Do you want to create an amazing science fair project on elephants. You are in the right place. Read the below given article to get a idea on elephants:- 1. Introduction to Elephants 2. Biological Organisation of Modern Elephants 3. Ancestry 4. Biological Trends 5. Palaeontological Procession.
Contents:
- Science Fair Project on Introduction to Elephants
- Science Fair Project on the Biological Organisation of Modern Elephants
- Science Fair Project on the Ancestry of Elephants
- Science Fair Project on the Biological Trends of Elephant Evolution
- Science Fair Project on the Palaeontological Procession of the Elephants
Science Fair Project # 1. Introduction to Elephants:
Proboscideans or the elephants constitute one of the largest and majestic groups in the animal kingdom. They represent uniqueness in their anatomical organisation. They possess an admixture of a large number of primitive as well as specialised characters and show the most spectacular success in course of phylogenetic development.
Evidences advanced by fossil elephants furnish an unmistakable transformation from simple to complex. The elephants have reached the peak of evolutionary perfection that indirectly led them into a blind alley. Though they were quite abundant in their geological career the kingly elephants are now represented by only two genera threatened with extinction.
The most striking feature in the elephants is the hugeness in size, pillar-like legs matching the proboscis and tusks. Because of the presence of peculiar anatomical features, its systematic position is quite problematic.
Excepting remote phylogenetic connection with the Sirenia and Hyracoidea, the elephants stand as an isolated group. Starting with their early evolutionary career, they acquired numerous peculiar features which separate them from others. Most of the features are adaptive in nature.
Science Fair Project # 2. Biological Organisation of Modern Elephants:
Before going to the actual process of evolution of proboscidea, a brief account of the anatomical organisation is necessary for better understanding. In addition to the possession of a large number of specialised adaptive features, the surviving elephants have retained many primitive characters.
The primitive features are largely confined to the soft parts, as they are more conservative in evolutionary dynamics than the hard parts.
I. Primitive Features:
To enumerate briefly, the primitive features are:
(a) The condition of cerebellum. It is well convoluted, but is uncovered by the cerebral hemispheres.
(b) The stomach is simple. The liver has two distinct lobes, but lacks gall bladder.
(c) Presence of two superior venae cavae carrying blood to the heart.
(d) The lungs are simple and not so much lobated.
(e) The testes are permanently abdominal.
(f) Presence of primitive placenta.
(g) There is a tendency towards the reduction of lateral digits, especially in African elephants. The feet are five-toed. The carpal bones are serially placed one above the other.
(h) Although there is a general tendency towards reduction of ulna in cursorial animals, the ulna forms a most dominant bone in elephants.
II. Specialised Features:
The skeleton shows many specialised features. The hugeness of size is a paramount feature in elephants. The development of proboscis by the elongation of snout with the support of upper jaw is a unique feature to note in elephants.
Transformation of the incisors into tusks is also notable. The limbs are pillar-like and are modified to carry the enormous weight of the body. The neck becomes shortened to carry the unusual weight of head with the proboscis.
The skull shows many specialised characteristics. It is smaller in comparison to the body, but is amply modified to offer leverage for the enormous weight of the proboscis. To minimise the unwanted weight, special formation of air spaces or diploe is observed in skull. The development of the diploe causes obliteration of most of the sutures.
The dentition is highly characteristic and the dental pattern is:
There is no enamel excepting at the tip of the tusk, which is lost later on. The evolution of dental pattern shows a phenomenon of disappearance of many teeth. The canines and the premolars are completely eliminated. The use of incisors and molars is predominant. The structure and use of molars are characteristics of the group. Each molar consists of a number of plates.
Each plate has a flattened mass of dentine covered by enamel. Such plates are bound together by cement. The use of the molars is also very peculiar. All the molars are not used at a time. Usually two of the molars in each section of the jaws work at one time and the remaining one remains idle.
As a result of continuous use, these molars diminish in size until they are completely worn out when the molar that is not used so far begins to work.
The brain is very large in size and its specialisation lies in it. Though the brain shows extensive convolutions, it possesses many primitive features. Elephants have a remarkable memory and mental development. They possess relatively dull vision, but olfactory and auditory senses are very well developed.
Though palaeontology has shown a variety of forms of elephants, they are represented today by two genera. Other elephants are all lost in evolutionary struggle. The living elephants are: Loxodonta africana of Africa and Elephas maximus of India or Asia.
Both of them possess common structural organisation, but differ slightly. In Loxodonta the molars are comparatively narrow and low crowned. The ridges are usually fewer in number and assume rhomboidal pattern. They are greater in size and possess big pinna. The tusks are longer and curved.
Occurrence of several subspecies of the genus Loxodonta is claimed by many, but definite evidences to establish them are lacking. They are most probably the geographical races rather than the subspecies.
In contrast to Loxodonta, the Indian form, Elephas maximus possesses short skull with a rounded vault. The tusks are short and more or less straight. The tusks are directed more downward than forward. The molars are broad and high crowned. The ridge plates are many and are closely appressed.
Science Fair Project # 3. Ancestry of Elephants:
The phylogenetic changes of the elephants are completely recorded by series of fossil forms (Fig. 1.19). But great controversies exist as regard the exact starting point of the proboscidean evolution. Authorities differ in their views regarding the earliest proboscidean.
Lull regards Moeritherium as the earliest form directing the channel of proboscidean evolution. But Scott assumes that this stage is rot in the main line but represents a side line originating from the common ancestor.
According to him, Palaeomastodon, another fossil proboscidean, is the main source for proboscidean evolution and holds the pivotal position from which all forms of elephants evolved in time and space. Modern researchers in this line also think that Palaeomastodon is the primal source.
Moeritherium:
The fossil forms of the Moeritherium have been discovered in the upper Eocene and early Oligecene bed of Egypt. Moeritherium possesses many elephantine features. Although they were much smaller in size than the latter forms, the height of the animals was estimated to be about three feet.
The skull was fairly long with eyes placed far forward. Initiation of development of air-cells was observed especially in the back of the skull.
There was no proboscis, but its development was initiated in the form of a short flexible tapir-like snout. Dentition shows the sign of proboscidean evolution in which there is reduction in the normal number of teeth.
The dental formula of the Moeritherium is represented as:
The molars had not yet been specialised. These were small and short crowned. Transverse crests were simple and filled with dentine. The formation of tusks has already begun. The second pair of upper incisors became elongated and sharply pointed. The second incisors of the lower jaw assumed the appearance of procumbent tusks and were horizontally directed.
Palaeomastodon:
The fossil forms of the Palaeomastodon were recorded in the Oligocene bed of Egypt. They were comparatively larger in size than Moeritherium. They attained appreciable size. The proboscis was better developed and was probably extensible.
The bones of the skull had air-spaces (diploe). Occurrence of diploe is a clear and definite indication of proboscidean evolution. The dental battery had more progressed towards proboscidean evolution in the reduction of teeth.
The dental formula is represented as:
The molars possessed three crests.
Science Fair Project # 4. Biological Trends of Elephant Evolution:
Linking the earliest fossil proboscideans and the modern surviving genera, series of fossil forms have been discovered. Fossil records of elephants furnish a complete evolutionary history. The most remarkable feature to note in proboscidean evolution is that their evolution has progressed towards certain basic biological trends.
The trends are as follows:
(a) Reduction in the number of teeth and change in the disposition and sequence of arrangement.
(b) Gradual transformation of incisors into tusks.
(c) Acquisition of specialisation of molars.
(d) Gradual loss of enamel.
(e) Gradual development of proboscis or trunk.
(f) Development of air-spaces (diploe) in the skull bones.
(g) Gradual increase in size (Fig. 1.20).
(h) Mechanical readjustment of the limbs to bear enormous weight of the body.
The above-mentioned biological trends are largely concerned with the head of the elephants and other parts have undergone little modifications with the progression of time.
Science Fair Project # 5. Palaeontological Procession of the Elephants:
Phiomia:
The fossils of this genus were also discovered in the lower Oligocene bed of Egypt. Exact position of Phiomia in the evolutionary series is controversial. Lull regards that Phiomia, originating from Moeritherium directed the channel of evolution.
But authorities like Scott inclines to think that Phiomia, differentiating from Palaeomastodon in late Oligocene represented a side line and showed the tendency towards deviation. Phiomia is undoubtedly a proboscidean of comparatively larger size than the previous forms.
This genus possesses the following features:
(a) The height of skull is increased considerably.
(b) The development of diploe in the skull is noticed in the skull bones.
(c) Indication of development of an extensible, short proboscis is observed.
(d) The dental formula shows loss of entire canines. The second pair of incisors have transformed into tusks.
The dental formula is:
(e) The molars have three transverse crests with distinct tubercles.
(f) The posterior cervical vertebrae tend to become shortened.
Trilophodon:
This genus appeared in the late Oligocene and was quite abundant in Miocene. The genus had its origin from the Palaeomastodon and became diverted on the way. Trilophodon was of considerable size and was as large as the Indian elephants. It had certain peculiar features of
its own, but it was more elephantine in nature. It had very long lower jaw with tusks. The upper tusks were downwardly curved and were enamel-banded. In adults the molars were of enormous size and contained three crests.
A marked increase of the diploe in the skull was observed. The nostrils were placed high on the skull. Trilophodon had a great power of migration and reached North America for the first time from Asia in Miocene period and constituted an important member of the North American fauna for a short time.
Mastodon:
Arising from the Palaeomastodon, Mastodon became a very dominant group in Miocene time. This group constituted the best known American elephants. The lower jaw was very much shortened. The molars were simpler and were devoid of intervening cusps. Vestigial and functionless tusks may occur in lower jaw of male. The upper incisors lack enamel.
The dental formula of Mastodon is:
The massiveness of the limb bones and broadness of the pelvis were the two noticeable features in Mastodon. The development of diploe was more pronounced. Only two fully developed molars were present in the jaws at one time.
Exact relationship of Mastodon is not precisely known. They were plenty in Pliocene and Pleistocene time and ranged from Europe to Alaska and the United States. Romer inclines to think that the Palaeomastodon and the Phiomia constituted the group known as the Mastodon. The Mastodons, though extinct today, were quite numerous and diversified group in tertiary age.
Stegodon—the Transitional Elephants:
The Mastodons were replaced by the Stegodon. Possession of transitional characters by the Stegodon made the issue confusing. They arose in Pliocene time and were placed by the palaeontologists in the direct line of proboscidean evolution.
They were considered to be the successful arrow line in the way of the evolution of elephants and hold the pivotal position from which the modern elephants evolved. Stegodon enjoyed a wide range of distribution and the members were well flourished in the Eastern hemisphere of the world. They were known as the transitional elephants.
They differ from the modern elephants by the possession of large skull and peculiar dental battery. The dental battery resembled the modern elephants excepting the condition of the molars. The vallies of the molar crests were deficiently laid with dentine.
Stegodon gave origin to the modern elephants. One of these forms persisted along with the early Pliocene Mastodon in North America, which later on invaded South America. This form became further advanced in jaw structure and molar structure where the cusps increased to the maximum of seven or eight.
Romer named this form as the Stegomastodon. There occurred a shortening of the facial portion. The fleshy nose above presumably became free to form a long proboscis like that of modern forms. The molars were high crowned and had gained cement.
True Stegodon fossils were abundant in Southern and Southeastern parts of Asia, which indicates the places as the original home of true proboscideans. Stegodon gave origin to the true elephants.
Mammoth:
During late Pliocene and early Pleistocene, in Asia and Europe, the first typical elephant took its origin possibly from the Stegodon or from the Stegomastodon. They were popularly known as the mammoth. Mammoths were adapted to cold climate which resulted in the development of a coat of long, coarse black hairs with a coat of brown wool beneath. They had short head and tuskless lower jaw.
The teeth exhibited maximum degree of complexities. The molars had a large number of cusps. During pleistocene period various other elephants were recorded which were referred to as the Mammoth. The remarkable frozen mammoth of the Siberia tundras preserved in nature’s cold storage presents a typical representative of mammoth. They became all extinct in Pleistocene.
Living Elephants:
Two well-defined groups had their origin from the Stegodon source and are surviving today in two widely separated parts of the earth. They are the Indian or Asiatic elephants, Elephas maximus and the African elephant, Loxodonta africana. Biological organisation of these two forms have already been discussed.
Fossil elephants have left behind a documentary record of their evolution. Fig. 1.21 shows the scheme of the phylogenetic development of elephants. The earliest recorded fossil forms of the elephants were present in the Eocene bed of Egypt. Great controversies exist as regards the exact starting point of proboscidean evolution.
Both the Moeritherium and the Palaeomastodon, whoever be the primal source, were discovered in the Eocene and the Oligocene bed of Egypt respectively. From this point it is natural to think the place of origin to be Egypt. Another opposite view exists which advocates the place of origin to be Central Asia.
The, study of proboscidean evolution forces the attention to the evolutionary train of species ranging from Eocene to the recent time. The elephants had a wide range of distribution and they were great immigrants.
They had travelled wide distance and reached the icy desert of Siberia, the temperate region like Asia and also to the subcontinent of Africa. They are now represented by two genera—Elephas and Loxodonta in two widely separated regions of the earth.