The Vertebrate SkeletonReynolds, Sidney H. (Sidney Hugh)
Science
The Vertebrate Skeleton
Reynolds, Sidney H. (Sidney Hugh)
Skeleton
_CARNIVORA VERA._ The axis of the facial portion of the skull is a
direct continuation of that of the cranial portion. The cranial
cavity though rather depressed is large, and generally long, though in
Cats it is comparatively short and wide. The occipital plane is nearly
vertical, and the exoccipitals are developed into fairly prominent
paroccipital processes. The interparietal is commonly distinct, and
the parietals unite in a long sagittal suture, which is often
developed into a crest. The nasals (fig. 73, 4) are well developed,
especially in Cats, and the nasal processes of the premaxillae do not
nearly reach the frontals. A considerable part of the palate is formed
by the palatine, and the maxillary portion is pierced by rather long
anterior palatine foramina. The pterygoid has a hamular process. The
zygomatic arch is strong, especially in Cats. Postorbital processes
are developed on the frontal (fig. 73, 10) and jugal, but never form a
complete postorbital bar. A carotid canal is well seen in the Ursidae,
and to a less extent in the Felidae; in the Canidae there is an
alisphenoid canal (fig. 75, 21).
The auditory bulla differs a good deal in the different groups. In the
Bears (Ursidae) it is not much inflated, and is most prominent along
its inner border; it is not closely connected with the paroccipital
process. In the Cats it is very prominent, and its cavity is almost
divided by a septum into two parts, the inner of which contains the
auditory ossicles. The paroccipital process is closely applied to the
bulla. In the Dogs the bulla is intermediate in character between that
of the Cats and that of the Bears; it is partially divided by a
septum, and is moderately expanded.
The mandible is well developed with a prominent angle (fig. 72, 26),
and a large coronoid process. The hyoid consists of a broad basi-hyal,
a long many-jointed anterior cornu and short thyro-hyals (fig. 72,
33).
The skull in the _CREODONTA_ is in most respects allied to that of the
Canidae, but presents some ursine affinities. The tympanic bulla is
fairly prominent, but has no well-developed septum. The cranial cavity
is very small and narrow, the zygomatic arch standing away from it.
The temporal fossa is of great size.
In the _PINNIPEDIA_ the cranial cavity is large and rounded. The skull
is much compressed in the interorbital region, and in correlation with
this compression the ethmo-turbinals are little developed, while the
maxillo-turbinals are large. The orbit is large, and the temporal
fossa smaller than in the Carnivora vera. In the Walrus (_Trichechus_)
the anterior part of the face is distorted by the development of the
huge canines. The Otariidae have an alisphenoid canal. The tympanic
bulla is small in _Otaria_, large in the Phocidae, and flattened in
the Walrus. The hyoid is similar to that in Carnivora vera.
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