Sometimes, organisms as innocuous as fungi can reveal the fate of mighty continents. Barely a week ago, news came out of the discovery of the world’s oldest known (till date) mushroom. The species is named Gondwanagaricites magnificus and existed 115 million years ago, on the now-lost super-continent of Gondwana. This was the Early Cretaceous, when the Earth was dominated by giant reptiles – dinosaurs on the land, plesiosaurs in the sea and pterosaurs in the air. Neither marsupial (pouch-bearing) nor placental (live-bearing) mammals had evolved. Instead, there were closely related but independent lineages – the multituberculates (that looked like rodents) and gobiconodonts (small carnivores).
There were forests but not of the kind we know today. Flowering plants were still evolving and towering over the landscape were great conifer, ginkgo and cycad trees. It was in such an environment that Gondwanagaricites magnificus flourished. It stood 5 cm tall, with a stalk and cap like extant mushrooms. Electron microscopy revealed that Gondwanagaricites had gills under its cap that would release spores. Scientists believe that the presence of gills and spores (through which it reproduced) makes it a member of the fungal order Agricales (gilled mushrooms). They are one of the most well known and abundant fungal orders, with as many as 13,000 species.
Gondwanagaricites magnificus happens to be the oldest known representative of the gilled mushrooms. Even more fascinating is the way in which it was fossilized. Paleontologists from the University of Illinois at Urbana-Champaign believe that the specimen was growing on a river bank, from where it tumbled down into the waters (probably due to the bank collapsing on account of a flash flood triggered by monsoon downpours). The river carried it into a lagoon where the mushroom sank through the salty water, reaching the bottom and getting covered by layers of fine sediment. Its tissues were slowly mineralized, forming the fossil that was discovered by scientists. All of this without being fragmented; nothing short of a miracle for such a frail organism.
But the most interesting part of the story is about the place where the mushroom was found – northeastern Brazil. Here stands a plateau, the Chapada do Araripe, dominating a dry and hot hinterland. At its base, lies the Crato Formation, a lagerstatte (scientific term used to describe ancient sedimentary deposits rich in fossils, including those formed by the soft tissues of long dead organisms). In the Early Cretaceous (between 146-100 million years ago), there existed a shallow inland sea in what is northeastern Brazil. Layers upon layers of sediment, containing the remains of insects, fish, frogs, lizards, dinosaurs, pterosaurs and conifers, were laid down. Over time, they turned into limestone. It was among these fossils that the paleontologists discovered Gondwanagaricites.
The name Gondwanagaricites magnificus means magnificent (magnificus) fossil mushroom of Gondwana (Gondwanagaricites). The name derives from the long-lost super-continent on which this species existed and which dominated the southern half of the globe. Gondwana comprised South America, Africa, Arabia, Madagascar, India, Antarctica, Australia and New Zealand, joined together as a vast landmass that stretched from the South Pole to the Equator. By the Early Cretaceous, it had begun to disintegrate. East Gondwana (made up of Madagascar, India, Antarctica, Australia and New Zealand) lay to the south, across the ocean from West Gondwana (South America, Africa and Arabia). Another rift was opening up between South America and Africa-Arabia, giving rise to the South Atlantic.
This is when the Crato Formation took shape and Gondwanagaricites magnificus flourished (about 115 million years ago). The name of the super-continent (and in turn, that of the mushroom) derives from a Dravidian people, the Gonds. Though spoken of as one tribe, they are actually a collection of multiple tribes, numbering between 12 to 15 million, and living over a wide expanse of Central India. Their homeland was known as Gondwana (the Forest of Gonds). The term was applied by Henry Benedict Medlicott (an Irishman working for the Geological Survey of India), in 1872, to the geological formations he had come across in the region. The name was then borrowed by the Austrian geologist Eduard Suess (who added the suffix ‘land’) to describe a great southern landmass he had proposed in his four volume work – Das Antlitz der Erde (‘The Face of the Earth’).
Published between 1883–1909, ‘The Face of the Earth’ put forward the idea of the Earth’s present continents being joined together at one point of time. This was his way of explaining the striking similarities observed in the geological formations of South America, Africa and India. This included fossils of an order of seed ferns, the Glossopteridales. Suess saw this as evidence of these lands being connected by a land bridge (formed by dropping sea levels). It was only in 1912 that the German meteorologist and geophysicist Alfred Wegener came up with the radical hypothesis of continental drift. Having noticed the close fit between the coastlines of South America and Africa, he argued that the continents of the world were once joined together and that the present configuration was the result of their disintegration and displacement.
The proposal were published in his Die Entstehung der Kontinente und Ozeane (‘The Origin of Continents and Oceans’). Wegener utilized both geological and paleontological evidence to explain his views, pointing out to the similarities between the southern landmasses. This approach was taken forward by the South African geologist Alexander Du Toit in his 1937 book – ‘Our Wandering Continents’. It pointed out the 290 million year old glacial deposits spread across these regions, as well as the unique flora and fauna that they shared, remains of which were preserved in Brazil’s Santana Formation, South Africa’s Karoo Supergroup, India’s Gondwana System, Australia’s Maitland Group and Antarctica’s Whiteout Conglomerate.
The Gonds after whom this mighty super-continent is named speak a language (Gondi) closely allied to my mother tongue, Telugu. Both belong to the South Central branch of the Dravidian language family. But one must not forget that human beings as a species (leave alone Dravidian speakers) came into existence a long, long time after the breakup and disappearance of Gondwana. The super-continent played a crucial role in the evolution of plant and animal life; evidence of which can be found scattered across its constituent landmasses. This is what makes the study of natural history such a fascinating pursuit. However, Brazil’s Crato Formation and fossilized mushroom are not the only link between South America and South India. There are other, equally illuminating aspects. More about that later.
Image Attribution: The image above, sourced from Wikimedia Commons, shows a Muria youngster in traditional attire. It was uploaded by Yves. The Muria are a tribe living in the Central Indian state of Chhattisgarh. Closely related to the Gonds, they speak the Muria language (of which there are three distinct types – Eastern, Western and Far Western).
- The Guardian
- Live Science
- Online Etymology Dictionary
- Gondwana: How It Got Its Name
- Encyclopaedia Britannica
- The Geological Society
- The Virtual Fossil Museum