14 Ramapithecus: Phylogenetic and Taxonomic status

Ms. Sangeeta Dey and Prof. A.K. Kapoor

Contents:

1. Introduction

2. Ramapithecus

3. Significant anatomical characteristics of Ramapithecus

4. Discovery and distribution of Ramapithecus

5. Paleoanthopological evidence from India with special references to Siwaliks

6. Phylogenetic position of Ramapithecus

7. Controversy regarding the taxonomy of Ramapithecus Summary

Learning Objectives:

To describe the physical features of Ramapithecus
To understand the Phylogenetic position of Ramapithecus
To describe the fossil evidences recovered in the context of Ramapithecus
To learn about the facts that leads to the evolutionary advancement of hominid line
To understand the taxonomic status of Ramapithecus

1. Introduction

The geological time scale starts with the formation of the earth, some 4.6 billion years ago. The first and longest span of time was the pre-Cambrian, where forms of life were small, simple and soft-bodied. The onset of Cambrian about 570 million years ago marked the rise of shelled animals in the sea. Then followed the “ages” of the fish, Amphibians and Reptiles, culminating in the domination of land by the dinosaurs, from about 200 to 65 million years ago.

Mammals first appeared more than 200 million years ago, but were overshadowed by the reptiles. However, some 65 million years ago all the dinosaurs – as well as other groups of reptiles on land, in the sea and in the air, and certain other animal groups and many plants too – became extinct over a relatively short period. This was only one of several “mass extinctions” that have occurred through geological time. The extinction marked the beginning of the Tertiary period and the Age of Mammals. The Tertiary is divided into epochs, and development in the primate group can be traced from the fossils they left in the rocks formed during the time.

The first hominids (members of our family Hominidae) crop up in the fossil record less than million years ago. Mammalian evolution covers only about 4 percent of the Earth’s entire history, and humans have been around for only 0.1 percent of the history of our planet.

The quest for our ultimate origins began with the origin of life itself. The earth is about 4.6 billion years old. Fossil evidence shows that small, simple organisms were living at least 3 billion years ago. A great deal of evidence supports the notion that all present day organisms are related to each other, and these forms as diverse as slime molds and elephants, oak trees and beetles, roses and humans – ultimately arose from a single common ancestor, some 3.5 billion years ago. This means that a single evolutionary tree or phylogeny, relates all organisms, living and extinct. Biologists and palaeontologists assume that life evolved from its simple beginnings through a succession of stages, as represented in the fossil record, toward the present day diversity of some 10 – 30 million species. This does not mean that today’s diversity is in some way the destiny or the end point of evolution; there has been great diversity in the past, and there may be in the future.

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2.Ramapithecus

The last and most important hominid from Miocene period is the Ramapithecus. It is accepted by many scholars to be the first true hominid. Ramapithecus dates back to the period between 14 – 10 million years ago. It was discovered and christened as Rama’s ape by Edward Lewis in the year 1934. The specimen was later analyzed by Simons in the year 1964. Simons gave the name Ramapithecus punjabicus to this find, which was a long time thought to be the highest evolved form in the Hominid evolution, belonging to the ape group of Dryopithecus. The fossils of Ramapithecus (Primarily teeth and jaw) come from two areas: the Siwalik Hills in India and Fort Ternan in Kenya. Other specimens have been discovered from Turkey, Hungary and Greece. The Ramapithecus fossils roughly date back to periods between 14 and 9 million years ago. The ecological setting of Fort Ternan and the Siwalik Hill fossils is that of a forest woodland environment. The Greek fossils, being younger, are that of a drier, savanna like environment.

The hominid features of Ramapithecus include reduced and vertically implanted incisors, and canines, little or no diastema, flattened and thick enamelled premolars and molars that appear to be adapted for heavy chewing and processing of heavy food stuffs. Moreover, the placements of chewing muscles indicated an increased chewing pressure brought to bear on the food being eaten. These features, sufficiently different from the earlier Miocene fossils, indicate Ramapithecus direction to hominid line – perhaps the first hominid.

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Ramapithecus specimens very strongly suggest the exploitation of a new dietary source – most likely seeds, nuts and grasses – that indicate a shift from the softer forest fruits and vegetables relied upon by apes. This dietary shift is rather clearly associated with the climatic changes in the later part of Miocene that led to an increase in open grasslands and the decrease in the forest habitat of apes. There is a greater probability that this hominid form apparently was moving into a new ecological niche; it was beginning to exploit a more open ground environment similar to that inhabited by later hominids. Ramapithecus is also the most likely candidate for the ancestry of later hominids because of its presence in an area where the next hominids – the Australopithecus – have been found.

The possible adaptation that Ramapithecus made to open – ground living include an increased degree of hand and finger preparation of food, perhaps more frequent use of tools in such preparation, a tendency towards upright posture and bipedal locomotion for movement with a wide field of vision through the tall grasses on the open plain, possibly longer periods of growth and development, and perhaps, even a more frequent inclusion of meat in the diet. None of these adaptations can be clearly demonstrated because of lack of fossil evidences, but what we do know is that these adaptations were clearly present by the time the next phase of hominid evolution – the Australopithecus – had began. It is highly likely that Ramapithecus had begun to evolve and acquire those hominid features that led to the evolution of Australopithecus.

3. Significant Anatomical Characteristics of Ramapithecus

Facial profile of Ramapithecus is orthognathus that the profile is the face nearly vertical with straight jawed with the front of the head or skull is perpendicular in consequence of the shortness of the jaws.
Ramapithecus has nearly vertical placement of incisors and canines opposite to apes which has teeth in slight procumbent position.
Generally apes have projected canines with large spaces in between whereas Ramapithecus canines are not projected and they posses very narrow spaces.
It has canine fossa or depression encountered in fossils Ramapithecus kenyapithecus.
The gap between two teeth is usually referred as diastema and it is evident in apes whereas in Ramapithecus, little or no diastema was found.

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The size of the front teeth that is incisors and the canines to that of the cheek teeth that is premolars and molars is nearly the same which is an indication of human characteristics.
The premolars and the molars due to the changed in food habits and because of adaptation from soft food to heavy chewing and grinding of hard food stuff led becomes flattening and deposited with thick enamel.
The molars posses the Y-5 cusp pattern as in Dryopithecus.
The size of the third molar is reduced as compare to the first and second molar.
Tooth rows are slightly divergent and have been identified as parabolic or slightly V-shape by some scholars.
Maxilla reduced in size which indicates a placement of the chewing muscles which actually increases the chewing pressures required to bear or chew the foods being eaten.
Inside the lower jaw of Ramapithecus shelf –like ridges are present.
There is a presence of large inferior torus on mandible
Ramapithecus posses rounded dental arcade.
Like humans, the palate of the Ramapithecus is arched.

4. Discovery and Distribution of Ramapithecus

G.E. Lewis in 1932 made the discovery of Ramapithecus for the first time ever in the Siwalik Hill region of India. He uncovered an upper jaw and assigned this fossil to a new genus and species as Ramapithecus brevirostris. The generic name with initial as ‘Rama’ represents being the mythical prince who is the gem of the Indian epic literature and the species name given by Lewis is a Latin word used for ‘short snouted’.

After that in 1961, another fossil of Ramapithecus was unearthed from south western Kenya near Fort Ternan by L.S.B. Leakey. Leakey called it the Kenyapithecus wickeri. The fossils include parts of both sides of an upper jaw. The species name is based on the name of the owner of the farm from where the fossil was recovered

RAMAPITHECUS FOSSIL DISCOVERY SITES WITH DISCOVERERS

During World War II, the fossils of next Ramapithecus were excavated in Greece by a German geologist, Von Freyburg. He also assigned the specimen into a new genus and species as Graecopithecus freyburgi. He unearthed lower jaw with complete set of tooth at the time of discovery.

Another fossil of Ramapithecus was invented and discovered in 1973 in Turkey near Candir some 40 mile north east of Ankara. This fossil is belongs to Miocene deposit. The fossil includes lower jaw. It was named as Sivapithecus alpani. The species name of the candir jaw honours the director of the Turkish Geological Survey.

A major group of Ramapithecus fossils has also been unearthed from the Rudabanya Mountains of north eastern Hungary in the coal deposits of Miocene age. They are also assigned to still another genus and species Rudapithecus hungaricus. The genus and species name is because of the place of their discovery.

5. Paleoanthopological Evidence from India with special references to Siwaliks

As India was assuming its present geographical and biotic features, there evolved various species of apes whose fossils are found in the Siwalik Hills bordering the Himalayas. Dating from 15 to 7.5 million years ago, these are the earliest members of our taxonomic superfamily, the Hominoidea, to appear in South Asia. Their evolutionary relationships to other extinct and contemporary ape species recovered in Europe, Africa and East Asia give them a significant place in the biological history of primates in general and the ancestry of humans in particular. Scientists who studied the Siwalik ape fossils assigned some of their species to fanciful taxonomic names taken from Hindu mythology. Thus Ramapithecus, Sivapithecus, Brahmapithecus and Sugrivapithecus came to be known collectively as the God – Apes of Siwaliks. During the course of past century and a half this fossil record of Miocene hominoids has been variously interpreted, a major question being the evolutionary affinity of God – Apes to the earliest members of our taxonomic family, the Hominidae.

6. Phylogenetic position of Ramapithecus

The possible hominid status or the Phylogenetic position of Ramapithecus has been the center of a great deal of debate. A great abundance of hominoid fossil materials of Ramapithecus has been found in the Miocene epoch which is certainly called the epoch of hominoids. The first radiation of the hominoid has its roots in the beginning of the explosive adaptive radiation of the Ramapithecus. The remarkable evolutionary success represented by this adaptive radiation is shown in the geographical range already established for hominoids during this period. Miocene hominoid fossils have been discovered in France, Austria, Spain, Czechoslovakia, Greece, Hungary, China, India, Pakistan, Turkey, Saudi Arabia, Egypt, Uganda and Kenya.

We need to understand the status of other fossils to conclude the phylogeny of the Ramapithecus such as Dryopithecus.

During Miocene and Pliocene epochs, the Dryopithecus made their appearance in Europe, Asia and Africa. They resemble the size of gibbon in the body form and with the gorilla for the body structure. The fossils or remains of Dryopithecus unearthed were mostly teeth and jaws. Thus, Scientists are restricted to the dentition pattern as characters to distinguish Dryopithecus from Hominidae. After observing the dentition pattern or dental characters, Gregory and Hellman came to an conclusion that Dryopithecus were the common ancestor of the anthropoid apes and man.

Lartet in the year 1856, discovered a lower jaw bone and assigned to the genus Dryopithecus from Miocene deposits in south France. The Phylogenetic position of Dryopithecus in the evolutionary tree has been found on the basis of peculiar patterns of dentition which is unique to Dryopithecus which is characterized by five cusped lower molars. It has been concluded by many scientists after careful examination of the fossil remains of different species of Dryopithecus like Dryopithecus fontani, Dryopithecus rheuanus and Dryopithecus darwini, that it probably be the ancestors of gorilla, chimpanzee and hominoid forms respectively.

The fossil remains discovered in Europe and Asia since 1970 suggests that Dryopithecus gave rise to atleast three genera between 10 and 15 million years ago. These three genera are Sivapithecus, Giogantopithecus and Ramapithecus. The first two genera primates have face as large as modern chimpanzee and gorilla. However, Ramapithecus had a small face which clearly reveals its resemblance or similarity to later hominids. Pilbeam in an attempt to draw attention towards the morphological features shared by the group which differentiate it from others and to peculiarly focus on adaptation and biology rather than phylogeny, has proposed that a number of the middle and late Miocene species of fossil remains can be classified together in Ramapithecinae. Within the Ramapithecid genera, the two most widely distributed are Ramapithecus and Sivapithecus.

The teeth of Ramapithecus and Sivapithecus is difficult to distinguish when in isolated form except on the basis of size. The front teeth especially the upper central incisors of Sivapithecus are often quite large while the canine is fairly good sized. The most distinctive aspect of Sivapithecus dentition is seen in the back tooth row, where molars are large, flat wearing, and thick enamelled. Facial remains of them have concave profiles and projecting incisors. However, the Ramapithecus teeth are smaller and show less canine dimorphism than Sivapithecus though larger than the Pliocene hominid Australopithecus afarensis.

It is considered that the fossil finds of Ramapithecus implant a new array of characters which provides insights for the human evolution and it is the most important fossil which provides this immense evolutionary knowledge. This is possible because of the efforts of G.E. Lewis who unearthed the fossilized remains of the Ramapithecus from the Siwalik hills of India and Simons who attempted and attributed a very significant phylogenetic position of Ramapithecus in the line of human evolution. Scientists by keen observation of Ramapithecus highlighted key points which are highly effective in the search of human ancestral pattern. Some described Ramapithecus as a weapon wielding terrestrial biped by examining the nature and extent of its teeth. The scientists who are the proponents of Ramapithecus as a human ancestor are Simon, Tattersall and Pilbeam. Conroy and Pilbeam conducted a review based study and made a plausible interpretation about Ramapithecus as the late Cenozoic ancestor of Australopithecus. However, the materials so far excavated discovered in context of Ramapithecus suggests that it belongs to a line between Dryopithecus group belonging to early Miocene and later modern hominids.

Thus, on the basis of the fossil findings and interpretations about Ramapithecus, it has been widely regarded as first hominid and ancestor of Australopithecus. It is suggested that it diverged from the ape line around 14 million years ago and marked the evolutionary beginning of the hominid line of evolution. The main characteristics which is responsible for giving Ramapithecus the status of a true hominid is its dental similarity with that of the later hominids. Swartz and Jordan, while discussing the status of Ramapithecus made a remarkable comment that when a creature is defined as hominid, it doesn’t mean that it is a modern man, but the term is just depict human like forms.

7. Controversy regarding the taxonomy of Ramapithecus

The taxonomic status of Ramapithecus depends on the fossil fragments of teeth and jaws unearthed and discovered after the first reported discovery by G. Edward Lewis in 1934. Lewis identified his initial discovery as a new form and he named it as Ramapithecus. Then a number of discoveries are carried out and unearthed an number of fossil remains which are recognized also an new form and the fossil remains are given separate genus and species names based upon the geographical sites from where they are discovered such as Kenyapithecus, Graecopithecus, Rudapithecus, Sivapithecus. Then, Simons and Pilbeam in the year 1965 attempted to review the entire group of fossil discoveries and suggested that all the varied forms of fossil remains actually belong to two species only. They indicated Sivapithecus as one the species form which was basically ape-like and thus it can be considered as an ape ancestor and the other was Ramapithecus which possess a number of hominid characters and thus regarded as an early hominid ancestor. However, a series of more recent studies cast doubt about it but the view was extent in 1977.

Lipson & Pilbeam and Andrews and Cronin in 1982 suggested that the two form that is Sivapithecus and Ramapithecus are actually one single species group with the males and females of sexually dimorphic species group. This idea is put forward probably because to make these data conform to the concept of molecular clock. The molecular clock assess the time duration from the common ancestry of two species using the concept that molecular evolution occurs or takes place in a linear fashion, suggesting that humans and apes had a common ancestor once upon a time about five million years ago or even closer to the present time. It this concept of molecular evolution was considered true, then it would be logically impossible that there existed prior ancestors of humans – Ramapithecines dated about 8 to 14 million years ago. Thus, the new views and suggestions on the fossils remains have been focussed on the ape-like features of Ramapithecines and the most powerful is the sexual dimorphism which was found in every great ape known but not present markedly in any species of the genus Homo so far discovered and identified. But then the discoveries from Yunnan, strongly suggests that the two species evolved there. One of the major evidence of from Yunnan is a large creature with larger dental features, sexual dimorphic, large canine dimorphism, large canine heights and areas with more herbivorous dentition. This has been identified as Sivapithecus ape-like features. Comparatively, the other creature is smaller possess smaller dentalal features, sexually dimorphic, smaller canine dimorphism, large canine heights and areas with more omnivorous dentition. Thus it is attributed that we would not deny that it is a adaptive radiation of pre-human form.

Summary

The last and most important hominid from Miocene is Ramapithecus. It dates back to the tie period between 14 – 10 million years ago. It was discovered and christened as the Rama’s ape by Edward Lewis in the year 1934. The specimen was later analyzed by Simons in the year 1964. The hominid features of Ramapithecus include reduced and vertically implanted incisors, and canines, little or no diastema, flattened and thick enamelled premolars and molars that appear to be adapted for heavy chewing and processing of heavy food stuffs. Ramapithecus specimens very strongly suggest the exploitation of a new dietary source – most likely seeds, nuts and grasses – that indicate a shift from the softer forest fruits and vegetables relied upon by apes. Ramapithecus is also the most likely candidate for the ancestry of later hominids because of its presence in an area where the next hominids – the Australopithecus – have been found.

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