Exam 5 Comparative Anatomy

What are unique characteristics of synapsids?

• A single pair of openings in the lateral skull

• Front teeth are different from the back teeth

• Limbs are positioned under the body

What are two groups of synapsids?

• Eupelycosaurs

• Therapsids

What are some traits of eupelycosaurs?

• Two types of teeth

• Quadrupedal

• Possess a dorsal sail

What species is an example of a eupelycosaur?

Dimetrodon

What are some traits of therapsids?

• Larger temporal fenestra

• More differentiated teeth

• More movement of the limbs

Therapsids can be roughly divided into non-cynodont and cynodont groups. What are some traits of non-cynodont therapsids?

• Increased metabolic rate

• Expanded dentary bone

• Incomplete secondary palate

What are two examples of non-cynodont therapsids?

• Anteosaurus

• Gorgonops

What are unique traits of cynodonts?

• Complete secondary palate

• Nasal turbinates

• A calcaneal heel

• No lumbar ribs

What is significant about the lack of lumbar ribs?

This implies the presence of a diaphragm

What are the characteristics of mammals?

• Hair or fur

• Warm blooded/endothermic

• Young are fed milk from the mammary glands

• Complex brain

• Squamosal-dentary jaw joint

• The definitive mammalian middle ear giving the ability to hear high frequency sounds

• Muscles of facial expression

Define “hormone”

A chemical messenger secreted into the blood by an endocrine organ and affecting a target tissue

Define “endocrine gland”

A gland that secretes hormones directly into the bloodstream

Where in the vertebrate body does the thyroid gland develop?

Floor of the pharynx

What element is key in the production of the hormones produced by the thyroid gland?

Iodine

Where are the parathyroid glands located in mammals?

Within or near the thyroid gland

What is the name of the hormone produced by the parathyroid glands and what
element does it effect?

Parathyroid hormone (also called parathormone). It affects calcium metabolism.

Where are the adrenal glands located in the vertebrate body?

At the cranial poles of the kidneys (they are like little hats on the kidneys)

What are the two types of cells present in the adrenal glands and what type of hormone does each type produce?

• Adrenocortical cells: produce corticosteroids (mineralocorticoids, glucocorticoids, and androgens)

• Chromaffin cells: produce catecholamines

What are the names of the two regions of the pituitary gland?

• Neurohypophysis

• Adenohypophysis

Where are the endocrine cells of the pancreas located?

In the islets of Langerhans

List the hormones produced by each of these pancreatic cell types:
a. Alpha cells
b. Beta cells
c. Delta cells
d. PP cells

A. Glucagon
B. Insulin
C. Somatostatin
D. Pancreatic polypeptide

How do the terms “endocrine” and “exocrine” relate to the mammalian pancreas?

• Endocrine- A gland that secretes its product directly into the blood to affect other organs.
  

• Exocrine- A gland that secretes its product through a duct or opening to a body surface
  

• The pancreas is both an endocrine and an exocrine gland. Its endocrine products include insulin which affects blood sugar. Its exocrine products are digestive enzymes that are secreted into the duodenum.

What are the three groups of living mammals?

• Monotremes

• Marsupials

• Eutherians

What are some defining traits of monotremes?

• Lay eggs through a cloaca

• Males have spurs on their hindlegs

• Milk is secreted directly onto the skin

What is an example of a monotreme?

• Platypus

• Echidna

Define “therian”

Mammals with placentas

What are some defining traits of marsupials?

• Young are born immature and develop within a pouch

• Epipubic bones

• Choriovitelline placenta

What is an example of a marsupial?

• Kangaroo

• Opossum

• Sugar glider

What are some defining traits of eutherians?

• A placenta allows for long development within the uterus

• Lack of epipubic bones

What is an example of a eutherian?

• Humans

• Dogs

• Rabbits

• Deer

Australian marsupials are very like many species of placental (eutherian) mammals. However, there are no marsupial equivalents of cetaceans (whales and dolphins) or even seals. Why?

It would be impossible for a marsupial to give birth underwater (as a cetacean does) because the neonate is so underdeveloped that it would be unable to survive.

Even if an aquatic marsupial gave birth on land, like a seal, the mother would have to spend a considerable amount of time in the water while the young was developing inside the pouch, and while underwater the pouch would fill with water and the infant would drown.

Explain and defend the assertion that, among tetrapods, only mammals suck and chew.

While many aquatic tetrapods suction feed underwater, only mammals can suck and breathe at the same time. This is due in part to the complete secondary palate that first evolved in cynodonts. It is this ability that allows neonatal mammals to suckle, which is a defining feature for the group.

Many vertebrates chew their food—but only mammals have teeth and musculature suited to processing food into very small pieces and a mechanism, deglutition, by which the tongue moves a bolus of food into the esophagus for further processing in the digestive tract.

Be able to read a dental formula

I 1/1, C 1/1, P 2/2, M 2/2

This formula indicates that each side of the jaw has one upper and one lower incisor, one upper and one lower canine, two upper and two lower premolars, and two upper and tow lower molars. There are 12 teeth on each side of the jaw and 24 total teeth in the mouth.

List the two main parts of the nervous system and which structures are associated with each part.

• Central nervous system - brain and spinal cord

• Peripheral nervous system - spinal nerves, cranial nerves and their ganglia

List the three main sections of the mammalian brain

Forebrain

Midbrain

Hindbrain

Identify which portion of the brain houses the reflex center for respiration

The hindbrain, specifically the medulla oblongata

Identify which portion of the brain maintains equilibrium

The hindbrain, specifically the cerebellum

Differentiate between the sympathetic and parasympathetic nervous systems

The sympathetic nervous system upregulates the body (fight or flight):

• Increases heart rate

• Increases respiratory rate

• Increases blood glucose

• Pupils dilate

  
  The peripheral nervous system downregulates the body (rest and digest):

• Decreases heart rate

• Decreases respiratory rate

• Stimulates the digestive tract

• Pupils constrict

Be able to describe which parts of the central nervous system in general are responsible for sensory reception and coordination and which are responsible for motor coordination and output.

In general, sensory input is received and coordinated in the dorsal portions of the central nervous system (the dorsal horn of the spinal cord and the tectum of the midbrain).
In general, motor output is coordinated in the ventral portions of the central nervous system (the ventral horn of the spinal cord and the tegmentum of the midbrain).

What are the anatomical traits of primates?

• Shortened muzzles

• Forward facing eyes

• A large brain

• Prehensile hands and feet. Hands have opposable thumbs

• Nails instead of claws

What is an example of a strepsirrhine primate?

A lemur

What is an anatomical feature that strepsirrhines have that affects their sense of smell? Do haplorrhine primates have this structure?

A rhinarium. Haplorrhine primates do not have this structure.

What types are primates are included in the Hominidae?

The great apes - orangutans, gorillas, chimpanzees, bonobos, and humans.

What are the unique traits of hominid primates?

• Large body size

• Males are larger than females

• Lack ischial callosities

What is unique about the pelvis of Ardipithecus?

The pelvis of Ardipithecus shows adaptations combining tree climbing and bipedalism.

What is unique about the toes of Ardipithecus?

There is a grasping big toe combined with a rigid foot

What features of Australopithecus support bipedalism?

• Foramen magnum positioned ventrally

• Short, broad pelvis

• Knees positioned over the ankles

• Lack of opposable big toes

Lucy is the most famous specimen of Australopithecus afarensis. What features of Lucy’s skeleton indicate that she was an adult?

Her growth plates and the sutures in her skull had fused completely and her wisdom teeth had erupted and were worn.

List the unique features of the skull of Paranthropus species

• Prominent brow ridge

• Flaring cheekbones

• Pronounced sagittal crest

• Large jaws

• Very large molars

What is special about the teeth of Paranthropus? What does this indicate about their diet?

The cheek teeth or molars are very large and have the thickest enamel of any known early human.

They needed to generate a lot of jaw force indicating that seeds, nuts, and tough vegetation were a part of their diet.

Which species of Homo first showed evidence of eating meat?

Homo habilis

Which species Homo first showed body proportions similar to those of modern humans?

Homo erectus

What four innovations are associated with Homo erectus?

• Hand axes

• Caring for old and weak group members

• Campfires

• Leaving Africa

What is the scientific name of the species nicknamed “hobbits”?

Homo floresiensis

What is the definition of insular dwarfism?

The process and condition of large animals evolving or having a reduced body size when the population range is limited to a small environment such as an island.

What are unique anatomical characteristics of Homo neanderthalensis?

• Shorter and stockier than modern humans

• Heavy brow ridges

• Large noses

• Oval shaped skulls

What social innovations began with Homo neanderthalensis?

• Wearing clothing

• Ceremonially bury the dead

What features differentiate the skulls and skeletons of Homo sapiens from other species of Homo?

• Lighter skeletons

• High, vaulted skulls

• Flat forehead

• Smaller jaws and teeth

What parts of the skeleton have changed in adaptation to bipedalism?

• The foramen magnum

• Spine

• Pelvis

• Legs

• Foot

What is the functional significance of the S-shaped bend in the vertebral column of
Homo sapiens?

The bend places the center of gravity of the body directly above the hips. When the knees are held straight, the leg bones transmit the weight of the body to the ground and the base of support formed by the area of contact between the feet and the substrate lies directly beneath the center of gravity. As a result, the leg bones support the weight of the body, and little muscular effort is required for a human to stand erect.
The vertebral column of chimpanzees lacks an S bend. When a chimpanzee stands bipedally, its center of gravity is anterior to its hips. As a result, a chimpanzee must bend its legs and knees to place its center of gravity above its feet, and this bent-leg posture requires muscular activity.

How is the shape of the pelvis different in bipeds as compared to quadrupeds?

In bipeds, the pelvis is broad and bowl-shaped rather than box like

What are two changes in the bones of the legs related to bipedalism?

The femurs angle medially, and the knees are positioned over the ankles. In the feet, the calcaneous is prominent, the metatarsals arch, and the big toe is parallel to the other toes rather than opposable.

What are two ways that tool use could have affected brain size?

• Stimulation of portions of the brain associated with visual-motor coordination and planning

• Availability of a higher quality diet

Which three structures changed in the evolution of spoken language?

• The larynx

• The hyoid

• The ear

How is the position of the larynx different in the human throat as compared to that of the chimpanzee? What risks are associated with this change?

The human larynx is descended further into the throat.

There is an increased risk of choking.

What sounds are associated with this change?

/a/

/i/

/u/

What are the functions of Broca’s area in the human brain?

Broca's area regulates breathing patterns for speech and controls the vocalizations required for normal speech.

What are the functions of Wernicke’s area in the human brain?

Wernicke's area is involved in speech comprehension.

Define “prevalence”

The total number of cases of a disease in a particular population at a given time

Define “congenital”

A medical condition present and existing at the time of birth

What parts of the body are affected by Chiari malformations?

The skull, the foramen magnum, and the cerebellum

What are the four changes of the heart that occur in Tetralogy of Fallot? In combination, what is the effect of these changes?

• Ventricular septal defect

• Pulmonary stenosis

• Enlarged and shifted aortic valve

• Ventricular hypertrophy

  The blood carried to the body is a mixture of oxygenated and deoxygenated blood and has a lower oxygen concentration

Besides humans, in which other species has Tetralogy of Fallot been reported?

• Dogs

• Horses

• Cats

Define “hip dysplasia”

Abnormal formation of the hip joint where the acetabulum does not completely cover the head of the femur.

Suppose that Bigfoot (Sasquatch, an imaginary primate alleged to live in the Pacific Northwest) or the Yeti (an equally imaginary primate that is supposed to live in the Himalayas) was found to be real and to be derived descendant of Homo erectus. What moral responsibility would we (Homo sapiens) have to a species that was as closely related to us as a coyote is to a dog? Would we feel responsible if it was more closely related to another species of great ape?

I think this can be thought of similarly as we think of dogs or monkeys. We think of ourselves as the alpha species, and the Bigfoot/Yeti would just live out in the wild. I don't think anyone would feel responsible for feeding a wild animal unless they want it to be a pet. Essentially, this is a wild animal. I wouldn't feel responsible for feeding something that is used to taking care of themselves like I would a baby.