Vertebrate Paleontology

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Vertebrate Paleontology
2014-02-17 13:52:44
Test 1
the last of the Agnathans, and the first of the jawed fishes (Gnathostomes)
Show Answers:

  1. Pituraspids
    • early Devonian of Australia
    • Heavy bony head shields
    • Unusual, large openings below the eye
  2. Gnathostomata
    • 1 degree upper palatoquadrate cartilage
    • 1 degree lower jaw =Meckel's cartilage
    • Supporting hyoid arch - all but placoderms
    • Separate endoskeletal pectoral and pelvic girdles and fin skeletons
  3. Fins!
    • Fins permit efficient swimming propulsion and control of position in water column
    • Paired fins allow horizontal stability
    • tail provides propulsion
    • Dorsal and anal fin skeletons supported by basals and radials
    • Horizontal semicircular canal
  4. beginning with Chondryicthyes
    • teeth erupt from dental lamina
    • nasal capsule fused to chondrocranium
    • postorbital connection between palatoquadrate and braincase
    • internal(=medial) rectus muscle inserts posteriorly in orbit
    • Superior and inferior obliques anterior in orbit
  5. characters of Ancanthodii and Osteichthyes
    • ventral cranial fissure
    • Glossophayrngeal (IX) nerve dorsal and posterior to otic capsule
    • palatobasal process
    • Interhyal
    • lateral line passing through scales
    • paired fin radials barely exit body walls
  6. jaws, the significance
    • increased adaptive pathways
    • increased diet and food handling possibilities, grasp prey firmly, cut slice or grind prey for swallowing, permit suction feeding
    • Allows animals to become predators
    • arose from major repatterning process, from improvements for water pumping, not feeding, from neural rest cells
    • jawless ancestors show a variety of stages toward evolution of jaws
    • jaws take many forms
    • jaws offer fishes and later forms a wider variety of means of feeding
  7. Gnathostomata
    jawed mouths
  8. Placodermi
    heavily armored, Silurian/Devonian - joint necked fishes
  9. Chondrichthyes
    cartilaginous fishes, modern sharks and ray ancestors
  10. Acanthodii
    late Ordovician, earliest gnathostomes "spiny sharks"
  11. Osteichthyes
    bony fishes - Actinopterygians and Sarcopterygians
  12. Placoderms
    • bony carapaces
    • cover head and anterior trunk
    • mobile
    • neck joint allows head lift
    • variable body forms
  13. Rolfosteus
    long nose from Australia
  14. Placodermi
    • 6 clades - most basal- most advanced
    • arose 420 mya
  15. acanthothoraci
    • placoderm
    • headshields=separate elements (juveniles); fused later (adults)
    • heavily ornamented
    • common in Australia
  16. Rhennanida
    • pladoderm
    • small scales ray like body
    • bottom feeder, swam with wavelike undulations
    • flattened dorsoventrally
  17. Anthiarchi
    • diverse, mid and late Devonian
    • Heavily armored
    • placoderm
    • Specialized, bottom-dwelling lifestyle
    • Swallowed mud to extract organics
    • Pectoral fins encased in bone, moveable at a complex joint
    • second joint halfway along fin
    • probably not for swimming but to cover animal in sand to bury itself to hide from predators
  18. Pterichthyodes
    • early placoderm species
    • high, domed trunk shield of large plates
    • pectoral fin encased on bone, with a complex joint
  19. Bothriolepis
    • placoderm
    • most successful antiarch
    • 100 species (middle to late Devonian)
    • worldwide distribution
    • may have had lungs and could breath air
    • slender-lightly scaled tail
    • paired pelvic fins
    • pectoral fins with jagged tooth-like edges
  20. petalicthyds
    • placoderm
    • early devonian of europe
    • bottom dwelling forms
  21. Lunaspis
    • placoderm-petalicthyd
    • short trunk shield and cornual plates
    • tiny scales around eyes and on rear of body
  22. Ptyctodonts
    • placoderm
    • reduced armor plating
    • small animals-long whip like tails
    • long dorsal spine
    • may have claspers
  23. Arthrodires
    • placoderm
    • overlapping bone plates
    • trunk and head shields
    • articulate by sliding (early) or knob and grove (later)
    • possible lateral line groves
    • many patterns of ornimentation
    • ossified braincases perichodral laminar bone (early) later, cartilaginous
    • pointed tooth like plates on edges of jaws for gripping prey
  24. Dunkleosteus
    • placoderm
    • most famous arthrodire
  25. Chondricthyes
    • cartilaginous fishes
    • ancestors of present sharks and rays
    • isolated scales and teeth in Ordovician and Silurian
    • common in Devonian
    • up to 2m in length
  26. Body features of acanthodians
    • large fin spines
    • large eyes and mouth openings
    • scales showing groth rings
  27. Climatius
    • arthrodire?
    • ovten called "spiny sharks"
  28. Psarolepis
    a "missing link" - placed at base of both sarcopterygian and actinopterygian lineages
  29. Actinopterygians
    • "ray finned" fishes
    • fins supported by slender rods or rays (-endoskeletal lepidotrichia)
    • Muscles controlling fin movements are within the body wall
    • Grades of organization of bony fishes
    • unnatural groups (old useage)
    • -Chondrostean=primitive
    • -holostean=intermediate
    • -teleost=advanced
  30. mid Devonian bony fish anatomy
    many variations on this theme
  31. Paleonisciformes
    actinopterygian (encompasses the old chondrosteans)
  32. Neopterygians
    • Actinopterygian (inclueds old Holosteans and teleosts)
    • have swim bladders to provide neutral buoyancy
    • ossified endoskeleton
    • dermal bone may also be present
    • overlapping body scales
    • two groups
    • -actinopterygians - largest group; ray-finned fishes
    • -Sarcopterygians - lobe finned fishes
  33. Paleonisciformes
    • palaeoniscoids (Cheirolepis)
    • Polypteriformes (Polypterus, common name bichir)
    • Acipenseriformes (sturgeons)
    • Paddlefishes (Polyodon)
    • others, from early Devonian in age to the present
  34. Palaeoniscids
    • earliest bony fishes
    • up to half meter long; most smaller
    • notochords with ossified neural and hemal arches
    • ganoid scales
    • active predators in marine and fresh water
    • Greatest diversity in Permian;most died out in Triassic
    • Some survived to present, Acipenser, Polypterus and paddlefish
  35. Ganoid scales
    small overlapping rhomboid shaped scales containing bone at the base, middle dentin and surfaces covered with ganoine(=enamel)
  36. Acipenser
    • sturgeon
    • caviar!
  37. Polypterus
    • bichir-african distribution has shark-like spiral valve as intestine
    • wide fins
    • large bony plates
  38. Polypterus
    • rhomboid ganoid scales
    • spiracle
    • paired swim bladders similar to ventral lungs
    • must gulp air occasionally or they will drown
    • Fleshy pectoral fins had them classified with sarcopterygians, but this is probably an independent evolution of this trait (=autapomorphy or unique derived character)
    • live in swamps and streams in Africa
  39. Polyodon
    paddlefish north american river fish Mississippi drainage
  40. Amiiformes
    amia bowfin
  41. Lepisosteiformes
    lepisosteus gars
  42. Neopterygians
    • 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
  43. Amia calva
    • bowfin-fresh water North American fish
    • Primitive neopterygian, with rhombic scales, although more flexible than palaeonsicids
    • Scale type also present in gars
  44. lepisosteus-gar
    • Teleostei
    • Advanced neopterygians (terminal bony fishes)
    • nearly 20000 living species
    • wide geographic distribution-in all watery habitats
    • appeared 225mya (late Triassic)
    • Monophyletic
    • homocercal tails
    • circular scales lacking ganoine
    • ossified vertebrae
    • swim bladders
    • Skulls with complex jaw apparatuses for greater mobility, for rapid prey capture, and food manipulation
    • many body forms-slender to deep
  45. swim bladders
    control buoyancy
    • Sarcopterygii
    • lobe-finned fishes
    • gave rise to amphibians; the first tetrapods
    • 2nd group of bony fishes
    • fins are at ends of appendages with internal bones and muscles=fleshy finned fishes
    • tetrapod limbs evolved from sarcopterygian fins
    • lungfishes have a wide variety of forms from Silurian to Devonian
    • body forms differ greatly, depending on location
    • indicates variety of evolutionary histories
  46. Why do fishes have lungs?
    • Allows intake of air from surface
    • permits animals to live in ephemeral water bodies
    • Survive by burrowing into mud and estivating until water returns
  47. lungfish teeth are unique and easily recognized fossil
    • Latimeria
    • extinct and extant coelacanths
    • similar body forms
  48. Cosmine
    same material as dentine
  49. lungfish body forms
    • diverse and successful
    • allow animals to live in less than optimal water environments
    • lungfish groups related to forms that gave rise to tetrapods
    • probably tetrapods arose as fish tried to return to good water
    • lungfish 1'2" long
    • Devonian
    • palatal tooth plates but no dermal teeth
  50. Osteolepis
    rhipidistian from Devonian with a heterocercal tail
  51. Eusthenopteron fordi
    • osteolepid
    • one meter long
    • three pointed symmetrical tail
    • labyrinthine teeth
    • fish that allowed understanding of evolution of tetrapod limb bones
    • bones in the fin and limb girdles were of the pattern seen in later evolved tetrapods
    • bones show homologies between those of fish and tetrapods