Dinosaurs | Egypt | Mesopotamia |Human Ancestors
Antorbital fenestra : "before the eye opening." Often
mistaken for the orbit by non-paleontologists, the function of this opening is not
clear.
It certainly lightens the skull, and it may have allowed room for the pterygoideus
muscle to expand as the muscle contracted.
Caudal Vertebrae : The caudal bones form the tail. Humans
have a vestigial set of caudals called the coccyx. A-Neural Spine. B-Zygopophysis.
C-Transverse
Process. D-Centrum.
Cervical Vertebrae : The cervical bones form the neck. Many dinosaurs have
small cervical ribs on their neck bones--a feature that rarely occurs in
man. A- Neural Spine. B-Zygopophysis. C-Transverse Process. D-Centrum.
Condyle of the Quadrate : the articular surface of the skull and the mandible.
On dinosaurs this joint is a cylinder-like projection of the quadrate bone
on the skull that is received by a dish-like impression on the mandible.
This opposite to the way mammal jaws work.
Deciduous teeth : teeth that are constantly replaced over the lifetime of
an animal. Dinosaurs and sharks are typical examples. A-Tooth germ, B-partially
formed tooth, C-Fully erupted tooth. (light gray is enamel, medium gray is
dentin, dark gray is pulp, and red is soft tissue)
Dorsal Vertebrae : The dorsals form the back of a dinosaur. Humans have two
kinds of back bones, the thoracic and lumbar spine, while dinosaurs have
only dorsals (similar to human thoracics). A-Neural Spine. B-Zygopophysis. C-Transverse Process. D-Centrum.
Femur : The thigh bone.
Fenestra : an opening. The plural is fenestrae.
Foramen : an opening--usually a smaller opening is called a foramen, a larger
one is a fenestra. The plural is foramina.
Humerus : The upper forearm bone. It articulates to the scapula/coracoid.
Heterodont : an animal that has more than one kind of teeth. A typical heterodont
(a camel, after Romer) is shown above. All mammals are heterodonts. A-Molars,
B- Canines, C-Incisors
Homodont : An animal with a single kind of teeth. Most dinosaurs are homodonts.
A homodont (Rhamphoryncus, after Romer) is shown above.
Mandibular foramen (fenestra):
Mandible : the lower jaw bone. The mandible is formed by about 9 bones on
each side, the dentary which holds the teeth is usually one of the largest
mandibular bones on a dinosaur. The surangular is another larger bone on
the lower jaw. Some animals have a predentary that forms an attachment for
a beak.
Maxilary or Maxilla : the part of the skull for by the maxilary bones that
holds the all the upper teeth except the incisors.
Nares : "nose." This is
the opening to the nasal passages. The large nares on some dinosaurs,
combined with large internal
nasal passages,
suggests
that many had quite capable senses of smell. A single nasal opening is
called the naris.
Nasal bone : the paired bones that form part of the external
nares.
Occipital condyle : the articular surface of the skull and the neck. On dinosaurs
this is a ball-like joint.
Orbital fenestra : "eye opening." This
area held the actual eyeball and its associated muscles. In birds and
in many
dinosaurs
the eye would
be surrounded by a ring of scleral bones. Also called, simply, orbit.
Premaxilary or premaxilla bone : the paired premaxilary bones form the front
of the upper jaw.
Postcranial: "behind the head," refers
to the rest of the skeleton not including the skull.
Sacral Vertebrae : The sacral vertebrae taken together form the sacrum. These
bones frequently fuse together to form one or two large units. They serve
to connect the spine to the hip of an animal. The large flattened bones visible
on the side of the hip are the Illia, and they attach to the sacrum, connecting
the hip with the spine.
Scapula and Coracoid : The two bones that form the shoulder. They serve to
connect the fore limbs (arms) to the upper body. This connection to the body
is a loose one formed with connective tissue. The semi-circular bone is the
coracoid, while the longer, blade shaped bone is the scapula.
Scleral bones : bony ring that occurs around the eyes on some dinosaurs.
Temporal fenestrae : Openings behind the orbit. This opening provided room
for the jaw muscles to bulge when the animal would bite down. The number
of temporal openings is used to classify many vertebrates. The presence of
2 temporal fenestrae is the diagnostic feature of the diapsids, a group to
which the archosaurs (and therefore the dinosaurs) belong. The two fenestrae
are called upper (sometimes superior) and lateral (sometimes lower, or inferior).
Tibia and Fibula : the two bones that form the lower leg abelow the knee
and above the ankle. The tibia (shin bone) is the larger of the two. The
length
of the lower leg in relation to the upper leg tells us about how fast an
animal can run (the larger the lower leg, the faster the animal can run).
The pes (foot) is attached to the tibia/fibula theough the acetabulum and
calcaneous (ankle bones).
Ulna and Radius : The two bones that form the forearm. The ulna is the larger
of the two bones and forms the major articulation with the humerous. The
specific arrangement of these bones can indicate the ability of an animal
to rotate its arms. The manus (hand) is attached to the ulna and radius through
the carpal (wrist) bones.
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