The evolution of increasingly diverse life forms is an outcome of a process of natural selection after life first arose. The origin of life on Earth is unknown, but it is thought to have occurred at least 3.5 billion years ago, during the Hadean or Archean ages, on a primordial Earth with a significantly different environment than that which exists today. Self-replication and inheritable features were essential characteristics of these life forms. 

Species that were unable to adapt to changing environmental conditions and competition from other living things died out. Many of these earlier species, however, may be found in the fossil record. All existing species can be traced back to the original primitive life forms, according to current fossil and DNA evidence.

The sun’s energy could be gathered to produce conditions that allowed for more sophisticated living forms when rudimentary forms of plant life developed the process of photosynthesis. The ozone layer formed as a result of the oxygen that collected in the atmosphere. The fusion of smaller cells into larger ones culminated in the formation of eukaryotes, which are more complicated cells. Colony cells got more specialized as time went on, resulting in real multicellular creatures. The ozone layer absorbed damaging UV light, allowing life to colonize the Earth’s surface.

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Fossil animal that represents an important intermediate step in the evolution of fish to land-dwelling animals

The “fishapod,” also known as Tiktaalik roseae, is a 375 million-year-old fossil fish discovered in the Canadian Arctic in 2004. Its finding throws light on a watershed moment in the evolution of life on Earth: the first fish to venture onto land.

Tiktaalik resembles a cross between the primordial fish it ate and the first four-legged animals (dubbed “tetrapods” from the Greek tetra-, which means four, and -pod, which means foot). In fact, all animals descended from these pioneer amphibians, including humans, are referred to be tetrapods). Tiktaalik was around 12 million years old when the first tetrapods appeared (which are approximately 363 million years old). As a result, the discovery of tetrapod traits in a fish like Tiktaalik is remarkable since it indicates the first occurrence of these unique features in the fossil record.

While this offers us a general idea of development from the time of the first land organisms to the time of the first mammals, many of the details are still unknown. Every new fossil find has the potential to reshape our evolutionary timeline. Tetrapod brains, for example, only fill around half of their skulls, according to one of the most recent studies. The rest was filled with fatty tissue or fluid, leaving plenty of room for the creatures to expand as they adjusted to life on land.

New human species 'Dragon man' may be our closest relative


The skull of an ancient human found in northern China may belong to a previously undiscovered human species known as Homo longi, or “Dragon Man,” according to scientists. The well-preserved skull of Dragon Man is the largest Homo erectus skull ever discovered. According to the study, Dragon man may be the most closely related species to Homo sapiens, perhaps closer than Neanderthals, who were previously thought to be our closest relatives.
This was the first time the scientific team had ever seen a skull like this. “His skull was enormous, with a long, low shape and a massive brow ridge over the eyes, enclosing a large brain.” He had a broad face, nose, and jaws, as well as large eyes. But, like a modern human, his face was low in height, with delicate cheekbones, and tucked back behind the braincase.”