90 terms

Comparative Anatomy

Exam 1
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Comparative Anatomy
Scientific Study of anatomical, morphological, and functional changes among vertebrates
Time Scales of comparative Anatomy
Historical(Evolutionary) and Nonhistorical
Historical (Evolutionary) timeframe
Examines evolutionary events to work out the history of life when comparing characters. Phylogenies
Nonhistorical Timeframe
Looks outside an evolutionary context with no intention of concluding with a classification or explanation of an evolutionary process.
Homology
2 or more characters that share a common ancestor
Homoplasy
Features in 2 or more characters/organisms that look alike but do not necessarily have the same functions
Look alike, but may or may not have common ancestry
Analogous
Characters with similar function - may or may not have common ancestry
Wings of Birds and Arms of Moles are Ex of
Homology - share common ancestry of reptiles
Wings of Bats and Wings of Bees are EX of
Analogy - similar function, no common ancestry
Turtle and Dolphin flippers share a common origin (___) and similar function (___) and they also look alike (___)
Homology
Analogy
Homplasy
Convergent Evolution
Phylogenetically distinct groups evolve similar morphological structures due to similarities in habitats
Hippo and Alligator eyes ex of
Convergent Evolution
Serial Homology is the
Similarity between successively repeated parts in the same organism
Chain of vertebrae and Myomeres are example of
Serial Homology
Symmetry
Describes how an animal's body meets the surrounding environment
Radial Symmetry
Regular or equal arrangement of the body around a central axis
Jellyfish have ___ symmetry
Radial
Bilateral Symmetry
A body in which left and right halves are mirror images of each other, seperated by midsaggital plane
Humans and ___ symmetry
Bilateral
Natural Selection
Through evolution - Process where only the best adapted to the environment survive and transmit their genes to future generations
Darwin's theory
Developed the theory of Natural Selection by which evolution occurs
Lamarck theory
Evolution by means of inheritance of acquired characteristics.
Body builder passes on large muscles to offspring is view of
Lamarck's
Owen
Correspondence between parts(homologies - common ancestry)
Each forelimb performs different function. Nearly the same bones and patterns are present in:
Forelimb of Mole = digging
Wing of bat = flight
Flipper of Dugong = swimming
Function is how
A particular part works in an organism and how it serves adaptively in the environment
Biological Role is how
A part is used in the environment during the course of the organism's life in history
Cheek muscles in mice function and biological role
-Close jaws
-food processing
Quadrate bone in reptiles function and biological role
-attach lower jaw to the skull and transmits sound waves to the ear
-feeding (food procurement) and hearing (detection of enemies)
Preadaptation
a structure or behavior possesses the necessary form and function BEFORE the biological role arises that it eventually serves
Feathers
Preadaptation in birds
Form differs because
Function differs
Chordates
Anyanimal of the phylum Chordata having a notochord or spinal column
3 groups of Chordates
-Cephalochordates
-Urochordates
-Vertebrates(largest group)
Ex of Cephalochordates
Amphioxus or lancets
Ex of Urochordates
Tunicates or sea squirts
Ex of Vertebrates
fishes, amphibians, reptiles and mammals.
Small group - hominids/humans
Cleavage
a rapid series of cell division that follows fertilization and produces a multicellular blastula
Schizocoelom
coelom, or body cavity, that develops in Protostomes by splitting of mesoderm
Enterocoelom
coelom, or body cavity, that develops in Deuterostomes by splitting of the mesoderm
Notochord is the
Hydrostatic organ with elastic properties that resist axial compression
This prevents collapse of the body
The Notochord
Myomere
Blocks of muscle arranged sequentially along the body and tail as part of the outer body wall
Myomeres are an example of
Serial Homology
Basic Tissue Layers
-Ectoderm - Outer
-Mesoderm - Middle
-Endoderm - Inner
Protostome Characteristics
Spiral Cleavage. Mouth arises from blastopore
Deuterostome Characteristics
Radial Cleavage. Anus forms from blastopore
3 types of evidence that there was an ancient and fundamental divergence between protostomes and deuterostomes
Embryological characteristics, modern molecular phylogenies, and the fossil record
Unique Derived Characteristic in Chordates
Pharyngeal slits
Protochordate groups and habitats
-Hemichordates: marine
-Chephalochordates: warm temperate and tropical seas
-Urochordates: marine
Nucleus Polposus is
The notochord, greatly reduced, in adult mammals with a full vertebral column. It is the most derived form found in mammals.
Endostyle
The glandular groove in floor of pharynx involved in filter feeding.
Phylogenetic predecessor of thyroid
Thyroid Gland
An endocrine gland that produces two major hormones
Similarities of Thyroid gland and endostyle
They both arise embryonically from floor of pharynx.
Both involved in iodine metabolism suggesting a homology between the two
Basic body plan of annelid/arthropod and chordate comparison
All are segmented
All exhibit similarities in gross brain regionalization with forebrain and hindbrain.
Basic chordate plan is present in these groups, just upside down(probably result of homology)
What group of protochordates does the Asicidiacea belong to?
Urochordata
Characteristics of Appendiculara
tiny marine animals. Named Larvacea because they stay in larval stage. Feeding apparatus independent of pharynx with feeding filter within. Live within a matrix it constructs, a House
Centrum
A solid cylindrical body that often encloses the notochord
Cranium
a composite structure of bone or cartilage that supports the sensory organs in the head and encases the brain
Allometry
The study of a change in size or shape of one part correlated with a change in size or shape of another part
Endotherm
An animal capable of maintaining an elevated body temperature with heat produced metabollically from within
Homeothermy
the condition of maintaining constant body temperature without regard to the method
Scaling
The study of size and it's consequences. Compensatory adjustments in proportion to maintain performance with changes in size.
Fulcrum
The point of pivot or the axis of rotation
Lever Arm
The perpendicular distance from the point at which the force is applied to the point about which a body rotates
What time frame does the early evolution of vertebrates take place?
Cambrian
Agnathan Characteristics
No Jaws and no bones
Gnathan Characteristics
Jaws and bones
Which group of fishes are extinct
Placoderms
What is the significance of Sarcopterygii
Gave rise to Amphibians
Common names of 3 living genera of Sarcopterygii
Australian, South American, and African Lungfish
What is the significance of the Rhipidistians?
Transitional sarcopterygians between fishes and tetrapods (between water and land)
Characteristics of Actinopterygii
Ray-finned fishes: rays are internally supported by numerous slender endoskeletal lepidotichia. Muscles in body wall control fin movements.
What is the significance of the group Salienti?
1st appearance of the Tympanum: an anatomical character for hearing in terrestrial environment
4 Primary skull types in Amniotes:
Anapsid
Synapsid
Diapsid
Euryapsid
What group did the 1st appearance of the amniotic egg show up in?
Reptilia
Name the groups the Diapsida gave rise to:
Birds and all living reptiles except turtles
(lizards, crocodilians, dinosaurs, and birds)
Name the 2 groups that belong to the Dinosaurs
Saurischia and Ornithischia
What class outnumber all vertebrates excepts fish?
Birds
What group are birds most closely related to?
Reptiles
Why are birds so closely related to reptiles?
They both lay eggs, and they both have similar bone and muscle structures.
What are the characters that contribute to endothermy and aid in homeothermy?
High metabolic rate, energy production and enzymatic activity as well as larger internal organs relative to body size.
What is a unique derived characteristic of birds and what is the origin?
Feather rose from ossified dermal scales
What is the significance of the bones of birds?
They are hollow so they provide strength while reducing weight for easier flight
What is the significance of the Synapsida group?
Gave rise to mammals - transition from the ectothermic to the endothermic
What class was dominant during the late Carboniferous and Permian?
Synapsida
Characteristics of Therapsids
Stance was quadrupedal, feet had 5 digits. Teeth were differentiated due to specialized functions. Skull and lower jaw became more simplified
What period did the class Mammali first appear?
Triassic
What is the lower mandible of mammals called?
Dentary
What is the largest known living animal?
Blue Whale (baleen whales)
2 primary characteristics that define mammals
Hair and skin glands
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