Tiny sponge fossil upsets evolutionary model

Jul 9, 2015

by Phys.org

Researchers have unearthed a fossil of a sponge, no bigger than a grain of sand, that existed 60 million years earlier than many expected.

This is the first time paleontologists have found a convincing fossil sponge specimen that predates the Cambrian explosion—a 20-million-year phenomenon, beginning about 542 million years ago, when most major types of animal life appear.

New tools could allow scientists to discover other fossils that significantly predate the start of the Cambrian explosion, according to David Bottjer, professor of earth sciences, biological sciences and environmental studies and co-author of a study announcing the finding of the sponge in the Proceedings of the National Academy of Sciences.

“It’s easier to look at large fossils that don’t require high-tech instruments,” Bottjer said. “We’re analyzing very tiny things that require sophisticated microscopy, and we’re really just starting to look at this kind of evidence.”

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8 comments on “Tiny sponge fossil upsets evolutionary model

  • @OP link – “This specimen is of an animal that had already evolved a number of fundamental sponge traits,” Bottjer said. “It implies that by the time this animal was living, most of the developmental genes for sponges had evolved.”

    This raises the possibility that some aspects of early animals’ evolution, a good deal of which happened during the Cambrian explosion, happened even more gradually.

    With an international team of colleagues, Bottjer discovered that the millimeter-wide, 600-million-year-old fossil has characteristics that many thought emerged in sponges only 540 million years ago.

    “Fundamental traits in sponges were not suddenly appearing in the Cambrian Period, which is when many think these traits were evolving, but many million years earlier,” Bottjer said.

    It is very interesting that new technologies are finding earlier fossils of early multicellular or colonial animals, as this is shaking up some of the speculative sensationalised claims which have been made as new discoveries have been made.


    .Animal origins shift to comb jellies.
    Genetic data confirm the marine predators have more ancient origin than simpler sponges

    Complex marine creatures called comb jellies should replace brainless, gutless, simple sponges at the base of the evolutionary animal tree of life, a new report asserts.

    .Scientists have long assumed that the ancestor of all living animals vaguely resembled sponges. Now, biologists must reformulate hypotheses on the evolution of the first animals more than 550 million years ago. “This finding makes people very uncomfortable,” says Joseph Ryan, an evolutionary biologist at the National Human Genome Research Institute in Bethesda, Md., and lead author of the study in the Dec. 13 Science.

    This earlier dating of sponge-type animals, makes these claims for Comb Jellies questionable, but of course we do not know what other early forms, new technologies may discover!

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  • Good article but headings like this are really driving me nuts. I have been reading about speculation that Cambrian explosion may have just appeared to be an explosion because of the evolution of hard bodied organisms, and that the time frame of the Cambrian was not as much a explosion as was implied. The Cambrian explosion has been used by creationists as an “insert God here” argument against evolution. So the content of the article speaks directly against the title. I could get an editor trying to gain click bait in a popular magazine but in a science based publication can they not at least be precise?

    Probably just another pedantic rant on my part though.

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  • The focus on life sharpens yet further; notwithstanding our natural propensities for artistic creativeness, what human activity other than scientific inquiry can achieve such advancements as this?

    Mother science never sleeps; nonetheless: “We are such stuff as dreams are made on; and our little life is rounded with a sleep.”.

    So, for what it’s worth, my advice is accept the rough with the smooth and just get on with it.

    It’s great to be living at this time.

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  • Thanny
    Jul 9, 2015 at 6:57 pm

    Let’s hope this becomes just the tip of the iceberg, and the stupid Cambrian Explosion meme finally starts to die.

    The palaeontology of the Cambrian explosion is in the fossil record.
    It is only a “short period”, in terms of geological time scales.

    The Cambrian explosion, or less commonly Cambrian radiation, was the relatively short evolutionary event, beginning around 542 million years ago in the Cambrian Period, during which most major animal phyla appeared, as indicated by the fossil record. Lasting for about the next 20–25 million years, it resulted in the divergence of most modern metazoan phyla. Additionally, the event was accompanied by major diversification of other organisms.[note 1] Prior to the Cambrian explosion,[note 2] most organisms were simple, composed of individual cells occasionally organized into colonies. Over the following 70 to 80 million years, the rate of diversification accelerated by an order of magnitude[note 3] and the diversity of life began to resemble that of today.

    The YEC meme that 20 – 25million years “is too short a period for evolution to take place”, is simply a reflection of the YEC inability to understand evolution or deep time!
    25 million + years does not fit into 6,000 or 10,000 years, or a few days of “god-did-it”, but has probably been referred to as “short”, in the context of three billion years, by some geologist or fossil hunter, – thus facilitating YEC mindless cherry-picking or quote-mining of the word “short”!!

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