The most remarkable feature about the marsupial dentition is that, at most, only a single pair of teeth is replaced in each jaw; this pair, on the assumption that there are four premolars, representing the third of that series.
The fish-eating, or piscivorous, type of dentition is exemplified under two phases in the dolphins and in the seals (being in the latter instance a kind of retrograde modification from the carnivorous type).
From this point of view the various adaptive modifications of mammalian dentition may be roughly grouped under the headings of piscivorous, carnivorous, insectivorous, omnivorous and herbivorous.
With the exception of this replacing pair of teeth in each jaw, it is considered by many authorities that the marsupial dentition corresponds to the deciduous, or milk, dentition of placentals.
In different groups of mammals the dentition is variously specialized in accordance with the nature of the food on which the members of these groups subsist.
The simplest dentition is that of many species of dolphin (fig.
In most cases, though by no means invariably, mammals with a heterodont dentition are also diphyodont (Gr.
The milk-dentition is expressed by a similar formula, d for deciduous, being added before the letter expressive of the nature of the tooth.
A dentition with its component parts so differently formed that these distinctive terms are applicable to them is called heterodont (Gr.
Beyond these three principal divisions, the dentition furnishes important characters for the classification, although that importance has sometimes been over-estimated.
The trend in dentition is from broad, brachydont cheek-teeth to narrow, semi-hypsodont cheek-teeth.
In all instances they are in the upperdentition and usually at the posterior end of the maxillary tooth-row.
An even greater reduction of P4 in the more complex dentition of Zapus argues for complete loss of this tooth as the next step in specialization, such as is seen in the more progressive Napaeozapus.
Nevertheless, Pliozapus cannot be considered as directly ancestral to Eozapus because of the progressive features in the dentition of Pliozapus.
The dentition is larger and heavier, and the ridges and depressions on the dorsal surface of the rostrum are more pronounced than in Recent E.
Dentition larger and heavier than that in rotundus, but otherwise differing only slightly from it; upper incisor less concave on cutting surface (see Figs.
External signs furnished by dentition may assist greatly in fixing both age and identity.
What purported to be a third dentition came under my notice some years ago, in the person of an old negro “voodoo doctor.
This sign, so valuable in childhood, loses its value as the dentition progresses.
The Genitalia, Jaw and Lingual Dentition of certain Pulmonata.
Anatomy and Lingual Dentition of Ariolimax and other Pulmonata.
Normally the dentition in the typical genus Zeuglodon (which is common to the Eocene of North America and Egypt) is i.
The fortunate discovery of all parts of the skull and dentition renders the generic determination of this Ground-Sloth now quite certain.
The portions of skull anddentition now under discussion indicate an animal much larger than G.
And it should be borne in mind that in a state of nature cats always bring raw food to their young as soon as they are able to eat; therefore raw meat is far the best to give them--their dentition proves this.
Kittens usually shed their first teeth from five to seven months old, and seldom possess even part of a set of the small, sharp dentition after that time.
So potent is the last agency that we dread a recurrence of ophthalmia so long as dentition is incomplete, and hope for immunity if the animal completes its dentition without any permanent structural change in the eye.
The period of final dentition is a time which renders it peculiarly susceptible.
Between the fifth and sixth years of life the second dentition begins.
Their dentition is powerful, formed of long, recurved fangs, arranged in one or more rows.
The Dipsadomorphinæ, in which the nostrils are lateral in position, and the dentition is highly developed.
Did you ever hear of a picture called the 'Dentition of the Jew?
Now we shall hear about the dentition of the Jew," said Mowbray, as we got to Mr. Montenero's door.
On no account should the habit of sucking the "pacifier" be allowed as a means of putting children to sleep, or of quieting them while restless from dentition or indigestion.
And passing from the American apes to the Lemurs, the dentition becomes still more completely and essentially different from that of the Gorilla.
Hence it is obvious that, greatly as the dentition of the highest Ape differs from that of Man, it differs far more widely from that of the lower and lowest Apes.
In all these respects the dentition of the Gorilla may be described in the same terms as that of Man; but in other matters it exhibits many and important differences (Fig.
Children under one year of age are not as liable to this affection as those who are older, and it is during their first dentition that the affection shows itself.
In later childhood, when the second dentition set in, the germs of the permanent teeth were so injured, evidently from the calomel that had been absorbed into the system, that the teeth were ragged and defective.
And passing from the American Apes to the Lemurs, the dentition becomes still more completely and essentially different from that of the Gorilla.
The dentition (or dental formula) of horse and cow.
The only special feature of this table is the fact that, of the cases of epilepsy under observation, convulsions at dentition were positively ascertained in 15 per cent.
The general type of dentition is feline, but in some instances more premolars are retained, as well as a small tubercular molar behind the lower carnassial.
The later forms, as well as some of the earlier ones, are more specialized as regards dentition than the modern Felidae, although in several other respects they exhibit more primitive features.
The milk dentition in the kitten is the same as to number, with the exception of the molars, which are absent, and appear only as permanent teeth.
The second dentition is incomplete; the third molars have not reached the level of the opening of their sockets.
The condition of the sutures, so far as their patency is concerned, does not bear the same relation to the stage of dentition as it does in man: all the sutures of this skull are more or less obliterated.
Both of the second upper premolars (P3) are lacking, although the mandibular dentition is normal.
M1, are sharp and the wear-facets resulting from occlusion with the lower dentition are small.
These probably did not evolve from the subfamily Entoptychinae because the dentition of entoptychines, especially the premolars and third molars, was already highly specialized by Miocene time.
If loss occurs, it usually is the anterior plate in the lower dentition and the posterior plate in the upper dentition, including the upper premolar.
The specializations in the dentition and the associated changes in the skull of the Thomomyini and Geomyini permit more efficient mastication of fibrous vegetation.
The temporal is one of several muscles holding the occlusal surface of the lower molariform dentition firmly against the upper cheek teeth during mastication.
Judging from the pre-final stages of wear, the dentition of the Geomyini provides a curious combination of patterns that resemble in part the Miocene genus Dikkomys and in part the early and middle Pliocene genus Pliosaccomys.
Of the molariform dentition only the lower premolar and first two lower molars are known.
The enamel pattern of the lower dentition is the same in all of the diverging lineages, with no evidence of additional loss of enamel from that which had already occurred in their common ancestor (see Figs.
Discovery of the upper molariform dentitionwould make a more precise assignment possible.
Only the upper dentition would make positive identification possible; however, reference to the subgenus Pappogeomys seems to be the best arrangement at this time.
Since pre-Miocene geomyids are unknown, the actual phyletic development of the dentition is a matter of speculation.
Reduction and loss of enamel plates began and was terminated in the lower dentition before reduction began in the upper dentition.
However, the structure of the molariformdentition of Griphomys does not exclude it from the phyletic ancestry of the Geomyidae.
