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MASTODON (Gr. µavTos, breast, &bobs, tooth) , a name given by Cuvier to the Pliocene andSee also: Miocene forerunners of the elephants, on account of the nipple-like prominences on the molar teeth of some of the See also: species (fig
.
2), which are of a much simpler type than those of true elephants
.
Mastodons, like elephants, always have a pair of upper tusks, while the earlier ones likewise have a See also: short pair in the See also: lower jaw, which is prolonged into a snout-like symphysis for their support
.
These long-chinned mastodons are now regarded as forming a genus by themselves (Tetrabelodon), well-known examples of this See also: group being Tetrabelodon angustidens from the Miocene and T. longirostris (fig
.
1 C.) from the Lower Pliocene of the Continent
.
In the former the upper tusks are bent down so as to See also: cross the tips of the short and chisel-like lower pair
.
These long-chinned mastodons must have had an extremely elongated muzzle, formed by the upper lip and nose above and the lower lip below, with which they were able to reach the ground, the neck being probably rather longer than in elephants
.
On the other See also: hand, in the short-chinned mastodons, as represented by the See also: Pleistocene See also: North See also: American Mastodon americanus and the Pliocene See also: European M. turicensis (fig
.
I), the See also: chin had shrunk
to the dimensions characteristic of elephants, with the loss of the lower incisors (or with temporary retention of rudimentary ones), while at the same See also: time a true See also: elephant-like trunk must have been See also: developed by the shortening of the lower lip and the prolongation of the combined upper lip and nose
.
Mastodons are found in almost all parts of the See also: world
.
In See also: Asia they gave rise to the elephants, while they themselves originated in See also: Africa from ungulates of more normal type
.
(See PROBOSCIDEA.)
The upper tusks of the early mastodons differ from those of elephants in retaining See also: longitudinal bands of enamel
.
The molar teethspecies the summits of the ridges are divided into conical cusps, and may have See also: accessory cusps clustering around them (as in M. arvernensis, fig
.
2)
.
When the summits of these are worn by mastication their surfaces See also: present circles of dentine surrounded by a border of enamel, and as attrition proceeds different patterns are produced by the union of the bases of the cusps, a See also: trefoil See also: form being characteristic of some species
.
Certain of the molar teeth of the See also: middle of the series in both elephants and mastodons have the same number of See also: principal ridges; those in front having fewer, and those behind a greater number
.
These teeth are distinguished as " intermediate " molars
.
In elephants there are only two, the last milk-molar and the first true molar (or the third and See also: fourth of the whole series), which are alike in the number of ridges; whereas in mastodons there are three such teeth, the last milk-molar and the first and second molars (or the third, fourth and
fth of the whole series)
.
In elephants the number of ridges on the intermediate molars always exceeds five, but in mastodons it is nearly always three or four, and the tooth in front has usually one fewer and that behind one more, so that the See also: ridge-See also: formula (i.e. a formula ex-pressing the number of ridges on each of the six molar teeth) of most mastodons can be reduced either to I, 2, 3, 3, 3, 4, or 2, 3, 4, 4, 4, 5
.
Three-ridged and four-ridged types occur both in Mastodon and Tetrabelodon
.
(R
.
L.*)
MAS'UD
!
(See also: ABU-L IIASAN `See also: ALI See also: IBN IIUSAIN IBN 'ALI UL-MAS'UDI] (d. c
.
956), Arabian historian, was See also: born at See also: Bagdad towards the close of the 9th century
.
Much of his See also: life was spent in travel
.
After he had
A, B, See also: Skull and Lower Jaw of Mastodon americanus
.
C, Lower Jaw 'of Tetrabelodon longirostris. been in See also: Persia and See also: Kerman,
he visited Istakhr in 915,
and went in the following See also: year to See also: Multan and See also: Mansura, thence to See also: Cambay, Saimur and See also: Ceylon, to See also: Madagascar and back to See also: Oman
.
He seems about this time to have been as far as See also: China
.
After a visit to the shores of the See also: Caspian See also: Sea he visited See also: Tiberias in See also: Palestine, examined the Christian See also: church there, and described its
See also: relics
.
In 943 he was in See also: Antioch, studying the ruins, and two years later in See also: Damascus
.
The last ten years of his life he spent in See also: Syria and See also: Egypt
.
His See also: great See also: object in life had been to study with his own eyes the peculiarities of every See also: land and to collect whatever was of See also: interest for archaeology, See also: history and See also: manners
.
Himself a Mo'tazilite (see See also: MAHOMMEDAN See also: RELIGION: Sects), he was singularly See also: free from bigotry, and took his information, when necessary, from Persians,
are six in number on each See also: side, increasing in See also: size from before back-wards, and, as in the elephants, with a See also: horizontal succession, the anterior teeth being lost before the full development of the posterior ones, which gradually move forward, taking the place of those that are destroyed by See also: wear
.
This See also: process is, however, less fully developed than in elephants, and as many as three teeth may be in place in each jaw at one time
.
There is, moreover, in many species a vertical succession, affecting either the third, or the third and second, or (in one American species, Tetrabelodon productus) the first, second and third of the six molar teeth
.
These three are therefore reckoned as milk-molars, and their successors as premolars, while the last three correspond to the true molars of other mammals
.
The mode of succession of the teeth in the mastodons exhibits so many stages of the process by which the dentition of elephants has been derived from that of more ordinary mammals . It also shows that the anterior molars of elephants do not correspond to the premolars of other ungulates, but to the milk-molars, the early loss of which in consequence of theSee also: peculiar process of horizontal forward-moving
(From See also: Owen.)
succession does not require their replacement by premolars
.
Specialized species like Mastodon americanus have completely lost the rudimentary premolars
.
Mastodons have fewer ridges on their molar teeth than elephants; the ridges are also less elevated, wider apart, with a thicker enamel covering, and scarcely any cement filling the space between them
.
Sometimes (as in M. americanus) the ridges are See also: simple transverse wedge-shaped elevations. with straight or See also: concave edges
.
In other
Jews, See also: Indians, and even the See also: chronicle of a Christian See also: bishop
.
His most extensive See also: work was the Kitab akhbar uz-Zaman or See also: Annals, in 3o volumes with a supplement, the Kitab ul-Ausat, a See also: chronological sketch of general history
.
Of these the first See also: part only of the former is extant in MS. in Vienna, while the latter seems to be in the Bodleian Library, also in MS
.
The substance of the two was See also: united by him in the work by which he is now best known, the Muriij udh-Dhahab wa Ma'adin ul-Jawahir (" Meadows of Gold and Mines of Precious Stones "), an See also: historical work which he completed in 947
.
In 956 he finished a second edition of this and made it See also: double its former size, but no copy of this seems to be extant
.
The See also: original edition has been published at Bulaq and Cairo, and with French See also: translation by C
.
Barbier de Meynard and Pavet de Courteille (9 vols., See also: Paris, 1861—1897)
.
Another work of Mas'udi, written in the last year of his life, is the Kitab ut-Tanblh wal Ishraf (the " See also: Book of Indication and Revision"), in which he summarizes the work of his life and corrects and completes his former writings
.
It has been edited by M
.
J. de See also: Goeje (See also: Leiden, 1894), and a French translation has been made by Carra de See also: Vaux (Paris, 1896) ; cf. also the memoir of S. de Sacy published in Meynard's edition of the Murisj
.
An account of Mas'udi's See also: works is to be found in de Sacy's memoir and in Goeje's preface to his edition of the Tanblh, and of the works extant in C
.
Brockelmann's Gesch. der Arabischen Litteratur, i
.
144—145 (See also: Weimar, 1898)
.
C
.
See also: Field's Tales of the Caliphs (19o9) is based on Mas'udi
.
(G
.
W
.
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