Hemichordates possibly similar to vertebrate ancestors

1
Hemichordatespossibly similar to vertebrate
ancestors
B.J. Swalla, Univ. of Washington,
http//faculty.washington.edu/bjswalla/
2
Urochordatespossibly similar to vertebrate
ancestors
B.J. Swalla, Univ. of Washington,
http//faculty.washington.edu/bjswalla/
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Cephalochordatesvertebrate ancestors - Pikaia
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Cephalochordatesvertebrate ancestors Amphioxus
(modern)
Museum of Paleontology University of California
at Berkeley http//www.ucmp.berkeley.edu/chordata/
cephalo.html Ellen Thompson, Researcher traces
gene development in 'last common link, WU-STL Tip
Sheet, http//news-info.wustl.edu/tips/2002/scienc
e-tech/vertebrate-invertebrate.html
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Conodonts (Paleozoic)1st fossil chordates not
ancestral preserved as teeth
Heterochrony in cavusgnathid conodonts are the
"Granton Animals" paedomorphic? Mark A.
PurnellUniversity of Leicester http//www.le.ac.u
k/geology/map2/abstractsetc/cavhet.html
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Ostracoderm (Ordovician)
http//www.emc.maricopa.edu/faculty/farabee/BIOBK/
BioBookPaleo4.html http//www.mysterynet.mb.ca/stu
rgeon/evolution.html
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Acanthodians (Silurian)
Palaeontological Museum,  University of Oslo,
Norway, 2001
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Acanthodians (Silurian)
http//www.alientravelguide.com/science/biology/li
fe/acanthod.htm
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Placoderms (Devonian)
http//cas.bellarmine.edu/tietjen/images/placoderm
_subphylum_vertebrata.htm