|
 Paleontological
research with respect to jaws and teeth has focused on limited aspects of
the maxillo-occlusal system, specifically dental and jaw anatomy.
This narrow scope
demonstrates a failure to view the fossil record using a dynamic or
systems approach. Modern craniofacial and maxillofacial surgery has based
its success on analysis of growth and development of a highly coordinated
and interrelated group of subsystems which comprise the maxillofacial-occlusal
system.
Use of the modern
systems approach in analysis of the fossil record with respect to the
development of chordate maxillo-occlusal apparatus to examine several
subsystems exposes a lack of fossil evidence supporting gradual
development of the occlusal-maxillary apparatus. Modern craniofacial/maxillafacial
genetics demonstrates that pleiotrapy is present in all of the
approximately one hundred genetic disorders.
Thus the simplistic
idea of genetic mutations being able to cause only incremental small
useful changes in the occlusion and/or jaw relationships is not supported
by current research. There are no known mutations affecting single
tooth morphology or single tooth enamel microstructure.
Any viable theory which
attempts to explain the complex interaction and precision of the
maxillofacial-occlusal complex must include genetic mechanisms,
developmental processes, and fossil evidences of these processes affected
by mutations and natural selection.
Current publications in
orthodontics and oral and maxillofacial pathology thoroughly document that
dysfunctions in all of the cranio- maxillo- occlusal systems actually do
occur, and are based on known mutations and malfunctions of development.
Examples include: (1) malpositions and eruption sequencing dysfunction
causing teeth to either remain unerupted and cause cysts or crowding; (2)
maxillo- mandibular growth discoordination causing mandibular prognathism
(protruding lower jaw).
These developmental
departures should therefore be expected in the fossil record, especially
since chordate- maxilloocclusal relationships are so widely varied
across species boundaries. An
endless parade of transitional variations of all the subsystems should be
evident, as well as the problematic effects caused by lack of coordination
between the subsystems.
Multiple examples of
malposed teeth, cysts in jaws, retained deciduous teeth, maxillary-mandibular
growth and size discoordination, losses of entire classes of teeth,
variation in eruption height of the various classes of teeth, tooth size
arch-discrepancy variation, animal size, and tooth size coordination,
should be in the fossil record.
This evidence is not
seen.
The subsystem of tooth
replacement presents a quandary. The reptiles have a "wave-like"
replacement of every third tooth, yet all early mammals have a whole set
replacement of their deciduous teeth.
There are no
transitional dentitions. The earliest deciduous dentitions are fully
functional.
The same quandary
appears with respect to tooth attachment. There are at least eight,
well-developed methods of tooth attachment in the chordates, none of which
could be called primitive or advanced or could be arranged in a sequence
from simple to complex. Furthermore, failure of the attachment apparatus
would be evidenced by missing teeth due to dysfunction in periodontal
attachment. Transitional
attachment mechanisms are not found in the fossil record
The homeobox which
controls dental development is specific for either the mandible or
maxilla. The postulate that independent mutations can affect both arches
and control the eruption height, eruption sequence, dental size, enamel
microstructure, arch position, as well as individual tooth morphology
while maintaining a continually functioning dentition has not been
experimentally demonstrated and is statistically highly unlikely.
What the craniofacial
and maxillary occlusal fossil evidences suggest is that all ten subsystems
(and probably more) were fully functional in all chordates from their
first appearance in the fossil record.
There is absolutely no
fossil evidence of either developmental processes or pathology which would
suggest any evolutionary process leading to the development of the
dentition.
There is also no known
genetic or developmental process to suggest a legitimate mechanism to
support an evolutionary basis for the development of the precision
exhibited by the dental apparatus.
* Dr.
Moeller’s credentials include Fellow, American Board of Oral and
Maxillofacial Surgeons (ABOMS);
and Diplomate, American Board, Oral and Maxillofacial Surgery
(ACOMS). His offices
are located at: 2300 Manchester Expressway, Building H, Suite 203,
Columbus, Georgia 31904. |
