Rosa Rubicondior: Refuting Creationism - A Star Is Born - And Rewrites The Story Of The Origin Of Starfish

Monday, 21 September 2026

Refuting Creationism - A Star Is Born - And Rewrites The Story Of The Origin Of Starfish

Artist's impression of Yujingia glutenotunica

Credit: Kaiyue He, et al

A star is born: half billion-year-old fossil rewrites the origin story of starfish | University of Cambridge

One of creationism’s favourite misrepresentations of the fossil record, promulgated By Stephen S. Mayer of the Discovery Institute, is that the Cambrian ‘explosion’ was a sudden creation event, when the major animal groups appeared without evolutionary ancestors, already equipped with their modern body plans. This depends on treating ‘rapid’ in the geological sense as ‘instantaneous’, and overlooking the transitional fossils that reveal how those body plans evolved. A newly described animal from China provides another awkward example for that narrative. And of course the existence of transition fossils themselves are a major problem for creationists who insist that they don't exist because their creation myth can't accommodate them.

Named Yujingia glutenotunica, this small, soft-bodied creature lived approximately 518 million years ago. As described by Kaiyue He and colleagues in their paper in Current Biology, its combination of anatomical features places it close to the common ancestor of two groups that now look remarkably different: the echinoderms, including starfish and sea urchins, and the hemichordates, including acorn worms. Together, these constitute the animal group known as Ambulacraria.

The fossils preserve a digestive tract and feather-like feeding tentacles, together with another set of appendages that may have anchored the animal to the seabed. Crucially, Yujingia possessed an elaborate feeding apparatus without a mineralised skeleton. Its anatomy therefore supports the evolutionary interpretation that specialised feeding structures preceded some of the defining features of later echinoderms.
This is what makes transitional fossils so informative. They need not resemble an animal caught halfway through changing into a modern species, nor must they be demonstrably the direct ancestors of anything alive today. They preserve combinations of characteristics that help scientists reconstruct the order in which evolutionary changes occurred. A fully functioning animal can be transitional in its anatomy: ‘transitional’ describes its relationship to other forms, not an inability to survive until evolution has finished building it.

There is an important distinction here between finding a fossil close to a common ancestor and identifying that ancestor itself. Yujingia’s position is an inference from comparisons of anatomical characters, and further discoveries may refine it. Nevertheless, the interpretation offers precisely the sort of connection that the creationist account says should not exist: an early animal combining features that help explain the emergence of markedly different descendant body plans.

The Cambrian fossil record is therefore doing something rather inconvenient for advocates of sudden creation. As its gaps are filled, it reveals more of the evolutionary history behind the major animal groups. Modern categories become less sharply separated when their early relatives are included, because the features used to distinguish those categories did not all arise together. What creationists present as the abrupt appearance of finished designs increasingly resolves into a history of branching lineages and anatomical changes — without any need to insert a magical creation event.

Transitional fossils^ some of the forms creationists say do not exist. A transitional fossil preserves a combination of ancestral characteristics and features associated with a later evolutionary group. It need not be a direct ancestor of a living species: a close relative on a neighbouring branch can also reveal how an anatomical transition occurred. Every such animal was a functioning organism, adapted to its own circumstances.

The following examples document several major transitions. Dates are approximate and indicate when the animals lived, not necessarily when the relevant features first evolved.

Yujingia glutenotunica — early ambulacrarian evolution, about 518 million years ago.
This Cambrian animal combined a soft body with sophisticated feather-like feeding tentacles, but lacked a mineralised skeleton. Anatomical analysis places it near the common ancestor of echinoderms and hemichordates, suggesting that specialised feeding structures evolved before some characteristic echinoderm features. Its precise position remains a phylogenetic inference, rather than proof that it was the direct ancestor of either group. Research paper.

Tiktaalik roseae — the transition from fins to limbs, about 375 million years ago.
Tiktaalik retained scales and fin rays while possessing a mobile neck, a flattened skull and limb-like bones and joints within its pectoral fins. It shows how parts of the skeletal equipment subsequently used by land vertebrates existed in an animal that still had fins. It was not a modern fish suddenly sprouting a complete terrestrial leg. Background: the origin of tetrapods.

Acanthostega — limbs with digits before effective walking on land, about 365 million years ago.
This early limbed vertebrate had eight digits on each hand, yet retained internal gills and a finned tail. Its anatomy indicates a predominantly aquatic animal. Together with other Devonian fossils, it demonstrates that digits and limbs evolved before the full package of adaptations needed for terrestrial walking. Background: aquatic origins of tetrapod anatomy.

Morganucodon — the mammalian jaw and middle-ear transition, around 200 million years ago.
This early mammaliaform possessed the mammalian dentary–squamosal jaw joint while retaining the ancestral articular–quadrate joint. That double articulation illustrates an intermediate arrangement in the transition during which bones formerly involved in the jaw became the hammer and anvil of the mammalian middle ear. The broader fossil sequence documents changes in the size, position and function of these bones. Background: jaws to ears.

Odontochelys semitestacea — the assembly of the turtle shell, about 220 million years ago.
Odontochelys had a well-developed underside shell, or plastron, but lacked a complete upper shell, or carapace. It also retained teeth. Its combination of expanded ribs, partial shell development and ancestral dental features provides evidence that the distinctive turtle body plan evolved through intermediate anatomical arrangements. Research paper.

Archaeopteryx — the dinosaur–bird transition, about 150 million years ago.
Archaeopteryx combined feathered wings with teeth, clawed fingers and a long bony tail. Its skeleton preserves numerous features shared with non-avian theropod dinosaurs. Other feathered dinosaurs reinforce the same conclusion: the characteristics of modern birds accumulated in stages. Birds remain dinosaurs, just as humans remain mammals; descent does not erase ancestry. Background: the origin of birds.

Pakicetus, Ambulocetus and Dorudon — whales’ transition from land to sea, roughly 50–35 million years ago.
These genera illustrate different stages of whale evolution, rather than a proven chain of direct ancestors. Pakicetus combined a terrestrial body with distinctive cetacean ear anatomy. Ambulocetus had powerful limbs and enlarged feet suited to swimming. The fully aquatic Dorudon had flippers and tiny hind limbs incapable of supporting walking. This fossil series documents extensive modification of an inherited mammalian skeleton. Background: the evolution of whales.

Australopithecus afarensis — early human bipedalism, about 3.85–2.95 million years ago.
Lucy's species combined adaptations for habitual upright walking with a small brain, long arms and curved fingers associated with climbing. It demonstrates that bipedalism evolved before the large brain and overall body proportions of modern humans. Human characteristics did not appear simultaneously as a finished package. Smithsonian species profile.

Why “it was still a fish/bird/ape” misses the point

Assigning a fossil to a named group does not remove its transitional anatomy. Classification summarises relationships; it does not impose a barrier that evolution must somehow cross. Nor does uncertainty about a fossil’s exact position erase the features it preserves.

These examples span different periods and evolutionary branches. The later fossils address the general claim that transitional forms do not exist; Yujingia bears directly on the evolution of Cambrian animals. Together, they expose the central error in that claim: the fossil record contains animals with precisely the combinations of ancestral and derived features expected from branching evolution.

The paper in Current Biology was accompanied by a University of Cambridge research report:

A star is born: half billion-year-old fossil rewrites the origin story of starfish
Scientists have discovered several 518-million-year-old fossils that reshape the origins of the group of animals that contains starfish, and found that they ate their food using tentacles, and not passively using their gills as previously thought.
The fossilised animals, discovered in southwestern China and named Yujingia glutenotunica, are thought to be close to the last common ancestor of ambulacrarians, the modern group that includes starfish, sea stars, sea urchins and acorn worms.

The international research team, including researchers from the University of Cambridge, say the fossils could also help us understand why two closely-related lineages – starfish and their relatives, and chordates, the phylum that includes humans – evolved wildly different body plans over millions of years. The results are reported in the journal Current Biology.

The fossilised animals date from a period of rapid evolutionary development known as the Cambrian explosion, when most major animal groups first appear in the fossil record.

Most animal fossils from the Cambrian are of hard-shelled creatures, but, in a handful of locations around the world – such as the Maotianshan Shales in China’s Yunnan Province where Yujingia was found – conditions are such that softer body part could be preserved before they decayed.

The Yujingia fossils measure between 8 and 22 millimetres in length, and preserve the body, gut and appendages, providing rare examples of ambulacrarians without a mineralised skeleton. The animals had two distinct sets of appendages: one set of feather-like feeding tentacles that captured organic particles from the water, and a second set thought to have temporarily anchored Yujingia to the seabed, although it was likely capable of some degree of movement.

There has been a tendency to think of the last common ancestor of ambulacrarians as more closely resembling a worm living in its seafloor burrow, filtering food from the water. This new fossil suggests instead that the common ancestor of the ambulacrarians might have actually fed with tentacles, and may have been more like starfish and their relatives.

Dr Giovanni Mussini, co-author
Department of Earth Sciences
University of Cambridge
Cambridge, UK.

Ambulacraria is one of the two major branches of deuterostome animals, and was first classified in the 1880s. Ambulacarians include echinoderms (such as starfish) and hemichordates (such as acorn worms), two groups with strikingly different body forms. However, fossil evidence of the origins of this group has remained scarce.

The fivefold radial symmetry of starfish and their relatives, and the bilaterally symmetrical, worm-like bodies of acorn worms and their relatives has been a bit of a mystery until now.

Dr Giovanni Mussini.

Chordates, echinoderms and hemichordates make up the principal branches of deuterostome evolution, yet differ profoundly in body organisation and feeding. Reconstructing the ambulacrarian ancestor is central to understanding how these lineages diverged. A longstanding hypothesis proposes that this ancestor was a tentacle-free worm that filtered food through its pharynx, resembling a modern acorn worm. Detailed anatomical study and phylogenetic analysis of Yujingia now challenge that view with direct fossil evidence.

The animal has an elongated, bottle-like form, with tentacles spreading above a rounded lower body. Its outline closely resembles the ritual vase, or yujingping, in traditional Chinese culture, which inspired the genus name Yujingia. All the specimens clearly preserve a pale, original membrane enclosing the visceral mass. Its soft, gelatinous appearance is the species’ most immediately recognisable feature and inspired the species name.

Kaiyue He, lead author.
Department of Geology
Northwest University (NWU)
Xi’an, China.

To establish the evolutionary position of Yujingia, Mussini and He assembled a large dataset comprising 505 morphological characters across 100 living and extinct taxa and analysed it using Bayesian phylogenetic reconstruction. The results place Yujingia closer to the last common ancestor of living ambulacrarians than previously described fossils, making it a key transitional form linking early Cambrian tentacled animals with hemichordates and echinoderms.

Although it lacked a hard skeleton, Yujingia possessed a complex tentacle-based feeding system, suggesting that sophisticated feeding structures evolved early, while echinoderm skeletons and other specialised features appeared later.

It tells us how ecology can drive different lineages onto very different evolutionary paths, and very different morphological specialisations. The chordates became reliant on movement for finding their food, so they streamlined their bodies and developed their brains, while members of the starfish lineage remained relatively anchored to the seafloor and specialised on this particle-feeding lifestyle.

Dr Giovanni Mussini.

How the major deuterostome groups diverged during the Cambrian explosion is one of the central questions in animal evolution. Yujingia helps connect primitive, tentacle-bearing animals living on the seafloor with modern echinoderms and hemichordates. It offers a new way to understand the profound transition from bilateral symmetry to the fivefold radial body plan of echinoderms, and adds an important fossil to a crucial gap in the early animal tree of life.

Degan Shu, co-author.
Department of Geology
Northwest University (NWU)
Xi’an, China.

The research team included scientists from Northwest University, the University of Cambridge, the State Natural History Museum Braunschweig in Germany, Georg-August University, palaeon Research Museum, and the China University of Geosciences.

Publication:
He K, Mussini G, Han J, et al.
Cambrian fossils illuminate the ambulacrarian common ancestor
Current Biology, 2026; 0

Highlights

A new early Cambrian ambulacrarian, Yujingia, preserves soft parts and tentacles
Yujingia possesses pinnate appendages with filter-feeding grooves
Phylogenetic analyses place Yujingia near the common ancestor of extant Ambulacraria
The fossils suggest living ambulacrarians evolved from tentaculate suspension feeders

Summary
The origins of ambulacrarians, which comprise the morphologically disparate echinoderms (sea stars and their relatives) and the worm-like hemichordates, are poorly constrained, obscuring the assembly of their exceptionally disparate body plans. We describe Yujingia glutenotunica, an ambulacrarian from the early Cambrian Chengjiang biota (518 Ma). Yujingia combines a simple cylindrical body plan with a crown of specialized appendages, including pinnate arms bearing filter-feeding grooves and alternating side-branches. Phylogenetic analyses recover Yujingia within a grade of tentaculate fossils immediately basal to the last common ancestor of all modern ambulacrarians. These results suggest that ambulacrarians evolved from semi-sessile organisms with complex suspension-feeding adaptations, otherwise only found in crown-group echinoderms and tentaculate hemichordates (pterobranchs). Yujingia fills a key gap in the early deuterostome fossil record, thus challenging the conventional worm-like, pharyngeal filter-feeder models for the ambulacrarian last common ancestor and supporting unexpectedly deep origins for the echinoderm and pterobranch body plans.

He K, Mussini G, Han J, et al.
Cambrian fossils illuminate the ambulacrarian common ancestor
Current Biology, 2026; 0

© 2026 Elsevier Inc.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.

For creationists who insist that transitional fossils do not exist, Yujingia glutenotunica presents another specimen to explain away. Its importance lies in the combination of features it preserves: a soft-bodied Cambrian animal with specialised feeding structures, helping to illuminate the ancestry of groups whose living members now look strikingly different. This is the sort of anatomical mosaic expected when evolution modifies inherited structures and different lineages follow different paths.

Its precise position in the animal family tree may change as further fossils are discovered and analyses improve. That is how science works. A revision would not make its anatomy disappear, nor would it turn uncertainty about a particular branch into evidence for supernatural creation. Scientists are investigating which evolutionary relationships best explain the evidence; the existence of questions within that investigation provides no support for a claim that the animals appeared by magic.

The wider lesson is especially uncomfortable for those who portray the Cambrian ‘explosion’ as the instantaneous arrival of completed modern body plans. Fossils such as Yujingia help reveal how characteristic structures arose in different combinations, with some features appearing before others. Together with the many transitional forms documented elsewhere in the fossil record, they expose the gulf between what palaeontology actually discovers and what creationist rhetoric says it should discover.

There was no requirement for these animals to anticipate starfish, acorn worms or any other eventual descendants. Their feeding structures served the animals that possessed them, in the environments in which they lived. The subsequent history emerged through branching evolution, without foresight or a predetermined destination. More than half a billion years later, their remains are helping scientists reconstruct that history — while leaving the claim that there are “no transitional fossils” ever further behind the evidence.

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