The type specimen of the genus Amebelodon is installed in the Nebraska State Museum, the University of Nebraska, Lincoln. It consists of a mandible with tusks and teeth, all of which are dense and perfect, barring minor cracks and breaks. One toe bone and part of a rib found associated with this mandible may belong to this animal. It was discovered by Mr. A. S. Keith on his farm near Freedom, Frontier County, Nebraska; was secured for the palaeontological collections of Hon. Charles H. Morrill by Mr. Phillip Orr, April 4, 1927; was briefly described and figured in a Museum bulletin June, 1927.1 After a long but unavoidable delay, this mandible has just been mounted and the first photographs with correct measurements are now possible and are presented herewith. Preliminary drawings and measurements were made while the specimen was still in its plaster cinches. This unique specimen, representing a new group of longirostral mastodonts, has been named Amebelodon fricki, and the group designated the Amebelodonts, or shovel-tuskers. Amebelodonts are such distinctive elephants that they plainly belong in a group by themselves, namely the sub-family Amebelodontinae. In them is realized the culmination, in the late Pliocene or early Pleistocene, of the flattened tusks and lengthened mandible of Phiomia osborni of the Egyptian Oligocene

Barbour, Erwin H.

English

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnBulletin of the University of Nebraska StateMuseum Museum, University of Nebraska State12-1929THE MANDIBLE OF AMEBELODON FRICKIErwin H. BarbourFollow this and additional works at: http://digitalcommons.unl.edu/museumbulletinPart of the Entomology Commons, Geology Commons, Geomorphology Commons, OtherEcology and Evolutionary Biology Commons, Paleobiology Commons, Paleontology Commons,and the Sedimentology CommonsThis Article is brought to you for free and open access by the Museum, University of Nebraska State at DigitalCommons@University of Nebraska -Lincoln. It has been accepted for inclusion in Bulletin of the University of Nebraska State Museum by an authorized administrator ofDigitalCommons@University of Nebraska - Lincoln.BULLETIN 15 VOLUME 1 DECEMBER, 1929 THE NEBRASKA STATE MUSEUM ERWIN H. BARBOUR, Director THE MANDIBLE OF AMEBELODON FRICKI By ERWIN H. BARBOUR The type specimen of the genus Amebelodon is installed in the Nebraska State Museum, the University of Nebraska, Lincoln. It consists of a mandible with tusks and teeth, all of which are dense and perfect, barring minor cracks and breaks. One toe bone and part of a rib found associated with this mandible may belong to this animal. It was discovered by Mr. A. S. Keith on his farm near Freedom, Frontier County, Nebraska; was secured for the palaeontological col-lections of Hon. Charles H. Morrill by Mr. Phillip Orr, April 4, 1927; was briefly described and figured in a Museum bulletin June, 1927.1 After a long but unavoidable delay, this mandible has just been mounted and the first photographs with correct measurements are now possible and are pre-sented herewith. Preliminary drawings and measurements were made while the specimen was still in its plaster cinches. This unique specimen, representing a new group of longi-rostral mastodonts, has been named Amebelodon fricki, and the group designated the Amebelodonts, or shovel-tuskers. Amebelodonts are such distinctive elephants that they plainly belong in a group by themselves, namely the sub-family Amebelodontinae. In them is realized the culmination, in the late Pliocene or early Pleistocene, of the flattened tusks and lengthened mandible of Phiomia osborni of the Egyptian Oligocene. Phiomia osborni gave rise to a varied but slowly declining race of long-jawed mastodons including Seridentinus, Dibelodon, Trilophodon, Tetralophodon, and Amebelodon. while Moeritherium and Palaeomastodon led to an expanding race of proboscideans such as the European and American Mastodon, Stegodon, Archidiskodon, Parelephas, the true· mammoth, and the living Indian and African elephants. Amebelodon may have been among the latest and most special-ized of the longirostral mastodonts, if his mandible and tusks are criteria, and may have been contemporaneous with the American mastodon and the mammoth. In massiveness and length, this mandible passes that of all proboscideans known 1 Preliminary notice of a new Proboscidean Amebelodon fricki gen. et. sp, nov. Bulletin 13, Volume I, June 1927, the Nebrask~ State Museum. Fig. 93. The mandible of Amebelodon fri cki , the shovel-tusked mast odo n, showing th e great shovel··tusk s and sy~physi al trough, in compariso n with a full-gr own man. Spec imen No. 4-4-27, t he collection s of H on. Charles H. M Ol'l' ill , the Ne braska St ate Museum, The Uni vers ity of Nebraska, Lin coln . Prepared by Phili p Orr, Henry Reider, and Miss Carrie A.. Barbour. Fig. 94. a . The mandible of Amebelodon fricki from above. In life the tusks met on the median line. They are tlu:own apart apparently by a sun crack in the bone. b. Same from below, showing a large sun crack. 142 THE NEBRASKA STATE MUSEUM as yet, and stands, in fact, as the largest jaw of any recorded land mammal. It is further characterized by two broadened, shovel-like, mandibular tusks and a great symphysial trough. The tips of the tusks are worn in such a way as to suggest their possible adaptation to digging, hence the name Amebelodon. The shovel-like tusks may have been used to uproot and dislodge aquatic plants in river bottoms, swamps, marshes, and bayous. By sweeping the jaw through the water, certain fresh-water algae a.nd other aquatic plants could be caught and by lifting the head many could flow down the great symphysial trough to the mouth or could be pushed along by the proboscis. Possibly the shovel-tuskers dug in loose sand for roots, tubers, and bulbs, but it is inconceivable that they could have dug in firm and dry ground because the leverage was too great, and the walls of the jaw seem too thin, especially at the point of greatest strain, at which spot the alveolar spaces are unduly large. Of course the tensile strength of bone is high. The alveoli when cast are about as large as, and very like, human cerebral hemispheres, each being 6112 inches (165 mm.) deep by 5112 inches (140 mm.) broad. At this spot the walls of the mandible are reduced in places to but one-half an inch in thickness. In heavy digging, if they dug at all, perhaps the trunk was wound around the jaw to lend it muscular reinforcement. It is not unlikely that this over-developed organ never really functioned as a shovel. To ascribe to the amebelodonts any aquatic adapta-tions, or any tendencies to shovel may be over-fanciful, but the association of ideas results naturally from the shovel-shape of the inferior tusks. It is quite as reasonable to assume that amebelodonts were lovers of forest, underbrush, and firm ground, and that the unique shovel-shaped jaw was but an excessive development that did not materially affect the life habits of this race. Finding themselves possessed of such a shovel, the creatures might have learned to put it to use as such, or they might have turned this abnormal jaw to good account in collecting herbage by pressing the coarse and calloused trunk against the tusks and the edges of the jaw, and thereby stripping off leaves, twigs, and heads of grain by a swing of the head. The mandibular tusks of Amebelodon are huge in com-parison with those of other tetrabelodons, the length being 45 inches (1144 mm.), and the width 5112 inches (140 mm.). The pulp cavities of the tusks seem to have been unduly short, but 14 inches (356 mm.), tapering abruptly. At the 'base of each, the inner and the outer borders are so folded together Fig. 95. Right lower m?Jar of ~mebeJodon fricki , crown. view show-ing five grinding r idges, Wlth trefolled patterns. Length 9 mches (229 mm.); width 3% inches (88 mm.) . . Very low~crowned. Fig. 96. A charcoal sketch showing a conjectural restoration of the ead of Amebelodon fricki. Total length of the mandible, 6 feet, - lh inches. Total length from the base of the skull to the tips of the mandibular tusks estimated to have been between 7 and 8 feet. THE NEBRASKA STATE MUSEUM as to make a deep groove, which is occupied by a pendant strip of bone about a foot long,· three inches deep, and a half inch thick. Amebelodont tusks are so immoderately de-veloped that they are very unlike those of other four-tuskers, of which average mandibular tusks are about one inch to an inch and three-fourths wide, and fifteen to eighteen inches long. The mandible of Megabelodon lulli when discovered was conceded to be the longest proboscidean jaw recorded, but in comparison, Amebelodon fricki is longer and more massive, except that the ascending rami of Amebelodon are actually not as large and massive as those of Megabelodon. Since the discovery and announcement of Amebelodon fricki, three other distinct species, found in Nebraska, have been added to the proboscidean collections of the State Museum and are now photographed and the descriptions ready for publication. In the case of one of these, fortunately, the lower and the upper dentition is known, as well as most of the skeleton, the first recorded. From the material already at hand it is plain that there are two very distinct types of amebelodonts, namely one group with straight, long tusks and straight jaws, another group with relatively short, curved tusks and curved jaws, which group we have already designated the dredge-tuskers, to be described in forthcoming papers. It seems a safe prediction that the next few years cannot fail to reveal a rich, interesting, and varied amebelodont fauna. In the field season of 1930 the quarry will be reopened and carefully explored in an attempt to recover other relics of Amebelodon fricki. It should be recorded that in the month of November last, twenty proboscideans, including tetrabelodons, mastodons. and mammoths, were located in Nebraska. Some at least of these will be secured in the field season of 1930. It is doubtful if any like area boasts of like numbers, for wherever ground is broken in Nebraska, the sand hills excepted, proboscidean bones may be expected. It may be interjected that the short grass of the treeless Great Plains would not sustain such hords of proboscideans, but the presumption is that the Great Plains wefe not always treeless, as is evidenced by widely distributed fossil woods and nuts. Perhaps such un-numbered herds aided in the destruction of forest and under-brush, thus reducing their own food supply and decimating their numbers. At this writing no reports on any of the Amebelodontinae have reached this office and no citations can be offered. Fig. 97. A pencil sketch showing a conjectural restor ation of Amebelodon fricki in its supposed habitat feeding upon aquatic plants. In their life habits they may have been like other longirostral mast.odonts, the jaw and tusks being simply extreme developments. ' 146 THE NEBRASKA STATE MUSEUM AMEBELODONT PUBLICATIONS Barbour, Erwin H. Preliminary notice of a new Proboscidean, Amebelodon fricki gen. et. sp. nov. Bulletin 13, Volume 1, June. 1927, the Nebraska State Museum. The mandibular tusks of Amebelodon fricki. Bulletin 14, Volume 1, December, 1929, the Nebraska State Museum. The mandible of Amebelodon fricki. Bulletin 15, Volume 1, Decem-ber, 1929, the Nebraska State Museum. The present bulletin. MEASUREMENTS Fig. 93. Depth of mandible at the tip, 61,-2 inches (165 mm.). Depth in front of molar, 8* inches (222 mm.). Depth back of molar, 7 inches (178 mm.). Depth at coronoid, 14 inches (356 mm.). Width of ascending ramus, 10* inches (274 mm.). Molar, 9 inches (229 mm.) long, by 31,-2 inches (89 mm.) wide, by 1 inch (25 mm.) high at the front ridge to 114 inches (32 mm.) at the heel. Fig. 94 a. Total length of mandible, 6 feet 51,-2 inches (1970 mm., approx-imately 2 meters). Length of mandible alone, 4 feet 10 inches (1475 mm.). Distance across condyle 20 inches (508 mm.). Distance across coronoids, 18 inches (457 mm.). Transverse diameter of condyle 51,-2 inches (140 mm.). Greatest thickness of ramus, 5* inches (147 mm.). Fig. 94 b. Width of tusks, 51,-2 inches (140 mm.). Greatest width of jaw, 101,-2 inches (268 mm.). Width at narrowest point, 7 * inches (197 mm.). Fig. 95. Molar: Length, 9 inches (229 mm.); width, 3 1h inches (89 mm.). The University of Nebraska Lincoln, Nebraska December 25, 1929 318B 

THE MANDIBLE OF AMEBELODON FRICKI

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University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Bulletin of the University of Nebraska State
Museum Museum, University of Nebraska State
12-1929
THE MANDIBLE OF AMEBELODON FRICKI
Erwin H. Barbour
Follow this and additional works at: http://digitalcommons.unl.edu/museumbulletin
Part of the Entomology Commons, Geology Commons, Geomorphology Commons, Other
Ecology and Evolutionary Biology Commons, Paleobiology Commons, Paleontology Commons,
and the Sedimentology Commons
This Article is brought to you for free and open access by the Museum, University of Nebraska State at DigitalCommons@University of Nebraska -
Lincoln. It has been accepted for inclusion in Bulletin of the University of Nebraska State Museum by an authorized administrator of
DigitalCommons@University of Nebraska - Lincoln.
BULLETIN 15 VOLUME 1 DECEMBER, 1929 
THE NEBRASKA STATE MUSEUM 
ERWIN H. BARBOUR, Director 
THE MANDIBLE OF AMEBELODON FRICKI 
By ERWIN H. BARBOUR 
The type specimen of the genus Amebelodon is installed in 
the Nebraska State Museum, the University of Nebraska, 
Lincoln. It consists of a mandible with tusks and teeth, all 
of which are dense and perfect, barring minor cracks and 
breaks. One toe bone and part of a rib found associated with 
this mandible may belong to this animal. It was discovered 
by Mr. A. S. Keith on his farm near Freedom, Frontier 
County, Nebraska; was secured for the palaeontological col-
lections of Hon. Charles H. Morrill by Mr. Phillip Orr, April 
4, 1927; was briefly described and figured in a Museum 
bulletin June, 1927.1 After a long but unavoidable delay, this 
mandible has just been mounted and the first photographs 
with correct measurements are now possible and are pre-
sented herewith. Preliminary drawings and measurements 
were made while the specimen was still in its plaster cinches. 
This unique specimen, representing a new group of longi-
rostral mastodonts, has been named Amebelodon fricki, and 
the group designated the Amebelodonts, or shovel-tuskers. 
Amebelodonts are such distinctive elephants that they plainly 
belong in a group by themselves, namely the sub-family 
Amebelodontinae. In them is realized the culmination, in the 
late Pliocene or early Pleistocene, of the flattened tusks and 
lengthened mandible of Phiomia osborni of the Egyptian 
Oligocene. 
Phiomia osborni gave rise to a varied but slowly declining 
race of long-jawed mastodons including Seridentinus, 
Dibelodon, Trilophodon, Tetralophodon, and Amebelodon. 
while Moeritherium and Palaeomastodon led to an expanding 
race of proboscideans such as the European and American 
Mastodon, Stegodon, Archidiskodon, Parelephas, the true· 
mammoth, and the living Indian and African elephants. 
Amebelodon may have been among the latest and most special-
ized of the longirostral mastodonts, if his mandible and tusks 
are criteria, and may have been contemporaneous with the 
American mastodon and the mammoth. In massiveness and 
length, this mandible passes that of all proboscideans known 
1 Preliminary notice of a new Proboscidean Amebelodon fricki gen. et. sp, nov. 
Bulletin 13, Volume I, June 1927, the Nebrask~ State Museum. 
Fig. 93. The mandible of Amebelodon fri cki , the shovel-tusked mast odo n, showing th e great shovel··tusk s 
and sy~physi al trough, in compariso n with a full-gr own man. Spec imen No. 4-4-27, t he collection s of H on. 
Charles H. M Ol'l' ill , the Ne braska St ate Museum, The Uni vers ity of Nebraska, Lin coln . Prepared by Phili p 
Orr, Henry Reider, and Miss Carrie A.. Barbour. 
Fig. 94. a . The mandible of Amebelodon fricki from above. In life the tusks met on the median line. 
They are tlu:own apart apparently by a sun crack in the bone. 
b. Same from below, showing a large sun crack. 
142 THE NEBRASKA STATE MUSEUM 
as yet, and stands, in fact, as the largest jaw of any recorded 
land mammal. It is further characterized by two broadened, 
shovel-like, mandibular tusks and a great symphysial trough. 
The tips of the tusks are worn in such a way as to suggest 
their possible adaptation to digging, hence the name 
Amebelodon. The shovel-like tusks may have been used to 
uproot and dislodge aquatic plants in river bottoms, swamps, 
marshes, and bayous. By sweeping the jaw through the 
water, certain fresh-water algae a.nd other aquatic plants 
could be caught and by lifting the head many could flow down 
the great symphysial trough to the mouth or could be pushed 
along by the proboscis. Possibly the shovel-tuskers dug in 
loose sand for roots, tubers, and bulbs, but it is inconceivable 
that they could have dug in firm and dry ground because the 
leverage was too great, and the walls of the jaw seem too thin, 
especially at the point of greatest strain, at which spot the 
alveolar spaces are unduly large. Of course the tensile 
strength of bone is high. The alveoli when cast are about as 
large as, and very like, human cerebral hemispheres, each 
being 6112 inches (165 mm.) deep by 5112 inches (140 mm.) 
broad. At this spot the walls of the mandible are reduced in 
places to but one-half an inch in thickness. In heavy digging, 
if they dug at all, perhaps the trunk was wound around the 
jaw to lend it muscular reinforcement. It is not unlikely 
that this over-developed organ never really functioned as a 
shovel. To ascribe to the amebelodonts any aquatic adapta-
tions, or any tendencies to shovel may be over-fanciful, but 
the association of ideas results naturally from the shovel-
shape of the inferior tusks. It is quite as reasonable to 
assume that amebelodonts were lovers of forest, underbrush, 
and firm ground, and that the unique shovel-shaped jaw was 
but an excessive development that did not materially affect 
the life habits of this race. Finding themselves possessed of 
such a shovel, the creatures might have learned to put it to 
use as such, or they might have turned this abnormal jaw to 
good account in collecting herbage by pressing the coarse and 
calloused trunk against the tusks and the edges of the jaw, 
and thereby stripping off leaves, twigs, and heads of grain 
by a swing of the head. 
The mandibular tusks of Amebelodon are huge in com-
parison with those of other tetrabelodons, the length being 45 
inches (1144 mm.), and the width 5112 inches (140 mm.). 
The pulp cavities of the tusks seem to have been unduly short, 
but 14 inches (356 mm.), tapering abruptly. At the 'base of 
each, the inner and the outer borders are so folded together 
Fig. 95. Right lower m?Jar of ~mebeJodon fricki , crown. view show-
ing five grinding r idges, Wlth trefolled patterns. Length 9 mches (229 
mm.); width 3% inches (88 mm.) . . Very low~crowned. 
Fig. 96. A charcoal sketch showing a conjectural restoration of the 
ead of Amebelodon fricki. Total length of the mandible, 6 feet, 
- lh inches. Total length from the base of the skull to the tips of 
the mandibular tusks estimated to have been between 7 and 8 feet. 
THE NEBRASKA STATE MUSEUM 
as to make a deep groove, which is occupied by a pendant 
strip of bone about a foot long,· three inches deep, and a half 
inch thick. Amebelodont tusks are so immoderately de-
veloped that they are very unlike those of other four-tuskers, 
of which average mandibular tusks are about one inch to 
an inch and three-fourths wide, and fifteen to eighteen inches 
long. The mandible of Megabelodon lulli when discovered 
was conceded to be the longest proboscidean jaw recorded, 
but in comparison, Amebelodon fricki is longer and more 
massive, except that the ascending rami of Amebelodon are 
actually not as large and massive as those of Megabelodon. 
Since the discovery and announcement of Amebelodon fricki, 
three other distinct species, found in Nebraska, have been 
added to the proboscidean collections of the State Museum 
and are now photographed and the descriptions ready for 
publication. 
In the case of one of these, fortunately, the lower and the 
upper dentition is known, as well as most of the skeleton, 
the first recorded. From the material already at hand it is 
plain that there are two very distinct types of amebelodonts, 
namely one group with straight, long tusks and straight jaws, 
another group with relatively short, curved tusks and curved 
jaws, which group we have already designated the dredge-
tuskers, to be described in forthcoming papers. It seems a 
safe prediction that the next few years cannot fail to reveal 
a rich, interesting, and varied amebelodont fauna. 
In the field season of 1930 the quarry will be reopened and 
carefully explored in an attempt to recover other relics of 
Amebelodon fricki. 
It should be recorded that in the month of November last, 
twenty proboscideans, including tetrabelodons, mastodons. and 
mammoths, were located in Nebraska. Some at least of these 
will be secured in the field season of 1930. It is doubtful if 
any like area boasts of like numbers, for wherever ground is 
broken in Nebraska, the sand hills excepted, proboscidean 
bones may be expected. It may be interjected that the short 
grass of the treeless Great Plains would not sustain such 
hords of proboscideans, but the presumption is that the 
Great Plains wefe not always treeless, as is evidenced by 
widely distributed fossil woods and nuts. Perhaps such un-
numbered herds aided in the destruction of forest and under-
brush, thus reducing their own food supply and decimating 
their numbers. 
At this writing no reports on any of the Amebelodontinae 
have reached this office and no citations can be offered. 
Fig. 97. A pencil sketch showing a conjectural restor ation of Amebelodon fricki in its supposed habitat 
feeding upon aquatic plants. In their life habits they may have been like other longirostral mast.odonts, the 
jaw and tusks being simply extreme developments. ' 
146 THE NEBRASKA STATE MUSEUM 
AMEBELODONT PUBLICATIONS 
Barbour, Erwin H. 
Preliminary notice of a new Proboscidean, Amebelodon fricki gen. 
et. sp. nov. Bulletin 13, Volume 1, June. 1927, the Nebraska 
State Museum. 
The mandibular tusks of Amebelodon fricki. Bulletin 14, Volume 1, 
December, 1929, the Nebraska State Museum. 
The mandible of Amebelodon fricki. Bulletin 15, Volume 1, Decem-
ber, 1929, the Nebraska State Museum. The present bulletin. 
MEASUREMENTS 
Fig. 93. 
Depth of mandible at the tip, 61,-2 inches (165 mm.). 
Depth in front of molar, 8* inches (222 mm.). 
Depth back of molar, 7 inches (178 mm.). 
Depth at coronoid, 14 inches (356 mm.). 
Width of ascending ramus, 10* inches (274 mm.). 
Molar, 9 inches (229 mm.) long, by 31,-2 inches (89 mm.) wide, by 
1 inch (25 mm.) high at the front ridge to 114 inches (32 mm.) at 
the heel. 
Fig. 94 a. 
Total length of mandible, 6 feet 51,-2 inches (1970 mm., approx-
imately 2 meters). 
Length of mandible alone, 4 feet 10 inches (1475 mm.). 
Distance across condyle 20 inches (508 mm.). 
Distance across coronoids, 18 inches (457 mm.). 
Transverse diameter of condyle 51,-2 inches (140 mm.). 
Greatest thickness of ramus, 5* inches (147 mm.). 
Fig. 94 b. 
Width of tusks, 51,-2 inches (140 mm.). 
Greatest width of jaw, 101,-2 inches (268 mm.). 
Width at narrowest point, 7 * inches (197 mm.). 
Fig. 95. 
Molar: Length, 9 inches (229 mm.); width, 3 1h inches (89 mm.). 
The University of Nebraska 
Lincoln, Nebraska 
December 25, 1929 
318B 


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