What is the significance of discovery of Dickinsonia?

The Bhimbetka Rock Shelters in Bhopal are known for beautiful cave paintings that depict human life thousands of years ago. But a recent fossil discovery, belonging to Dickinsonia, an earliest-known creature, at the site transports us back to 550 million years ago, when life forms were strange and enigmatic. What’s Dickinsonia? What’s the significance of the discovery?

Two researchers from the Geological Congress scheduled to take place in March 2020 but cancelled due to the COVID-19 pandemic. While looking at the cave art, the experts noticed something unusual-leaf-like impressions – on the rocky wall of the ‘Auditorium Cave’, about 11 feet above the ground. They believed what caught their eye was something more than prehistoric art. They took photographs and later studied them through 3D image-based models. Further analysis led researchers to conclude that they were not cave art, but fossils belonging to the oldest-known creature –Dickinsonia.

The discovery includes three 550-million-year-old fossils of Dickinsonia. While one fossil is 17 inches long, the other two are much smaller. The new discoveries have been published in a research journal from Elsevier. The Dickinsonia fossils are the first of its kind found in India and they are similar to the ones seen in south Australia. What’s Dickinsonia? And what’s the singnificance of the discovery? Let’s find out in this five Ws and One H…

What’s special about the Bhimbetka caves?

The Bhimbetka Rock Shelters are an archaeological site located in the foothills of the Vindhya Mountains. A Unesco World Heritage Site, it consists of seven hills and over 750 rock shelters distributed over 10 km in the Raisen District, Madhya Pradesh. The speciality of the site is that it is home to the oldest-known rock art in India. The site hosts  thousands of cave paintings that date from the Upper Paleolithic (between 50,000 and 12,000 years ago) though Mesolithic Period to as recent as the Medieval period (from the 5th to the late 15th century). Carved on rock, the cave art depicts huge figures of animals and humans, hunting scenes, religious symbols and battles between rulers carrying weapons. The cave paintings provide evidence of early human settlement and evolution.

What’s Dickinsonia?

Dickinsonia is an organism which lived during the Late Ediacaran nearly 570 million years ago. In 2018, scientists described Dicknsonia as something that looked like quilted bath mat. Oval in shape, they had a squishy, flattened, ribbed body and could grow up to four feet. Are they animals or fungi or some other life form? Scientists are inconclusive about where to fit Dickinsonia and other bizarre Ediacaran organisms on the tree of life. However, the discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that it was an animal.

Dickinsonia fossils have earlier been found in Australia, Russia, Ukraine , and China. Though Dickinsonia Eventually went extinct, the organism is one of earth’s earliest life, before giving rise to modern menagerie.

What are Ediacarans?

Organisms belonging to the Ediacaran Period, extending from approximately 635 million to 541 million years ago, are called Ediacarans, named after the Ediacara hills in South Australia, where fossils of a large group of early multicellular organisms were discovered in 1946.

They are thought to have evolved along with rising oxygen levels in the water near the ocean’s surface. The organisms are believed to have had blob-like structure reminiscent of modern jellyfish, worms, and sponges. These creatures arose in a world devoid of predators, and had no need for hard protective carapaces or skeletons.

Fossils of Ediacaran, creatures have been excavated from more than 30 locations on all continents except Antarctica. More than 1,500 well-preserved specimens have been collected from the Ediacara Hills alone, resulting in the naming of more than 60 species.

What happened when the Ediacaran period ended?

Ediacaran animals are the precursor to the complex life form we know today. When the Ediacaran period ended and the Cambrian period began, the world underwent an evolutionary uprising of sorts. The Cambrian explosion, as it is called, set the stage for the evolution of modern creatures. It gave rise to animals with far more familiar anatomies and behaviours, such as creatures with shells, spines, limbs, teeth and jaws. But scientists still do not know what sparked this eruption of life forms.

How significant is the recent Bhimbetka discovery?

  • The discovery makes India home to one of the oldest animal fossils in the world. It puts India on the map for studies of the Ediacarana era along with Australia and Russia.
  • The study emphasises that Ediacaran creatures perhaps survived well on land, which has intensified the debate over the organisms’ habitat. While some experts believe they survived mostly on the seafloor, others state that they lived on land as well.
  • The latest research also suggests that Dickinsonia were lichens.
  • Further, the discovery confirms the assembly of Gondwanaland by 550 Ma(mega annum). Dickinsonia fossils from India were found to be identical to the Rawnsley Quartzite in South Australia, providing evidence of their age, and suggesting the possible proximity of the land masses-India and Australia –in Gondwanaland of that era.

What is Gondwanaland?

Landmasses on Earth are in a constant state of slow motion, and have, at multiple times, come together as one. Gondwana was a southern supercontinent which assembled about 500 million years ago, during the late Ediacaran Period. Gondwana included most of the landmasses in today’s Southern Hemisphere, including Antarctica, South America, Africa, Madagascar, Australia-New Zealand. It also included Arabia and the Indian subcontinent, which have now moved into the northern Hemisphere.

 

Picture Credit : Google