PYROTHERIUM 
157 
to 
w 
~ 
co 
‘o 
Upper tush 
PyYROTHERIUM 
Inc. t enlarged 
PALAEOMASTODON 
Inc. t enlarged in 
Lower tush 
TOXODONT, DIPROTODON 
NESODON 
Inc. © reduced Inc. 1 tush 
Nasal opening 
Basicranial axis 
Over molar t 
Over molar 1 
Plane of base of 
cranium bent up, 
makes 140° with 
plane of palate 
Plane of base of 
cranium bent up, 
makes 155° with 
plane of palate 
Moeritherium. |Inc. 2 caniniform 
Inc. 2 tush Inc. 2 tush tush Inc. 2 reduced 
Upper molars Bilophodont Bilophodont in |Rhinoceros-like |Bilophodont 
Mastodon and 
Dinotherium 
Inc. 2 (?) Inc. 2 ness Inc. I 
Lower molars Bilophodont 'Bilophodont in | Bicrescentric Bilophodont 
Mastodon and 
Dinotherium 
Over incisors Over diastema 
Plane of base of|Plane of base of 
cranium parallel] cranium parallel 
with plane of} with plane of 
palate palate 
Pterygoids 
Pterygoids plus 
alisphenoids 
make great verti- 
cal plates 
Petrygoids plus 
alisphenoids 
make great verti- 
cal plates 
Pterygoids normal|Pterygoids normal 
Jugal 
Takes small part 
on glenoid fossa 
squamosum 
Tympanic bulla 
Palatine bones 
Premaxilla 
Antorbital foramen 
Posttympanic process of 
16 
‘Intercellular laminae 
‘Atlas 
Axis 
Surrounds meatus, 
and crowds out. 
tympanic 
Takes small part 
on glenoid fossa 
Takes no part on|Extends to glenoid 
glenoid fossa fossa 
Surrounds meatus 
and crowds out 
tympanic 
Surrounds meatus|Not surround me- 
and crowds out! atus nor crowd 
tympanic out tympanic 
Small, inflated, 
hollow 
Narrow in front, 
expanding behind 
Crowded out from 
forming any por- 
tion of palate 
2 foramena 
Present 
‘Small, inflated, 
| hollow 
Large, inflated, 
hollow 
‘Narrow in front, 
| expanding behind 
|Crowded out from 
forming any por- 
tion of palate 
2 foramena 
|Present 
Long, has hypo- 
physis 
| 
Long, has hypo- 
physis 
Hemispherical 
odontoid 
‘Rounded odontoid 
Wide in front, nar- 
rowing somewhat 
behind 
Makes front of|Fused to maxilla 
palate 
t foramen 1 foramen 
None None 
Long, no hypo-;Short, no hypo- 
physis physis 
Peg like odontoid|Odontoid slightly 
flattened on top 
