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“Bizarre” fossil is thought to solve half-billion year old mystery

artist’s conception of Gyaltsenglossus /Emily S. Damstra. © Royal Ontario Museum

An “intermediate” fossil:

Despite being just two centimeters in length, the remarkably preserved soft tissues of the Gyaltsenglossus fossils reveal incredibly detailed anatomical structures. These details include the oval-shaped proboscis of acorn worms and a basket of feeding tentacles similar to those of pterobranchs. The age of these fossils, combined with the unique morphological combination of the two major hemichordate groups, makes this discovery a critical find for understanding early hemichordate evolution.

“An ancient animal with an intermediary anatomy between acorn worms and pterobranchs had been hypothesized before but this new animal is the clearest view of what the ancestral hemichordate may have looked like,” says Dr. Christopher Cameron, Associate Professor at the University of Montreal and a co-author on this study. “It’s exciting to have so many new anatomical details to help drive new hypotheses about hemichordate evolution.” …

In this particular case, Gyaltsenglossus suggests that the ancestral hemichordate may have been able to use the feeding strategies of both of the modern groups. Like acorn worms, the long proboscis may have been used to feed on nutrient-filled marine mud, while at the same time, and like the pterobranchs, the array of six feeding arms was probably used to grab suspended food particles directly from the water above where it was crawling.

Hemichordates belong to a major division of animal life called Deuterostomia, which includes chordates like fish and mammals, and not the division of animal life called Protostomia, that includes arthropods such as insects and annelids such as earthworms. Dr. Nanglu explains, when looking at Gyaltsenglossus, we’re actually looking at a very, very distant relative of our own branch of vertebrate and human evolution.

Royal Ontario Museum, “Early Cambrian fossil: Bizarre half-billion-year-old worm with tentacles solves evolutionary mystery” at ScienceDaily

Paper. (open access)

The importance of the controversy that is said to be settled now does not seem nearly as great as the significance of the Cambrian explosion itself.

That’s a pretty interesting point, I would assume they have a way of discerning the difference, Again I’m assuming but would there be a way to test that? AaronS1978
Looking at the pix of the fossils, I'm wondering if this is a combination of two animals mistakenly treated as one. If the tentacled critter was a habitual parasite or commensal on the worm critter, they'd often be seen together. Presumably the researchers have good reasons for treating it as one, but the history of fossil mysteries breeds caution on this point. polistra
It's a great find but it doesn't really settle any important questions about how all that diversity exploded suddenly. Perhaps the next great find will be of a life form with a completely different feeding strategy. More new information all the time. News
So how does this solve the mystery it sounds like this worm was better than both its Ancestors Second of all this really Explain why both feeding strategies even exist? Or if it truly is the origin of those feeding strategies? And how is this any more exciting than finding the platypus and pretending that a duck a marsupial and a beaver all evolved from this one animal AaronS1978

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