Fossils and evolution of life in Newfoundland

In addition to the continental drift stories, I found the evidence for very ancient life forms in Newfoundland, in the form of fossils also very interesting. The findings in Newfoundland add significantly to our current understanding of evolution. The fossils here are not the giant fossils of dinosaurs we usually think of when we speak of fossils, but very tiny fossils as in the picture below, of very early visible complex living things from around 600 million years ago. A lot of it was again, new information for me.

Let me put the time frame of living things on earth in perspective. Here again, there are a few controversies, but also consensus on many topics. I found it difficult to get the chronological information of life on earth in an easily understandable manner online. And so, I have put stuff together from many different sources. Most of the evidence comes from fossils found in different parts of the earth. People have also used other types of dating methods. The fossils from microscopic organisms are not of themselves but of structures large numbers of them together (colonies) have produced together. I think, probably like a beehive indicating presence of large numbers of bees.

Time periods from the beginning of the Earths existence, is divided into specific periods using a geological time scale and these have specific names. I did not know much about these timelines or terminologies when I started reading about these. Hence, I thought it will be a good idea to summarise some information from a web site I found useful https://www.geologyin.com/2014/12/geologic-time-scale-major-eons-eras.html.  

Time from 4.6 billion years ago to the present is divided into 4 Eons – Hadean, Archean, Proterozoic and Phanerozoic, each being millions to billions of years long. All four Eons are further divided into eras, periods, epochs and ages. Phanerozoic Eon is the current one with visible life and in which we live. I found this picture, summarising and providing clarity to our thoughts on the history of life on earth.

Life as single celled microscopic organisms appeared possibly around 3.5 billion years ago or even a few million years earlier, during Archean Eon. Photosynthetic microorganisms capable of producing oxygen arose probably around 3.4 billion years ago and slowly enriched the atmosphere with oxygen. Complex multicellular forms appeared may be three billion years after that, during the Ediacaran period which is in the late Proterozoic Eon.

Fast forward to Phanerozoic Eon in which we live, is divided into three eras, based on major changes in climate, geography and diversity of life and are named Palaeozoic, Mesozoic, and Cenozoic. The eras are further divided into periods, as in the picture. Palaeozoic or the era of ancient life spans from around 540 million years ago to 250 million years ago. During most of this era, as you will remember, earths land mass was joined together as a single super continent called Pangea. This era is also important for life on earth. During the initial period of this era, the Cambrian period, several different life forms including precursors of animals and plants we know now started appearing and spreading to most parts of the earth. This is called the Cambrian explosion. Invertebrates, fish, amphibians, reptiles and land plants increased considerably and spread to many parts of the earth during this Era.

Scientists are still debating what caused this explosion of life forms, especially since the evolution of life was much slower and the variety minimal in the pre-Cambrian periods. Large scale deglaciations I mentioned earlier, must have led to increase in ocean oxygen and development of probably the earliest multicellular visible creatures. Some theories suggest that the abundance of plant life around the Cambrian period led to increase in oxygen and then development of other forms of life.

There were also major extinctions of species at the end of Palaeozoic era and at the end of Mesozoic era. It is believed that over 99% of species that evolved from ancient times are now extinct.  Cenozoic era, our era started 66 million years ago and during this period continents drifted to their current positions and humans appeared. We have been here only for a short period in the grand scheme of things.

I was struck by some similarities between this scheme of evolution and what is described in the Bible. Obviously, nothing happened in one day. But it could be that the ancient authors described a time-period as a day, or it may be the concept of ‘thousand years as one evening gone’. The Book of Genesis talks about light as the first thing happening and a formless expanse later being covered with water. Then land appears surrounded by water. And then abundance of plants happened followed by abundance of all kinds of other creatures. Sea life appeared before land creatures and lastly man. I was wondering how the ancient authors had this concept of evolution, but they called it creation. It may be that they just meant that this is how it happened. The creation sequence also puts appearance of moon (night light) sometime after the earth was created and evidence now suggests that this was the case. Amazing!!

Now, coming back to the fossils in Newfoundland. In most situations you find evidence of past life in digs and the more remote in the history, deeper the dig. Based on the picture, one will probably have to dig really, really, very deep to find fossils of life millions of years ago. But Newfoundland has many areas where ancient ocean floors lie exposed and so evidence for ancient marine life can be seen directly on the surface. These fossils can be found along cliffs, beaches, streams, quarries, rock out crops and so on. Unlike dinosaur fossils, these are very small impressions of the tiny bodies in the rock.

For a very long time, it was believed that there was no life during pre-Cambrian period and that life appeared with Cambrian explosion. And this was a very important missing link for Darwin’s theory.  It so happens that a rocky outcrop in downtown St. Johns carried the crucial evidence for pre- Cambrian life. Some discoidal fossils found here around 1872 was later identified after much debate as pre- Cambrian. It was named Aspidella terranovica, meaning ‘little shield from Newfoundland’.  This is one of the earliest known detections of pre-Cambrian multicellular life.

Now we know that the earliest recognisable complex organisms appeared in the Ediacaran period which ended about 540 million years ago, immediately before the Cambrian period started. So about 300 million years before dinosaurs. Ediacaran period saw some profound changes on earth such as changes in ocean chemistry, atmospheric oxygen levels nearly reaching current levels and ice age retreating.  Life during this period is collectively called Ediacaran biota and consisted of in addition to colonies of microorganisms, about 200 different complex visible living things. There is now conclusive evidence that there was a global spread of Ediacaran biota, based on findings in England, Australia, Russia, Namibia and other places.  These dominated the earth for about 40 million years and then for some reason disappeared. Some people refer to it as a ‘failed experiment in evolution’. It is interesting to read more details of this period including how these finds helped with Darwin’s theory of evolution http://www.ediacaran.org/the-ediacaran-biota.html

The  fossils from Newfoundland are believed to be the oldest in the Ediacaran period, going back to about 575 to 560 million years. These can be seen in Conception Bay and St johns’ rocks. Impressions of thousands of these diverse sea floor creatures that lived during that period are preserved as discoidal fossils to those that are three dimensional, in different locations in this region. These are some pictures from a location near Spaniards Bay.

The Mistaken point Ecological Reserve is one important location which organises guided tours to study these ancient fossils. They are also exhibited in museums

Other interesting fossil facts – Newfoundland has the earliest fossil evidence for life that could move/shuffle. And, the official location that defines the boundary between Ediacaran and Cambrian periods is in Newfoundland.

In addition to these, there are also several locations in Newfoundland where there are fossils from later periods, still millions of years ago – Cambrian period onwards in the Palaeozoic era https://www.gov.nl.ca/iet/mines/publicoutreach/fossils/fossils-nl/ . These fossils differ in the three zones and include early animal and plant fossils. In the eastern region, Cambrian and Ordovician shales and slates in many different locations on the Avalon Peninsula carry fossils. In the central areas several other types of fossils are found on Ordovician and Silurian age marine deposited conglomerate, limestones, sand stones, shale and slate. Western Newfoundland has an abundance of a variety of animal and plant fossils belonging to Cambrian to Carboniferous periods. Newer finds are being made continually.

Cambrian fauna found in west and east are different. Eastern fossils bear similarities to those found in Sweden, Norway and some other countries now in Europe.

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