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The study of body structure.
Study of similarities and differences among groups.
Combining knowledge of structure with function.
Anatomy is primitively essential why?
Because animals are a food source.
Medical purposes of anatomy
-Trepanation vented increased cranial pressures and some surgical subjects survived because in some cases several different degrees of healing were observed on a single skull.
in the 5th century, described human blood vessel plan.
In the 4th century, created the earliest comparative animal anatomy studies and established taxonomy based on morphology.
Organisms move up ladder to perfection.
3rd century physician, named sigmoid and tricuspid heart balves, and related heart as an organ to blood flow.
T. H. Huxley
- "Darwin's Champion"
- Supported Darwin to popularize evolution.
a concept of Sir Richard Owen. The underlying patterns in the vertebrate body were a repeating series of vertebral units.
Sir Richard Owen
- Anatomist who first descriped Archaeopteryx lithographica and invented the name "Dinosauria"
- Studied many extinct species as well as living ones.
- Difficult to interact with on a personal level.
- Tried to take credit for finding Iguanaton from Gideon Mantell.
Created the modern system of binomial names.
Founded the Museum of Comparative Zoology at Harvard.
Two main different body plans for animals
Radiata and Bilateria
Animals showing radial symmetry, such as echinoderms.
Animals showing bilateral symmetry, with two sides to the body form that were mirror images of each other.
One theory of chordate origins
Echinoderms -> Hemichordates -> Prechordate -> Urochordates -> Cephalochordates -> Vertebrates
- Subphylum Urochordata
- Subphylum Cephalochordata
- Subphylum Vertebrata
- -Superclass Vertebrata
- -Class Myxini, hagfishes
- -Class Petromyzoniformes, lampreys
- -Class Conodonta
- Five main characters:
- -Pharyngeal slits
- -Hollow, dorsal nerve cord
- -Postanal tail
- -Endostyle or thyroid
- Include Hemichordates
- -Acorn worms contain some chordate characters.
Vertebrate Evolutionary innovations
Vertebral column, intervertebral disks, notochord, neural arch, hemal arch.
Separate bones or cartilage blocks that devine body's major axis.
Thin compression pads separating the bones of the vertebral column.
Enclosed by the solid body (centrum) of the vertebral column.
Encloses spinal cord dorsally.
Encloses blood vessels ventrally.
Neural and hemal spines.
- Another vertebrate innovation.
- Contains special sense organs.
- Anterior end of spinal cord enlarged to form brain.
Source of many head structures; these cells found only in vertebrates.
Vertebrate origins in marine waters
- Prevertebrate conditions
- Cilia Pump
- Cartilate replaced pharyngeal bar collage.
- Muscle contraction squeezed water from pharyngeal slits.
- At relaxation, cartilage spring action restored shape and took in new water.
- Initially assisted ciliary pump in moving water through pharynx.
- Increased body mass made muscular pump necessary.
- Muscular pump allowed greater body size.
suspension feeders common among Hemichordates, Urochordates and Cephalochordates.
- Similar to that in prevertebrates.
- Able to tolerate estuary conditions.
- Pharynx acquired encircling band of muscle.
- Jawless fish
- Deposit feeders on suspended particles.
- Pharyngeal muscular pump mechanism present.
- Extensive radiation.
- Evolved as a result of expanded pharyngeal pump.
- Lack bone.
- Single nostril.
Show five main characters of chordata as well as vertebral columns and heads were specialized sensory organs are located.
- First jaws
- Allowed ingestion of larger particles.
- Grasping single objects became possible.
- Became predators.
- Could eat wary food or that which was difficult to capture.
- Could capture faster moving food items.
- Jaws allowed increased force to be applied to food capture.
- Active predation became a viable lifestyle.
- 544-400 mybp
- Echinoderm like skeletons.
- Resembled flattened crinoids.
- Probably related to echinoderms.
- Cambrian to Triassic
- Laterally compressed, slender.
- Soft-bodied vertebrates identified in 1980's.
- Contain conodont elements, tooth-like microfossils.
- V-shaped myomeres.
- Caudal fin rays.
- Post-anal tails.
- Possible dorsal verve cord.
- Vertebrate tissues, neural crest cells present.
Allow age correlation of different strata.
- Jawless forms
- Lack biting apparatus derived from branchial arches.
- Appeared in Late Cambrian.
- Greatest radiation in Silurian and early Devonian.
- First vertebrates to have bone in their exoskeletons.
- Extinct jawless fishes.
- Late Cambrian, radiated in Silurian and early Devonian.
- Bony exoskeletons and dentin-like tissues.
- Small size, complex eye muscles.
- Bony head plates fused as a solid head shield (exoskeleton).
- Long spines and fins.
- Paired fins present.
- Lateral lines.
- Two semicircular canals.
Ostracoderms (Late Ordovician - Late Devonian)
- Single nasal opening, often merged with hypophyseal opening to form a keyhold-shaped nasohypophyseal opening.
- Small scales cover posterior of body.
[(=all agnathans; Ostracoderms, Pteraspidiomorpha=Diplorhina; Cephalaspidiomorpha=Monorhina) NOT a monophyletic group] and early gnathostomes
- Slime hag (Bdellostoma)
- Hagfish (Myxine)
- Lamprey (Petromyzon)
- lack bone
- single nostril
- round mouths
- -hagfish and lampreys
- Deep sea, mud burrowing animals.
- Scavengers with rasping tongues with cornified "teeth" to remove flesh from prey or to help in swallowing prey.
- Eel shaped.
- They secret mucus from skin glands that makes them slippery and gives them the name "slime hag"
- They possess both ovaries and testes, but only one set is functional.
Early vertebrate - early Cambrian, Agnathan Little spcialization of head structure excludes this animal from being a craniate.
Early vertebrate - from early Cambrian, also not a craniate but an agnathan.
- Two sets of paired fins:
- Fins anchored to body wall by pectoral and pelvic girdles.
- Specialized muscles controlled fin movements.
- Fins give stability and movement control of swimming maneuvers.
- Girdles could be cartilaginous or bony.
Two major lineages ofGnathostomes
- Condrichthyes (cartilaginous fishes)
- -sharks, skates and rays.
- Teleosteomi (bony fishes)
- -the most diverse vertebrate group.
- -Tetrapods emerge from this group.
- Appeared in early Silurian.
- Most common in Devonian.
- "Plate skin" bony armor, large
- Often had bony armor, small tails with head shields of fused bony plates.
- All had jaws and paired pectoral and pelvic fins.
- Notochords often also had paired neural and hemal arches.
- No centrum, but arches often fused into "synarcual"
- Able to raise heads independent of vertebral column.
- As long as several meters.
- Often flattened body forms=bottom dwellers.
- Scavengers, probably benthic.
- Lighter armored forms-active predators (Dunkleosteus)Both fresh and salt water forms.
- Wide Devonian radiation.
- Replaced ecologically by Chondrichthyes and Osteichthyes that are not closely related to them in Carboniferous.
- No living descendants.
- Rhenanids-flattened, bottom dwellers.
- Antiarchs and arthrodires, active predatory pelagic forms.
- Arthrodires-2/3 of the group - joint-necked fishes because of how the head shields were joined to the posterior body.
- Chimera-like males may have had claspers.
- Placoderms may be unnatural group.
double bone layer with superficial dentin and enamel. (Sarcopterygians)
Thick enamel (=ganoin) - no underlying dentin layer. Double dermal bone base layer. Shiny, overlapping, interlocking scales. Occur in Polypterus and gars.
Retain only lamellar bone - grown in annual rings.
- Modern cartilaginous fishes
- Elasmobranchii and Holocephali
- Share common characters:
- -Cartilaginous skeletons
- -Pelvic claspers in males
- -Primitive members show similar patterns of serial tooth replacement.
- -Placoid scales
- Pointed or cone shaped
- Show no signs of growth
- Ordovician 1st appearance
- Radiated in Devonian (Age of Fishes)
Agnathans to Chondrichthyes
- Earliest Agnathans had bone loss in Chondrichthyes must be secondary.
- Teeth and placoid scales may show bone traces.
- Thin bone veneer on vertebrae.
- Large livers provide buoyancy.
- Small numbers of young born alive or from eggs in leathery cases.
- Cartilaginous vertebrae, not notochord.
- First gill slit reduced to a spiracle.
Symmetrical tail exerts equal forces - drives body forward - keeps fish level in water.
Asymmetrical tail lobes generate lift in fishes lacking swim bladders.
- "spiny sharks"
- ?Late Ordovician - early Silurian origin, radiated in Devonian - lasted into Permian.
- Rows of spines along dorsal and ventral body midline; others defined fin leading edges.
- Ossified neural and hemal arches surrounding a notochord.
- Heterocercal tails with longer upper lobe.
- Body armor reduced to small scales on body but persisted on heads but no head shields.
- Large eyes and short snouts, no tooth enamel.
- Active predators.
- Between cartilaginous and bony fishes with charactes of both groups.
- Had hyoids, ossified gill covers and gill flaps (=branchiostegal rays) as do bony fishes.
- Bony fish - most common living vertebrates.
- Scales first appeared in late Silurian.
- Highly ossified internal bony skeletons as well as external bone present.
- Swim bladders provide neutral buoyancy.
- Ossified endoskeletons.
- Some also have dermal bone.
- Overlapping body scales.
- Fins supported by lepidotrichia - slender rods or fins "rays"
Two groups of Osteichthyes
- Actinopterygians - largest; ray finned fishes
- Sarcopterygians - lobe-finned fishes
- "ray-finned" fishes
- Fins supported by rays (endoskeletal lepidotrichia)
- Muscles controlling fin movements in body walls.
- Grades of organization of bony fishes:
- Unnatural groups
- Present classification uses two groups only:
- Paleonisciformes (old chondrosteans) and Neopterygians (old Holosteans and teleosts)
- Earliest bony fishes.
- UP to half meter long; most smaller.
- Had notochords with ossified neural and hemal arches.
- Ganoid scales - Small overlapping rhomboid-shaped scales containing bone at the base, middle dentin and surfaces covered with ganoine (enamel-like).
- Active predators in marine and fresh water.
- Greatest diversity in Permian; most died out in Triassic.
- Some survived to present, Acipenser and Polypterus and paddlefish.
sturgeon, used as a sorce of caviar
- bichir - African distribution - has shark-like spiral valve as intestine.
- Rhomboid ganoid scales.
- Paired swim bladders ~ venteral lungs.
- Gulp air occasionally or they drown.
- Fleshy pectoral fins caused classification with sarcopterygians, but probably are an independent evolution of this trait (=autapomorphy or unique derived character)
- Live in swamps and streams in Africa.
- Replaced palaeoniscids in Triassic as dominant group to present.
- Live in all Habitats
- Jaw modifications allowed for greater mobility and different feeding habits.
- Scales became more rounded and thinner.
- More active swimmers.
- Notochords replaced by a series of vertebrae.
- Symmetrical homocercal tails.
- freshwater N Am. fish.
- Primitive Neopterygian, with rhombic scales, although more flexible than palaeoniscids.
- Scale type also present in gars.
- Advanced Neopterygians (terminal bony fishes)
- ~20,000 living species.
- Wide geographic distribution; live in all water habitats.
- Appeared 225 mybp (late Triassic)
- Homocercal tails.
- Circular scales lacking ganoine.
- Ossified vertebrae.
- Swim bladders-control buoyancy.
- Skulls with complex jaws.
- Apparatuses for greater mobility for rapid prey capture and food manipulation.
- Many body forms from slender to deep.
- bony fishes
- Fins at ends of appendages with internal bones and muscles=fleshy finned fishes.
- Gave rise to first terrestrial vertebrates.
- Tetrapods limbs evolved from sarcopterygian fins.
- lung fish 1'2" long
- Palatal tooth plates but no dermal teeth.
rhipidistian from Devonian with a heterocercal tail.
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