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Date: Thu, 7 Nov 2024 17:50:37 -0800
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Subject: Re: Possible stem cnidarian at ~600 Mya
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From: John Harshman <john.harshman@gmail.com>
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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.