CHAPTER 1 - The Skeleton Flashcards
Palaeontology
the study of all prehistoric life.
fossil
any preserved evidence left behind by a prehistoric organism. The word fossil literally means “dug up”
Adaptations
are traits that have evolved to serve specific functions.
4 Adaptations that Bones help animals to survive by serving four major functions?
1 - bones passively resist gravity and maintain an animal’s form
2 - bones provide a ridged framework for muscle attachment.
3 - bones provide protection and can also be major components of horns and other robust weapons
4 - bones store mineral reserves
Vertebrates
are animals that have two special kinds of skeletal adaptations: skulls and vertebrae
Vertebrae
are structures made primarily of bone and/or cartilage that surround a portion of the spinal nerve cord.
The brain case
is a hollow chamber formed by multiple skull bones that houses the brain.
Dinosaur skulls also have multiple pairs of large openings. Name the five
1 - The nares (singular: naris) are the pair of openings for the nostrils.
2 - The orbits are the pair of openings for the eyes.
3 - lateral sides of the skull are called the laterotemporal fenestrae
4 - fenestrae on the top of the skull are called the supratemporal fenestrae.
5 - antorbital fenestrae. The function of the antorbital fenestra is unclear. They may have simply been adaptations that made dinosaurs skulls lighter, or they may have also housed large sinus cavities that helped warm the air that dinosaurs breathed.
centrum.
vertebra has a spool- or disk-shaped body,
neural arch
Above the Centrum, which covers the neural cannel
neural canal
is the opening in each vertebra, through which the spinal nerves run.
Vertebral processes
provide attachment surfaces for muscles and sometimes provide articulation surfaces for ribs.
Two common types of vertebral processes are
transverse processes, which extend from the lateral sides of the vertebrae, and spinous processes, which extend upwards from the neural arch.
cervical vertebrae
Vertebrae (singular: vertebra) in the neck. Cervical vertebrae often have extra-large openings for blood and nerve channels and are adapted to support the weight of an animal’s head.
dorsal vertebrae
Vertebrae in the back. Dorsal vertebrae often have tall spinous processes and large rib articulation surfaces.
sacral vertebrae
Vertebrae in the hips. Because the pelvic bones serve as solid anchors for powerful leg muscles, the pelvic bones (later discussed in detail) are fused to the sacral vertebrae.
sacrum
To further increase the strength of the hips, the sacral vertebrae are also fused with one another and form a single solid bone structure
caudal vertebrae
vertebrae in the tail
chevrons.
Underneath caudal vertebrae are bones. Chevrons protect a large blood and nerve channel and provide support for tail muscles.
Discuss the difference between the ribs in animals and dinos
In dinosaurs, all dorsal vertebrae connect with ribs; however, in mammals, the dorsal vertebrae close to the hips do not. Also unlike mammals, some dinosaurs had gastralia, or “belly ribs”.
Gastralia
are small ribs positioned across a dinosaur’s underbelly, underneath the ribcage.
Tetrapods
animals that evolved from an ancient ancestor with four feet and four limbs. Most tetropods still have four feet and limbs, although some, like humans, have hands instead of front feet and some, like snakes, have lost their limbs altogether.
The forelimbs of a tetrapod connect to the
pectoral girdle
scapula
is the largest bone in each side of the pectoral girdle.
The hindlimbs of a tetrapod connect to the
pelvic girdle, or hip bones
The upper hip bone is called the
ilium.
Below the ilium are the
pubis and the ischium.
acetabulum
the depression or (as in dinosaurs) the hole in the pelvic girdle into which the hind limb articulates.
Between the shoulder and elbow is the largest bone in the forelimb, called the
humerus.
Between the elbow and the wrist are two parallel bones
called the radius and ulnaIn. In most tetropods, the radius is the thinner of the two.
carpels
The bones in the wrist
metacarpals.
The bones between the wrist and fingers
Finger bones are called
phalanges
Between the hip and knee is the largest bone in the hindlimbs, called
femur.
Between the knee and the ankle are two parallel bones,
the fibula and tibia. The tibia is the bone that forms our shin.
The bones in the ankle are called tarsals. The bones between the ankle and toes are called
metatarsals.
There are two major groups of dinos
saurischians and ornithischians
Saurischian dinosaurs are those that share an evolutionary ancestor that had a pubis that
extended downwards and forwards, towards the ribcage.
Ornithischian dinosaurs are those that share an evolutionary ancestor that had both
special beak-forming bone in the upper jaw (called the predentary) and a pubis that extended downwards and backwards, towards the tail.
“Saurischian” means “__”, and “ornithischian” means “__”.
lizard hipped and bird hipped
Birds are part of a special group of saurischian dinosaurs that changed their pubis from
extending forward to extending backwards
There are two major groups of saurischian dinosaurs:
sauropodomorphs and theropods.
Sauropomorphs
large herbivores with elongated necks and relatively small heads.
Prosauropods
were an early group of sauropodomorphs and were the first group of large-bodied herbivorous dinosaurs to evolve
Sauropods
were a later group of sauropodomorphs. Many sauropods attained truly gigantic size, and the group includes the largest animals to ever walk the earth.
Theropods
were bipedal saurischian dinosaurs that shared a carnivorous ancestor. Many theropods were carnivorous and have serrated
blade-like teeth and sharp hooked claws, but some were herbivorous and a few lack teeth altogether.
The backwards extending pubis, which gives ornithischians their name, was an adaptation that
created more space in the ribcage. This extra space was probably filled by extra-large digestive organs.
There are five major groups within the ornithischians:
ornithopods, pachycephalosaurs, ceratopsians, stegosaurs, and ankylosaurs.
Ornithopods include
a wide range of dinosaurs that lack armor and that either walked bipedally all the time or assumed a bipedal stance when running. Many ornithopods are small antelope-sized dinosaurs, but some, like the iguanodonts and hadrosaurs, grew to be multi-ton giants.
Iguanodonts
large ornithopods with a spike-shaped claw on each hand.
Hadrosaurs are the famous
“duckbilled dinosaurs”. Hadrosaurs evolved late in the history of dinosaurs, but were highly successful
tightly packed rows of small teeth in the rear of the Duckbill mouths. Together, these teeth form large chewing surfaces and are collectively referred to as
dental batteries.
Pachycephalosaurs
were bipedal with short arms, unusually stout and strong tails, and armored skulls. pachycephalosaurs may have rammed predators or have butted heads with each other in competitions for territory or mating rights.
Ceratopsians
Ceratopsians have large parrot-like beaks and skulls that are greatly expanded in the rear. Ex. Triceratops
a group of quadrupedal dinosaurs with rows of projecting osteoderm plates down their backs and long osteoderm spikes on their tails.
Stegosaurs
Osteoderms
are bones that develop within the skin and are a common component of animal armor.
Anklyosaurs
The backs and skulls of most ankylosaurs are covered in spikey protective osteoderms. Some anklosaurs also have large osteoderms on the ends of their tails, forming a mace or “tail club”.
bones are the most common dinosaur fossils because
bones decay less rapidly than do softer tissues. This makes it difficult to know what a dinosaur’s integument (body covering) was like.
Keratin
a tough but flexible material that also composes hair, feathers, fingernails, and the outside of claws, beaks, and horns.
melanosomes
pigment cells within a feather
In crocodiles and many birds, there is a large muscle called the __. What does it do?
caudofemoralis.The caudofemoralis pulls backwards on the hind leg and is important for powering birds and crocodiles when they walk and run.
The femurs of crocodiles and birds have a prominence of bone, called a
trochanter
On most theropods, the trochanter is located high on the femur. A high muscle attachment would have
allowed the caudofemoralis to repeatedly retract quickly – a useful adaptation for carnivorous animals that depend on their ability to swing their legs fast when sprinting after prey.
On hadrosaurs, the trochanter is located further down on the femur, this would…
have reduced the speed at which the caudofemoralis could have repeatedly retracted but would have granted the muscle better endurance, because each retraction would have pulled with greater leverage – endurance would have been important for an animal that needed to be constantly on the move and grazing from one patch of vegetation to the next.
