slide1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Origin of Vertebrates PowerPoint Presentation
Download Presentation
Origin of Vertebrates

Loading in 2 Seconds...

play fullscreen
1 / 26

Origin of Vertebrates - PowerPoint PPT Presentation


  • 57 Views
  • Uploaded on

Origin of Vertebrates. 14 September 2012. Devonian Sea Karen Carr Studio, Inc. Vertebrates – What are they?. Two major characteristics Vertebrae — bony (or cartilaginous) structures that usually surround the notochord and …

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Origin of Vertebrates' - angelo


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Origin of Vertebrates

14 September 2012

Devonian Sea

Karen Carr Studio, Inc.

vertebrates what are they
Vertebrates – What are they?
  • Two major characteristics
    • Vertebrae— bony (or cartilaginous) structures that usually surround the notochord and …
    • Cranium— bony (or cartilaginous) structure that encases brain and …
      • Cephalization – anterior clustering of …
      • Anterior neural tube enlarged into…
vertebrae
Vertebrae

Fig. 3.2

vertebrates what are they1
Vertebrates – What are they?
  • Neural crest cellsand epidermal placodes
    • Embryonic, transient, do not fossilize
    • Give rise to some sensory organs of the cranium (lens, olfactory mucosa, inner ear) and distinctive teeth

Fig. 5.28

origin of vertebrates
Origin of Vertebrates
  • Three evolutionary steps most likely
  • Prevertebrates
    • Hemichordata, Cephalochordata, Urochordata
    • Key features:
  • Agnathans (“agnathostomes”)
    • “without jaw mouth”
    • Key features:
  • Gnathostomes
    • “jaw mouth”
    • Key features:
origin of vertebrates1
Origin of Vertebrates

Read pp. 84-86

Fig. 3.3

slide7

Lampreys

Hagfishes

Fig. 3.4

hagfishes
Hagfishes
  • Single median nostril
  • No paired fins or …
  • Partial cranium, but no …
  • Scavengers; rasps on tongue
  • Very few fossils
  • 1991 Myxinikelasiroka found
    • ~300 million years ago
    • Little change in hagfish since
lampreys
Lampreys
  • Like hagfish, lamprey:
    • Have a single median nostril
    • Have no paired fins or bone
    • Have a limited fossil record
  • Unlike hagfish, lamprey:
    • Have true …
    • Display a complete braincase (cartilaginous)
    • Go through a larval stage (“ammocoetes”)
      • Larvae are passive feeders; trap food in mucus
    • Latent ability to produce …
extinct agnathans conodonts
Extinct Agnathans - Conodonts
  • Have characteristics of chordates:
    • Notochord
    • Dorsal nerve cord
    • Postanal tail
    • Pharyngeal slits (from impression)
  • Conodontelements show evidence of tissue that is derived from …
  • BUT!
    • No lower jaw (still Agnathans)
    • Specialized feeding apparatus
conodonts
Conodonts

Project and impale!

Slice and crush!

Fig. 3.7

conodonts1
Conodonts
  • Where do they fit?

M.A. Purnell and P.C.J. Donoghue (1997) Architecture and functional morphology of the skeletal apparatus of ozarkodinidconodonts. Phil. Trans. R. Soc. Lond. B, 352: 1545-1564

extinct agnathans ostracoderms
Extinct Agnathans - Ostracoderms
  • Mostly small …
  • Absent or small …
  • Bony dermal armor
  • Cartilaginous skeleton

Pteraspidomorphs – no paired fins, paired nasal openings

“Other ostracoderms”– some with (non-homologous) paired fins, most single nasal opening

gnathostomes
Gnathostomes
  • Jawed fishes
  • Paired pectoral and …
  • New Food-Gathering Technique: …
    • Placoderms (Plate-skinned fish)
    • Chondricthyes(Cartilaginous fish)
      • Elasmobranchii (Sharks and Rays)
      • Holocephali (Chimaeras)
    • Acanthodii (“Spiny Forms”)
    • Teleostsor “Osteichthyes” (Bony fish)
      • Sarcopterygii (lobe-finned fishes)
      • Actinopterygii (ray-finned fishes)
osteichthyes
Osteichthyes
  • Most living vertebrates

Fig. 3.15

actinopterygii
Actinopterygii
  • Ray-finned fishes
  • Most diverse vertebrates – ~20,000 species!
sarcopterygii
Sarcopterygii
  • Fleshy-finned fishes
  • Actinistia (Coelacanths) – 2 species?
  • Dipnoi (Lungfishes) - ~6 species
  • “Rhipidistians” –

Eusthenopteron

Lungfish

Panderichthys

Coelacanth

“Rhipidistians”

what s the difference
What’s the difference?

Actinopterygian

Sarcopterygian

sarcopterygian fins
Sarcopterygian Fins

Eusthenopteron

Panderichthys

Tiktaalik

Acanthostega

H= humerus; Int = intermedium; R = radius; U = ulna; Ure = ulnare.

Scale bar, 1 cm

tetrapods
Tetrapods

Fig. 3.21

early tetrapods
Early Tetrapods
  • Acanthostega – mostly aquatic
    • Internal gills; tail; girdles
  • Ichthyostega – more terrestrial
    • More robust limbs and girdles; tail

Ichthyostega

Acanthostega

the move to land
The Move to Land
  • What challenges did early tetrapods face during the transition to land?
    • Or, what things would have to change morphologically, and why?