A strange Cambrian fossil named Salterella may hold the key to understanding how early animals first built skeletons.
As the season of skeletons approaches, it’s worth remembering that the real “age of skeletons” began hundreds of millions of years ago during the early Cambrian Period, roughly 538 to 506 million years in the past.
During this transformative era, most major animal groups developed their own ways of creating mineralized skeletons or shells. These structures typically formed in one of two ways: some organisms built mineral tissues on an organic framework (similar to how humans grow bones and teeth), while others collected minerals from their surroundings and bonded them together to form protective coverings.
Once those techniques evolved, they endured for more than 540 million years. After all, as the saying goes, “if it ain’t broke…”
Among the few exceptions to this long-standing pattern is Salterella, a small organism that flourished during the early Cambrian. Its fossils are so abundant in rocks from that period that scientists use them as index fossils to identify and date geological layers.
Salterella bucked the “either-or” trend by growing a conical shell around its body and then packing the shell’s cavity full of carefully selected minerals to form a snug inner lining. Scientists have rarely observed this type of doubling up in any other animal group.
“It makes Salterella difficult to place on the tree of life,” said Prescott Vayda, a geosciences graduate student who authored a study of the enigmatic Salterella published in the Journal of Paleontology.
A Fossil with an Identity Crisis
Scientists first classified Salterella with squids and octopuses, said Vayda. Then they were categorized with creatures closely related to sea slugs. Later, they were grouped with ancestors of jellyfish. Then with worms. Finally, in the 1970s, a researcher created a new classification for Salterella, along with a slightly older fossil with similar construction called Volborthella.
And there they languished, disconnected and misunderstood.
Until Vayda, working with University Distinguished Professor Shuhai Xiao, started tracking down connections.
“Finding the right place for these fossils is important for our understanding of how animals evolved skeletons and shells,” Vayda said.
Vayda spent the past four years collecting fossil samples from places such as Death Valley and Yukon, Canada, as well as from much closer to home in Wythe County, Virginia.
Working with colleagues at Virginia Tech, Johns Hopkins University, Dartmouth College, the University of Missouri, and the Denver Museum of Nature and Science, he studied the shape, mineral composition, and crystal structure of these organisms in hopes of finding them a context.
A Selective Builder
Salterella was a scrappy creature, as Vayda found, but was selective about its building materials.
No clays, for instance, ew. Quartz was acceptable, but not ideal. Titanium was choice, of course. Who wouldn’t like a Titanium skeleton?
The variety of minerals selected led researchers to believe that the internal structure served a distinct purpose, likely something to do with feeding or enhanced stability. The findings also imply that the creatures must have had some sort of appendage to pick and grab.
“We’re starting to get an image of their biology and where they fit in the larger web of life,” Vayda said.
Based on the combined evidence of morphology, ecology, and shell structure, the research team suggested that Volborthella and Salterella belong with cnidarians, a group made up of more than 9,000 living species, including corals, jellyfish, and sea anemones.
Reconnecting this unique and long missing fragment of evolutionary lineage may lead to new answers about why and how creatures formed shells and skeletons.
And for Vayda? It’s all about “truly learning where we come from and the history of life on Earth, which is an amazing and beautiful thing.”
Reference: “A Cnidarian affinity for Salterella and Volborthella: implications for the evolution of shells” by Prescott J. Vayda, Shuhai Xiao, Noah D. Keller, Amy P. I. Hagen, Justin V. Strauss, James W. Hagadorn, Mary C. Lonsdale, Tara Selly and James D. Schiffbauer, 13 October 2025, Journal of Paleontology.
DOI: 10.1017/jpa.2025.10164
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25 Comments
The master treatise on the emergence of Phyla is surely James Valentine’s ON THE ORIGIN OF PHYLA (University of Chicago Press, 2004, (xxiv + 614 pp.)
I read in a book, “your inner fish” which substantiates the theory of evolution very concisely and simply from the perspective of Anatomy, Geology, the Fossil record, and Biology, that the first bones to develop were actually teeth. Even the first hard skull was made entirely of teeth merging together to form a protective layer around the brain.
An excellent book. I’ve not only read it but studied parts of it. I especially liked how he went about discovering a missing evolutionary link.
Totally absurd. Impossible chemically, biologically, mathematically. Suckers
What’s confusing is why you get comments from Luddites who claim the Earth and Sun and universe formed 6,000 years ago, and that “evidence” (a term they completely misunderstand but believe they do) confirms unattested, unvideotaped, unphotographed, bizarre and magical claims about the likes of Jesus and his claimed magical powers. Such claims can never be investigated because there is no scientific evidence of them! It’s all hearsay and wishful thinking.
If religion believers would study and understand the scientific method, they would realize those magical claims about magical powers are completely unfounded. Simply no basis for them, and certainly none that could be investigated or studied or analyzed.
It looks like a bunch of shells. I doubt VERY much if it is even 7,000 years old. Salty shells. I’m so sure that they prove there wasn’t a global flood!
Hate science much?
But it was .
The fossils are real. Jesus is just a myth.
Jesus is a historical figure with more historical evidence than ANY ancient person.
As anyone can observe, your personal chosen myth text person remains a myth with absolutely no evidence outside those texts.
This is a boring topic: the universe is now known to be produced by an entirely natural process of space expansion, which fact killed my interest in your magic agency myths.
It is also of dubious morals to inject science sites with this falsehood.
As anyone can observe, your personal chosen myth text person remains a myth with absolutely no evidence outside those texts.
This is a boring topic: the universe is now known to be produced by an entirely natural process of space expansion.
I note that you in other comments impose magic ritual stuff.
The evidence shows that Jesus existed, but there is no proof of his magical powers. It’s delusional to believe everything a 3-year-old would, with NO SCIENTIFIC evidence, only claims available by ancient texts which are hearsay written comments, not valid scientifically – – which is obvious if you learn the scientific method.. Presumably you are older than that??
What part of your “historical evidence” claimed re: Jesus is scientifically repeatable, and verifiable?
It does seem clear that a now-highly-esteemed person named Jesus who preached selflessness did exist about 2,000 years ago in the Middle East, but really that’s almost all that can be said about him (or her??) as far as evidence for his accomplishments.
Since you seem to know so much about what evidence consists of, you must know that only relying on something merely written as an unverifiable claim by someone 2,000 years ago does NOT count as scientifically reliable, verifiable evidence, don’t you??
What exactly do you think is scientific about the evidence you know about?
/s? If so, you are teasing the magic believers into tedious action.
Are your doubts founded in the scientific method? And there is nothing said in this article about a 7,000 year old flood, that would be a completely different investigation, proof of which could be found in the geologic record if it occurred, using scientific methods which are verifiable and repeatable by anyone with the skills and necessary equipment. Since you’re commenting here should I presume you are familiar with the scientific method, or are you voicing arrogant views out of ignorance?
Your comment looks like those from Luddites who claim the Earth and Sun and universe formed mere thousands of years ago, and that “evidence” (a term they completely misunderstand but believe they do) “confirms” their unattested, unvideotaped, unphotographed, bizarre and magical claims about the likes of Jesus and his claimed magical powers.
FACT: Such claims can never be investigated because there is no scientific evidence of them! It’s all hearsay and wishful thinking.
If religion believers would study and understand the scientific method, they would realize those claims about magical powers are completely unfounded. Simply no basis for them, certainly none that could be investigated or studied or analyzed by modern science, which is incredibly technically adept at finding out facts about the natural world. The bases of all religions have no relationship to scientific facts, only “shock and awe”-type claims possibly intentionally crafted to break readers (or listeners in the centuries before widespread literacy) out of their cramped medieval mentality into a different medieval mentality bereft of grounding in demonstrable and verifiable reality.
The fossils are real. Jesus is just a myth.
No; probably a real bloke who simply challenged the teachings of his church. And got his undue come-uppance from the mob.
A very common story.
Jesus Christ died on the cross for your sins and mine. He fulfilled the prophecies of the old testament. He rose again 3 days later, just as He said He would.
As someone who had been brainwashed to believe it’s not real, it’s just a story, never happened. They were wrong! So wrong. Praise Jesus, it’s not just a story. It’s true🩷✝️ it’s true.
Wow delusional
Jesus Christ died on the cross for your sins and mine. He fulfilled the prophecies of the old testament. He rose again 3 days later, just as He said He would.
As someone who had been brainwashed to believe it’s not real, it’s just a story, never happened. They were wrong! So wrong. Praise Jesus, it’s not just a story. It’s true🩷✝️ it’s true.
An excellent summary in the paper:
” First, morphological similarities in the aperture divergence angle and ratio of central tube diameter to agglutinated layer thickness suggest Salterella and Volborthella are related. Second, both fossils exhibit agglutinated grain compositions that are distinctive from their surrounding environments and demonstrate selectivity on the part of their producers. Finally, the calcitic shell composition and simple layers of blocky prismatic shell microstructure in Salterella suggest a possible cnidarian affinity.”
And an interesting conclusion:
“Skeleton-building cnidarians are relatively rare in the Cambrian (Leme et al., Reference Leme, Van Iten and Simões2022); from their known fossil record, they do not flourish until the Ordovician (Savarese et al., Reference Savarese, Mount, Sorauf and Bucklin1993; Baars et al., Reference Baars, Pour and Atwoods2013; Elias et al., Reference Elias, Lee and Pratt2020). However, numerous cnidarian taxa are well documented from the early Cambrian, including many conical forms (Chang et al., Reference Chang, Clausen, Zhang, Feng, Steiner, Bottjer, Zhang and Shi2018; Sun et al., Reference Sun, Zhao and Zhu2022; Qu et al., Reference Qu, Li and Ou2023; Zhao et al., Reference Zhao, Parry, Vinther, Dunn, Li, Wei, Hou and Cong2023), many of which are nonbiomineralized. This phylogenetic assignment supports the notion that cnidarians had the capability to both biomineralize and agglutinate a shell since the Cambrian, and thus similar behaviors observed in modern cnidarians may be deeply ancestral. The transition from an organic outer sheath like that of Volborthella to a biomineralized shell like that of Salterella, is potentially coincident with a shift from aragonite seas to calcite seas in the early Cambrian (Wei et al., Reference Wei, Hood, Planavsky, Li, Ling and Tarhan2022; Xiong et al., Reference Xiong, Wood and Pichevin2023), lending support to the hypothesis that this shift in ocean chemistry played a key role in the development of biomineralization in many early animals (Porter, Reference Porter2010).”
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