All primates have evolved from a common ancestor through the process of adaptive radiation. Primates are the most advanced group of animals belonging to Kingdom Animalia. The Cenozoic era saw the commencement of Primates and the decline of the Dinosaurs, hence this era is also known as the ‘Age of Mammals’. The main reason for the evolution of mammals and the decline of dinosaurs is the radical climatic and geographical changes occurring during that time. Changes in temperature, vegetation cover, behavioural changes, etc. all lead to the evolution of mammals. Such changes favoured the growth, development, and reproduction of mammals and thus began the journey of the most advanced species on planet Earth.
Figure 1- Primate Fossils
The Cenozoic era is divided into two periods- The tertiary period and The quaternary period. Both of these periods had specific conditions and variations which led to the evolution of mammals.
This period comprises of Paleogene and Neogene periods.
It extends from 65 mya to 2.6 mya.
This period contains 5 epochs- Paleocene, Eocene, Oligocene, Miocene, and Pliocene.
The climatic conditions during this era is warm and humid, thus mammals such as primates and flowering plants evolved.
This is the latest period and is only 2.6 million years old.
This period witnessed various environmental and geographic changes such as ice ages, drifting of continents, floods, etc.
These conditions went on for many years and thus were responsible for the extinction of various huge mammals- such as mammoths, saber-toothed cats, mastodons, etc and birds. Also, humans started migrating to various places.
Quaternary period is divided into two epochs- Holocene and Pleistocene Epoch.
The early tertiary primates evolved and had a large brain, limbs having flat nails, and rounded molars and premolars. The fossils obtained during this period are classified as follows
The oldest primates were found in paleocene fossils. They were found in regions of France and North America. Most of the fossils found were teeth and jaw segments, which gave information regarding the eating habits of these organisms. The primates obtained were separated into 3 families- Carpolestidae, Phenacolemuridae, and Plesiadapidae
During this epoch proper primates were present because fossils from this epoch very resembling the various primate characteristics, thus they were known as true primates or Euprimates. They had larger brains and better features as compared to paleocene epoch fossils. These were first found in North America and some parts of Asia. These fossils resemble lemurs and tarsiers. Also, monkey-like primates arose in China. They were divided into 2 families- Adapidae and Omomyidae
During this epoch the separation between primitive and advanced primates took place. This was thought because the fossil of the skull of Rooneyia was found in Texas and had a mixture of features of both primitive and advanced primates. Most of the fossils found were of anthropoids. The Oligocene primates were divided into 3 taxonomic groups- Parapithercidae, Propliopithiescidae, and Platyrrhini. These fossils were found in Egypt, Europe, Cairo, etc.
Due to various climatic changes there was the formation of huge grasslands during this epoch. This formation led to the development of new types of primates which were terrestrial and ground walking. Fossil evidence of ancestors of orangutans(Sivapithecus) was found in Eurasia and ancestors of humans, gorillas, and chimpanzees (Dryopithecus) were found in Africa and Eurasia.
Not many fossils of this epoch are found. Most of the information obtained is regarding monkey families. Thus, this interval is considered the time when human lineage began to form in the regions of central and east Africa.
The period was known for various ice ages, the extinction of mammals, and the spread of humans. The fossils obtained are classified as follows
The Pleistocene age is known as the ice age since due to climatic changes ice sheets started covering land masses. During this time lots of animals became extinct. The fossils of dwarf mammoths were found in California. Also, remains of Shasta ground sloth, Harringtins mountain goat, etc were found in Carlsbad Caverns, Mammoth caves, and Grand Canyon national parks.
This is the ongoing epoch in which we all are living. There are no fossils for this epoch found yet. This is the time when humans have spread all over the globe and have led to various developments. Additionally, human activities are causing disturbances in the environment, which is not only affecting us but also the flora and fauna present around us.
The information regarding the ancestors of various current primates is obtained from various fossil records. The tertiary fossil records have been classified into Paleocene, Eocene, Oligocene, Miocene, and Pliocene fossils. The quaternary fossil records included the Pleistocene fossils. These fossil records show how primates have evolved and what were the climatic conditions which led to their evolution. Also, specific features, such as teeth and jaws, nails, fingers, etc gave information regarding their food habits and modes of locomotion.
Q1. What are fossils?
Ans: Fossils are paleontological information that gives data regarding the history of any particular organism. Thus fossils of various periods give us information regarding the organism, their structure, and the environmental conditions prevailing in that period.
Q2. How are primates classified?
Ans: Primates are classified into
Strepsirrhines- which retain primitive features, eg- lemurs, bushbabies, etc.
Haplorhines- these have advanced features, eg- monkeys, apes, tarsiers, etc.
Q3. What is Paleoanthropology?
Ans: Paleoanthropology is a subtype of anthropology, which is known as the study of extinct primates. They study various fossils and based on scientific principles gain a better view of the environmental conditions which led to evolution.
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