Armored Worms reveal hidden chapters in animal evolution

In a stunning reversal of misidentification for more than a century, researchers revealed that the fossil long believed to be a caterpillar, millipede or marine worm, is actually a fallen leaf, an ancient, gentle relative of modern arthropods. What is even more surprising is that it lives in fresh water, not in the ocean. This makes Anthrax The first well-known non-marine spotted leaf of all time and the youngest of its kind.

Fossils have been mistaken for 160 years

Originally described in 1865 from the Mazon Creek deposit in Illinois and Montceau-Mines in France, Gupapa Paleontologists have been plaguing for decades. But in a published new study Communication Biologya team led by Harvard-trained paleontologist Richard Knecht reclassified it as freshwater Lobo plants – a group of legs, worm-like creatures known primarily from Cambrian marine environments such as Burgess Senale.

Using advanced imaging and spectroscopy on more than 40 specimens in museum collections around the world, the team identified the characteristics of the Telltale Lobopodian: ten pairs of ring-shaped legs, head shields and dense coats of nearly 1,000 brain-type pricks, which are in symmetrical multiple forms. These thorns are twice the width of the human body, unlike anything seen in ocean relatives.

Chemically twisted spike

What settings Gupapa Not only its defensive armor, but also the chemical residues preserved at the tips of these thorns. Fourier conversion infrared spectroscopy (FTIR) shows that these tips have unique organic characteristics consistent with aldehydes, the common chemical deterrent used in modern invertebrates.

• The spines contain internal partitions and jagged ridges, indicating mechanical and chemical defenses
• FTIR analysis confirms unique chemical composition at the tip of the spine
• The tip of the spine may secrete toxic fluid under pressure

“This marks the first evidence of chemical defense in any leaf pedestal,” the author writes. He notes that toxins may not be injected, but passively secreted to cope with danger.

Freshwater life in coal forest

half Gupapa The fossils come from Montceau-Les-Mines, a tropical inland site surrounded by coal forests, with no evidence of ocean influence. The other half was found at Mazon Creek, which contains a mixture of land, freshwater and marine fossils. These suggestions Gupapa The freshwater habitat inhabited, which may be at least partly amphibious.

Its closest relative is Hadranax AugustusIt is a Cambrian from Greenland, lacking thorns and living in a deep-sea environment. This evolutionary gap (almost 200 million years) cannot determine the rarity and significance of the newly discovered.

Rewrite the story of falling leaves

The most famous leaflets are preserved in Cambrian marine sediments, leading scientists to think they are marine residents. but Gupapa Change the narrative. Its armored corpse, freshwater adaptation and chemical defense capabilities have begun to diversify into new ecological walls before it has begun to extinction.

This discovery was achieved through a reexamination of the fossils that had been stored in the museum for more than a century, emphasizing the enduring scientific value of the old collection. In Knecht’s words, “Sometimes, the biggest discovery is the discovery that is waiting to be seen again.”

Magazine: Communication Biology
doi: 10.1038/s42003-025-08483-0

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