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dinoguy2
Joined: 22 Aug 2006
Posts: 41
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 Posted: Tue 05 Sep, 2006 2:34 pm Post subject: |
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Only due to lack of evidence. If Caudipteryx or Microraptor had been found in the early 20th century, they would certianly have been placed within Aves, and the definition would likely be anchored with them instead of or in addition to Archaeopteryx.
A better parallel would if a definition of planet had been adopted using only the standard nine planets and a qualifyer that a planets orbit must be closer to the sun than Pluto, and subsequently discovering that Xena was in fact a gas giant. Oops. |
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tmkeesey
Site Admin
Joined: 14 Aug 2006
Posts: 287
Location: Los Angeles, CA, USA
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| Posted: Tue 05 Sep, 2006 3:40 pm Post subject: |
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| Quote: | | Only due to lack of evidence. If Caudipteryx or Microraptor had been found in the early 20th century, they would certianly have been placed within Aves, and the definition would likely be anchored with them instead of or in addition to Archaeopteryx. |
But now you're playing the mind reader. I don't think this is true because even Archaeopteryx' position in Aves was never that secure. I remember books written as late as the 1980s saying that it was better to consider it a birdlike dinosaur than a dinosaurlike bird.
We can't base our nomenclature on what we think earlier systematists would have done.
| Quote: | | A better parallel would if a definition of planet had been adopted using only the standard nine planets and a qualifyer that a planets orbit must be closer to the sun than Pluto, and subsequently discovering that Xena was in fact a gas giant. Oops. |
No, because none of the definitions use geography. 
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T. Michael Keesey
Director of Technology, Exopolis, Inc. |
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tmkeesey
Site Admin
Joined: 14 Aug 2006
Posts: 287
Location: Los Angeles, CA, USA
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| Posted: Tue 05 Sep, 2006 3:55 pm Post subject: |
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Returning to an earlier point.
| Quote: | | Well, not entirely new. If the apomorphy-defined 'Linnean' groups (sans ranks, naturally, when used in a phylogeny) are reduntant with the new ones, use those. Chordata would have priority over New-name-ata so long as the content of the apo-clade matches that of the node-based clade (as currently done when you have two node- and stem-based clades which, at the moment, describe the same content). |
You couldn't ever prove that a node-based name and an apomorphy-based name are synonyms unless you had an amazingly complete genealogy. Ditto for node- vs. branch-based and branch- vs apomorphy-based. It's possible in theory, but, in the vast majority of circumstances, practically impossible to prove.
Thus the practice of treating names with different types of definitions as synonyms if they circumscribe the same known content is invalid. See Note 14.1.2 (which does provide one interesting example where a branch-based name might be synonymous with an apomorphy-based name).
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T. Michael Keesey
Director of Technology, Exopolis, Inc. |
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