Photo of the Charnia holotype in Leicester Museum by author
Not long ago I was lucky enough to visit Leicester Museum which holds a very important fossil. When this fossil was described in 1957 it changed everything palaeontologists knew about animal evolution. Charnia might not seem much but it showed that animal life was far much older than previously thought. The Precambrian period, over 550 million years ago, was actually home to animals!
Discovery and Fossils
The fossils of Charnia were meant to be impossible in the 1950s – life before the Cambrian were believed to simply be single-celled organisms that could not be found with the naked eye. The location of where the first fossils were found was close to where David Attenborough grew up, and the young naturalist never bothered searching his local area as they were Precambrian so would not have the fossils that he was looking for. That was until a 15-year old girl called Tina Ford found a fossil in 1956 in the Woodhouse Beds of Charnwood Forest in Leicester, England. Unfortunately, she told her geography teacher whose narrowmindedness dismissed her claim – a sad trend in archaeology and palaeontology of figures ignoring older evidence due to it being ‘impossible.’ I would not be surprised if Tina being a 15-year old girl had something to do with her account being dismissed. The next year another teen called Roger Mason found the same fossil, took a sketching, and then sent it to a geologist at Leicester University who thankfully was not as small-minded as Tina’s geography teacher. In 1958 the paper describing the fossil was published naming the fossil Charnia masoni – Mason’s Charnwood. The young lad not only got a fossil named after him but it inspired him to become a geologist who now works at the China University of Geosciences in Wuhan.
The holotype of Charnia is very well preserved, and as mentioned above I was lucky enough to see it in person on a trip to Leicester Museum. Since then the impossible has been found many more times, so much so that we have potentially have three species of Charnia: C. masoni, C. grandis, and C. siberica. There is some debate if the two later described species could belong to other genre, so we will sort of cover Rangea and Glassnerina due to their similarities.
When and Where
I normally do not put this section after the ‘Discovery and Fossils’ section, but I feel I need to have this section now to properly get across how important the discovery of Charnia was in 1958. Charnia fossils date from around 570 to 550 million years ago which is a staggeringly far back in time, so far back in time that it palaeontologists had previously did not believe that animals could live that far back. This was the Precambrian, specifically the Ediacaran period, in a vastly different time. Rising carbon dioxide levels in the atmosphere led to warming temperatures ending the ‘Snowball Earth’, when the planet was almost entirely frozen. Life on the land was non-existent but life had started diversifying in the ocean. Especially close to thermal vents, single-cell organisms began evolving so this is the reason why Charnia was so important a discovery. Charnia was not a single-cell organism, it was an actual animal, which pushed back the evolution of animals from the Cambrian by a good 30 million years. Originally found in Charnwood, Leicester they have now been found in Newfoundland, Siberia, and Australia showing that this was not a unique thing – Charnia was widespread. And now, we know it was not alone in being an animal during the Precambrian period, but more of that later.
Biology
The Charnia holotype is not the largest of animals – about 19 centimetres – which is understandable as it was one of the earliest known multicellular organisms, never mind one of the first animals. However, some specimens are truly large large reaching 2 metres (around 6 feet) tall which is staggering how big a multicellular organism could get so far back in time. On the surface Charnia looks more like a plant than an animal. A disc is attached to the sea bed, from there a stem grows to form a frond that has branches connected to one another to form a tightly packed disc-shaped organism. There are plenty of animals today that are permanently rooted to sediment – notably corals, anemones, and, most importantly sea pens. A living sea pen is pictured below.
You can see why for a while palaeontologists thought that Charnia may have been an ancient ancestor to sea pens, although a 2008 paper by Jonathan Antcliffe and Martin Brasier have highlighted that sea pens evolved from a separate burrowing cnidarians (jellyfish, anemones, corals, and hydroids). This could be a case of convergent evolution – where unrelated organisms evolve similar attributes to similar environments (think of how bats and birds independently evolved flight). As sea pens evolved from burrowing cnidarians this could also indicate that Charnia as well evolved from burrowing or sediment living organisms giving us a potential insight into how animals evolved.
As Charnia comes from such an alien time it has been hard for palaeontologists to theorise how they lived in life. We could simply point to sea pens, but they resemble Charnia, not being related to sea pens, so a one-to-one analogy should not be entirely used. For example, sea pens reproduce by issuing polyps from the ends of their branches which bud and grow into a new sea pen, but Charnia‘s branches do not match the part of sea pens which develops polyps. Palaeontologists still do not know how Charnia ate – it seems to lack a digestive system or some form of mouth. One theory had Charnia living symbiotically with algae like modern corals, offering the algae a home and in return the algae gives them nutrients produced in photosynthesis. However, we now know Charnia lived in the benthic zone of the ocean, or the very bottom of the ocean. Considering how rare we see deep-sea animals having a fossilised one is amazing! What this means is that it is in too deep water to photosynthesise as you need light to photosynthesise. However, the deep water is still full of floating nutrients caused by dead organisms and the clouds issuing from thermal vents which Charnia could have used via filter-feeding.
The Precambrian World of Charnia
We have already discussed the state of the planet during the Ediacaran period – starting to come out of the Snowball Earth period where the surface was almost inhospitable for life. Since the discovery of Charnia palaeontologists have managed to identify so many more multicellular organisms and animals which has offered interesting insights into the evolution of animals. Several of these are indeed older than Charnia and some can be directly linked to living animal groups – Cyclomedusa, for example, may potentially be a very early jellyfish. In 2022 a fossil from Charnwood Forest was discovered, around the age of Charnia, that seems to be an early cnidarian, that not only had a skeleton but may have been a predator. While it did not swim around like a fish, Auroralumina attenbourghii (named after David Attenborough) lived like an anemone using its tentacles to grab prey. Charnia lived in an amazing world where life was setting the stage for an explosion of diversity.
Bibliography:
- T.D. Ford, ‘Pre-Cambrian fossils from Charnwood Forest’, Proceedings of the Yorkshire Geographic Society, 31, (1958), 211-217
- Jonathan Antcliffe and Martin Brasier, ‘Charnia at 50: Developmental Models for Ediacaran Fronds’, Palaeontology, 51:1, (2008), 11-26
- Frances S. Dunn, Philip R. Wilby, Charlotte G. Kenchington, Dmitriy V. Grazhdankin, Philip C. J. Donoghue, and Alexander G. Liu, ‘Anatomy of the Ediacaran rangeomorph Charnia masoni‘, Papers in Palaeontology, 5:1, (2019), 157-176
- H.J. Hofmann, S.J. O’Brien, and A.F. King, ‘Ediacaran biota on Bonavista Peninsula, Newfoundland, Canada’, Journal of Paleontology, 82:1, (2008), 1-16
- ‘Charnia’, Prehistoric-Wildlife.com, [Accessed 01/12/2023]
- Angeles Gavira Guerrero and Peter Frances, (eds.), Prehistoric Life: The Definitive Visual History of Life on Earth, (London: DK, 2009)
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