Rosa Rubicondior: Refuting Creationism - Why There Are No fossils Of The Early Sponges From 650 Million Years Before 'Creation Week'

Saturday, 28 February 2026

Refuting Creationism - Why There Are No fossils Of The Early Sponges From 650 Million Years Before 'Creation Week'

A giant barrel sponge from Indonesia. Sponges were the first reef builders and maintain a fundamental role in modern marine ecosystems.

January: Bristol scientists discover early sponges were soft | News and features | University of Bristol

Creationists have a massive gap to try to close; a gap so wide it makes the Grand Canyon look like a mere ditch. It is the gap between the earliest signs of life in the fossil record and the timeline a literal reading of the Bible allows. And that gap just got a lot wider.

Creationists could once take comfort from the fact that there was little solid fossil evidence of multicellular life much before the Cambrian, when organisms with hard body parts that fossilise begin to appear in the record. That gap was closed, not by fossils as we normally understand the term, but by chemical fossils contained in ancient rocks, as I explained in my last blog post. This evidence, together with genetic evidence from other work, shows that the common ancestors of multicellular animal life were very probably sea sponges.

But to a creationist, conditioned to believe that the Theory of Evolution is a theory about fossils—so that any gaps in the fossil record must be fatal for the theory—there is still some comfort in the fact that whatever left these chemical fingerprints in ancient rocks left no tangible fossils.

Now a team of palaeontologists, led by the University of Bristol, have shown that the lack of fossil evidence of these ancestral sponges has a simple explanation: they were soft-bodied, having yet to evolve the characteristic skeletons composed of millions of microscopic glass-like spicules. These did not evolve until about 560 million years ago. The team have recently published their findings, open access, in the journal Science Advances.

The Bristol-led team have now pushed back the evolution of these soft-bodied sponges to between 615 and 600 million years ago by using a combination of genetic evidence from 133 protein-coding genes and fossil evidence. This approach also showed that the spicules evolved independently in different sponge groups by convergent evolution.

Background^ The Earliest Animals – Sponges and the Origin of Multicellular Life. Sponges (phylum Porifera) are widely regarded by biologists as the most ancient lineage of living animals. Their simple body plan, lack of true tissues, and distinctive feeding system suggest they closely resemble the earliest multicellular animals that evolved in the late Precambrian oceans more than 600 million years ago.

Unlike most modern animals, sponges have no nervous system, muscles, or digestive organs. Instead, their bodies are built around a system of pores and canals through which water continuously flows. Specialised cells called choanocytes, or “collar cells,” use beating flagella to draw water through the sponge’s body, trapping microscopic food particles such as bacteria and algae. This filter-feeding lifestyle allows sponges to survive in environments where food is sparse.

Many modern sponges possess a supporting skeleton made of tiny mineral elements known as spicules. These microscopic structures may be composed of silica (“glass sponges”) or calcium carbonate, and they help maintain the sponge’s shape while providing protection against predators. Because these mineralised spicules fossilise readily, they form the basis of much of the sponge fossil record.

However, evolutionary studies increasingly suggest that the earliest sponges lacked these mineral skeletons entirely. Instead, they were soft-bodied organisms supported mainly by flexible organic fibres. Without hard parts, their remains would have decayed quickly after death, leaving almost no conventional fossils. This helps explain why clear sponge fossils appear relatively late in the geological record.

Evidence for these early soft-bodied animals comes from several independent sources. Molecular studies comparing genes across modern animals indicate that sponges diverged very early in animal evolution. In addition, certain biomarker molecules preserved in ancient rocks—chemical traces associated with sponge metabolism—suggest that sponge-like animals were already present hundreds of millions of years before the Cambrian explosion.

Together, genetic evidence, chemical fossils, and newly reinterpreted geological data point to a deep evolutionary history for sponges, extending well back into the Ediacaran Period. These humble filter-feeders may therefore represent some of the earliest experiments in multicellular animal life, long before animals developed shells, skeletons, or complex body plans.

The work of the Bristol-led group is explained in a University of Bristol news item.

Bristol scientists discover early sponges were soft
Sponges are among earth’s most ancient animals, but exactly when they evolved has long puzzled scientists. Genetic information from living sponges, as well as chemical signals from ancient rocks, suggest sponges evolved at least 650 million years ago.
This evidence has proved highly controversial as it predates the fossil record of sponges by a minimum of 100 million years. Now an international team of scientists led by Dr Eleonora Rossi, from the University of Bristol’s School of Biological Sciences, have solved this conflict by examining the evolution of sponge skeletons. The research is published in Science Advances. Living sponges have skeletons composed of millions of microscopic glass-like needles called spicules. These spicules also have an extremely good fossil record, dating back to around 543 million years ago in the late Ediacaran Period. Their absence from older rocks has led some scientists to question whether earlier estimates for the origin of sponges are accurate. Dr Rossi and her team solved this mystery using a two-step approach. Firstly, they combined high-quality data from 133 protein-coding genes with fossil evidence to construct a new timescale for sponge evolution. They dated the origin of sponges to between 600-615 million years ago, closing the gap with the fossil record. Secondly, they investigated the evolution of sponge skeletons, revealing that spicules evolved independently in different sponge groups.
Our results show that the first sponges were soft-bodied and lacked mineralised skeletons. That’s why we don’t see sponge spicules in rocks from around 600 million years ago — there simply weren’t any to preserve.

Dr Maria Eleonora Rossi, lead author.
Bristol Palaeobiology Group
School of Earth Sciences
University of Bristol
Bristol, UK.

We already had some clues that suggested sponge skeletons evolved independently. Modern sponge skeletons may look alike, but they’re built in very different ways. Some are made of calcite, the mineral that makes up chalk, others of silica, essentially glass, and when we examine their genomes we see that entirely different genes are involved.

Dr Ana Riesgo, co-author
Life Sciences Department
The Natural History Museum
London, UK.

In order to reconstruct sponge skeleton evolution, the team used a statistical computer model.

We used a Markov process, a type of predictive model that’s widely applied in fields like finance, AI, search engines, and weather forecasting. By modelling transitions between different skeletal types, including soft-bodied forms, we found that almost all models strongly reject the idea that the earliest sponges had mineralised skeletons. Only an unrealistic model treating all mineral types as equivalent suggests otherwise, and even then the results are ambiguous.

Dr Joseph Keating, co-author on the study.
Bristol Palaeobiology Group
School of Earth Sciences
University of Bristol
Bristol, UK.

The results of this study raise interesting questions about early sponge evolution.

Given that nearly all living sponges have skeletons composed of mineralised spicules, we might naturally assume that spicules were important in early sponge evolution. Our results challenge this idea, suggesting that early sponge diversification was driven by something else entirely—and what that was is still a tantalising mystery.

Professor Philip C.J. Donoghue, co-author
Bristol Palaeobiology Group
School of Earth Sciences
University of Bristol
Bristol, UK.

But this is not only about sponges. Sponges are the first lineage of reef building animals to evolve and might as well have been the very first animal lineage, although this is still debated. Understanding their evolution provide key insights on the origin of the very first reef systems. This is about how life and Earth co-evolved, and how the evolution of early animals changed our planet forever, ultimately enabling the emergence of the animal life forms we are familiar with, humans included

Professor Davide Pisani, corresponding author
Bristol Palaeobiology Group
School of Earth Sciences
University of Bristol
Bristol, UK.

Publication:
Maria Eleonora Rossi et al.
Independent origins of spicules reconcile paleontological and molecular evidence of sponge evolutionary history.
Sci. Adv. 12, eadx1754 (2026). DOI:10.1126/sciadv.adx1754

Abstract
Sponges (Porifera) are ecosystem engineers that play a critical role in global biogeochemical processes. Their evolution is key to understanding Neoproterozoic paleoecology but remains mired in controversy. Molecular timescales suggest a Tonian or Cryogenian origin, while their oldest unequivocal fossils consist of disarticulated siliceous spicules from the Late Ediacaran. We derived a new, dated sponge phylogeny and tested whether ancestral sponges had mineralized skeletons. We resolve the sponge phylogeny in good agreement with current knowledge and date their origin to the early Ediacaran. Our results suggest that early sponges were not biomineralized and that both biosilicification and biocalcification evolved independently multiple times across Porifera. We reconcile fossil evidence and molecular estimates of sponge evolution by showing that the Neoproterozoic history of Porifera is limited to the Ediacaran and providing evidence suggesting that sponges are largely absent from the Ediacaran record because they were yet to evolve biomineralized skeletons.

Fig. 1. Time-calibrated phylogeny dates the origin of sponges to the early Ediacaran.
Porifera timetree with posterior estimates of divergence time estimated using the Bayesian CAT-Poisson tree in fig. S1, under the spicule-bearing Demospongiae (SDN) calibration strategy, with the IR model in MCMCtree. Bars on nodes represent the 95% highest posterior densities. The colors of the bars identify the four main sponge lineages (Calcarea, Homoscleromorpha, Hexactinellida, and Demospongiae). Gray bars indicate internal nodes outside these clades. Red circles represent the two mutually exclusive calibrations strategies Spiculate Porifera Node (SPN) and Spiculate Demosponges Node (SDN). Full red dots represent calibrations used in both strategies. Species in bold were sequences as part of this study. Timescale on x axis in hundreds of millions of years. The green dotted line marks the start of the Cambrian. Ne, Neoproterozoic; C, Cambrian; O, Ordovician; S, Silurian; D, Devonian; C, Carboniferous; P, Permian; Tr, Triassic; J, Jurassic; K, Cretaceous; Pe, Paleogene. Support values for the nodes can be found in fig. S1. Differences between our ML, Bayesian, and Astral topologies are described in text and can be investigated comparing the tree here and fig. S1 against those in figs. S2 and S3. Silhouettes are from https://phylopic.org/. Specific attributions: G. Dera is the author of the following silhouettes: Chrysaora quinquecirrha, Plakina jani, Leucandra aspera, Euplectella aspergillum, Homaxinella balfourensis, and Spongia officinalis. Amphimedon queenslandica is by seung9park; Isodyctia grandis by M. Keesey; Cladorhizidae is by D. Schultz; and Hormiphora californensis is by S. Haddock and K. Wothe. All the above mentioned silhouettes have been released under license CC0 1.0 Universal Public Domain Dedication. Aplysina is by M. Vingiani (license link: https://creativecommons.org/licenses/by/4.0/). Axinellidae is by Tree of Life App (license link: https://creativecommons.org/licenses/by/4.0/). Cliona celata is by M. Eppley (license link: https://creativecommons.org/licenses/by/4.0/). The silhouettes of Aplysina, Axinellidae, and C. celata were reduced in size and their transparency was enhanced.

For creationists, discoveries such as this steadily widen the already enormous gap between the scientific evidence and the timeline permitted by a literal reading of Genesis. If animals resembling modern sponges were already living in the oceans more than 600 million years ago, then complex multicellular life existed hundreds of millions of years before the Earth itself is supposed to have been created according to young-Earth chronology. That discrepancy cannot be resolved by appealing to gaps in the fossil record, because the new research shows that the absence of early sponge fossils was itself predictable once we understand that their ancestors lacked mineral skeletons.

More importantly, the study illustrates how evolutionary biology actually works. Scientists combine independent lines of evidence—genetics, comparative biology, and the fossil record—to reconstruct the history of life. When these different sources converge on the same conclusion, they strengthen the case for that conclusion, even when the fossil record is incomplete.

In this case, the combined genetic and palaeontological evidence shows that the earliest animals were probably simple, soft-bodied filter feeders inhabiting the oceans hundreds of millions of years before the Cambrian explosion produced the abundant fossil record of skeletonised organisms. What once looked like a puzzling gap in the fossil record now turns out to be exactly what evolutionary theory would predict.

So once again the creationist hope that “missing fossils” might rescue their narrative evaporates in the face of new evidence. The gap has not closed—it has widened, revealing yet another chapter in the long and complex evolutionary history of life on Earth.

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