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Review cranial placodes #135
Some points to consider:
referenced this issue
May 20, 2016
Many of the features that distinguish the vertebrates from other chordates are found in the head. Prominent amongst these differences are the paired sense organs and associated cranial ganglia. Significantly, these structures are derived developmentally from the ectodermal placodes. It has therefore been proposed that the emergence of the ectodermal placodes was concomitant with and central to the evolution of the vertebrates. More recent studies, however, indicate forerunners of the ectodermal placodes can be readily identified outside the vertebrates, particularly in urochordates. Thus the evolutionary history of the ectodermal placodes is deeper and more complex than was previously appreciated with the full repertoire of vertebrate ectodermal placodes, and their derivatives, being assembled over a protracted period rather than arising collectively with the vertebrates
HOWEVER this looks like a simple terminological mismatch. I believe this paper is talking about what we would call the UBERON:0002546 ! cranial placode
There are a lot of tickets and notes attached to this class - should be visible in OntoBee
added a commit
May 21, 2016
I agree. Cranial keeps the term specific to vertebrates.
Outside of this context, developmental biologists just understand an ectodermal placode as a thickening of the ecotdermal epithelium - see tracheal placode in Drosophila. Please move the taxon restriction to cranial placode.
You may wish to consider expanding taxon constraints for cranial placodes to chordates and not verts, or having some other homologous structure:
I think the naming of some of the placodes came from work I did long ago in ZFA, they are actually fairly diverse in their coalescence/naming across species, we should revisit that.
Also, the lateral line placodes should be limited to species with lateral lines :-)