Comparative Anatomy of teeth and evolutionary aspects of teeth. From where did the teeth come from? How did they evolve? Which factors have contributed to this process?

1. COMPARATIVE ANATOMY OF
TEETH AND EVOLUTION OF IT
VNMU 2019
Reporters: Turgut Novruzlu, Reem Alrefai
Scientific supervisor: prof. Sergey Shuvalov MD, PhD

2. ORIGIN OF TEETH IN VERTEBRATES
• The first occurrence of tooth like structures was found in
posterior pharynx of jawless fishes (Romundina 400-419
million years ago)
• There are 2 actual theories about the reason why teeth
have occurred in first place
• 1. Oral teeth evolved with jaws for predation and
mastication
2.Teeth have appeared as external dental armor for
protection from predation.

3. CHANGES IN SHAPE OF DENTITION
Reduction of size of teeth over 2000 years

4. REASONS FOR CHANGES
• The evolution of human masticatory complex is strongly related to diet, the
use of tools and fire. And the current look of our teeth are nothing like what
we used to have.
• There are several factors that were changed by time; Change in our habitat,
use of fire, the fact that after humans started consume food that they acquire
from agriculture and etc.

5. EVOLUTION OF ALVEOLAR SOCKET
Bones grow in shape and size in response to frequent and habitual strain and
loose mass in absence of force.
This explains epigenetic trait in size of alveolar process.
In early man, the teeth were big, and alveolar sockets were large to hold on the
teeth, but as the forces for chewing reduced, the size of teeth and alveoli
decreased as well

6. SPECIAL ATTENTION TO TEETH OF
LAMPREYS
• Teeth of lampreys represent a very early stage in evolution of teeth of
vertebrates.
• Each teeth consists of a thick, horny, epithelial thorn with a pulp within, which
is ready to grow another thorn when it is broken.
• Lampreys belong to class Cyclostomata which literally
means round mouthed.And they are polyphyodont
Polyphyodontia means that specie has more than 2 sets of
teeth

7. ANCIENT ANCESTORS
• Predecessors of vertebrates probably fed upon small organisms and organic
matter, which were scooped into mouth cavity and may have been passed along
stomach by of lashing of cilia.
• However, there is another predecessor, namely Lamprey (Ostracoderm) from
order of Anaspida, which the body form seems adapted for fast movement
through water, and in which the mouth is strengthened by a bony strip with a
knob on its front end.

8. CHANGES IN PALATAL ARCH
• The reduction in size of all teeth, especially the canines, has been an important
factor in shortening the palatal arch.
• The change of of palatal arch from shaped type of anthropoids, with wide
space between Canines , to the short human form of palate with narrow
space between canines.

9. PALATAL ARCHES OF ANTHROPOIDS
AND MAN
-The upper lateral incisors in anthropoids as a rule are more primitive in
retaining the bluntly pointed tips.
-A significant difference between dentition of man his anthropoid cousins
lie in the fact, that in man the canine teeth even in milk set are much
reduced in size.
-While, in the anthropoids, especially males, the canines form large sharp-
tipped tusks
-Our molars tend to be smaller as they go posteriorly and they rotate
slightly, while in most of other apes this phenomena is absent

10. GENUS HOMO
• Loss of gap between canines and premolars are of great importance
• This is clear evidence of decrease in tough fiber and less reliance on meat in
genus Homo
• Australopithecines, who had large and flat molar teeth were suitable for hard
and brittle food like some fruits, nuts, flowers and buds.
• Also these species started to use tools to cut and grind meat, so the need for
adaptive characteristics such as strong jaw bones, large canines and stronger
masticatory muscles started to decrease

11. MUTATIONS IN CASE OF DECREASED
NATURAL SELECTION
• Reduction of jaw size is strongly related to transition from hunter gatherer
community to a fully Neolithic (agriculturist) community.
• In the absence of natural selection, mutations will be the main force acting
towards a reduction of structural size and comlixity of teeth and other organs.
• Cooking is another factor on lessening the need for carnivore adaptation. It is
knows that australopithecines used flake tools.

12. MODERN DESCENDANT OF
OSTRACODERMS

13. COMPARATIVE ANATOMY OF THE
HUMAN PALATE
• Determining the course of evolution in mammals and man, there is clear
evidence of progressive changes in palatal region.
• In early amphibians the air taken into olfactory chamber was passed through a
pair of tubes opening by the into the mouth, and they were literally
swallowing the inspired air
• However, in early mammal-like reptiles the choanae opened into a depression
lying considerable above the general level of tooth-bearing margins of
the upper jaw and it was the beginning of a fleshy palate.

14. HUMAN EMBRYO PASSES THROUGH A STAGE
WHEREBY ITS OLFACTORY CAPSULES LOOK
LIKE THOSE OF SHARKS

15. TRACES OF FIRST APPEARANCE OF
TEETH
• In early vertebrates in the margins of oral cavity, there were teeth in a conical
shape, which were serving as tool to hold the food inside of oral cavity.
• However, in some other vertebrates which have evolved further, they serve to
tear apart bolus into smaller pieces.
• Evolution of teeth starts from appearance of ectodermal thickening, which had
some-what connective tissue like appearance to the skin.

16. DEVELOPMENT OF MAIN FORMS OF
PERMANENT TEETH IN MAMMALS

17. WISDOM TEETH AND EVOLUTIONARY
TRACES
• Our species used to have larger jaws and they could contain more teeth. So
wisdom teeth were useful for chewing grass stronger and faster. But now they
are just vestigial organ.
• However by time we migrated from trees to land, surroundings where our
anthropoid ancestors could not find fruits and grass to eat.
• So we started to consume meat. Meat is totally different than grass,
nutritionally and by its consistency. So our jaw size started to decrease, while
our cranial cavity size have increased to make more space for brain.
• And after we started to use fire, there was no need to have extremely strong
teeth to complete chewing process.

18. CHANGES OF CUSPS THROUGHOUT
EVOLUTIONC
The earliest therian mammals (placentals and marsupials)
had teeth with three cusps, arranged in a triangle, with the
base running along the labial edge of tooth.
As our ancestors faced diet and habitat changes, structure
Of our teeth have changed as well

19. CONCLUSION
• From all of analyses and comparations we can come into conclusion, that our
teeth are spotlight on our past and they are great tool to understand the
changes our anthropoid ancestors faced and adaptations that they have made.
• Many studies have proved, that the changes that our teeth have faced, they are
strongly inter-related to our muscular and cerebral development

20. LITERATURE
• Goethe, J.W. 1963. Schnfen zur Botanik undWissenschafslehre. 240 pp. DeutscherTaschenbuch
Verlag. Miinchen.
• https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2015.0326
• https://evrimagaci.org/20-yas-disleri-korelmis-organlar-ve-evrim-259
• Marine Biological Laboratory Library Our Face from Fish to Man
• https://phys.org/news/2018-03-homo-naledi-wear-resistant-molars.html#nRlv
• Gidley, J.W. 1906. Evidence bearing on tooth-cusp development.Proceedings of theWashington
Academy of Sciences 8. 9 1-1 10.
• Gingerich. P.D. 1976. Cranial anatomy and evolution of early Tertiary Plesiadapidae (Mammalia.
Primates). University of Michigan. _Museurn of Paleontology, Papers on Paleontology 15, 1-
141. Gingerich, P.D. &

21. THANKS FOR YOUR ATTENTION