Re: Possible stem cnidarian at ~600 Mya

On 11/7/24 5:50 PM, John Harshman wrote:

On 11/7/24 8:02 AM, erik simpson wrote:

On 11/6/24 8:52 PM, John Harshman wrote:

On 11/6/24 3:33 PM, erik simpson wrote:

 > On 11/5/24 10:06 AM, John Harshman wrote:
 >> On 11/5/24 8:48 AM, erik simpson wrote:
 >>> https://onlinelibrary.wiley.com/doi/10.1111/pala.12242
 >>>
 >>>
 >>> "Abstract
 >>>
 >>> The early Ediacaran Lantian Formation in South China contains some of the oldest known representatives of morphologically complex macroorganisms, including various macroalgae and putative animals. The macroalgal fossils have been described previously in several publications, but no taxonomic treatment has been published for the putative animal fossils. This hampers our ability to fully evaluate and communicate the significance of these potentially important Ediacaran macrofossils. To address this deficiency, here we provide a systematic description of these putative animal fossils from the Lantian Formation, including four new genera and five new species: Lantianella laevis gen. et sp. nov., L. annularis gen. et sp. nov., Piyuania cyathiformis gen. et sp. nov., Qianchuania fusiformis gen. et sp. nov. and Xiuningella rara gen. et sp. nov. Morphological comparisons of these fossils and potential modern analogues are provided and critically assessed."
 >>>
 >>> This is an article I missed (2016) that describes very-well preserved fossils in the Lantian formation.  Among other hard-to-assign specimens is a conical specimen consisting of a basal holdfast and topped with structures strongly suggesting tentacles. The resemblance to cnidarians is unmistakable.  The authorship has strong credentials in Ediacaran research.
 >>
 >> If they're metazoans, they might be the oldest metazoan fossils, though apparently they're roughly contemporaneous with the Doushantuo biota.
 > All true, they're only ~10 My after the Doushantuo.  Any further with a particular phylum identification is bound to be uncertain.
>
I belatedly remember that lophophorated also have tencacle-like structures.  If the fossils are lophophorates, that would move the origin of cnidarians comfortably forward in the Ediacaran, about the time the probable tunicates appeared. I belatedly remember that lophophorated also have tencacle-like structures.  If the fossils are lophophorates, that would move the origin of cnidarians comfortably forward in the Ediacaran, about the time the probable tunicates appeared.

>
Not familiar with any Ediacaran tunicates. What?

https://link.springer.com/article/10.1007/s12542-021-00596-1

 If correct, that pushes the origin of chordates way back, and thus of deuterostomes too. I'd like to see how the people competent to analyze these fossils sort out.

According to Mary Droser, the first clearly bilaterians, about the size of rice grans, also appeared about the same time.  I forget when the deuterstome/protostome happened.  Was it about the same time too, or later?