Parazoa” refers to sponges (and placozoa), and “Eumetazoa” refers to animals with defined tissue systems.

I guess plain-old “metazoa” is to distinguish true animals from animal-like protists, or “protozoa.”

Stanton said:

I guess plain-old “metazoa” is to distinguish true animals from animal-like protists, or “protozoa.”

Come to think of it, “metazoa” sounds to me like it refers to an intermediate level of organization. Where do we look to find the next level up, say “Euzoa”?

William said:

Sponges and Corals are not metazoa and they are multi-celled animals (I apologize I over react to wrong definitions you were probably just simplifying it I guess).

TOLWeb has both corals and sponges as metazoa.

Oops. Henry beat me to it: Read all the comments, RBH!

Joe Felsenstein said:

Stanton said:

I guess plain-old “metazoa” is to distinguish true animals from animal-like protists, or “protozoa.”

Come to think of it, “metazoa” sounds to me like it refers to an intermediate level of organization. Where do we look to find the next level up, say “Euzoa”?

Eumetazoa is split up into Radiata (which comprises of Cnidaria and Ctenophora), and Bilateria, which comprises of the arrowworms, a handful of arcane, insidiously microscopic animals, the superphylum Deuterostomia, and Protostomia, which may or may not be divided into separate superphyla (Ecdysozoa, Platyzoa and Lophotrochozoa). According to what I read on Wikipedia, the division of Protostomia into superphyla is rather contentious.

Stanton said:

Joe Felsenstein said:

Come to think of it, “metazoa” sounds to me like it refers to an intermediate level of organization. Where do we look to find the next level up, say “Euzoa”?

Eumetazoa is split up into

… [snip good information that is not relevant to my wise-ass comment]

According to what I read on Wikipedia, the division of Protostomia into superphyla is rather contentious.

Yeah, but those are all mere Metazoans. The name clearly implies there is more, and better! Where do we find them, and what do we call them?

;-)

Joe Felsenstein said:

Yeah, but those are all mere Metazoans. The name clearly implies there is more, and better! Where do we find them, and what do we call them?

;-)

“Betterzoa”?

If they’re too high-calorie, we could call them “Butterzoa”

Nah, “butterzoa” would have to refer to things like cows or goats.

Henry J said:

Nah, “butterzoa” would have to refer to things like cows or goats.

What about butterfish and butterflies?

I just looked up “meta-” and find that

Wikipedia: Meta- (from Greek: μετά = “after”, “beyond”, “with”, “adjacent”, “self”), is a prefix used in English (and other Greek-owing languages) to indicate a concept which is an abstraction from another concept, used to complete or add to the latter.

as opposed to “meso-” which is “middle” or “intermediate” which is probably what I was thinking of. So we need not expect to find more animals than the metazoa, at least if etymology is any guide. I’m relieved.

Of course there is a group, now somewhat called into question, called the “Mesozoa” but that is not the whole or even a big part, of the Metazoa,

Meta is the middle of ortho , meta, para. I know orthodox. and paradox,but what is the meaning of metadox?

Old Ari said:

Meta is the middle of ortho , meta, para. I know orthodox. and paradox,but what is the meaning of metadox?

Metadoxy means you get to make the rules that define meta/ortho/para… maybe.

From the older thread this creationist would point out a problem. First these fossils are from a single event in geology. The flood event. There was no glacial action during these events. no snowball earth. They only can claim glaciers based on simply scratchings in the rock. Yet in geomorphology these creations are better explained as from water carrying debris. no need to invoke glaciers. Thats a old wrong idea. Keep up with the times boys.

Robert Byers said:

From the older thread this creationist would point out a problem. First these fossils are from a single event in geology. The flood event. There was no glacial action during these events. no snowball earth. They only can claim glaciers based on simply scratchings in the rock. Yet in geomorphology these creations are better explained as from water carrying debris. no need to invoke glaciers. Thats a old wrong idea. Keep up with the times boys.

What problem? You assertions based on no facts at all mean nothing.

mrg said:

Oh, I almost hate to bring up the old Steve Wright joke: “You know, sponges grow on the bottom of the ocean … did you ever wonder how much deeper it would be if they didn’t?”

If fossil sponges first appear in the flood layers as Robert Byers seems to think, perhaps they were God’s answer to the problem of getting rid of the excess water.

Robert Byers said: *SNIP*

DNFTT

A pretty strong argument seems to have been made, albeit in a blog posting, that these fossils are not definitively Ediacaran metazoans. If both the age and the morphology of the fossils argue at least moderately against that, the best we can say is that we certainly can’t be confident that they are.

We are lucky to have any Ediacaran fossils at all.

Still, it is too bad that we will (presumably) never have any molecular genetic data about multicellular life forms from the Ediacaran. That might provide some fascinating insights into early multicellularity, the genetics of morphology, and so on. (With the caveat that current major, well-funded molecular, biochemical, and genetic studies tend to be very human- and mammal-centric, with a supporting role played by Drosophila, E. coli, Saccharomyces cerivisiae and some well-studied pathogens. Other than Drosophila, which was chosen early in the scientific era for convenience, all of the other non-mammalian models are microbes with some kind of a relationship to humans. Major food crops also get a fair amount of study, although agricultural research is less well-funded than biomedical research.)

Also, of course, Ediacarans are only the oldest multicellular forms known from preserved morphology. As I have seen pointed out in comments about both paleontology and archaeology, assuming that the oldest known example of something is necessarily the true oldest example is illogical. On the other hand, that doesn’t mean that markedly different ages for a well described phenomenon are likely to occur, either.

Dave Lovell said: … perhaps they were God’s answer to the problem of getting rid of the excess water.

“Where did all the water go after the Flood?” “The sponges soaked it up!” Works for me – after all, when I have a spill, I usually clean it up with a sponge.

About this Entry

This page contains a single entry by Richard B. Hoppe published on January 2, 2011 7:45 AM.

Jars to Stars was the previous entry in this blog.

NABT Molecular Insights videos available online is the next entry in this blog.

Find recent content on the main index or look in the archives to find all content.

Categories

Archives

Author Archives

Powered by Movable Type 4.361

Site Meter