Fossil Primates

Primates classify the highest order of the animal kingdom. All the living primates have evolved and ‘adaptively radiated’ from a common ancestor. . Fossil primates show a palaeontological record of evolutionary processes. These changes mainly stretch over the last 65 to 80 million years. They help form a substantiated and solid bridge between living primates and fossil primates. The geological time scale is significant in understanding the major characteristics of fossil primates. They undergo significant changes due to climate and other conditions. It also provides crucial evidence related to the appearance and dominance of ancestral primate forms. The Cenozoic era is marked as a significant era concerning primate evolution and origins. Radical climatic and topographical changes took place during this geological era.  

Beginning of the primates

The Cenozoic era marks the beginning of the primates. This era is mainly divided into seven epochs. The climatic condition during this era was mainly tropical and subtropical. The Cenozoic Era is primarily characterised by the end of the “Age of the Dinosaurs” and the beginning of the “Age of the Mammals.”

The period was favourable for the living conditions of the primates. Anthropologists divide the Cenozoic era into two major periods:

1. Tertiary Period
2. Quaternary Period

These two periods are further divided into Epochs. The tertiary had five epochs, namely Paleocene, Eocene, Oligocene, Miocene, and Paleocene. 

The Quaternary period is divided into two epochs. They are the Pleistocene and the  Holocene epochs.

The oldest primate fossil is considered to be the Purgatorius. It was a small mammal that fed on small insects on the trees. It is considered to have evolved from the Cretaceous epoch from the Mesozoic era. 

The tertiary and Quaternary Period

The tertiary fossil period occurred 65-1.8 million years ago. The climatic conditions of this epoch were warm and humid. Mammals were evolving in more numbers, and mammals called primates evolved. Vegetation was also substantially blooming.

The quaternary period was present 1.8 million years ago. This epoch marked the ice age. The drifting of continents and the adverse climatic conditions marked the extinction of many animals and plants. Also, primates started moving to new places. 

Tertiary Fossil Primates

Many anthropologists study tertiary fossil primates to study the evolution and origin of primates. The teeth and jaw modifications mainly recognise the fossil primates of this epoch. Sometimes, the skull of the fossil primate is also studied. The fossil primates are classified into:

• Palaeocene primates

The fossil evidence of the oldest primates is found in the Paleocene era. The deposits of fossil primates are found in the middle of this era in the hilly and sloppy areas of France and North America. Teeth and jaw fragments are the main parts of the found fossil primates. The primate fossils discovered are categorised into three different families. Carpolestidae, Phenacolemuridae and the Plesiadapidae. The skeletal remains of the Plesiadapidae were found.

• Eocene primates

The fossil primates of this epoch were found in North America and parts of Asia. These primates were called the true primates. They had a bigger brain and other features compared to the Paleocene era. The primates of the Eocene epoch are categorised as Euprimates. Most Eocene fossil primates are typically divided into two major families – the Adapidae and the Omomyidae, which resembled the lemurs and tarsiers. 

• Oligocene Primates

Not many primate fossils are discovered from this era. The vast majority of mammals became extinct during this transition. Rapid and significant changes were seen in primate habits, climate, and geography. The oldest fossil primates were discovered in the late Oligocene epoch, and all these primate fossils majorly constituted anthropoids. Most Oligocene primates can be categorised into three principal taxonomic groups – Parapithecidae, Propliopithecidae, and Platyrrhini. Many primate fossils are found in Egypt and Europe. The parapithecids are the most common primate fossils recovered from Fayum in East-west Cairo. The dental formula of the primate dug had small teeth.

The members of pro-Pitheciidae are comparatively larger than the parapithecids. They are considered to be closely related to the apes. They are regarded as an intermediate between the Prosimians and the Anthropoids. 

• Miocene – Pliocene primates

The fossil primates of these epochs are considered together. Because they show a continuity of lineage in certain traits of Anthropoidea. Primate fossils of various Hominid forms were found in this era. They were discovered from different locations in Asia, Europe, and Africa.

From this period, the primate fossil remains of 

• Pliopithecus

 Primate fossil remains were discovered from early Pliocene deposits of Europe. An incomplete jaw represents it. Also, they show similarities to gibbon-like animals.

• Dryopithecus

Dryopithecus primate fossils are represented by teeth and jaw bones excavated from Miocene and Pliocene deposits of Europe and India. They were considered to be the most common ancestors of Apes and Man. These fossil primates are known for their dental orientation and jaw parts. Proconsul can be regarded as the African variety of Dryopithecus. 

• Ramapithecus

The Genus Ramapithecus represents hominid forms from the Miocene period. They were the initial step in the evolutionary divergence of humans from the common hominoids. 

Conclusion

The evolution of the tertiary primates is a crucial and complex step in understanding the evolution of primates. The climatic conditions majorly affected the evolutionary process. The palaeontologists draw major morphological and adaptable characters with the help of the fossil primates dug up from different regions. This enables them to study the various patterns and drawbacks of the evolution of primates.