Late Precambrian bilaterians: grades and clades.

@article{Valentine1994LatePB,
  title={Late Precambrian bilaterians: grades and clades.},
  author={James William Valentine},
  journal={Proceedings of the National Academy of Sciences of the United States of America},
  year={1994},
  volume={91 15},
  pages={
          6751-7
        }
}
  • J. W. Valentine
  • Published 19 July 1994
  • Biology, Medicine
  • Proceedings of the National Academy of Sciences of the United States of America
A broad variety of body plans and subplans appear during a period of perhaps 8 million years (my) within the Early Cambrian, an unequaled explosion of morphological novelty, the ancestral lineages represented chiefly or entirely by trace fossils. Evidence from the fossil record can be combined with that from molecular phylogenetic trees to suggest that the last common ancestor of (i) protostomes and deuterostomes was a roundish worm with a blood vascular system and (ii) of arthropods and… 
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A generally conical cutting head for an underwater dredger includes a plurality of helical cutting arms 1 having teeth 4 mounted thereon. The arms are fixed at one end to a hub 2 and at the other end
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From the combination of knowledge and actions, someone can improve their skill and ability. It will lead them to live and work much better. This is why, the students, workers, or even employers