development team principal...

1

Anthropology

Identification and Description of Fossil casts

Paper No. : 14 Human Origin and Evolution

Module : 26 Identification and Description of Fossil casts

Prof. Anup Kumar Kapoor Department of Anthropology, University of Delhi

Development Team

Principal Investigator

Paper Coordinator

Content Writer

Content Reviewer

Dr. Satwanti Kapoor (Retd Professor)

Department of Anthropology, University of Delhi

Dr. Vijeta

Department of Anthropology, University of Delhi

Prof. R.K. Pathak Department of Anthropology, Panjab University, Chandigarh

2

Anthropology


Contents:

Introduction

Cast of fossils

Identification and Description of Fossil casts (Kenyapithecus, Dryopithecus, Sivapithecus,

Ramapithecus, Australopithecines)

History and context of the fossil discoveries

Early Humans (homo habilis, Homo erectus, Homo neanderthalensis)

Modern Humans (Cro-Magnon, Grimaldi and chancelade)

Summary

Learning Objectives:

1. To know about the cast of fossils.

2. To explain the identification and description of fossil casts.

Description of Module

Subject Name Anthropology

Paper Name Human Origin and Evolution

Module Name/Title Identification and Description of Fossil casts

Module Id 26

3

Anthropology


Introduction

Evolution is confined almost entirely to the Miocene epoch, from 23 to 5 million years ago, which

probably covers most of the earlier history of the group. The first evidence for a diversification of the

apes is in the early Miocene, and an origin of the group in the latest Oligocene or earliest Miocene

seems likely. During the middle and late Miocene, apes underwent an extensive phyletic and

geographic radiation, expending their range throughout the equatorial and subequatorial regions of the

Old World. Before the end of the Miocene, apes had become extinct over much of the area that they

had once occupied. Ape lineages did persist into the Plio-Pleistocene, although some subsequently

became extinct. All these surviving lineages were probably more widespread than they are today.

However, their record after about 8 million; years ago includes only scanty remains of Pleistocene

gibbons and orangutans, dental remains of a recently extinct Pleistocene giant ape (Gigantopithecus)

and Pliocene fossils of uncertain affinity, all from southeastern Asia (Hills, 1992). The discovery of

human remains more than 10000 years old is always a cause for scientific celebration. Such finds are

rare and valuable, as each new sample or technique may reveal threads of evidence in our

understanding of human evolution. Consequently, there is a persistent requirement to measure, cast and

sample from existing and newly discovered human bones (Cook & Ward, 2008).

Fig-1: Fossil Records of Human Evolution

(Source Link: www.googleimage.com)

4

Anthropology


Cast of fossils: Cast, the positive replica (plaster, plastic, bronze etc.) made from the mold and mold is

the material (usually a type of rubber) that is brushed or poured over the original to make the negative.

The cast may be made from the bone or soft tissues. The important points about the original are:

What is the material and condition of your original? (Note: porous materials may be darkened

by the molding process).

Cast from Bone Cast from Soft tissues

Is it exfoliating? Is it fresh?

Is it fractured, and /or is cancellous bone

exposed?

Is it frozen?

Is it oily? Is it infused with embalming fluid?

Is it wet (water)? Is it muscle, fat, ligament or cartilage?

Is it infused with embalming fluid? Is the original expendable

Is it covered with preservative? -

Are parts of it glued? -

Is the original expendable? -

(Source: Alfonso & Powell, 2007)

The easiest material to use is plaster, which comes in any varieties. Some casting in material

include the following-

Common Plaster of Paris is soft & easily scratched.

High strength gypsum cements & dental plasters are harder, especially when mixed with

hardener instead of water. Details on casts in these materials can be excellent & shrinkage is

minimal.

Many plastics & epoxys are also available but shrinkage of these materials combined with their

tendency to shorten mold lives.

There are various techniques for colouring casts of all materials to bring out details. All involve a

vehicle such as alcohol for dissolving and spreading artist’s pigments. Artist’s fixatives and spray

lacquer add a long-lasting appealing & protective finish to the final protect (White at al., 2011).

5

Anthropology


Identification & Description of Fossil casts: The fossil record shows a sequence from simple bacteria

to more complicated organisms through time and provides the most compelling evidence for evolution.

There are fossil casts from African, Asian, and European hominids to study the process of evolution.

Kenyapithecus: In Africa, Kenyapithecus is found at sites that span most of the middle Miocene, such

as Maboko, Fort Ternan and Nachola in northern Kenya. Kenyapithecus has derived facial and dental

features that differ from those of the early Miocene genera and are more like those of modern apes.

The identifying features are:

It has thick layer of enamel on its molar teeth.

Very robust jaws (which indicate a shift in food preferences and habitat).

Its teeth and jaws certainly suggest powerful biting and prolonged chewing, perhaps on very

hard and tough foods a diet unlike that of any living primate.

There was substantial sexual dimorphism in the danines and probably in body size.

The recently discovered Otavipithecus from the late middle Miocene of Namibia represents the

first record of Miocene apes from southern Africa. It is so far known from one specimen, a

lower jaw that, unlike Kenyapithecus, appears to have restively thin-enamelled teeth.

Dryopithecus: Somewhat later than the earliest Eurasian representatives of apes with thick-enamelled

teeth is Dryopithecus, sporadically known from western and central Europe. The distinctive features

are: Dryopithecus has thin-enamelled teeth and probably had a diet different from that of the apes with

thick enamel. The genus ‘Ramapithecus’ (which is historically important in the study of human

evolution) was once thought to be present at some of these sites as well as at the middle Miocene sites

of Fort Teman, Maboko and Pasalar, but it is now clear that the only distinguishing feature of

specimens attributed to this genus was their small size. These are probably females or small species of

the genera at these various sites (Hills, 1992).

Sivapithecus: The Siwalik record of Sivapithecus favors the more recent of each range and none of

these dates conflicts with the fossil evidence. Sivapithecus shares with the orangutan several features

of the skull and face that are almost certainly derived within the Hominoidea, and some of which are

uniquely shared to the exclusion of all other simian primates. These include:-

The absence of a bony sinus in the brow area of the skull.

6

Anthropology


A very narrow bony partition between the eyes

Vertically elongated orbits and,

A set of features in the sub-nasal area that relates to the way the hard palate joins the pre-

maxillary bone at the base of the nose where the incisors are embedded, (the naso-

alveolarclivus). Forelimbs of Sivapithecus are monkey-like, implying quadrupedal walking and

climbing.

Oreopithecus: A virtually complete skeleton of Oreopithecus has been unearthed. This is similar to

modern apes in many features of the trunk and limbs. Oreopithecus thus seems to have been more

adapted for suspension than was either Sivapithecus or Rudapithecus (Hills, 1992).

Ramapithecus: Ramapithecus was considered a possible human ancestor on the basis of the

reconstructed jaw and dental characteristics of fragmentary fossils. The first Ramapithecus fossil

(fragments of an upper jaw and some teeth) were discovered in 1932 in fossil deposits in the Sivalik

hills of Northern India. Ramapithecus represented the first step in the evolutionary divergence of

humans from the common hominid stock that produced modern apes and humans. Identifying features

are:-

1. Incisors and canines are smaller in relation to molar.

2. Absent of molar cusps.

3. Upper jaw is shortened & does not protrude forward but is long vertically.

4. Palate is arched & wider from behind than the front.

5. Face is short & deep, suggestive of not used teeth as weapon.

6. He used hands for hunting & defense i.e. Ramapithecus was probably an erect biped with hands free.

Fig-1: Fragments of Upper teeth of Ramapithecus compared with Man and Ape

(Source: www.googleimage.com)

Ramapithecus

1977-present

Ape

Chimpanzee

7

Anthropology


Australopithecines: Most fossil hominids back to 2 million years ago, and perhaps just beyond, are

more closely related to modern humans than they are to chimpanzees and belong to our own genus,

Homo. The earlier part of the lineage has been allocated to several fossil species, of which Homo

erectus and Homo habilis are the two best known. Compared with the African apes, most of all these

forms of Homo have a relatively large brain, relatively reduced chewing (or molar) teeth and limb

bones that are, except in points of detail, like those of modem Homo sapiens. However, there are at

least four, and perhaps five, species of hominid that lack the expanded brain, the reduced molar teeth

and the skeletal features of Homo. They antedate or overlap with the earliest representatives of Homo,

and are known collectively as the australopithecines (Hills, 1992).

Fig-3: Species of Australopithecines

(Source Link: www.googleimage.com)

8

Anthropology


Types of Australopithecines: Australopithecines are conventionally split into two groups on the basis

of their body types –

1. The gracile (more lightly built) and

2. Robust (more ruggedly built) forms.

The robust australopithecines can be divided into at least two species of the genus Paranthropus: P.

robustus from southern Africa and. P. boisei from eastern Africa. The name Australopithecus

(‘southern ape’) is then reserved for the two gracile australopithecine taxa: A. africanus from southern

Africa and A. afarensis from eastern Africa. Paranthropus is here used as a separate genus for the

robust australopithecines.

Table-1: Two -schemes for tire-nomenclature and taxonomy of Australopithecines

One genus Two genera

Gracile Forms Australopithecus (Dart)

(1) Australopithecus (Dart)

(2) Paranthropus (Broom)

A. africanus A. africanus

A. afarensis A. afarensis

Robust Forms A. robustus (including P. robustus (including

A. crassidens) P. crassidens)

A. boisei P. boisei (including

P. aethiopicus)

(Source: Cambridge Encyclopedia of Human Evolution)

Australopithecines are classed as hominids rather than pongids because, like Homo. The features

included reduced canine teeth and their limbs were substantially adapted for bipedal walking.

However, their brains-were relatively small and details of the brain fissures were different from those

of later hominids. Moreover, although australopithecine limb bones could resist the loads and stresses

of upright stance and locomotion, they did so without having the characteristic shape of the Homo

pelvis and thigh bone (femur).

9

Anthropology


Fig-4: Distinguishing Features of Australopithecines


History and context of the fossil discoveries: It is not easy identifying the Features that mark the

human genus Homo, as the group contains not just all living people but our closest fossil relatives as

well. Moreover, many features that distinguish humans are behavioral, and leave no fossil evidence. It

is very difficult judging whether a particular kind of early human had developed a language, society or

art, and other features that can be recognized in fossils are usually used to infer these attributes.

Southern African australopithecines: The first australopithecine fossil was found-in southern Africa

in 1924 in a cave that was exposed at the Buxton Limeworks, which is close to Taung, hear Kimberley.

The Taung cave, like those at the other australopithecine sites in southern Africa, was formed as

expansions of water channels that ran through the limestone. Once the caves started forming, they

developed openings onto the ground surface, through which soil and debris, including bone, was

washed in.

10

Anthropology


Eastern African australopithecines: Australopithecine fossils from eastern Africa are found very

different geological circumstances. The first fossil discovered at Garusi in Tanzania, a site that is now

included in the Laetoii site complex. More than 40 years elapsed between that first discovery and the

re-exploration of the area by Mary Leakey, which resulted in the' discovery of fossils that make up part

of the collection attributed to Australopithecus afarensis, now considered to be a gracile

australopithecine species distinct from A africanus. Three views predominate about the relationship

between the australopithecines and Homo. In the first scheme, A. afarensis is the common ancestor of

two lineages, one leading to Homo, the other leading via A. africanus to P. robustus and P. boisei. The

second scheme also sees A. afarensis as ancestral to A. africanus, but it has the latter as the common

ancestor of two lineages, one being Homo and the other leading to, and including, and the robust

australopithecines. A third scheme has fewer supporters, but it may prove to be more durable than the

others. In this arrangement, the australopithecines and Homo share a common ancestor, which has not

yet been found in the fossil, record. Two lineages result from such an ancestor. One leads to the robust

australopithecines via A: afarensis; the other leads, via A. africanus, to Homo. These and other

differences in our perceptions of hominid relationships, however, still owe as much to disagreements

about methodology as to differences in interpretations of the fossils themselves (Hills, 1992).

Early Humans: A large brain has usually been the single most important feature, although on its own

this may be an unreliable guide to membership of the genus Homo. In early fossils; body size must also

be taken into account to give an idea of relative brain size; if this were not done, some small-bodied

and small-brained early humans might not qualify as human at all. Most members of the genus Homo

do have a brain volume of more than 700 milliliters (ml), considerably larger than that of the largest

robust australopithecine or living ape. To house a brain of such a size, the human cranial ' vault is large

in relation to the face, and the face is tucked under the vault more than is the case in early apes or

hominids. Other diagnostic features of humans include the-presence of a prominent nose (as

represented by raised bone Surfaces around the nasal opening) and a bony spine at the centre of the

base of the nasal opening. These characteristics are further reflected in various measurements of the

face. The base of the human skull is short and well flexed or folded up. Such distinctive features may

be related to the development of language and the remodeling of the throat to give a lower position for

11

Anthropology


the voice box. The jaws of humans are also notable, because the bone of the lower jaw is rather thin

and there may be a vertical front to the jaw or even a bony prominence - a chin. The teeth, and in

particular the last of the cheek teeth, are small. Tooth eruption is slow compared with that in apes and

early hominids.

Homo habilis: In the early 1960s, stone tools were found scattered among hominid bones close to the

site where A. boisei had been unearthed. Because of its association with tools, this early human was

called Homo habilis, meaning “handy man.” The distinguishing features are:

Brain volume of about 680 cubic centimeters, larger than the australopithecine range of 400 to

550 cubic centimeters.

Small in stature, with arms longer than legs (Hills, 1992).

Fig-5: Two hominid skulls of Homo habilis


12

Anthropology


Fig-6: Reconstruction of large and small Homo habilis skulls


Homo erectus: Homo erectus was a lot larger than Homo habilis—about 1.5 meters tall. It had a large

brain, about 1000 cubic centimeters and walked erect. Its skull had prominent brow ridges and, like

modern humans, a rounded jaw.

Java man: A Dutch doctor and anatomist named Eugene Dubois unearthed a skull cap and a thighbone

in 1891. He informally called Java man, for three reasons: 1. The structure of the thigh bone clearly

indicated that the individual had long, straight legs and was an excellent walker. 2. The size of the skull

cap suggested a very large brain, about 1000 cubic centimeters. 3. Most surprisingly, the bones seemed

as much as 500,000 years old, judged by other fossils Dubois unearthed with them (Hills, 1992).

13

Anthropology


Fig-7: Homo erectus skull

(Source: www.mhhe.com)

Homo neanderthalensis: Neanderthals, Homo neanderthalensis, lived in Europe and the Near East

from 200,000 to 28,000 years ago. They were thick-boned with a larger brain, they buried their dead,

and they made hunting tool.

Fig-8: Reconstructed skulls of two Neanderthals showing distinguishing features


14

Anthropology


Modern Humans: The first modern humans were anatomically distinct from neanderthals with their

less –prominent brow ridges, higher, shorter and more rounded skulls,shorter lower jaws with a bony

chin and a less robust skeleton.they also had a hip bones od modern type, suggesting that the hip joints

functional like those of modern people. Three species of modern man are- Cro-Magnon, Grimaldi and

chancelade.

Cro-Magnon remains are representative of the earliest anatomically modern human beings. However,

the skull of Cro-Magnon show traits that are unique to modern humans, including the tall, rounded

skull with a near vertical forehead. A large brow ridge, no longer tops the eye sockets and there is no

prominent prognathism of the face and jaw (http://humanorigins.si.edu). Grimaldi: The fossil remains

were found in the village Grimaldi, on the Mediterranean coastal region. Two Skulls were found i.e. of

a woman (30 yrs. old) and a boy (15 yrs. old). The characters are-mastoid processes are small and

supraorbital ridges are feebly developed & the forehead is well developed. Large orbits with sub-

rectangular shape and broad nose with low bridge were observed. Chin is poorly developed and teeth

are large. Majorities of characters show affinities with the Negroids.

Chancelade Man: Fossil remains were discovered in 1888 in a rock shelter at Chancelade,

southwestern France. The skull is long and narrow measuring 19.4 cm in length and 18.75 cm in

breadth and thus showing a cranial index of 70.9 (dolichocephalic). The vault is high and supraorbital

ridges are slightly marked. The forehead is almost vertical while the parietal tuberosities were well

marked. The mastoid processes are fully developed. The Chancelade man resembles the modern

Eskimo in the following characters: short stature; large, high dolichocephalism head; elevated sagittal

region; a very wide and long face; flat, prominent cheek-bones; narrow nasal aperture; powerful

masticator apparatus (http://www.shareyouressays.com).

http://humanorigins.si.edu/

15

Anthropology


Fig-9: Specimens of the Cro-Magnon (early modern humans)


16

Anthropology


Table-2: Distinguishing features of early human Species

Characteristics Homo habilis

(small)

Homo habilis

(Large)

Homo erectus Neanderthals Early modern

Homo sapiens

Height 1 c.1.5 1.3-1.5 1.5-1.7 1.6-1.85

Physique Relatively

long arms

Robust but

‘human’

skeleton

Robust but

‘human’

skeleton

Robust but

‘human’ skeleton

;

Adapted for cold

Modern

skeleton; adapted

for warmth

Brain size (ml) 500-650 600-800 750-1250 1200-1750 1200-1700

Skull form Relatively

small face;

nose

developed

Larger, flatter

face

Flat, thick

skull with large

occipital and

brow ridge

Reduced brow

ridge; thinner

skull; large nose;

mid face

projection

Small or no

ridge; shorter,

high skull

Jaws/teeth Thinner jaw;

smaller,

narrow molars

Robust Jaw;

large narrow

molars

Robust jaw in

larger

individuals;

smaller teeth

than H. habilis

Teeth smaller

except for

incisors; chin

development in

some

Shorter jaws

than

Neanderthals:

teeth may be

smaller

Known date

(years ago)

2.1.6 million 2.1.6 million 1.8-0.3 million 150000-30000 130000-60000


17

Anthropology


Fig-10: Fossil cast of early human Species

Source Link: www.googleimage.com

(A=Archaic H. sapiens B=H. neanderthalis C= Homo sapiens sapiens D= Homo erectus E= Homo

ergaster F=Archaic H. sapiens)

Summary

The discovery of human remains more than 10,000 years old is always a cause for scientific

celebration. Such finds are rare and valuable, as each new sample or technique may reveal threads of

evidence in our understanding of human evolution. Consequently, there is a persistent requirement to

measure, cast and sample from existing and newly discovered human bones. Cast, the positive replica

(plaster, plastic, bronze etc.) made from the mold and mold is the material (usually a type of rubber)

that is brushed or poured over the original to make the negative. The cast may be made from the bone

or soft tissues. The fossil record shows a sequence from simple bacteria to more complicated

organisms through time and provides the most compelling evidence for evolution. There are fossil

casts from African, Asian, and European hominids to study the evolution i.e. Kenyapithecus,

Dryopithecus, Sivapithecus, Ramapithecus, Australopithecines and early humans (Homo habilis,

Homo erectus, Homo neanderthalensis & modern man are- Cro-Magnon, Grimaldi and Chancelade).

A

F E D

C

B

http://www.googleimage.com/

development team principal...

Documents