Virginia Tech geobiologist Shuhai Xiao with a 550 million-year-old sea sponge fossil, filling in a gap in the evolutionary family tree of one of the earliest animals.
Photo by Spencer Coppage for Virginia Tech.
That mountain of evidence against creationism just grows and grows!
Today, we have evidence of multicellular life in the form of an early sponge from about 550 million years before creationism's 'Creation Week' when they believe everything was magicked into existence in 6 days from nothing by some magic words spoken by a magic man made of nothing.
And it gets even worse.
Creationists also like to pretend the so-called 'Cambrian Explosion' when a lot of different multicellular body plans appear in the geological record, was an actual explosive creation as a single event, so the organisms in the Cambrian biota had no ancestors. It wasn't, of course; it lasted some 6-10 million years during which there are recognizable phases with characteristic organisms in each phase showing clear evolutionary progress - and it was preceded by the Ediacaran biota when some of the earliest multicellular organisms are found in the geological column.
Tell me about sponges and their evolution, please. Overview of SpongesAnd it gets still worse!
Sponges, belonging to the phylum Porifera, are simple multicellular animals that are primarily found in marine environments, though some species inhabit freshwater. They are characterized by their porous bodies and the ability to filter feed by pumping water through their porous structure.
Characteristics
- Body Structure: Sponges have a unique body plan lacking true tissues and organs. Their bodies are composed of loosely organized cells embedded in a gelatinous matrix called mesohyl.
- Feeding: They feed by filtering water through their pores (ostia), trapping food particles with specialized cells called choanocytes.
- Reproduction: Sponges can reproduce both sexually, by producing sperm and eggs, and asexually, through budding or fragmentation.
Evolution of Sponges
Origin and Early Evolution
- Ancient Lineage: Sponges are among the oldest known animal groups, with fossil evidence dating back to over 600 million years ago, predating the Cambrian Explosion.
- Morphological Simplicity: Their simple body plan suggests that sponges may resemble the common ancestor of all animals, making them crucial for understanding early animal evolution.
- Molecular Evidence: Genetic studies support the ancient origins of sponges. Genome sequencing has shown that sponges possess many genes involved in cell communication and adhesion, which are essential for multicellular life.
Phylogenetic Significance
- Basal Metazoans: Sponges are considered basal metazoans, meaning they occupy a foundational position in the animal tree of life. This basal position provides insights into the transition from unicellular to multicellular organisms.
- Sponge-Microbe Associations: Sponges harbor diverse microbial communities that contribute to their physiology and ecology. These symbiotic relationships are thought to have played a significant role in the evolution of early multicellular life.
Fossil Record
- Precambrian Fossils: Fossilized remains of sponge-like organisms from the Precambrian period (e.g., Ediacaran biota) suggest that sponges were among the first multicellular organisms.
- Cambrian Explosion: During the Cambrian Explosion, sponges diversified alongside other early animal groups. Fossil records from this period show a variety of sponge forms, indicating their early ecological success and adaptability.
Modern Sponges
- Diversity: Today, there are over 8,000 known species of sponges, classified into three main classes: Demospongiae (the largest group), Calcarea, and Hexactinellida (glass sponges).
- Ecological Roles: Modern sponges play vital roles in marine ecosystems, including nutrient cycling, providing habitat for other organisms, and maintaining water quality through their filtering activity.
Evolutionary Significance
The evolutionary study of sponges sheds light on several key aspects of early animal evolution:
- Multicellularity: Understanding sponges helps scientists explore the origins and evolution of multicellularity.
- Developmental Biology: Research on sponge development and gene regulation provides insights into the evolution of developmental mechanisms in animals.
- Symbiosis: The study of sponge-microbe interactions offers clues about the evolution of symbiotic relationships in early metazoans.
Conclusion
Sponges represent an ancient and fundamental branch of the animal kingdom, providing a window into the early evolution of multicellular life. Their simple structure and diverse ecological roles highlight their importance in understanding the origins and evolution of animals.
Scientists use a form of dating called a 'genetic clock' to date the origins of living species or extinct species from which DNA can be recovered. This is a rough and ready estimate based on the fact that some parts of a genome contain redundant sections that can accumulate mutations over time without being detrimental to the organism (something that creationist dogma claims is impossible because, a. there is no redundancy in the genome and b. all mutations are invariably fatal [sic]).
Based on the idea that these mutations accumulate at a more or less constant rate, scientists can work out when the organism first evolved.
Using that method, scientists have worked out that sponges, one of the oldest metazoan species, arose some 700 million years ago. But that creates a gap in that the earliest known sponges in the fossil record are only about 540 million years old, leaving 160 million unaccounted for.
That gap has now been filled by Virginia Tech geobiologist Shuhai Xiao and his collaborators, with this latest discovery and lends support to the explanation for the 'gap', which was that earlier sponges had not evolved the hard body-parts that could easily mineralize to form fossils.
The find and its significance is explained in a Virginia Tec News release and in a paper published a few days ago in Nature:
At first glance, the simple sea sponge is no creature of mystery.
No brain. No gut. No problem dating it back 700 million years. Yet convincing sponge fossils only go back about 540 million years, leaving a 160 million-year gap in the fossil record.
In a paper released June 5 in the journal Nature, Virginia Tech geobiologist Shuhai Xiao and collaborators reported a 550 million-year-old sea sponge from the “lost years” and proposed that the earliest sea sponges had not yet developed mineral skeletons, offering new parameters to the search for the missing fossils.
The mystery of the missing sea sponges centered on a paradox.
Molecular clock estimates, which involve measuring the number of genetic mutations that accumulate over time, indicate that sponges must have evolved about 700 million years ago. And yet there had been no convincing sponge fossils found in rocks that old.
For years, this conundrum was the subject of debate among zoologists and paleontologists
This latest discovery fills in the evolutionary family tree of one of the earliest animals, explaining its apparent absence in older rocks and connecting the dots back to Darwin’s questions about when it evolved.
Xiao, who recently was inducted into the National Academy of Sciences, first laid eyes on the fossil five years ago, when a collaborator texted him a picture of a specimen excavated along the Yangtze River in China.
I had never seen anything like it before. Almost immediately, I realized that it was something new.
Shuhai Xiao, co-corresponding author
Department of Geosciences and Global Change Centre,
Virginia Tech, Blacksburg, VA, USA.
Xiao and collaborators from the University of Cambridge and the Nanjing Institute of Geology and Paleontology began ruling out possibilities one by one: not a sea squirt, not a sea anemone, not a coral. They wondered, could it be an elusive ancient sea sponge?
In an earlier study published in 2019, Xiao and his team suggested that early sponges left no fossils because they had not evolved the ability to generate the hard needle-like structures, known as spicules, that characterize sea sponges today.
Xiao’s team members traced sponge evolution through the fossil record. As they went further back in time, sponge spicules were increasingly more organic in composition and less mineralized.
If you extrapolate back, then perhaps the first ones were soft-bodied creatures with entirely organic skeletons and no minerals at all. If this was true, they wouldn’t survive fossilization except under very special circumstances where rapid fossilization outcompeted degradation.
Most often, this type of fossil would be lost to the fossil record. The new finding offers a window into early animals before they developed hard parts.
Shuhai Xiao.
Later in 2019, Xiao’s international research group found a sponge fossil preserved in just such a circumstance: a thin bed of marine carbonate rocks known to preserve abundant soft-bodied animals, including some of the earliest mobile animals.
The surface of the new sponge fossil is studded with an intricate array of regular boxes, each divided into smaller, identical boxes.
This specific pattern suggests our fossilized sea sponge is most closely related to a certain species of glass sponge.
Dr. Xiaopeng Wang, first author
State Key Laboratory of Palaeobiology and Stratigraphy
Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China And Department of Earth Sciences
University of Cambridge, Cambridge, UK.
Another unexpected aspect of the new sponge fossil is its size.
When searching for fossils of early sponges I had expected them to be very small. The new fossil is about 15 inches long with a relatively complex, conical body plan, which challenged many of our expectations for the appearance of early sponges.
Alexander G. Liu, co-author
Department of Earth Sciences
University of Cambridge, Cambridge, UK.
While the fossil fills in some of the missing years, it also provides researchers with important guidance about how to search for these fossils — which will hopefully extend understanding of early animal evolution further back in time.
The discovery indicates that perhaps the first sponges were spongey but not glassy. We now know that we need to broaden our view when looking for early sponges.
Shuhai Xiao.
AbstractDiscoveries such as these not only utterly refute the childish mythology of creationism and show the ignorance of those who wrote Genesis, they also show how the idea of 'punctuated equilibrium' that gained popularity in the 1980's and 90's is simply a misinterpretation of the fossil record which is for most organisms, by its very nature, a series of random snapshots, with, in this case a gap of 160 million years. The cause of these gaps on which so much of the 'PE' notion depends is because fossilisation is a rare event requiring exceptional circumstances, and for the early history of multicellular life, because very few organisms has evolved hard body parts which fossilize.
Sponges are the most basal metazoan phylum1 and may have played important roles in modulating the redox architecture of Neoproterozoic oceans2. Although molecular clocks predict that sponges diverged in the Neoproterozoic era3,4, their fossils have not been unequivocally demonstrated before the Cambrian period5,6,7,8, possibly because Precambrian sponges were aspiculate and non-biomineralized9. Here we describe a late-Ediacaran fossil, Helicolocellus cantori gen. et sp. nov., from the Dengying Formation (around 551–539 million years ago) of South China. This fossil is reconstructed as a large, stemmed benthic organism with a goblet-shaped body more than 0.4 m in height, with a body wall consisting of at least three orders of nested grids defined by quadrate fields, resembling a Cantor dust fractal pattern. The resulting lattice is interpreted as an organic skeleton comprising orthogonally arranged cruciform elements, architecturally similar to some hexactinellid sponges, although the latter are built with biomineralized spicules. A Bayesian phylogenetic analysis resolves H. cantori as a crown-group sponge related to the Hexactinellida. H. cantori confirms that sponges diverged and existed in the Precambrian as non-biomineralizing animals with an organic skeleton. Considering that siliceous biomineralization may have evolved independently among sponge classes10,11,12,13, we question the validity of biomineralized spicules as a necessary criterion for the identification of Precambrian sponge fossils.
Wang, X., Liu, A.G., Chen, Z. et al.
A late-Ediacaran crown-group sponge animal. Nature (2024). https://doi.org/10.1038/s41586-024-07520-y
© 2024 Springer Nature Ltd.
Reprinted under the terms of s60 of the Copyright, Designs and Patents Act 1988.
Hard body parts are mostly defensive or offensive structures such as shells, teeth and spines, or needed for mobility, such as exo- and endo-skeletons. There was no need for any of those until mobility enabled predation and provided new selection pressure to evolve sensory apparatus such as eyes, and greater mobility - hence the 'explosion' of biodiversity in the Cambrian, and the long gap between the sedentary Ediacaran biota and the mobile Cambrian biota.
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There are quite a number of living fossils, some of them even living in our gardens and houses and as pets.
ReplyDeleteSponges and Jellyfish may be up to 700 million years ago in the late Precambrian Era. The early to mid Precambrian was anaerobic, while the late Precambrian was likely hypoxic. The highest oxygen content during the late Precambrian was 15 percent, or alot less than that. It could have been as miniscule as only 1 percent.
Scorpions are known from the Silurian period with fossils dated at 436 million years ago, and spiders such as Attercopus are dated at 380 million years ago in the Devonian period. Primitive spiders such as Tarantulas existed anywhere from 120 million years ago in the Cretaceous period, to 350 million years ago in the Carboniferous period. Some sources say Tarantulas are 400 million years old or more which would place their origin in the early Devonian period.
The earliest Insects appeared sometime during the Devonian period or earlier in the Silurian period in the middle Paleozoic Era. Early Sharks also arose during this time as did Horseshoe Crabs. It's well known that Trilobites and Eurypterids or Sea Scorpions ruled much of the Paleozoic Era, and the Coelacanth appeared in the late Devonian to early Carboniferous period and still exists today. Cockroaches and Dragonflies appeared in the Carboniferous period.
We know Dinosaurs ruled the Mesozoic Era, and many Mammals and Birds appeared in the Tertiary period. The primitive Tuatara is a reptile from the Jurassic period that still exists in New Zealand.
Hominids appeared during the late Miocene to early Pliocene and the first true Humans appeared in the Pleistocene. The point of all these figures is to show how much vastly older life is than the 6000 to 10,000 years of Biblical Creationism. Even agriculture is older than the 6000 years of Creationism. The creation is way way way older than 6000 years of Creationism.