Bengaluru: Two years ago, the discovery of a rare 550-million-year-old fossil of Dickinsonia, a primitive marine animal, was reported from the Bhimbetka rock shelters near Bhopal, Madhya Pradesh. However, the ‘fossil’, which received widespread attention, including coverage from ThePrint, turned out to be something else altogether.
When a new team of researchers from the University of Florida visited the spot to conduct a follow-up study, they discovered that the purported fossil was nothing but an imprint of a recently decayed beehive.
The team of researchers travelled to the site last December to confirm the ‘hiding in plain sight’ findings along with geologist Manoj Pandit from the University of Rajasthan. They said that the isolated occurrence of Dickinsonia at Bhimbetka is a case of “mistaken identity”. Instead, what appears to be a fossil is actually a decayed imprint of a beehive, they added.
Gregory Retallack, the lead author of the original paper, has said that he and other authors agree with the new findings.
The new peer-reviewed findings were published this week in the scientific journal Gondwana Research.
The new findings have once again left the age of the Vindhyan sandstone of Bhimbetka open. Some experts believe it is much younger than 500 million years, while others date the formation to 1 billion years ago. Due to the absence of fossils, this formation in central India has proven difficult to date.
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Dickinsonia is an extinct primitive animal that inhabited seabeds around what is today Australia, China, Russia, Ukraine, in the Ediacaran period, 600-500 million years ago. It was classified as an animal after discovery of cholesterol molecules in the fossils.
It is believed to be one of the earliest animals to have existed on earth.
This was also around the time that the paleo landmass called Gondwanaland was thought to have been assembled. At the time, India, Australia, South America, Africa, and Antarctica accreted together to form a single landmass. But these Dickinsonia fossils have not been reported elsewhere in the world.
All discovered fossils have been only imprints in sandstone shaped like ribbed ovals, symmetric across a vertical axis. These fossils form when these animals are covered in sand which solidifies before the animal decomposes.
Back in 2020, a group of geologists decided to travel to geological formations in India after a scientific conference was cancelled due to the Covid pandemic. Upon visiting the Bhimbetka Rock Shelters, a UNESCO World Heritage site in Madhya Pradesh that holds evidence of inhabitation going back 100,000 years, they saw patterns on walls they hadn’t expected to see.
There are many theories for various estimates of the age of layers of rock and sandstone in Bhimbetka. The authors stated that some were consistent with 550 million years ago, which added weight to their argument that their photographs of the pattern showed a single fossil of Dickinsonia.
The authors of the study, which was released the next year, stated that this showed evidence that not only had Gondwanaland finished assembling by 550 million years ago (the exact time period is unclear), but Dickinsonia were present at temperate and subtropical latitudes as well. The finding also dated the rocks at Bhimbetka to at least 500-550 million years old.
There had been no follow up studies until now on the lone fossil.
In December 2022, the new team of scientists went to Bhimbetka to confirm the findings. In their paper, they put down seven points after their observation as to why it’s not a fossil, but a beehive.
Firstly, they said that the rocks all around were home to several honey bee nests, and they were located approximately 10-20m above ground level — the same level where the imprint was found. The dark staining of the hives over time resembles soot that covers fossils.
They pointed out that the imprint is not located on a seabed. Instead, the location of the fossil was a joint from which material collapsed to form the cave. The fossil is located at an angle to the bedding material as well. Additionally, it is not located on a complete flat surface, it wraps around a curved surface into a crack.
They also said that the fossil appears to be decaying. The original team stated that soot from fires used by ancestors when they occupied the caves would have led to the decay. However, the new team believes that it is simply the physical honeycomb rapidly decaying.
The team also discovered another abandoned and decaying hive a few feet away which looked similar to the purported fossil. The top part of the decayed hive had also left an imprint similar to the fossil, which upon closer magnification also showed hexagonal imprints of a hive.
Lastly, the new authors say that a large point of contention is that there has been only one fossil found of Dickinsonia, and had it been present in the region, more would have been discovered.
The team combed the area for two days and found no others.
The University of Florida reported that the authors of the earlier paper agree with the findings of the new team.
“It is rare but essential for scientists to confess mistakes when new evidence is discovered,” Retallack said in the statement.
Retallack’s team plans to submit a comment in support of the new paper to the journal.
Joseph Meert, the first author of the new paper, stated that zircon crystal evidence and magnetic signature of the rocks still points to the rock formation being a billion years old. Currently, due to a complete lack of fossils, it is impossible to date the Vindhyan sandstone at Bhimbetka.
“A 550 million year age would have implied that India occupied a particular paleogeographic position in relation to other continents as Gondwanaland was being assembled,” explained Suvrat Kher, sedimentary geologist. “All those interpretations no longer hold. It suggests that sedimentation in the Vindhyan basin stopped by 1 billion years ago, likely in response to collision between the southern Indian block (Dharwar) with a northern block (Bundelkhand). A larger Indian continent took shape at this time by this merger.
“The merger of various Indian blocks, including the Aravallis, and the termination of basins like the Vindhyans were part of this larger continental reconfiguration taking place between 1 to .9 billion years ago,” he added.
This is an updated version of the article.
(Edited by Geethalakshmi Ramanathan)
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