Dickinsonia: Earliest Known Living Animal

• 15 Feb 2021

Why in News

Recently, researchers have discovered three fossils of the earliest known living animal, the 550-million-year-old ‘Dickinsonia’ on the roof of the Bhimbetka Rock Shelters.

• The fossils were found in the roof of the Auditorium Cave at Bhimbetka Rock Shelters.

Note:

• It was believed that sponges were the oldest living organism however there is currently no evidence that sponge-like animals conquered the oceans before 540 million years ago, when the first unambiguous fossils of sponges and most other groups of animals start to appear in the geological record.
• The earliest evidence for animals on Earth is now the 558 million-years-old Dickinsonia and other Ediacaran animals.

Key Points

• About Dickinsonia:
  • Discovery:
    
    • In September 2018, an international team of researchers claimed to have discovered the world’s oldest fossil of Dickinsonia, which first appeared around 571 million to 541 million years ago.
    • Current fossil evidence dates back around 100 million years from Dickinsonia.
  • Period and Area:
    
    • It is an extinct genus of basal animal that lived during the late Ediacaran period in what is now Australia, Russia and Ukraine.
      
      • Basal animals are animals which have radial symmetry in their body plans. They have very simple bodies and tend to be diploblastic (derived from only two embryonic cell layers).
  • Appearance:
    
    • Thought to represent the earliest flowering of complex multicellular life on our planet, these creatures arose in a world devoid of predators, and had no need for hard protective carapaces or skeletons.
      
      • Their soft, squishy bodies resembled tubes, fronds or even thin, quilted pillows, they bore scant similarity to the anatomy of animals today.
  • Classification:
    
    • Its affinities are presently unknown, its mode of growth is consistent with a stem-group bilaterian affinity, though some have suggested that it belongs to the fungi or even an “extinct kingdom”.
    • The discovery of cholesterol molecules in fossils of Dickinsonia lends support to the idea that Dickinsonia was an animal.
• Significance:
  
  • It is further proof of the similar paleoenvironments and confirms assembly of Gondwanaland by the 550 Ma (mega annum).
    
    • A paleoenvironment is simply an environment that has been preserved in the rock record at some time in the past.
    • Mega-annum, usually abbreviated as Ma, is a unit of time equal to one million years.
      • It is commonly used in scientific disciplines such as geology, paleontology, and celestial mechanics to signify very long time periods in the past.
  • This finding could help scientists better understand the interaction of geology and biology that triggered the evolution of complex life on Earth.
• Bhimbetka Caves:
  
  • History and Period Span:
    
    • The Bhimbetka rock shelters are an archaeological site in central India that spans the prehistoric Paleolithic and Mesolithic periods, as well as the historic period.
    • It exhibits the earliest traces of human life in India and evidence of Stone Age starting at the site in Acheulian times.
    • It is a UNESCO World Heritage Site that consists of seven hills and over 750 rock shelters distributed over 10 km.
  • Discovery:
    
    • The Bhimbetka rock shelters were found by V S Wakankar in1957.
  • Location:
    
    • It is located in Raisen District between Hoshangabad and Bhopal in Madhya Pradesh.
      
      • It is about 40 kilometres south-east of Bhopal in the foothills of the Vindhya Mountains.
  • Paintings:
    
    • Some of the Bhimbetka rock shelters feature prehistoric cave paintings and the earliest are about 10,000 years old (c. 8,000 BCE), corresponding to the Indian Mesolithic.
    • Most of these are done in red and white on the cave walls.
    • A multitude of themes were covered in this form of rock art and it depicted scenes like singing, dancing, hunting and other common activities of the people staying there.
      
      • The oldest of the cave paintings in Bhimbetka is believed to be about 12,000 years ago.

Source:TH